HSE Health & Safety

Executive

Measurement and modelling of combustion products from flueless gas appliances

Prepared by BRE Environment for the Health and Safety Executive 2004

RESEARCH REPORT 127

HSE Health & Safety

Executive

Measurement and modelling of combustion products from flueless gas appliances

Stuart Upton, Dr David Ross and Bridget Pierce BRE

Environment Division Bucknalls Lane

Garston Watford

WD25 9XX

Concentrations of combustion products emitted from a range of flueless gas appliances have been measured in a chamber capable of being ventilated in a controlled and reproducible manner, including “worst case” simulations that would be experienced in extremely air-tight rooms. This enabled subsequent prediction of the likely concentration of combustion products for a range of ventilation provisions, room sizes and potential uses of the flueless gas appliances. In the absence of UK indoor air quality guidelines, the concentrations of combustion products emitted have been compared with the World Health Organisation (WHO) guidelines and HSE Occupational Exposure Standards (OES). When ventilation in the chamber was through purpose-provided open­area ventilation (as specified by the appliance manufacturer or BS 5440-2: 2000), levels of all combustion products were elevated, with carbon dioxide (CO2) in particular reaching concentrations much higher than the HSE OES value. Even when mechanically provided with higher and more typical levels of ventilation, concentrations of CO2 in the chamber higher than the value set for the HSE Occupational Exposure Standard (OES) were measured.

Modelling using the BREEZE program showed that the concentration levels set for the HSE Short-Term Exposure Limits for CO2 and carbon monoxide (CO) will rarely be exceeded within typical UK dwellings. However, those for the HSE eight-hour OES for CO2, and the WHO guideline concentrations for CO are much more likely to be exceeded in situations where there is prolonged use of a flueless appliance. For nitrogen dioxide (NO2), it is very unlikely that the HSE limits will be exceeded in dwellings, but the WHO guideline concentrations will be commonly exceeded.

The current guidance given within BS 5440:2 is for the installation of purpose-provided open-area ventilation of at least 100 cm2 in rooms where flueless heating appliances may be fitted. The build up of pollutants to concentrations in excess of the recognised HSE and WHO guidelines was not prevented by the purpose-provided ventilation currently required within BS 5440-2. This could be exacerbated as dwellings are made more airtight to meet the increasingly strict requirements of the Building Regulations, unless other ventilation provisions in homes (windows, fans, passive stacks etc.), as required under the Building Regulations are also used in practice.

This report and the work it describes were funded by the Department of Trade and Industry (DTI) and the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect DTI or HSE policy.

HSE BOOKS

© Crown copyright 2003

First published 2003

ISBN 0 7176 2704 7

All rights reserved. No part of this publication may bereproduced, stored in a retrieval system, or transmitted inany form or by any means (electronic, mechanical,photocopying, recording or otherwise) without the priorwritten permission of the copyright owner.

Applications for reproduction should be made in writing to:Licensing Division, Her Majesty's Stationery Office, St Clements House, 2-16 Colegate, Norwich NR3 1BQ or by e-mail to hmsolicensing@cabinet-office.x.gsi.gov.uk

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FOREWORD BY DTI/HSE

The use of flueless gas appliances, for domestic cooking and heating purposes, has been widespread over many years, and continues to be so. Such appliances are usually covered by specific product or installation standards, and all new appliances are subject to certification by an independent Notified Body against compliance with the essential safety requirements of the Gas Appliances Directive (enacted by the Gas Appliances (Safety) Regulations 1995 (GASR)). The Certification process includes an assessment of the manufacturer’s installation instructions, and the appliances are currently being installed to these instructions and British Standards installation specifications. However, questions have arisen over the possible health risks from the combustion products emitted by such appliances in normal operation. In order to start to assess any possible risks posed by flueless gas appliances, information was required on the type and concentrations of the emission products. The Department of Trade and Industry (DTI) and HSE, therefore, agreed to co-sponsor the work of BRE, reported here. It should be noted that the appliances were chosen at random as representative of their type, and the work should not be construed as a report on individual manufacturers’ appliances.

The DTI have responsibility for ensuring only safe products may be placed on the market, in this instance under the GASR, while HSE has responsibility for appliance installation requirements under the Gas Safety (Installation and Use) Regulations 1998. Therefore, the question of the suitability of the use of flueless gas appliances is a matter of joint responsibility. To this end, DTI/HSE have also been assessing information obtained in a previous study*1, carried out by Advantica Technologies Ltd for HSE. This and the present (BRE) work has been carried out against a background of proposed changes to HSE occupational exposure standards for certain combustion products and an increasing awareness of indoor air quality issues. Currently, there are no UK published standards for domestic indoor air quality, but guidelines are being considered by the Department of Health (DoH) and its advisory committees.

In the absence of published information, advice was requested from the DoH Advisory Committee on Medical Effects of Air Pollutants (COMEAP), as to “acceptable” indoor air levels for the pollutants emitted from the flueless gas fires examined in the previous study. The Advisory Committee have recommended comparing the level of pollutants with guidelines and standards published by the World Health Organisation (WHO)*2 and the Expert Panel on Air Quality Standards (EPAQS)*3, 4. The report references the WHO guidelines*5, but comparison is also made with HSE occupational exposure standards where no WHO guideline is published. It is important to stress that, while pointing to a possible health effect, the raw comparisons provide no indication of risk level or significance.

It should be noted that some manufacturers dispute the validity of the previous study, pointing out that they represent a “worst case scenario” that would seldom, if ever, be encountered in practice. Similar arguments may be directed to parts of this study, which as the report acknowledges, includes some experiments simulating emissions from appliances into extremely airtight rooms and appliances operating in “fault” modes.

However, the basic rationale for this approach is to provide sufficient information to subsequently enable likely concentrations of combustion products to be predicted for a

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wide range of ventilation provision, room size and potential use of the gas appliances. Such predictions can only be based on work where all the parameters can be controlled, e.g. in a test chamber as used in this case. This report contains examples of predictions covering those appliances with the worst and typical emission rates for the main combustion products studied. Care should be taken in interpreting these predictions and applying them to the other appliances, as the operating period on which a particular prediction is based may not be representative of the normal period of use of those other appliances.

While acknowledging the limitations of this laboratory study, DTI/HSE are publishingthis report in the public interest, as a contribution to the wider discussion on product and installation standards for flueless gas appliances. As part of this debate, DTI/HSE are working closely with relevant bodies e.g. the British Standards Institution (BSI), to ensure that the implications of this work are explored in developing future standards and guidelines for flueless gas appliances.

*1 Hill RW and Marks S, Flueless gas fires – concentration of carbon monoxide, carbon dioxide and nitrogen dioxide, and particulate level produced in use, HSE RR 23/2004.

*2 World Health Organisation. Air Quality Guidelines for Europe. Second Edition. WHO Regional Publication, European Series, No 91. Copenhagen: WHO Regional Office for Europe, 2000.

*3 Department of the Environment. Expert Panel on Air Quality Standards. Carbon Monoxide. London: HMSO, 1994.

*4 Department of the Environment. Expert Panel on Air Quality Standards. NitrogenDioxide. London: HMSO, 1996.

*5 World Health Organisation . (1999). Air Quality Guidelines. WHO, Geneva. From www.WHO.int.org. [The guideline levels from this reference: CO 8-hour mean of 9 ppm and NO2 1-hour mean of 105 ppb; are slightly different from those quoted byCOMEAP from reference *2: CO 8-hour mean of 10 ppm and NO2 1-hour mean of 100 ppb. The differences arise from the conversion of the guideline values, which are quoted in microgramme/m3 to ppb at standard temperatures of either 20oC or 25oC.]

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EXECUTIVE SUMMARY

This is a report on measurements and modelling of the combustion products emitted from flueless gas appliances. Measurements were made using a range of such appliances, at varying firing rates, in a controlled chamber, including “worst case” simulations that would be experienced in extremely air-tight rooms. Ventilation in the chamber was either in the form of purpose-provided vents in the chamber walls, or at controlled air exchange rates via a mechanical ventilation system. This enabled subsequent prediction of the likely concentration of combustion products for a range of ventilation provisions, room sizes and potential uses of the flueless gas appliances. Concentrations of carbon dioxide (CO2), carbon monoxide (CO), nitrogen dioxide (NO2), nitric oxide (NO) and oxygen were monitored, together with ultrafine particles, aldehydes and fuel usage.

In the absence of UK indoor air quality guidelines, the concentrations of combustion products emitted have been compared with the World Health Organisation (WHO) guidelines and HSE Occupational Exposure Standards (OES). When ventilation in the chamber was through purpose provided open-area ventilation (as specified by the appliance manufacturer or BS 5440-2: 2000), levels of all combustion products were elevated, with carbon dioxide (CO2) in particular reaching concentrations much higher than the HSE OES value. Even when mechanically provided with higher and more typical levels of ventilation, concentrations of CO2 in the chamber higher than the value set for the HSE Occupational Exposure Standard (OES) were measured.

Catalytic converters fitted within some of the appliances reduced emissions of CO, through conversion to CO2. However, these catalysts only worked well at the higher burn rates where outlet gas stream temperatures were also high. Higher concentrations of CO than the specified HSE 8-hour OES concentration were produced from the pilot light of one of the appliances tested. This was a result of both an incorrect setting of the pilot light gas pressure (as supplied to BRE) and the poorly designed position of the pilot light relative to the decorative logs that formed part of the appliance tested.

Elevated concentrations of nitrogen oxides (NOx) were emitted into the room by these appliances, with the WHO 1-hour mean guideline concentration of 105 ppb for NO2 being exceeded in most of the tests conducted.

The WHO 30-minute guideline concentration of 100 Pg m-3 for formaldehyde was exceeded in a small number of the tests. Acetaldehyde emissions were low.

The number concentration of ultrafine particles within the chamber was always raised during tests, with most tests showing a marked increase in the number of particles from background concentrations of around 10,000 particles cm-3 of air to in excess of 500,000 particles cm-3. Higher concentrations of ultrafine particles in the chamber coincided with higher burn-rate tests and tests with lower ventilation rates. Still higher rates were recorded during the burn-in tests on new appliances. There are currently no health standards in place for exposure to ultrafine particles.

BREEZE modelling was conducted to predict the likely resulting concentrations of pollutants within typical UK dwellings. It showed that the HSE STEL for CO2 and CO will rarely be exceeded. However, the HSE eight-hour OES for CO2, and the WHO guidelines for CO are much more likely to be exceeded in situations where there is prolonged use of a flueless

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appliance. For NO2, it is very unlikely that the HSE limits will be exceeded in dwellings, but the WHO guideline concentrations will be commonly exceeded.

The current guidance given within BS 5440:2 is for purpose-provided open-area ventilation of at least 100 cm2 to be installed in rooms where flueless heating appliances may be fitted. The build up of pollutants to concentrations in excess of the recognised HSE OES and WHO guidelines was not prevented by the purpose-provided ventilation currently required within BS 5440-2. This could be exacerbated as dwellings are made more airtight to meet the increasingly strict requirements of the Building Regulations, unless other ventilation provisions in homes (windows, fans, passive stacks etc.), as required under the Building Regulations are also used in practice.

This work was jointly funded by the Health and Safety Executive (HSE) and the Department for Trade and Industry (DTI), but the opinions and conclusions expressed in this report are those of the authors alone and do not necessarily reflect HSE or DTI policy.

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CONTENTS

1. INTRODUCTION 1

2. TEST CHAMBER, APPLIANCES AND EMISSION MONITORING 3 2.1 TEST CHAMBER 3 2.2 APPLIANCES TESTED 4 2.3 MEASUREMENT EQUIPMENT 5 2.4 TEST METHODOLOGY 7

3. STANDARDS FOR POLLUTANTS AND EXPOSURES 9 3.1 INORGANIC GASEOUS POLLUTANTS 9 3.2 ULTRAFINE PARTICLES 9 3.3 ALDEHYDES 9

4. RESULTS - CLOSED STOVE 11 4.1 STANDARD TESTS 11 4.2 TESTS WITH CATALYST REMOVED 11 4.3 TESTS AFTER SERVICING 12 4.4 TESTS WITH PILOT LIGHT ONLY 12

5. RESULTS - DECORATIVE FIRE 15 5.1 STANDARD TESTS 15 5.2 TESTS WITH CATALYST REMOVED 15 5.3 INITIAL “BURN-IN” TEST 16

6. RESULTS - LPG CABINET HEATER 17

7. RESULTS – INSTANT WATER HEATER 19 7.1 AFTER 5 MINUTES RUNNING 19 7.2 AFTER 30 MINUTES RUNNING 19

8. RESULTS – GAS COOKER 21 8.1 OVEN 21 8.2 GRILL 21 8.3 HOBS ALONE 22 8.4 HOBS WITH PANS OF WATER 22

9. RESULTS OF ALDEHYDE MEASUREMENTS 25 9.1 GENERAL 25 9.2 CLOSED STOVE 25 9.3 DECORATIVE FIRE 26 9.4 CABINET HEATER 26 9.5 INSTANT WATER HEATER 26 9.6 COOKER 26

10. EFFECT OF VENTILATION PROVISION 29

11. BREEZE MODELLING 31 11.1 INTRODUCTION 31 11.2 EMISSION RATES 31 11.3 BREEZE COMPUTER CODE 32 11.4 BREEZE MODEL OF FLUELESS APPLIANCE OPERATION 32

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11.5 BREEZE RESULTS 33 11.6 COMPARISON WITH AIR QUALITY STANDARDS AND GUIDELINES 35

12. CONCLUSIONS 37

13. ACKNOWLEDGEMENTS 39

14. REFERENCES 41

15. TABLES 43

16. FIGURES 66

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1. INTRODUCTION

There is a long history in the UK of the use of many types of flueless gas appliances, including cookers, instantaneous water heaters, fires and LPG cabinet heaters. BRE analysis of data from the English House Condition Survey (1991) indicated that portable heaters were used in about 5% of homes, representing about 1 million households. These heaters were typically fuelled by bottled gas (normally butane) or paraffin, the former being the most common. However, recently introduced to the UK is a wide range of fixed flueless gas space heaters that are likely to be attractive as a low cost heating option. There are lower costs associated with these appliances arising from the lack of installation of a flue to conduct the gases produced from combustion to the outside of the building, where they could then disperse into the atmosphere. They are also claimed to have lower running costs, with manufacturers stating a gain in energy efficiency, describing them as “100% efficient as no heat is lost up the chimney”.

Questions have been raised about the potential for combustion products from these “innovative” appliances to present a health risk within the dwellings in which they are operating. This has also re-awakened interest in the pollutants emitted from all types of indoor flueless gas appliances.

Within the current guidance on ventilation provision for this type of appliance (BS 5440-2) a certain amount of purpose provided open-area ventilation is specified for rooms likely to house them. The recommendation within Part L1 of the Building Regulations (2002), that unwanted air leakage in buildings should be reduced, should result in new properties having significantly less background ventilation as they are built more airtight.

In January 2002, the Health and Safety Executive (HSE) and the Department of Trade and Industry (DTI) commissioned BRE to investigate the concentrations of combustion products likely to result within rooms from a range of flueless gas appliances including:

x a closed stove; x a decorative fire; x a cabinet heater; x an instantaneous water heater; and x a cooker.

To investigate the pollutant concentration, full-scale measurements were carried out in a controlled chamber and a numerical model (BREEZE simulations) representing a typical house was used to predict the effect of altering various parameters. Parameters investigated in the model included:

x pollutant emission rate; x house airtightness; x additional ventilation provision; x internal doors in the house open/closed; x winter and autumn/spring temperature differences between the indoor and outdoor air;

andx effects of wind direction.

In the absence of UK indoor air quality guidelines, the concentrations of combustion products emitted have been compared with the World Health Organisation (WHO) guidelines and HSE Occupational Exposure Standards (OES).

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2. TEST CHAMBER, APPLIANCES AND EMISSION MONITORING

2.1 TEST CHAMBER

2.1.1 Construction

The test chamber was constructed within an existing building, using stainless steel sheeting, with all of the joints between panels being taped and sealed to prevent air leakage. The chamber had a volume of 48 m3. This ensured that it was in excess of the minimum room volume specified within BS 5440-2 for the installation of this type of appliance (40 m3). The dimensions of the test chamber were:

x length = 5 m; x width = 4 m; and x height = 2.4 m.

Figure 1 shows two of the appliances within the test chamber, prior to testing.

2.1.2 Ventilation

Fresh air from outside of the building was mechanically supplied to the building housing the test chamber. This ensured that the whole area was properly supplied with “fresh” air from outside and any combustion products escaping from the vents in the chamber were quickly ventilated away.

Two methods of providing ventilation within the chamber were used, purpose-provided open­area and mechanical ventilation. The first method used was to provide the specified open-area ventilation by simply cutting a hole in the walls of the chamber. Installation of purpose­provided open-area ventilation is all that is normally specified with the instructions supplied with the appliances so that they meet the requirements of BS 5440–2. Normally the amount of purpose-provided open-area ventilation that is specified for a room of this size is 100 cm2, although for one of the appliances tested here, only 50 cm2 was specified by the manufacturer. Accordingly, open-area ventilation of either 50 or 100 cm2 was provided in the test chamber, in line with the manufacturer’s recommendations for the specific appliance under test.

With little or no leakage out of the chamber in the purpose-provided open-area ventilated experiments, it may well be that the vents installed will be ineffective, as the air has no pathways through which to flow out. Also, as the test chamber was housed within another building, the vents would experience lower temperature differences than might be expected to occur between the chamber and outdoors. They would also not be subject to wind-driven pressure effects. As such, these are “worst case” experiments which would only simulate emissions from appliances into extremely airtight rooms.

The second method of ventilation used in the chamber was a controlled mechanical system. Variable speed fans were installed into supply and extract ducting fitted to the chamber so that the air-exchange rate could be set to any desired value. Typically, fixed air change rates of either 0.5 or 1 air changes per hour (ach) were used in the tests with mechanical ventilation. All of the supply air to the chamber was drawn from outside the building. The air extracted from the chamber containing the combustion products was discharged to a different location outside. Air change rates in the chamber were verified by measuring the volume flow rates of air into and

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out of the chamber at the inlet and outlet grilles, using a Flow Finder model 153 balanced volume flow meter. The inlet air supply grille to the chamber can be seen in Figure 1.

During experiments with the purpose-provided open-area ventilation, the mechanical ventilation system fans were turned off and the grilles within the chamber were sealed over. Similarly, in the mechanically ventilated tests, any purpose-provided open-areas were sealed over. This ensured that the planned levels of ventilation were provided within the chamber during each of the tests.

For some of the tests on the water heater and cooker there was no purpose-provided ventilation in the chamber at all, as none is required to be installed within BS 5440-2 for a room of this size in an existing dwelling. However, it should be noted that, under Part F of the Building Regulations, any new dwellings are required to have extract ventilation in their kitchens.

2.1.3 Air mixing and heat removal

A chilled beam with a large fan was installed in the chamber to control the chamber temperature and to ensure good mixing of the air and combustion products from the appliances under test. Chilled water was passed through the beam so that excess heat produced by the gas appliances during the tests could be removed from the chamber. The fan was used to draw air through the porous section of the beam for cooling, and also ensured that the air within the chamber was well mixed. The controller on the chiller unit was set to introduce cold water into the beam so that the room was normally kept at around 23qC or below. The fan drawing air through the beam and mixing the air within the chamber ran continuously during all tests. The chilled beam can be seen in the upper part of the photograph of the chamber (Figure 1).

2.2 APPLIANCES TESTED

2.2.1 Closed Stove

The closed stove tested ran on natural gas, see Figure 2. It consists of gas burners operating below some decorative logs. The main burners can be controlled from a dial containing numbered settings ranging from 1 to 7. It has a pilot light that in normal use would probably be operated continuously. The unit tested was an ex-display model in good working order. It was initially tested as received. Later in the measurement programme it was fully cleaned and serviced by a CORGI registered gas engineer. Some of the tests were then repeated to see if any differences could be detected.

The combustion gases exit through the top of the appliance after passing through a catalyst to remove carbon monoxide (CO). The catalyst is in the form of a ceramic honeycomb block through which the exhaust gas stream is passed.

The appliance contains a safety device which “constantly monitors the oxygen level in the room, if this should fall by as little as 1.5%, the flame is automatically extinguished”.

2.2.2 Decorative Fire

The decorative fire tested ran on natural gas, see Figure 3. It consists of gas burners operating below some decorative coals. The main burners can be controlled from a dial containing numbered settings ranging from 1 to 6. It has a pilot light that in normal use would probably be operated continuously. The appliance was bought in new for the purposes of these tests.

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The combustion gases exit through the top of the appliance after passing through a catalyst to remove CO. The catalyst is in the form of a ceramic honeycomb block through which the exhaust gas stream is passed.

According to the manufacturer, the appliance contains: “a combustion monitoring safety device (ODS)”. If this operates, the user is advised to: “switch the appliance OFF and call in your installer to check the appliance and ventilation”.

2.2.3 Cabinet heater

The cabinet heater tested ran on bottled LPG, see Figure 4. The gas is burned directly on ceramic panels. The appliance has three ceramic panels. All three panels are used when the heater is on the “high” setting, with only one being used on the “low” setting. The appliance was bought in new for the purposes of these tests.

The appliance contains an “oxygen analyser” and “automatic pilot-light cut-off system” safety device.

2.2.4 Instant Water Heater

The instant water heater tested ran on natural gas, see Figure 5. It consists of gas burners operating below a heat exchanger through which water is passed, the combustion gases then exit through the top of the appliance. The burner can be controlled from a dial containing settings ranging from low to maximum power. It has a pilot light that would probably normally be operated continuously. The appliance was bought in new for the purposes of these tests.

These appliances are specified by the manufacturers as: “intended for intermittent use…to supply hot water to one draw off point such as a kitchen sink or a wash basin”. Within the instructions supplied with the unit tested it states that such appliances: “must not be operated continuously for more than five minutes”.

The appliance contains a safety device which: “when the oxygen in the atmosphere in the locality of the heater becomes diminished…..interrupts the thermoelectric circuit and the pilot and main burner are extinguished”.

2.2.5 Gas cooker

The gas cooker tested ran on natural gas, see Figure 6. It consists of an oven, four hobs of different sizes and a high level grill. All ignition was through a piezo-electric system, so no pilot light was used. Although the appliance was not new, it had been used comparatively little, having been purchased new for a previous series of experiments at BRE.

2.3 MEASUREMENT EQUIPMENT

A photograph of the gas analysers, data logger and PC described in the following sections is given in Figure 7.

2.3.1 Temperature

Temperatures were measured at three heights at the centre of the chamber, the supply air entry to the chamber and at the outlet to the appliance under test. Type K thermocouples were used, connected to a Solartron SI 3535D “Scorpio” data logger. This has its own internal cold junction

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thermocouple reference. Temperature measurements were logged every 10 seconds and recorded on a PC. Measurements were made at five locations, numbered T1 to T5 respectively:

x T1 thermocouple positioned at 0.5 m height near the centre of the chamber; x T2 thermocouple positioned at 1.1 m height near the centre of the chamber; x T3 thermocouple positioned at 1.6 m height near the centre of the chamber; x T4 thermocouple positioned at the air supply to the chamber (either at the purpose­

provided open-area hole or inlet air supply grille, depending on the nature of the ventilation used in the test); and

x T5 thermocouple positioned in the exhaust stream of the appliance under test.

2.3.2 Relative humidity

Relative humidity was measured using a Vaisala HMP44 probe positioned at a height of 1.1 m at the centre of the chamber. As with the thermocouples, this was logged every 10 seconds via the Scorpio data logger, with values then recorded on the PC.

2.3.3 Oxides of Nitrogen (NOx)

Measurements were made of nitric oxide (NO), nitrogen dioxide (NO2) and total oxides of nitrogen (NOx). They were measured using a Thermo-Environment chemi-luminescent analyser, with the entry to the analyser inlet tube being positioned at a height of 1.1 m, near to the centre of the chamber. The calibrated output from the analyser was logged every 10 seconds via the Scorpio data logger, with values then recorded on the PC. The calibration of the instrument was checked on at least a weekly basis using both zero air and span gas from bottled calibration gas standards.

2.3.4 Carbon Monoxide (CO)

CO was measured using a Thermo-Environment infra-red absorption based CO analyser, with the entry to the analyser inlet tube being positioned at a height of 1.1 m, near to the centre of the chamber. The calibrated output from the analyser was logged every 10 seconds via the Scorpio data logger, with values then recorded on the PC. The calibration of the instrument was checked on at least a weekly basis using both zero air and span gas from bottled calibration gas standards.

2.3.5 Carbon Dioxide (CO2)

CO2 was measured using a Leybold Binos 1 analyser, with the entry to the analyser inlet tube being positioned at a height of 1.1 m, near to the centre of the chamber. The instrument operates by measuring the absorption of infra-red radiation by CO2. The calibrated output from the analyser was logged every 10 seconds via the Scorpio data logger, with values then recorded on the PC. The calibration of the instrument was checked on at least a weekly basis using both zero air and span gas from bottled calibration gas standards.

2.3.6 Oxygen concentration

The oxygen concentration was measured within the test chamber to see if it declined during the tests as the appliances were operating. The measurement was made at a height of 1.1 m, near to the centre of the test chamber. As a reference, the oxygen level outside of the chamber was also measured simultaneously. The measurements were made using electrochemical cells supplied by City Technology (Model numbers 7OX). The calibrated outputs from these cells were logged every 10 seconds via the Scorpio data logger, with values then recorded on the PC.

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2.3.7 Ultrafine particles

Measurements of the concentration of ultrafine particles within the chamber were made during most of the tests reported here. The exceptions were the longer, overnight tests as the instrument used would only operate for a period of about 6 hours. The instrument used was a P-Trak particle counter made by TSI Inc. The measurement was made at a height of 1.1 m, near to the centre of the test chamber. The instrument counts the particles present within the air in the approximate size range of 0.02 to 1 Pm. Particles of this size are typically formed as the products of combustion. They are counted rather than weighed, as their small size makes their mass almost negligible.

2.3.8 Aldehydes

Samples of aldehydes were taken during selected tests, covering all of the appliances tested. The samples were collected by pumping known quantities of air through analytical cartridges containing an adsorbent material specifically used for collecting aldehydes. These were then subsequently analysed chemically through a combination of high performance liquid chromatography (HPLC) with UV detection. During the tests, the measurement equipment was stationed at a height of 1.1 m, near to the centre of the test chamber.

2.3.9 Measurement of fuel used during tests

The amount of fuel used was recorded for every test. This acted as a secondary check on the burn-rate of the appliance, as at low firing rates the appliances could sometimes cycle thermostatically, giving lower emissions of pollutants into the chamber than otherwise might have been expected. An in-line gas meter was used for measuring the amount of fuel used in the tests using natural gas from the main supply. This was read before and after each test and the amount of gas used (in litres) recorded. The resolution of the gas meter used was to 0.1 litres. For the tests using the cabinet heater, the cylinder of gas was weighed before and after each test and the amount of gas used (in grams) recorded. The resolution of the balance used was to 0.1 g.

2.4 TEST METHODOLOGY

2.4.1 Burn rates and ventilation

Tests on all of the appliances were conducted at both high and low burn rates. Ventilation provision was via one of the two methods described earlier in Section 2.1.2 (either purpose­provided open-area or controlled mechanical ventilation). For some of the tests on the water heater and cooker there was no purpose provided ventilation in the chamber at all, as none is required to be installed within BS 5440-2 for a room of this size in an existing dwelling. However, it should be noted that, under Part F of the Building Regulations, any new dwellings are required to have extract ventilation in their kitchens.

2.4.2 Test Periods

Tests were normally operated for each appliance type for standard periods. The exceptions were tests where the appliance shut down automatically during the course of the tests.

Tests on the room heating appliances (closed stove, decorative fire and the cabinet heater) were typically conducted for periods of four hours. Tests on the oven of the cooker were also typically of four hours duration.

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However, some tests were conducted on the oven at a low burn rate for much longer periods (overnight). These longer period tests were conducted as it is quite possible that an oven could be used for such periods at a lower burn rate, either for slow-cooking of food, or possibly for background heating, for example in a kitchen or bedsit (although strictly this would constitute a “misuse” of the appliance). Tests on the emissions from pilot lights within some of the appliances were also conducted overnight so that data from a longer period of time could be collected.

Measurements of the emissions from the hobs and grill of the cooker were conducted over test periods of 30 minutes, as these would be broadly typical of operating times often used during this type of cooking.

Measurements of the emissions from the water heater were conducted over test periods of 30 minutes. Although the heater is specified not to run for period of more than 5 minutes (see Section 2.2.4), there is nothing to stop an operator from running it for periods in excess of this figure. Therefore, the tests were run for 30 minutes, with concentrations of pollutants also being reported after 5 minutes of operation as well.

2.4.3 Standard Test Procedure

In a standard test the procedure was as follows: x install the required appliance within the chamber; x read the gas meter or weigh the gas cylinder as appropriate; x set up the required ventilation condition (open area or mechanical air change rate); x turn on the circulation fan and chilled beam; x start all of the analytical equipment logging to obtain background readings; x light the appliance and seal the chamber door; x at the end of the test period shut down the appliance, leaving the analytical system

logging for a few minutes; x read the gas meter or weigh the gas cylinder as appropriate; x shut down the logging system and save all results to disc; x ventilate the chamber completely, prior to any subsequent test.

The test procedure minimised the amount of time that an operator needed to be inside the chamber at the end of the testing period. As an additional safety precaution, chamber concentrations of combustion products were checked before entering.

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3. STANDARDS FOR POLLUTANTS AND EXPOSURES

The results obtained from the tests were compared with the following standards and guideline concentrations for air quality and exposure: the UK Health and Safety Executive’s Occupational Exposure Limits (HSE EH40 (2001)) and the World Health Organisation Air Quality Guidelines (WHO (1999)).

The HSE OELs are designed for the workplace, where the working population is assumed to be fit and healthy. These are normally quoted as Occupational Exposure Standards (OES), a time weighted average concentration not to be exceeded, usually over an 8-hour working period, or a short-term exposure limit (STEL) covering a maximum exposure in any 15 minute period.

In the absence of any published UK indoor air quality standards, the WHO guidelines were used. The WHO guidelines are set at a lower level than the HSE OEL’s and are generally taken as being more relevant to the population in general, which encompasses elderly and sick people as well as infants. In terms of potential exposures within homes arising from the emissions from flueless appliances, the WHO guideline concentrations are therefore more appropriate to use as a reference for comparison.

3.1 INORGANIC GASEOUS POLLUTANTS

Tables 1 to 4 contain guideline concentrations (where they exist) from both the HSE OELs and the WHO Air Quality Guidelines for the gaseous pollutants measured in these tests (CO, CO2, NO, NO2).

3.2 ULTRAFINE PARTICLES

Currently there are no standards concerning exposure levels to ultrafine particles. They were included in the measurements made here as the information gained may be useful in understanding how concentrations of these particles can change as a result of unvented gas combustion.

Ultrafine particles were included in the measurements made here, as they are typically generated by combustion processes.

3.3 ALDEHYDES

Guideline concentrations for formaldehyde (methanal) and acetaldehyde (ethanal) taken from the World Health Organisation (WHO) are given in Table 5. Aldehydes can cause sensory irritation of the eyes and respiratory symptoms.

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4. RESULTS - CLOSED STOVE

The results of the tests conducted on the closed stove are shown in Table 6, with some examples given in Figures 8 and 9.

4.1 STANDARD TESTS

The measured concentrations of combustion products varied broadly in line with the burning and ventilation rates used in the experiments, with higher burn rates and lower ventilation rates leading to higher pollutant concentrations.

The maximum NO2 concentrations recorded during the tests on this appliance were typically between approximately 50 and 600 ppb, with most of the concentrations being above the WHO 1-hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded during the tests on this appliance were typically between approximately 800 and 11000 ppm. The maximum CO2 concentrations reached in the chamber during the maximum burn rate tests were always above the HSE’s 8­hour OES concentration of 5000 ppm, whereas those from the tests at the lower burn rates were below this concentration.

Maximum measured concentrations of CO recorded during the tests on this appliance were typically between approximately 2 and 48 ppm. The maximum concentrations recorded during the higher burn rate tests were always much lower (around 3 ppm) than those at the lower burn rates (up to 48 ppm). At the higher burn rate the maximum concentrations of CO reached were well below the HSE’s 8-hour OES concentration of 30 ppm, and the WHO 1-hour mean guideline concentration of 26 ppm. However, at the low burn rates both of these concentrations were often exceeded. Subsequent tests showed that majority of the emissions of CO was being produced by the pilot light of the appliance, see Section 4.4.

Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0.2 and 2.1% of normal atmospheric levels in absolute terms. The internal safety device of the appliance automatically shut it down during all of the tests conducted where purpose-provided open area ventilation was used.

4.2 TESTS WITH CATALYST REMOVED

Two tests were conducted on the closed stove with the catalyst block removed. The catalysts have a nominal service life specified by the manufacturers of around 10 years, after which it is recommended that they are replaced. Removing the catalyst allowed an evaluation to be made on both the effect that it was having during normal operation, and also the effect that any degradation over time or removal might have on pollutant emissions.

The tests were conducted at maximum and minimum burn rates, at a room ventilation rate of 1 air change per hour (ach). It was clear that the catalyst had a significant effect in converting CO to CO2, as during the maximum burn rate test without the catalyst, the CO concentration in the room reached 50 ppm, compared with a value of only 3.8 ppm in the corresponding test with it in place. Similarly, for the tests at the minimum burn rate, the CO concentration in the room

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reached 39.6 ppm, compared with a value of only 2.2 ppm in the corresponding test with it in place.

The catalyst block also affected the balance between the NO and NO2 emitted into the chamber. For the tests with the catalyst present there was approximately 5 to 8 times more NO emitted than NO2. However, with the catalyst removed at the higher burn rate there was at least 10 times more NO2 emitted than NO.

4.3 TESTS AFTER SERVICING

The appliance was tested as received from the supplier. It had been in use previously for demonstrations in a showroom. The servicing revealed that the appliance was clean and working properly, but the supply pressure to the pilot light was set at too high a level. This was adjusted to be within the manufacturer’s specified values.

Maximum recorded NO2 concentrations at the maximum and low burn rates were 130 and 540 ppb before servicing and 150 and 420 ppb after servicing, showing that servicing had had only a small effect on the NO2 concentrations being produced.

Maximum measured concentrations of CO2 at the maximum and low burn rates were 3700 and 11000 ppm before servicing and 3500 and 8600 ppm after servicing, showing that servicing had had a small effect on the CO2 concentrations being produced.

Maximum measured concentrations of CO at the maximum and low burn rates were 3.8 and 48 ppm before servicing and 2.1 and 15.6 ppm after servicing, showing that servicing had reduced CO emissions at the lower burn rate. This lower CO concentration is likely to have arisen from reduced emissions from the pilot light, see Section 4.4.

4.4 TESTS WITH PILOT LIGHT ONLY

During some of the early tests at the low burn rate, the appliance reached the pre-set desired room temperature (according to the setting on the control dial) and then “dropped back” to pilot light only operation. This operation was part of the normal thermostatic “cycling” of the appliance on achieving the desired room temperature (i.e. these were not automatic shut-downs resulting from the intervention of the internal safety device). It was during these periods that higher CO emissions were recorded. It therefore seemed likely that much of the CO being emitted from the appliance was coming from the pilot light. This was probably being compounded by the reduction in the efficiency of the catalytic block once the outlet gas temperature from the appliance fell, leading to higher emissions of CO into the room.

To investigate if the pilot light really was the source of the CO emissions, some tests were conducted with just the pilot light running, see Figure 9. During these tests the pilot light was left running for several hours overnight, with the room being ventilated at a rate of 1 air change per hour. In these tests, the concentrations of the other main gaseous pollutants (CO2 and NOx) rose slightly from their original background concentrations. However, the concentrations of CO increased more significantly. Prior to servicing, the maximum CO concentration reached in the chamber after running a test overnight was 46.5 ppm. For the final 8 hours of the test the concentration of CO was steady at around 45 ppm, indicating that the HSE 8-hour OES concentration of 30 ppm would have been exceeded. After servicing a similar test produced a level of 15.6 ppm, showing that the reduction in pilot jet pressure had reduced CO emissions.

During servicing a small sooty deposit on the decorative log that had been positioned next to the pilot light was noticed. To investigate this, a test was run with just the pilot light operating but

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this time with all of the decorative logs removed. The resulting CO concentration in the room with the appliance in this configuration was only 1.1 ppm.

The results from the tests on the pilot light alone indicate that potentially it can be a major source of CO. When the appliance is running properly, with higher temperatures within the catalyst block, the catalyst is capable of converting much of the CO produced to CO2. However, at lower burn rates, much less of the CO is converted to CO2 and is therefore emitted into the room. Reducing the pilot light supply pressure to within the correct specifications lowered but did not eliminate CO emissions. The design of the decorative logs used within the appliance was such that it was difficult to prevent the pilot light flame from playing on to them. Once the pilot light flame contacted the decorative logs its combustion efficiency was reduced and higher concentrations of CO were produced.

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5. RESULTS - DECORATIVE FIRE

The results of the tests conducted on the decorative fire are shown in Table 7, with an example given in Figure 10.

5.1 STANDARD TESTS

The measured concentrations of the pollutants emitted varied broadly in line with the burning and ventilation rates used in the experiments, with higher burn rates and lower ventilation rates leading to higher pollutant concentrations.

The maximum NO2 concentrations recorded during the tests on this appliance were typically between approximately 300 and 1500 ppb, i.e. always higher than the WHO 1-hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded during the tests on this appliance were typically between approximately 2000 and 9500 ppm. The maximum CO2 concentrations reached in the chamber during the higher burn rate tests were always above the HSE’s 8-hour OES concentration of 5000 ppm, whereas those from the tests at the lower burn rates were below this concentration.

Maximum measured concentrations of CO recorded during the tests on this appliance were typically between approximately 0.5 and 4 ppm. These concentrations being below the HSE’s 8­hour OES concentration of 30 ppm, and the WHO 1-hour mean guideline concentration of 26 ppm.

Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0 and 1.6% of normal atmospheric levels in absolute terms. The internal safety device of the appliance automatically shut it down during the tests conducted at the maximum burn rate with the minimum room ventilation.

5.2 TESTS WITH CATALYST REMOVED

Two tests were conducted on the decorative fire with the catalyst block removed. The catalysts have a nominal service life specified by the manufacturers of around 10 years, after which it is recommended that they are replaced. Removing the catalyst allowed an evaluation to be made on both the effect that it was having during normal operation, and also the effect that any degradation over time or removal might have on pollutant emissions.

The tests were conducted at the maximum and minimum burn rates at a room ventilation rate of 1 air change per hour (ach). It was clear that the catalyst had a significant effect in converting CO to CO2, as during the maximum burn rate test without the catalyst, the CO concentration in the room reached 124 ppm, compared with a concentration of only 3.9 ppm in the corresponding test with it in place. Similarly, for the tests at the minimum burn rate, the concentration of CO in the room for the test without the catalyst was higher, but not by such a large amount.

The catalyst block also affected the balance between the NO and NO2 emitted into the chamber. For the tests with the catalyst present there was approximately 2 to 3 times more NO emitted than NO2. However, with the catalyst removed at the higher burn rate there was about 3 times

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more NO2 emitted than NO, whereas at the lower burn rate the two pollutants were approximately equally divided.

5.3 INITIAL “BURN-IN” TEST

The fire was brand new when obtained. The manufacturer’s instructions recommend that “On initial lightup of a new appliance, the “newness” will very quickly burn off within the first 5 minutes of operation….the room should be well ventilated with all windows and doors open during this period”. Therefore, a “burn-in” test was conducted to investigate any differences in pollutant emission between a new appliance and one that had been in operation for some time. During the initial burn-in test, it can be seen that levels of CO2 and NO production were similar, as was the reduction in room oxygen level. However, higher levels of both CO and ultrafine particles were recorded.

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6. RESULTS - LPG CABINET HEATER

The results of the tests conducted on the cabinet heater are shown in Table 8, with an example given in Figure 11.

The measured concentrations of the pollutants emitted varied broadly in line with the burning and ventilation rates used in the experiments, with higher burn rates and lower ventilation rates leading to higher pollutant concentrations.

The appliance produced very little NO, with most of the NOx produced being in the form of NO2. The maximum NO2 concentrations recorded during the tests on this appliance were typically between approximately 300 and 900 ppb, i.e. always higher than the WHO 1-hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded during the tests on this appliance were typically between approximately 4000 and 9500 ppm. These concentrations were close to, or above the HSE’s 8-hour OES concentration of 5000 ppm.

Maximum measured concentrations of CO recorded during the tests on this appliance were typically between approximately 7 and 17 ppm. These concentrations were below the HSE’s 8­hour OES concentration of 30 ppm, and the WHO 1-hour mean guideline concentration of 26 ppm. However, they were very close to, or above the WHO 8-hour mean guideline concentration of 9 ppm.

Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0.2 and 1.4% of normal atmospheric levels in absolute terms. The internal safety device of the appliance automatically shut it down during all of the maximum burn rate tests and also during the low burn rate at the minimum ventilation condition.

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7. RESULTS – INSTANT WATER HEATER

7.1 AFTER 5 MINUTES RUNNING

Concentrations for the pollutants within the test chamber after 5 minutes were obtained from the full data set in addition to concentrations measured at the end of the normal 30 minute test period.

The results of the tests conducted on the water heater after 5 minutes of operation are shown in Table 9a. The measured concentrations of the pollutants emitted varied broadly in line with the burning and ventilation rates used in the experiments, with higher burn rates and lower ventilation rates leading to higher pollutant concentrations.

The maximum NO2 concentrations recorded after 5 minutes during the tests on this appliance were typically between approximately 700 and 1100 ppb, i.e. always higher than the WHO 1­hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded after 5 minutes during the tests on this appliance were typically between approximately 1500 and 2200 ppm. These concentrations were below the HSE’s 8-hour OES concentration of 5000 ppm.

Maximum measured concentrations of CO recorded after 5 minutes during the tests on this appliance were typically between approximately 0.4 and 1.3 ppm. These concentrations were below the HSE’s 8-hour OES concentration of 30 ppm, and the WHO 1-hour mean guideline concentration of 26 ppm.

Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0 and 0.4% of normal atmospheric levels in absolute terms. However, the test periods were very brief.

7.2 AFTER 30 MINUTES RUNNING

Although the appliance is specified by the manufacturers to run for a maximum continuous period of up to of 5 minutes only, in practice there is nothing to stop it from being used for longer periods. Therefore, the tests were allowed to run for 30 minutes to record the resulting pollutant concentrations.

The results of the tests conducted on the water heater after a 30 minute period of operation are shown in Table 9b, with an example given in Figure 12. The measured concentrations of the pollutants emitted varied broadly in line with the burning and ventilation rates used in the experiments, with higher burn rates and lower ventilation rates leading to higher pollutant concentrations.

The maximum NO2 concentrations recorded during the tests on this appliance were typically between approximately 800 and 1200 ppb, i.e. always higher than the WHO 1-hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded during the tests on this appliance were typically between approximately 6700 and 10500 ppm. The maximum concentrations reached

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during all of the 30 minute tests were always above the HSE’s 8-hour OES concentration of 5000 ppm.

Maximum measured concentrations of CO reached during the tests on this appliance were typically between approximately 2 and 4 ppm. These concentrations were below the HSE’s 8­hour OES concentration of 30 ppm, and the WHO 1-hour mean guideline concentration of 26 ppm.

Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0.4 and 2.1% of normal atmospheric levels in absolute terms.

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8. RESULTS – GAS COOKER

The results of the tests conducted on the gas cooker are shown in Table 10 with some examples given in Figures 13-17. The measured concentrations of the pollutants emitted varied broadly in line with the burning and ventilation rates used in the experiments, with higher burn rates and lower ventilation rates leading to higher pollutant concentrations.

8.1 OVEN

The maximum NO2 concentrations recorded during the tests on this appliance were typically between approximately 450 and 1650 ppb, i.e. always higher than the WHO 1-hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded during the tests on this appliance were typically between approximately 2200 and 17000 ppm. The maximum concentrations recorded during the high burn rate tests were always close to, or above the HSE’s 8-hour OES concentration of 5000 ppm. For the tests at the lower burn rate where ventilation was provided, the maximum concentrations were between approximately 2000 and 3000 ppm. However, during an overnight test at the low burn-rate with no purpose-provided ventilation, the CO2 concentration in the room rose to above 17000 ppm, which exceeds the HSE’s limit concentrations both for an 8-hour OES and for a 15 minute short term exposure (STEL) which is currently set at 15000 ppm.

Maximum measured concentrations of CO were between approximately 2 and 7 ppm for the high burn rate tests. At the lower burn rate, concentrations were around 2 ppm for the ventilated tests, but in the tests with no purpose-provided ventilation the CO concentration reached a higher value of 18 ppm. However, all of these concentrations were below the HSE’s 8-hour OES concentration of 30 ppm, and the WHO 1-hour mean guideline concentration of 26 ppm.

Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0.2 and 0.9% of normal atmospheric levels in absolute terms for the ventilated tests. However, at the two conditions where there was no purpose-provided ventilation in the chamber, the oxygen level dropped quite considerably, by 3% during the 4 hour high burn rate test and by 4.7% during the overnight low burn rate test.

8.2 GRILL

The maximum NO2 concentrations recorded during the tests on this appliance were typically between approximately 85 and 131 ppb, i.e. around the level of the WHO 1-hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded during the tests on this appliance were typically between approximately 2700 and 4200 ppm. The maximum concentrations reached during all of the 30 minute tests were always below the HSE’s 8-hour OES concentration of 5000 ppm.

Maximum measured concentrations of CO reached during the tests on this appliance were typically between approximately 7 and 9 ppm for the high burn rate tests. At the lower burn rate CO concentrations were higher at between approximately 16 and 21 ppm, probably indicating poorer combustion of the gas. All of these concentrations were below the HSE’s 8-hour OES

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concentration of 30 ppm. However, at the low burn rate with no purpose-provided ventilation, the WHO 1-hour mean guideline concentration of 26 ppm was approached.

Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0.3 and 0.5% of normal atmospheric levels in absolute terms.

8.3 HOBS ALONE

Tests conducted on the hobs alone represent the situation where they might be used for space heating rather than for cooking, although strictly this would constitute a “misuse” of the appliance.

The maximum NO2 concentrations recorded during the tests on this appliance were typically between approximately 400 and 750 ppb, i.e. above the level of the WHO 1-hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded during the tests on this appliance were typically between approximately 2200 and 5600 ppm. Apart from the high burn rate test with no purpose-provided ventilation, the concentrations reached were below the HSE’s 8-hour OES concentration of 5000 ppm.

Maximum measured concentrations of CO reached during the tests on this appliance were typically between approximately 1.6 and 1.8 ppm for the high burn rate tests. At the lower burn rate CO concentrations were higher at between approximately 14 and 30 ppm, indicating poor combustion of the gas. All of these concentrations were below the HSE’s 8-hour OES concentration of 30 ppm. However, at the low burn rate with no purpose-provided ventilation, the WHO 1-hour mean guideline concentration of 26 ppm was approached.

Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0.3 and 0.7% of normal atmospheric levels in absolute terms.

8.4 HOBS WITH PANS OF WATER

The tests conducted on the hobs with pans of water on them were conducted to approximate the conditions likely to occur during cooking processes.

The maximum NO2 concentrations recorded during the tests on this appliance were typically between approximately 310 and 890 ppb, i.e. above the level of the WHO 1-hour mean guideline concentration of 105 ppb.

Maximum measured concentrations of CO2 recorded during the tests on this appliance were typically between approximately 1870 and 5300 ppm. Apart from the high burn rate test with no purpose-provided ventilation, the concentrations reached were below the HSE’s 8-hour OES concentration of 5000 ppm.

Maximum measured concentrations of CO reached during the tests on this appliance were typically between approximately 37 and 50 ppm for the high burn rate tests. At the lower burn rate, concentrations were lower at between approximately 14 and 20 ppm. At the high burn rate, the concentrations of CO reached were above the HSE’s 8-hour OES concentration of 30 ppm. At the low burn rate the WHO 1-hour mean guideline concentration of 26 ppm was approached, but not exceeded, during the course of the 30 minute test.

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Lowering of oxygen levels within the chamber depended on burn and ventilation rates and varied between reductions of 0.2 and 0.9% of normal atmospheric levels in absolute terms.

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9. RESULTS OF ALDEHYDE MEASUREMENTS

9.1 GENERAL

The results of all of the measurements to monitor the concentrations of aldehydes (formaldehyde and acetaldehyde) emitted into the test chamber are given in Table 11.

Formaldehyde (Methanal) The concentrations of formaldehyde measured here were sampled over quite similar periods to the 30 minutes specified for the WHO guideline concentration of 100 Pg m-3, typically 30 minutes to 4 hours. A number of measurements exceed the WHO guideline concentration . The tests where the WHO guideline concentration for formaldehyde was closely approached or exceeded were:

x four out of the five tests on the cabinet heater – at both high and low settings; x the test at the low setting on the closed stove; x the tests without the catalyst blocks fitted to either the closed stove or decorative fire; x the “burn-in” test on the decorative fire; x tests on the cooker for the grill and the hobs with pans of water.

Acetaldehyde (Ethanal) The concentrations of acetaldehyde measured here were sampled over much shorter periods (typically 30 minutes to 4 hours) than the 24-hour guideline concentration specified by the WHO of 2000 Pg m-3. However, from the tests reported here it would seem highly unlikely that concentrations of acetaldehyde would ever approach the WHO 24-hour guideline concentration.

As a result of the generally low concentrations of acetaldehyde measured here, in the following sections only formaldehyde emissions from the appliances are discussed

9.2 CLOSED STOVE

Formaldehyde concentration for the closed stove operating at its maximum setting were similar for both the 50 cm2 purpose-provided open-area and 1 ach ventilation regimes, at 69 and 87 Pg m respectively, with both of these concentrations being below the WHO guideline concentration of 100 Pg m-3.

In the tests for other set-ups of this appliance, the emission of formaldehyde broadly follows the behaviour for the emission of CO seen earlier. Servicing the appliance, including the pilot light setting, reduced formaldehyde concentrations in the chamber during the tests. At the maximum burn-rate and a ventilation rate of 1 ach concentrations fell from 87 to 35 Pg m-3.

The high formaldehyde concentration (313 Pg m-3) associated with the test on the closed stove running at the low setting may well result from the high levels of emissions found to be coming from the pilot light.

The catalyst blocks seem to have a significant effect in reducing the rate of formaldehyde emission from the appliance during combustion. At the maximum burn rate at 1 ach, without the catalyst block the formaldehyde concentration in the chamber reached 1730 Pg m-3, compared with a value of only 87 Pg m-3 when it was in place.

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9.3 DECORATIVE FIRE

Formaldehyde concentrations for the decorative fire operating at its maximum setting, for the 100 cm2 purpose-provided open-area and 1 ach ventilation regimes, were 64 and 28 Pg mrespectively. At the low setting of the appliance, concentrations of formaldehyde in the chamber fell to 17 Pg m-3. All of these concentrations were below the WHO guideline concentration of 100 Pg m-3.

The catalyst block seems to have a significant effect in reducing the rate of formaldehyde emission. At the maximum burn rate at 1 ach, without the catalyst block the formaldehyde concentration in the chamber reached 509 Pg m-3, compared with a concentration of only 28 Pg m-3 when it was in place.

The “burn-in” test produced higher levels of emission of formaldehyde than normal running, with concentrations of 192 and 28 Pg m-3 respectively.

9.4 CABINET HEATER

The cabinet heater seemed to produce formaldehyde fairly readily. The “high” and “low” settings on this appliance do not refer to operating temperatures, but only to the fact that at the low setting only one of the three radiant ceramic panels was in use.

Formaldehyde concentrations for the cabinet heater operating at its maximum setting for the 100 cm2 purpose-provided open-area, 0.5 and 1 ach ventilation regimes, were 337, 159 and 189 Pg m-3 respectively. All of these concentrations are above the WHO guideline concentration of 100 Pg m-3.

At the low setting of the appliance, concentrations of formaldehyde in the chamber at the 0.5 and 1 ach ventilation conditions were 78 and 99 Pg m-3 respectively.

9.5 INSTANT WATER HEATER

Only one measurement of formaldehyde concentration was made during the tests on the instant water heater at its maximum burn rate at a ventilation rate of 1 ach. The formaldehyde

-3concentration was 64 Pg m-3, which is below the WHO guideline value of 100 Pg m .

9.6 COOKER

9.6.1 Oven

Only one measurement of formaldehyde concentration was made during the tests on the oven, at its maximum burn rate and a ventilation rate of 1 ach. The formaldehyde concentration was

-374 Pg m-3, which is below the WHO guideline value of 100 Pg m .

9.6.2 Grill

Only one measurement of formaldehyde concentration was made during the tests on the grill, at its maximum burn rate and a ventilation rate of 1 ach. The formaldehyde concentration was

-3101 Pg m-3, which is almost identical to the WHO guideline value of 100 Pg m .

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9.6.3 Hobs

One measurement of formaldehyde concentration was made during the tests on the hobs in each of the two conditions, with and without pans of water. These tests were conducted with the hobs at their maximum burn rate and a chamber ventilation rate of 1 ach. For the hobs alone, the formaldehyde concentration was 28 Pg m-3, which is below the WHO guideline value of 100 Pg m-3. For the hobs with pans of water, the formaldehyde concentration was 149 Pg m , which is above the WHO guideline value of 100 Pg m-3.

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10. EFFECT OF VENTILATION PROVISION

Within the tests reported here, a variety of different ventilation regimes were employed. To compare the performance of these regimes, values for the CO2 concentration in the chamber after 1 hour of burning with the closed stove at its maximum rate have been extracted from the measurements (only the closed stove was tested in all of the possible ventilation conditions). A time of 1 hour was selected since the unit shut itself down after about 80 minutes at the conditions where the lowest amount of ventilation was provided.

The concentrations of CO2 in the chamber after 1 hour with the following ventilation regimes are given in Table 12:

x 50 cm2 of purpose-provided open-area ventilation installed near to floor level in one of the walls of the chamber;

x 100 cm2 of purpose-provided open-area ventilation installed near to floor level in one of the walls of the chamber;

x 100 cm2 of purpose-provided open-area ventilation installed in the chamber (50 cm2

near to floor level in one of the walls of the chamber and 50 cm2 near to the ceiling in one of the opposite walls of the chamber);

x a mechanically controlled air change rate of 0.5 air change per hour; and x a mechanically controlled air change rate of 1 air change per hour.

As would be expected, regimes that increase the ventilation rate by a greater amount reduce the concentration of CO2 within the chamber by a greater amount. The CO2 concentrations reached for the 50 and 100 cm2 purpose-provided open-areas were very similar at 8402 and 8370 ppm respectively. Placing half of the purpose-provided open-area across the chamber near to the ceiling improves the air movement within the room, but the reduction in CO2 concentration (down to 7767 ppm) was small. Mechanically ventilating the chamber at 0.5 and 1 air changes per hour reduced the CO2 concentration further, to 6367 and 5645 ppm respectively.

All of the CO2 concentrations measured after 1 hour of firing were in excess of the HSE’s 8­hour OES concentration of 5000 ppm, independent of the nature of the ventilation provided. Even at the ventilation rate of 1 air change per hour (which is about twice that which might be expected in a typical room), the CO2 concentrations were still above this level.

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11. BREEZE MODELLING

11.1 INTRODUCTION

The previous sections described a series of controlled experiments to investigate the pollutant emissions of flueless appliances under different conditions. The next step was to use the experimental data to model the resultant pollutant concentrations in UK dwellings.

The following approach has been taken and is described in this section.

1. Determine representative emission rates from the experimental data. 2. Incorporate the emission rates into BREEZE, BRE’s indoor air quality computer code. 3. Use BREEZE to evaluate the resultant pollutant levels in UK dwellings for typical

conditions. 4. Compare the pollutant levels with health-based air quality standards and guidelines.

11.2 EMISSION RATES

A range of pollutants has been monitored in the experimental study. Through discussion between HSE and BRE it was decided to focus on three pollutants: NO2, CO and CO2.

A typical emission rate and a maximum emission rate were calculated for each of these three pollutants. These were determined by first reviewing the data from the different experiments and then selecting those experimental conditions that best characterised typical and maximum emission rates for each pollutant. The experimental conditions are shown in Table 13.

Then for each experiment, the actual emission rate value was determined by comparing the experimental data against a theoretical mass-balance model. The basic equation is of the form:

Rate of change of Flow of mass Flow of mass Sources in Removal in -pollutant mass in = into the room - out of the + the room the room

a room room

The model shows that the build-up of pollutant concentration for a single well-mixed room follows the equation below.

(Q.Co �S/V) §¨̈Ci �

(Q.Co �

Q

S/V)·¸¹¸ .e

�QtC(t) �Q ©

where,

C(t) = the concentration in the room at time t Ci = the initial concentration Co = the outside concentration Q = the air change rate S = the source emission rate V = the room volume

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For each of the experiments, all of these parameters were known except for the emission rate. The emission rate was determined by correlating the experimental data with the theoretical model. In each case good correlation was obtained (R2 > 0.98). The emission rates are given in Table 14.

11.3 BREEZE COMPUTER CODE

BREEZE is a suite of integrated and user-interactive computer programs to evaluate ventilation rates and inter-zonal airflows in buildings, from single-celled to large multi-storey multi-celled buildings. The building is taken to consist of a number of inter-connected zones with air moving from zones at high pressure to those at low pressure. The pressure differences are set up by mechanical ventilation devices, the actions of wind on the external surface of the building and the temperature difference between air inside and outside

In BREEZE, the user describes the geometry of the buildings by drawing the plans of the building on the screen. The user then superimposes air paths onto these plans, each air flow path being a window, a door, a crack, a vent, a fan etc.

BREEZE also includes a contaminant analysis routine which, given a contaminant emission rate, employs an adaptive step-length method to determine cell concentration histories and determine the time weighted average (TWA) for user set-time intervals. Possible contaminant sources can include those from outside air, sources within rooms or pollutants released from surfaces. Adsorption and desorption from surfaces can also be addressed. Contaminant input data provided by the user includes emission rate, initial concentration and adsorption characteristics.

11.4 BREEZE MODEL OF FLUELESS APPLIANCE OPERATION

11.4.1 Basic model

A two-storey modern terraced house was modelled. Its dimensions were taken from a set of ‘standard’ dwellings normally used with the BRE Domestic Energy Model (BREDEM). Detailed descriptions of the dwelling are included in Figure 18. As a first approximation, the pollutant concentration in another dwelling would be inversely proportional to the volume of the dwelling. The model assumes that the concentrations of pollutants are fully mixed within the rooms (in reality there will be less mixing in normal rooms and more stratification of pollutants, leading to localised variations in concentrations).

The background ventilation conditions in the home have been modelled to meet current recommended provisions in Building Regulations Approved Document F. Thus a trickle ventilator has been included in each room, with a size of 8000 mm2 for habitable rooms and 4000 mm2 for the kitchen and bathroom.

The source (the flueless appliance) was located in the living room. The emission rates are provided in Table 14. The source was run until equilibrium was reached. It was assumed that there were no other sources of the pollutants being modelled, so that the effect of the appliance alone could be determined. In practice there would be other sources, e.g. pollution from outside and the impact of human metabolism for CO2.

NO2 is a reactive gas and is removed by the interior surfaces in a dwelling. Based on the differences between internal and external NO2 concentration in all-electric homes in BRE’s Indoor Air Quality in Homes survey, a removal rate of 0.84 hr-1 was derived and used, (i.e.

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equivalent to a ventilation rate of 0.84 air changes per hour). This has been incorporated into the NO2 cases only.

It was assumed that the home was situated in a suburban/urban environment with a typical meteorological wind speed of 4 ms-1 (from BS 5925). Results were obtained for four wind directions (0º, 90º, 180º and 270º) and averaged, representing typical figures that might be expected to occur during the course of a year. However, the “worst case” wind direction conditions within this analysis would lead to slightly higher concentrations of pollutants than are shown in the results tables.

11.4.2 Variable parameters

A number of input parameters were varied and their impact was determined. These are described below.

x Airtightness levels of 3 ach @ 50 Pa and 10 ach @50 Pa have both been modelled. These represent both the maximum and typical airtightness levels in UK homes.

x In addition to background ventilation, further ventilation provision has been included in the living room to provide air supply for combustion. Three levels of ventilation provision have been compared: 50 cm2, 100 cm2 and 200 cm2 openings respectively. The ventilation provision was placed 10 cm above the floor.

x Two internal door cases were modelled. In the first case, all doors in the house were kept closed (with a small gap around the door) and this investigates the case where the occupant is in the same room as the appliance. In the second case, all the doors in the house were kept open and this investigates the migration of the pollution to other rooms in the home (e.g. with someone sleeping in the bedroom).

x Winter and spring/autumn conditions were separately modelled. The external temperatures chosen were 4.6qC and 9.3qC respectively. These temperatures were taken from CIBSE Guide J (2002) and are daily average temperatures for the months of January and April respectively.

x In total, nearly 600 simulations were performed.

11.5 BREEZE RESULTS

11.5.1 Main analysis

Figure 19 provides an example of the pollutant build-up in the living room, where the source is located. At the start the pollutant level increases rapidly and then slows down as equilibrium is approached.

The results are presented in Tables 15-20. Three values are given in the tables: the equilibrium level and the times T50 and T90. Both of these times are illustrated on this Figure and have the following definitions.

x T50 is the time taken for the pollutant level to reach 50% of the equilibrium level.

x T90 is the time taken for the pollutant level to reach 90% of the equilibrium level.

Thus these times indicate the speed at which the equilibrium level is reached. Hence, for an appliance usage pattern, the level that would have been reached in the dwelling during use can be estimated.

33

The main conclusions can be briefly summarised as follows. x By opening internal doors, the living room level was reduced by a factor of 75 - 80%.

x With internal doors open, for CO and CO2, the living room level was approximately 10% higher than that in the master bedroom. For NO2, the difference was greater, with the living room equilibrium level approximately 40% higher than in the bedroom, owing to removal effects by internal surfaces.

x An increase in vent area from 50 cm2 to 200 cm2 reduced the equilibrium level by 10­20%.

x A reduction in airtightness (3 ach to 10 ach), reduced the equilibrium level by 10-20%.

x The T50 and T90 times were reduced with increased ventilation and inclusion of removal effects for NO2.

x In all cases T50 was under two hours. Heating appliances would tend to be used for at least this period. If a cooker was used for cooking food (as distinct from heating the home), in a number of cases T50 may not be reached.

x In all cases T90 was under six hours. In a number of cases it would be expected that T90 would not be reached whilst the appliance is on.

Figure 20 provides an example of the effect of having the internal doors open or closed. As expected, opening the internal doors significantly reduces the level in the living room as the air is transported more readily to the other rooms in the house.

Figure 21 provides an example of the level in the source room and bedroom with the internal doors open. The hot buoyant gases emitted from the flueless appliance are quickly mixed in the home, with a relatively small difference between the final pollutant levels in the two rooms modelled.

Finally, Figure 22 compares results for CO2 and NO2 in a case with the internal doors open. Because NO2 is removed by interior materials as it is transported through the house, there is a larger difference in the level of NO2 in between the living room and the bedroom.

11.5.3 Additional BREEZE calculations

The BREEZE runs described previously are for dwellings that meet currently recommended ventilation provisions in Part F of the Building Regulations. Further runs were undertaken for the case of an older dwelling that was not built to current Building Regulations. The conditions were the same as previous except that no background trickle ventilators were included in the model. In addition, less airtight dwellings (with an airtightness of 10 ach) were included, as these are more representative of older homes.

The results were approximately 30-60% higher than the previous calculations for dwellings of 10 ach airtightness. With the internal doors open, there was a 10-20% reduction in the equilibrium level in going from 50 to 200cm2 supply vent area. For the cases of internal door closed, the increase in vent area resulted in up to 40% reduction in the equilibrium level.

34

11.6 COMPARISON WITH AIR QUALITY STANDARDS AND GUIDELINES

11.6.1 Carbon dioxide

Table 21 shows when concentrations of CO2 were predicted to exceed the value of both the HSE 8-hour OES concentration and WHO guideline concentration for the different conditions. Where appropriate, the table also includes typical times for which the limit/guideline would be exceeded after turning the flueless appliance on. The HSE STEL concentration is predicted to only just be exceeded for the case of maximum emission rate with trickle vents not included (or closed) and the living rooms door closed. The HSE eight-hour OES concentration is predicted to be exceeded for the maximum emission rate only.

Overall, it suggests that the STEL concentration will rarely be exceeded (although the health impact would also need to be considered in any risk assessment). However, the eight-hour OES concentration is much more likely to be exceeded in situations where there is prolonged use of a flueless appliance.

11.6.2 Carbon monoxide

Table 21 also provides data for carbon monoxide. The HSE STEL concentration is predicted to be only just exceeded for the case of maximum emission rate with the living room door closed. The HSE eight-hour OES concentration is predicted to be exceeded for the maximum emission rate only (living room door open and closed). The WHO guideline concentrations are predicted to be exceeded, although which guidelines are exceeded and the times taken to be exceeded are dependent on the condition considered.

Overall, the results suggest that the STEL concentration will rarely be exceeded. The eight-hour OES concentration may be exceeded for prolonged use of the appliance for cases where the emission rate is somewhat higher than those typically found. The WHO guideline concentrations are likely to be exceeded in situations where there is prolonged use of a flueless appliance and, indeed, may be exceeded for shorter uses where the emission rate of the appliance is somewhat higher than that typically found.

11.6.3 Nitrogen dioxide

Table 21 also provides data for nitrogen dioxide. Neither of the HSE limit concentrations are predicted to be exceeded. However, at maximum emission rate and with no background ventilation, the equilibrium level is predicted to be only 10% lower than the HSE eight-hour OES concentration. The WHO one-hour guideline concentration is predicted to be exceeded by the time-integrated levels in all cases.

Overall, it very unlikely that the HSE OES concentration limits will be exceeded in dwellings. However, the WHO guideline concentration will be commonly exceeded for both short and long term use of a flueless appliance.

35

36

12. CONCLUSIONS

Combustion products emitted from a range of flueless gas appliances at varying firing rates have been measured in a sealed chamber of 48 m3 volume, ventilated in a number of controlled and reproducible ways, including “worst case” simulations that would be experienced in extremely air-tight rooms.

When ventilation in the chamber was through purpose-provided open-area ventilation (as specified by the appliance manufacturer or BS 5440-2: 2000), levels of all combustion products were elevated, with carbon dioxide (CO2) in particular reaching concentrations much higher than the HSE OES value. Even when mechanically provided with higher and more typical levels of ventilation, concentrations of CO2 in the chamber higher than the value set for the HSE Occupational Exposure Standard (OES) were measured.

The use of catalytic converters in some of the appliances reduced emissions of CO, through conversion to CO2. However, these only worked well at high burn rates where the outlet gas stream temperature was also high. Higher concentrations of CO than the specified HSE 8-hour OES concentration were produced from the pilot light of one of the appliances tested.

Elevated concentrations of NOx were produced by these appliances, with the balance of the NOx emissions (between NO and NO2) depending on the nature of the appliance. The presence of catalysts also affected the distribution of NO and NO2 within the overall emissions of NOx. The WHO 1-hour mean guideline concentration of 105 ppm for NO2 was exceeded in most of the tests conducted here.

The WHO guideline 30-minute concentration of 100 Pg m-3 for formaldehyde was exceeded in a small number of the tests. Levels of acetaldehyde emitted were below guideline concentrations.

The number concentration of ultrafine particles within the chamber was always raised during tests, with most tests showing a marked increase in the number of particles from background levels of around 10,000 particles cm-3 of air to in excess of 500,000 particles cm-3. Higher concentrations of ultrafine particles in the chamber coincided with higher burn-rate tests and tests with lower ventilation rates. Still higher rates were recorded during the burn-in tests on new appliances. There are currently no health standards in place for exposure to ultrafine particles.

In general terms, poorer combustion led to the increased production of CO, formaldehyde and ultrafine particles. Two of the conditions leading to poorer combustion were lower burning rates and the playing of flames directly on to surfaces (such as on grills, pans or decorative logs).

As in the manufacturer’s installation recommendations, additional ventilation should be provided during the initial “burning in” of an appliance, as emissions from it will be higher than normal.

BREEZE modelling was conducted to indicate the likely resulting concentrations of pollutants within typical UK dwellings. It predicted that:

x the HSE STEL concentration for both CO2 and CO will rarely be exceeded; x the HSE eight-hour OES concentration for CO2, and the WHO guideline concentrations

for CO are much more likely to be exceeded in situations where there is prolonged use of a flueless appliance; and

37

x for NO2, it is very unlikely that the HSE limit concentrations will be exceeded in dwellings, but the WHO guideline cocentrations will be commonly exceeded.

38

. 13. ACKNOWLEDGEMENTS

This work was funded by the Health and Safety Executive (under Contract RSU Ref: 4369.1/Z41.125) and the Department of Trade and Industry.

39

40

14. REFERENCES

1. British Standard BS 5440-2 (2000). Installation and maintenance of flues and ventilation for gas appliances of rated input not exceeding 70kW (1st , 2nd and 3rd family gases) - Part 2: Specification for installation and maintenance of ventilation for gas appliances. BSI, 389 Chiswick High Rd, London, W4 4AL. ISBN 0 580 33098 2.

2. British Standard BS 5925 (1991). Code of practice for ventilation principles and designing for natural ventilation. BSI, 389 Chiswick High Rd, London, W4 4AL.

3. Building Regulations – Part F (1995). Approved Document F - Ventilation. The Stationery Office. UK. ISBN 0-11-752932-X.

4. Building Regulations – Part L1 (2002). Conservation of fuel and power in dwellings. The Stationery Office. UK.

5. Chartered Institute of Building Service Engineers (CIBSE). Guide J: Weather, solar and illuminance data (2002).

6. English House Condition Survey (1991). Published by Department of the Environment, UK. 1993. ISBN 0 11 7528803.

7. Health & Safety Executive (2001). Occupational Exposure Limits, 2001. Health and Safety Executive, EH40/2001. Updated annually.

8. Indoor Air Quality in Homes. The Building Research Establishment Indoor Environment Study (1996). R Berry, V Brown, S Coward, D Crump, M Gavin, C Grimes, D Higham, A Hull, C Hunter, I Jeffery, R Lea, J Llewellyn and G Raw. BRE Report 299. CRC Publications, 151 Roseberry Avenue, London. ISBN 1 86081 0594.

9. World Health Organisation. (1999). Air quality guidelines. World Health Organisation, Geneva. From www.who.int.org.

41

42

15. TABLES

Table 1.Standards and guideline concentrations for exposure to Carbon Monoxide (CO)

Standard Concentration (ppm) HSE 8 hour TWA OES 30 HSE 15min STEL 200

WHO 8 hour mean 9 WHO 1 hour mean 26 WHO 30 minute mean 52 WHO 15 minute mean 85

Table 2.Standards and guideline concentrations for exposure to Carbon Dioxide (CO2)

Standard Concentration (ppm) HSE 8 hour TWA OES 5000 HSE 15min STEL 15000

Table 3.Standards and guideline concentrations for exposure to Nitric Oxide (NO)

Standard Concentration (ppm) HSE 8 hour TWA OES 25 HSE 15min STEL 35

Table 4.Standards and guideline concentrations for exposure to Nitrogen Dioxide (NO2)

Standard Concentration (ppb) HSE 8 hour TWA OES 3000 HSE 15min STEL 5000

WHO 1 hour mean 105

Table 5.WHO guideline concentrations for exposure to the aldehydes measured

Pollutant and exposure period Concentration (Pg m-3) Formaldehyde 30 minute mean 100

Acetaldehyde 24 hour mean 2000 Acetaldehyde annual mean 50

43

44

Tabl

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sults

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(p

pm)

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pm)

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)

Ultr

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Tabl

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and

ultr

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Tabl

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and

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Tabl

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as c

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7950

G

rill

Low

1

ach

30

121.

4 16

.2

2732

21

10

1 10

1 0.

3 >5

00,0

00

Hob

s (2)

M

ax

0 cm

2 30

21

9.5

1.8

5588

23

39

756

3088

0.

7 17

8400

H

obs (

2)

Max

1

ach

30

215.

5 1.

6 44

74

1809

57

6 23

78

0.6

1671

66

Hob

s (2)

Lo

w

0 cm

2 92

12

7.6

30.4

33

77

221

664

880

0.6

4639

6 H

obs (

2)

Low

1

ach

91

141.

9 14

.2

2206

23

1 39

6 62

1 0.

3 68

926

Hob

s (2)

Pl

us P

ans

Max

0

cm2

30

214.

3 50

.2

5344

90

0 88

4 17

79

0.9

2126

33

Hob

(2) P

lus

Pans

M

ax

1 ac

h 30

21

1.4

36.9

43

16

770

766

1530

0.

6 32

8466

Hob

(2) P

lus

Pans

Lo

w

0 cm

2 90

13

2.1

20.0

34

33

301

576

870

0.4

1539

3

Hob

(2) P

lus

Pans

Lo

w

1 ac

h 92

11

5.7

13.7

18

69

71

313

381

0.2

1446

5

*CO

2 an

alys

er st

oppe

d w

orki

ng d

urin

g th

is te

st, s

o fin

al m

axim

um c

once

ntra

tion

wou

ld h

ave

been

hig

her

50

Table 11.Results of aldehyde measurements

Appliance Setting

Ventilation (open-area or

ach)

Burn Time

(mins)

Formaldehyde Concentration

(Pg m-3)

Acetaldehyde Concentration

(Pg m-3) Closed stove Max 50 cm2 83 69 27 Closed stove Max 1 197 87 35 Closed stove Low (#2) 1 255 313 52 Closed stove Max 1 132 1730 95 (No catalyst) Closed stove Max 1 240 35 14 (Serviced)

Decorative fire Max 100 cm2 103 64 62 Decorative fire Max 1 243 28 14 Decorative fire Low (#2) 1 474 17 10 Decorative fire (Burn-in test)

Max 100 cm2 96 192 152

Decorative fire Max 1 240 509 53 (No catalyst)

Cabinet heater Max 100 cm2 56 337 55 Cabinet heater Low 0.5 96 78 59 Cabinet heater Max 0.5 226 159 95 Cabinet heater Max 1 128 189 128 Cabinet heater Low 1 260 99 54

Water heater Max 1 30 64 75

Oven Max (#9) 1 252 74 58 Grill Max 1 30 101 33 Hobs (x2) Max 1 30 28 12 Hobs (x2) Max 1 30 149 29 (plus pans)

51

Table 12.Effect of ventilation provision on concentration of CO2 in the test chamber after 1 hour

(Closed stove at maximum burn-rate)

Ventilation provision CO2 (ppm) after 1 hour 50 cm2 purpose-provided open-area 8402 100 cm2 purpose-provided open-area 8370 50 cm2 + 50 cm2 purpose-provided open-area 7767 0.5 ach (mechanical ventilation) 6367 1.0 ach (mechanical ventilation) 5645

Table 13.Experimental conditions to determine emission rates

Case Appliance Experimental conditions Typical NO2 emission rate Decorative fire Low position Maximum NO2 emission rate Water heater Maximum position Typical CO emission rate Cabinet heater Low position Maximum CO emission rate Cooker Two hobs plus pans on maximum Typical CO2 emission rate Closed stove Low position Maximum CO2 emission rate Cabinet heater Maximum position

Table 14.Emission rate for the pollutants

Case Emission rate (g/min)

Typical CO2 5.59 Maximum CO2 7.27 Typical CO 0.0058 Maximum CO 0.085 Typical NO2 0.0020 Maximum NO2 0.0033

52

Tabl

e 15

. R

esul

ts fo

r Typ

ical

Em

issi

on R

ate

of C

arbo

n D

ioxi

de

(a) L

ivin

g ro

om w

ith in

tern

al d

oors

clo

sed

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

1074

2 1:

15

4:30

84

44

1:00

3:

30

100

1010

8 1:

15

4:30

78

56

1:00

3:

15

200

9129

1:

15

4:15

72

41

0:45

3:

00

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

9648

1:

15

4:00

78

53

1:00

3:

15

100

8695

1:

00

3:30

74

06

1:00

3:

00

200

7537

1:

00

3:15

67

21

0:45

2:

45

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

(b) L

ivin

g ro

om w

ith In

tern

al d

oors

ope

n

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

2343

1:

15

5:00

20

05

1:00

4:

00

100

2211

1:

00

4:30

18

85

0:45

3:

45

200

2035

1:

00

4:15

17

23

0:45

3:

15

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

1564

0:

30

2:45

13

49

0:30

2:

15

100

1507

0:

30

2:45

12

93

0:30

2:

00

200

1419

0:

30

2:30

12

03

0:30

2:

00

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

53

Tabl

e 15

.R

esul

ts fo

r Typ

ical

Em

issi

on R

ate

of C

arbo

n D

ioxi

de (C

ont’d

)

(c) M

aste

r bed

room

with

Inte

rnal

doo

rs o

pen

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

2064

1:

45

5:30

17

44

1:30

4:

30

100

1947

1:

45

5:15

16

41

1:30

4:

15

200

1791

1:

30

4:45

15

04

1:15

4:

00

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

1245

1:

00

3:30

10

59

1:00

2:

45

100

1201

1:

00

3:15

10

20

1:00

2:

45

200

1131

1:

00

3:00

95

4 0:

45

2:30

3a

ch a

irtig

htne

ss

10ac

h ai

rtigh

tnes

s

54

Tabl

e 16

. R

esul

ts fo

r Max

imum

Em

issi

on R

ate

of C

arbo

n D

ioxi

de

(a) L

ivin

g ro

om w

ith in

tern

al d

oors

clo

sed

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

1397

3 1:

15

4:30

10

982

1:00

3:

30

100

1314

5 1:

15

4:30

10

219

1:00

3:

15

200

1187

4 1:

15

4:15

94

16

0:45

3:

00

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

1254

7 1:

15

4:00

10

212

1:00

3:

15

100

1130

6 1:

00

3:30

96

31

1:00

3:

00

200

1089

2 1:

00

3:15

87

41

0:45

2:

45

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

(b) L

ivin

g ro

om w

ith in

tern

al d

oors

ope

n

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

3048

1:

15

5:00

26

07

1:00

4:

00

100

2875

1:

00

4:30

24

51

0:45

3:

45

200

2646

1:

00

4:15

22

41

0:45

3:

15

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

2034

0:

30

2:45

17

54

0:30

2:

15

100

1960

0:

30

2:45

16

82

0:30

2:

00

200

1846

0:

30

2:30

15

65

0:30

2:

00

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

55

Tabl

e 16

. R

esul

ts fo

r Max

imum

Em

issi

on R

ate

of C

arbo

n D

ioxi

de (C

ont’d

)

(c) M

aste

r bed

room

with

inte

rnal

doo

rs o

pen

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

2685

1:

45

5:30

22

68

1:30

4:

30

100

2533

1:

45

5:15

21

35

1:30

4:

15

200

2330

1:

30

4:45

19

56

1:15

4:

00

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

1620

1:

00

3:30

13

77

1:00

2:

45

100

1562

1:

00

3:15

13

26

1:00

2:

45

200

1470

1:

00

3:00

12

41

0:45

2:

30

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

56

Tabl

e 17

. R

esul

ts fo

r Typ

ical

Em

issi

on R

ate

of C

arbo

n M

onox

ide

(a) L

ivin

g ro

om w

ith in

tern

al d

oors

clo

sed

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

18

1:15

4:

30

14

1:00

3:

30

100

17

1:15

4:

30

13

1:00

3:

15

200

15

1:15

4:

15

12

0:45

3:

00

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

16

1:15

4:

00

13

1:00

3:

15

100

14

1:00

3:

30

12

1:00

3:

00

200

12

1:00

3:

15

11

0:45

2:

45

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

(b) L

ivin

g ro

om w

ith In

tern

al d

oors

ope

n

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

4 1:

15

5:00

3.

69

1:00

4:

00

100

4 1:

00

4:30

3.

11

0:45

3:

45

200

3 1:

00

4:15

2.

84

0:45

3:

15

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

3 0:

30

2:45

3

0:30

2:

15

100

2 0:

30

2:45

2

0:30

2:

00

200

2 0:

30

2:30

2

0:30

2:

00

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

57

Tabl

e 17

. R

esul

ts fo

r Typ

ical

Em

issi

on R

ate

of C

arbo

n M

onox

ide

(Con

t’d)

(c) M

aste

r bed

room

with

Inte

rnal

doo

rs o

pen

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

3 1:

45

5:30

3

1:30

4:

30

100

3 1:

45

5:15

3

1:30

4:

15

200

3 1:

30

4:45

2

1:15

4:

00

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

2 1:

00

3:30

2

1:00

2:

45

100

2 1:

00

3:15

2

1:00

2:

45

200

2 1:

00

3:00

2

0:45

2:

30

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

58

Tabl

e 18

. R

esul

ts fo

r Max

imum

Em

issi

on R

ate

of C

arbo

n M

onox

ide

(a) L

ivin

g ro

om w

ith in

tern

al d

oors

clo

sed

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

259

1:15

4:

30

203

1:00

3:

30

100

244

1:15

4:

30

189

1:00

3:

15

200

220

1:15

4:

15

174

0:45

3:

00

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

232

1:15

4:

00

189

1:00

3:

15

100

209

1:00

3:

30

178

1:00

3:

00

200

182

1:00

3:

15

162

0:45

2:

45

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

(b) L

ivin

g ro

om w

ith in

tern

al d

oors

ope

n

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

56

1:15

5:

00

48

1:00

4:

00

100

53

1:00

4:

30

45

0:45

3:

45

200

49

1:00

4:

15

42

0:45

3:

15

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

38

0:30

2:

45

33

0:30

2:

15

100

36

0:30

2:

45

31

0:30

2:

00

200

34

0:30

2:

30

29

0:30

2:

00

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

59

Tabl

e 18

. R

esul

ts fo

r Max

imum

Em

issi

on R

ate

of C

arbo

n M

onox

ide

(Con

t’d)

(c) M

aste

r bed

room

with

inte

rnal

doo

rs o

pen

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

50

1:45

5:

30

42

1:30

4:

30

100

47

1:45

5:

15

40

1:30

4:

15

200

43

1:30

4:

45

36

1:15

4:

00

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pm)

T 50

T90

E

qm

leve

l (p

pm)

T 50

T90

50

30

1:00

3:

30

26

1:00

2:

45

100

29

1:00

3:

15

25

1:00

2:

45

200

27

1:00

3:

00

23

0:45

2:

30

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

60

Tabl

e 19

. R

esul

ts fo

r Typ

ical

Em

issi

on R

ate

of N

itrog

en D

ioxi

de

(a) L

ivin

g ro

om w

ith in

tern

al d

oors

clo

sed

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb

T 50

T90

E

qm

leve

l (p

pb

T 50

T90

50

1555

0:

30

1:45

14

24

0:30

1:

30

100

1511

0:

30

1:45

13

76

0:30

1:

30

200

1436

0:

30

1:30

13

19

0:30

1:

30

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

1501

0:

30

1:30

13

78

0:30

1:

30

100

1434

0:

30

1:30

13

39

0:30

1:

30

200

1339

0:

30

1:30

12

70

0:30

1:

15

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

(b) L

ivin

g ro

om w

ith In

tern

al d

oors

ope

n

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb

T 50

T90

E

qm

leve

l (p

pb

T 50

T90

50

380

0:15

1:

30

363

0:15

1:

15

100

372

0:15

1:

30

354

0:15

1:

15

200

359

0:15

1:

30

340

0:15

1:

15

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

333

0:15

1:

15

313

0:15

1:

00

100

326

0:15

1:

15

306

0:15

1:

00

200

316

0:15

1:

00

293

0:15

1:

00

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

61

Tabl

e 19

. R

esul

ts fo

r Typ

ical

Em

issi

on R

ate

of N

itrog

en D

ioxi

de (C

ont’d

)

(c) M

aste

r bed

room

with

Inte

rnal

doo

rs o

pen

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

234

0:45

2:

00

224

0:45

1:

45

100

229

0:45

2:

00

219

0:45

1:

45

200

222

0:45

1:

45

211

0:45

1:

45

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

192

0:30

1:

30

181

0:30

1:

30

100

188

0:30

1:

30

178

0:30

1:

30

200

182

0:30

1:

30

172

0:30

1:

30

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

62

Tabl

e 20

. R

esul

ts fo

r Max

imum

Em

issi

on R

ate

of N

itrog

en D

ioxi

de

(a) L

ivin

g ro

om w

ith in

tern

al d

oors

clo

sed

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

2498

0:

30

1:45

22

87

0:30

1:

30

100

2427

0:

30

1:45

22

09

0:30

1:

30

200

2306

0:

30

1:30

21

19

0:30

1:

30

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

2411

0:

30

1:30

22

13

0:30

1:

30

100

2304

0:

30

1:30

21

50

0:30

1:

30

200

2151

0:

30

1:30

20

41

0:30

1:

15

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

(b) L

ivin

g ro

om w

ith in

tern

al d

oors

ope

n

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

611

0:15

1:

30

584

0:15

1:

15

100

597

0:15

1:

30

569

0:15

1:

15

200

577

0:15

1:

30

546

0:15

1:

15

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

534

0:15

1:

15

503

0:15

1:

00

100

524

0:15

1:

15

491

0:15

1:

00

200

507

0:15

1:

00

471

0:15

1:

00

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

63

Tabl

e 20

. R

esul

ts fo

r Max

imum

Em

issi

on R

ate

of N

itrog

en D

ioxi

de (C

ont’d

)

(c) M

aste

r bed

room

with

inte

rnal

doo

rs o

pen

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

376

0:45

2:

00

360

0:45

1:

45

100

368

0:45

2:

00

351

0:45

1:

45

200

356

0:45

1:

45

339

0:45

1:

45

Ven

t are

a (c

m2 )

Sea

son

Spr

ing

Win

ter

Eqm

leve

l (p

pb)

T 50

T90

E

qm

leve

l (p

pb)

T 50

T90

50

308

0:30

1:

30

291

0:30

1:

30

100

302

0:30

1:

30

286

0:30

1:

30

200

293

0:30

1:

30

276

0:30

1:

30

3ach

airt

ight

ness

10

ach

airti

ghtn

ess

64

Table 21. Modelled conditions in the Living Room that would exceed Standards and Guidelines

Standard/Guideline Maximum Emission Rate Typical Emission Rate Living Room Door Closed

Living Room Door Open

Living Room Door Closed

Living Room Door Open

Carbon Dioxide HSE 15min STEL Yes† No No No HSE 8 hour OES 4 – 6 hours 5 – 7 hours No No

Carbon Monoxide HSE 15min STEL Yes No No No HSE 8 hour OES 2 – 3 hours 6 – 11 hours No No WHO 15 minute mean <1 hour No No No WHO 30 minute mean <1 hour No No No WHO 1 hour mean <1 hour 1.5 – 5 hours No No WHO 8 hour mean 1 – 1.5 hours 1.5 – 5 hours 5 – 9 hours No

Nitrogen Dioxide HSE 15min STEL No No No No HSE 8 hour OES No No No No WHO 1 hour mean <0.5 hours <0.5 hours <0.5 hours <0.5 hours † No background trickle ventilation

65

Figure 1. Interior of test chamber, showing two flueless appliances, chilled beam

and mechanical ventilation supply grille

Figure 2. Closed Stove

66

Figure 3. Decorative Fire

Figure 4. Cabinet Heater

67

Figure 5. Instant Water Heater

Figure 6. Cooker

68

Figure 7. Gas analysers, data logger and PC outside of test chamber

69

10000 10000

1000 1000

Concentration Concentration (ppm) (ppb)

CO2 100

NOxCO

100 NO2

NO10

1 10

1000 100

80

60 % (°C) 100

Temperature RH

Appliance O240Room

20

10 0

100000 Ultrafine Particles

10000 (cm-3)

1000

100 0 1 2

Time (hours)

Fig 8. Closed Stove.

Maximum burn-rate, 50 cm2 purpose-provided open area ventilation

70

10000

10000

1000 1000

Concentration Concentration (ppm) (ppb)

CO2 100

NOCO

100 NO2

NO10

1 10

1000 100

80

60 %

(°C) 100Temperature

RH Appliance O240Room

20

10 00 4 8 12 16

Time (hours)

Figure 9. Closed Stove.

Pilot light only, 1 air change per hour ventilation rate

71

x

10000 10000

1000 1000

Concentration Concentration (ppm) (ppb)

CO2 100

NOxCO

100 NO2

NO10

1 10

1000 100

80

60 % (°C) 100

Temperature RH

Appliance O240Room

20

10 0

100000 Ultrafine Particles

10000 (cm-3)

1000

100 0 1 2

Time (hours)

Figure 10. Decorative Fire.

Maximum burn-rate, 100 cm2 purpose-provided open-area ventilation

72

1000010000

1000

1000

Concentration Concentration (ppm) 100

(ppb) CO2 NOxCO

10 100 NO2

NO

1

10

1000 100

80

60 %

(°C) 100Temperature

RH Appliance O240Room

20

10 0

100000

UltrafineParticles

10000(cm-3)

1000

1000 1

Time (hours)

Figure 11. Cabinet Heater.

Maximum burn-rate, 100 cm2 purpose-provided open-area ventilation

73

10000

10000

1000 1000

Concentration Concentration(ppm) (ppb)

CO2 100

NOxCO

100 NO2

NO10

1 10

1000 100

80

60 %

(°C) 100Temperature

RH Appliance O240Room

20

10 0

100000

UltrafineParticles

10000(cm-3)

1000

100 00 10 20 30

Time (minutes)

Figure 12. Instant water heater.

Maximum burn-rate, no purpose-provided ventilation

74

10000

10000

1000 1000

Concentration Concentration(ppm) (ppb)

CO2 100

NOxCO

100 NO2

NO10

1 10

1000 100

80

60 %

(°C) 100Temperature

RH Appliance O240Room

20

10 0

100000

UltrafineParticles

10000(cm-3)

1000

1000 1 2 3 4

Time (hours)

Figure 13. Oven.

Maximum burn-rate, no purpose-provided ventilation

75

10000

10000

1000 1000

Concentration Concentration (ppm) (ppb)

CO2 100

NOCO

100 NO2

NO10

1 10

1000 100

80

60 %

(°C) 100Temperature

RH Appliance O240Room

20

10 00 4 8 12 16

Time (hours)

Figure 14. Oven.

Low burn-rate, no purpose-provided ventilation

76

x

1000010000

1000

1000

Concentration Concentration (ppm) 100

(ppb) CO2 NOxCO

10 100 NO2

NO

1

10

1000 100

80

60 %

(°C) 100Temperature

RH Appliance O240Room

20

10 0

100000

UltrafineParticles

10000(cm-3)

1000

100

Time (minutes)

0 10 20 30

Figure 15. Grill.

Maximum burn-rate, no purpose-provided ventilation

77

1000010000

1000

1000

Concentration Concentration (ppm) 100

(ppb) CO2 NOxCO

10 100 NO2

NO

1

10

1000 100

80

60 %

(°C) 100Temperature

RH Appliance O240Room

20

10 0

100000

UltrafineParticles

10000(cm-3)

1000

1000 10 20 30

Time (minutes)

Figure 16. Hobs.

Maximum burn-rate, no purpose-provided ventilation

78

1000010000

1000

1000

Concentration Concentration (ppm) 100

(ppb) CO2 NOxCO

10 100 NO2

NO

1

10

1000 100

80

60 %

(°C) 100Temperature

RH Appliance O240Room

20

10 0

100000

UltrafineParticles

10000(cm-3)

1000

1000 10 20 30

Time (minutes)

Figure 17. Hobs plus pans of water.

Maximum burn-rate, no purpose-provided ventilation

79

Modern Mid-Terrace House – Plans

Modern Mid-Terrace House – Elevations

Figure 18. Plan and elevation of typical dwelling used in BREEZE model

80

0

CO

2 con

cn (p

pm)

T50

T90

500

1000

1500

2000

2500

00:00 02:00 04:00 06:00 08:00 10:00 12:00

Time

Figure 19. Example of the build-up of a pollutant in the source room

0

CO

2 con

cn (p

pm)

1000

2000

3000

4000

5000

6000

7000

8000

9000

00:00 02:00 04:00 06:00 08:00 10:00 12:00

Time

l losedInternal Doors Open Interna Doors C

Figure 20. Comparison of the build-up of pollutant in the source room with the door open and closed

81

0

CO

2 con

cn (p

pm)

500

1000

1500

2000

2500

00:00 02:00 04:00 06:00 08:00 10:00 12:00

Time

iLiv ng Room Master Bedroom

Figure 21. Example of the transport of pollutant through the home with the internal doors open

0

CO

2 con

cn (p

pm)

0

50

100

150

200

250

300

350

400

NO

2 con

cn (p

pb)

250

500

750

1000

1250

1500

1750

2000

2250

0:00 2:00 4:00 6:00 8:00 10:00 12:00

Time

Living Room CO2 Bedroom CO2 Living Room NO2 Bedroom NO2

Figure 22. Comparison of carbon dioxide and nitrogen dioxide transport

with the internal doors open

82

Printed and published by the Health and Safety ExecutiveC30 1/98

Printed and published by the Health and Safety Executive C1.10 09/04

ISBN 0-7176-2704-7

RR 127

9 78071 7 627042£25.00