Continuing Professional Development (CPD)

Presentation on Ventilation

& Control of Condensation & Mould

Presentation by

John D HousdenBA(Hons)Arch MCIM FInstSMM MIEx

Chartered Marketer, Member of Institute of Directors

30 years experience in the domestic and socialhousing market,

10 of which in ventilation

Authorised by Chartered Institute of Marketing to undertakeCPD presentations

AcknowledgmentsThis presentation has been made possible by the help and contributions from the following:

Research:Patrick Gallagher, Paul Gallagher, Howard Morley, and John Housden

of Kair Ventilation Ltd

Acknowledgments to:Tim Hudson, The Green Doctor, Groundworks Leicester and Leicestershire

Professor Paul Fleming, Institute of Energy and Sustainable Development, De Montfort University, LeicesterTom White, Health Benefits Feasibility Study

Bernard Willis, Heat Recovery Ventilation, Energy Efficiency and HealthBruce Pittingale, Home Environment Officers Network, UK Council for Economic and Environmental

DevelopmentDavid Tripp, Broxbourne Housing Association

Mark Lowers, HECA Officer, London Borough of HaveringProfessor, Dr Stirling Howieson, Strathclyde UniversityHM Government Building Regulations part F VentilationHM Government Building Regulations part L Insulation

ABB VentilationThe Energy Saving Trust

The Carbon TrustGreenwich UniversityPortsmouth University

Dr Bill Beauford – Advanced Chemical SpecialistsBlackmould.org.uk

DEFRADr. Chin S. Yang

Overview

Ventilation for Decent HomesCondensation & Mould Growth

Current LegislationHeat Recovery Ventilation

Energy Efficiency

Ventilation for Decent HomesWhat is a Decent Home?

“One that is wind and weather tight, warm and has modern facilities”– Government Definition

A Decent Home must also meet the following criteria:

• The current statutory minimum standard for housing• Be in reasonable state of repair• Have reasonably modern facilities and services• Provide a reasonable degree of thermal comfort

• If dwellings are adequately insulated, but not appropriately ventilated, the following will occur: • Increase in airborne contamination• Poor air quality• Mould growth• Reduction in air circulation• Increase in condensation

• If the air quality within a dwelling falls below acceptable levels, it will give rise to health hazards such as allergies and headaches, and also damage the building fabric in the form of mould growth.

Ventilation for Decent HomesWhat is a Decent Home?

Ventilation for Decent Homes

The three main reasons to install a ventilation system are:

To reduce the likelihood of respiratory illnesses such as asthma

To reduce the potential to be sued

To reduce damage to the building fabric

a home should have “adequate provision for lighting, heat and ventilation” and be “free from dampness prejudicial to the health of the occupants”

(Housing Act 1985)

Within the Housing Health and Safety Rating System, ‘Damp and Mould Growth‘ is identified as one of the 24 hazards. The vulnerable group is children (5-14 yrs) and the ideal is a relative humidity of 40%-60%.

Ventilation for Decent Homes

Ventilation in homes is essential to ensure the safety of occupants and help keep the building itself in a good condition.

Without adequate ventilation, rooms can become damp, which can lead to the build-up of dangerous toxic moulds. Excessive damp can also affect the building structure, leading to costly repair bills for landlords.

It is more expensive to heat rooms that have high humidity, than when humidity is controlled to within 40-60%RH.

• There is always some moisture in the air• When moisture is allowed to accumulate, the atmosphere becomes

saturated and condensation occurs• Condensation can occur either as surface, or interstitial condensation.

• This can result in damage to the structure of the building and its contents. • This leads to expensive repairs and discomfort for the occupants. • The point at which moist air may begin to cause deterioration is 50%

Relative Humidity (RH).

Condensation & Mould GrowthWhat is Condensation?

Interstitial condensationSurface condensation

Condensation & Mould GrowthThe Problems Condensation Can Cause

• The British Isles has a naturally humid environment. An estimated 4.5 million British homes suffer from the damaging effects of condensation.

• Expensive consequences of condensation include rotting wooden window frames, peeling wallpaper, mould growth, damp and eventually, rotting of the building fabric itself.

• Condensation is aggravated by a reduction in natural ventilation. This is common in today's sealed and insulated buildings.

• If moist air is unable to escape, it will condense on cooler surfaces and migrate to colder parts of the dwelling.

• Moist air is detrimental to air quality and health. It can aggravate asthma or any other upper respiratory problems.

• Moist air provides ideal living and breeding conditions of the house dust mite, whose droppings can cause asthma, rhinitis, bronchial and other allergic problems.

Condensation & Mould Growth Relative Humidity

• Relative Humidity is a measure of water vapour in the air.• 100% RH at a given temperature denotes saturation.• Optimum Relative Humidity is between 40% and 60%.• Relative Humidity below 40% causes the spread of bacteria and viruses which attack the

respiratory system.• Relative Humidity above 60% not only promotes bacteria and viruses, but also encourages

mould growth and increased activity by house dust mites, which can trigger allergies.

Condensation & Mould GrowthMould

Would you wear these shoes?

Would you eat this bread?

Condensation & Mould GrowthMould

Would you drink this water?

Condensation & Mould GrowthMould

Condensation & Mould GrowthTypes of Mould

http://www.blackmould.org.uk

• Moulds spread by releasing spores into the air. • They need moisture to grow.• Mould growth is unacceptable because of its appearance and odour, as well as health and

hygiene concerns.• Airborne mould spores can produce allergic reactions in sensitive people similar to hay fever.• People who experience allergic reaction to mould spores are also more likely to suffer from

asthma.• Water - condensed on walls, ceilings and other cold surfaces - supports mould growth. • There are three principal features common to the broad range of mould fungi:

1. Simple food requirements: able to exist on non-nutrient materials such as plaster and brick which have traces of contaminating organic matter.

2. Produce vast number of spores which allow rapid adaptation to particular environments.3. Grow very quickly under suitable conditions.

• The longer surfaces are under conditions of high moisture or local high humidity the greater the probability of mould growth developing.

• There have been approximately one hundred species of fungi detected in dwelling houses. The species commonly encountered are Penicillium, Cladosporium, Rhizopus, & Mucor.

• The appearance of mould growth in buildings often suggests poor standards of property maintenance and/or domestic activities encouraging condensation.

• Prolonged exposure to mould growth will cause disintegration and disruption of materials.

Sexual Reproduction

The life-cycle of a mould starts from the spore.

Asexual Reproduction

Again, the spore commences the cycle

Condensation & Mould GrowthThe Life Cycle of Mould

• The more humid the air, the greater the concentration of spores.

• Long-term prevention of mould and control of outbreaks is only possible by effective environmental control to ensure that conditions are unsuitable for growth.

• Good preventative measures include:

- Temperatures Below 10ºC - Relative Humidity Below 70% - Oxygen-free environments will slowly kill most moulds.

N.B. high temperatures above 50ºC will dehydrate and kill most fungi within a few hours. This can, where appropriate, be used as a control measure.

The spores can stay dormant for long periods of

time, but when the conditions are right they will

germinate.

Hyphae are filaments that are the growing stage of the mould. They secrete enzymes at their tips which dissolve organic material. The resulting solution is

absorbed back by the hyphae and used as food for growth.

When a mass of hyphae are present, the fungal colony is

known as a mycelium.

Haploid hyphae join in nuclear fusion

A zygospore results from this fusion

When the zygospore germinates, triggered by the environment, spores are released,

beginning the cycle anew.

When the environment is suitable, the spores

germinate

Hyphae grow and generate food.

Sporangiophores form, each topped with a sporangium, which

contains new spores.

New spores are released.

http://www.blackmould.org.uk

Chin S. Yang, Ph.D., 1994• Some moulds have been known to produce toxins that are harmful to animals and humans when

ingested, inhaled or in contact with the skin. • Toxigenic moulds produce the substance ergot, which causes ergotism. Gangrenous ergotism

affects the extremities as well as causes gastrointestinal symptoms. Convulsive ergotism affects the nerve system causing brain and spinal lesions which can lead to death or permanent mental impairment.

• Many moulds produce secondary toxic metabolites, such as alkaloids, cyclopeptides, and coumarins. Metabolites that can produce adverse health effects (mycotoxicoses) in animals and humans are collectively known as mycotoxins.

• There are more than 200 mycotoxins produced by a variety of common moulds. Historically, mycotoxins are a problem to farmers and food industries, as well as in Eastern European and third world countries. However, many toxigenic moulds have been found to infest buildings with known indoor air and building-related problems.

• In addition to mycotoxins, volatile organic compounds (mouldy odours) released from actively growing moulds may also pose a health risk.

• Adverse health effects of Mycotoxins range from immediate toxic response and immune-suppression to the potential long-term carcinogenic effects.

• Symptoms due to mycotoxins or toxins-containing airborne spores include dermatitis, recurring cold and flu-like symptoms, burning sore throat, headaches and excessive fatigue, diarrhoea, and impaired or altered immune function.

• The ability of the body to fight infectious diseases may be weakened resulting in opportunistic infections. Certain mycotoxins, such as zearalenone (F2 toxin), can cause infertility and stillbirths in certain animals.

Condensation & Mould GrowthToxic Effects of Mould

Condensation & Mould GrowthAsthma & Upper Respiratory Problems

• The UK has by far the highest prevalence of asthma in the world. (Howieson)

• Increasing levels of insulation, double-glazing and the sealing of open chimneys dramatically reduced domestic ventilation rates, which in turn produced warm, humid and polluted indoor environments.

• Such conditions proved ideal for the colonisation and proliferation of the house dust mite.

• The adoption of a preventative strategy will require a new approach to house design, construction and specification.

• Such an approach must be adopted if we wish to save the next generation from a lifetime spent wheezing.

The House Dust Mite

Condensation & Mould GrowthThe House Dust Mite

• The mite family ‘Pyroglyphidae’ produce a large range of particularly allergenic proteins, which have a direct causal and a dose-response relationship with asthma. (Howieson)

• It is mainly their faecal matter that is responsible.

• The only regulating factor in their common habitats is the availability of moisture.

• They have an ability to adapt and hibernate through non-optimum conditions.

• Fossil studies show that mites have existed on Earth for over 400 million years. There may be over 100 million different species of mites in existence.

• ‘Dust mite’ is the generic term for all the species of mite commonly found in homes. 13 species of mite have been found in house dust.

Condensation & Mould GrowthSpace Heating

• Space heating accounts for a great proportion of energy usage in residential households. (Bernard Willis)

• This expensively acquired heat can be wasted owing to poor ventilation and insulation.

• Ways of recovering and recycling this heat are now

available.

• One of these ways involves the application of Heat Recovery Ventilators.

Reasonable provision shall be made for the conservation of fuel and power in buildings by: - 

(a) limiting the heat gains and losses:

(i) through thermal elements and other parts of the building fabric;(ii) from pipes, ducts and vessels used for space heating, space cooling and hot water services;

(b) providing and commissioning energy efficient fixed building services with effective controls; and

(c) providing to the owner sufficient information about the building, the fixed building services and their maintenance requirements so that the building can be

operated in such a manner as to use no more fuel and power than is reasonable in the circumstances.

In essence these regulations are to ensure a degree of air-tightness in buildings to reduce energy wastage.

However, an air-tight dwelling will encourage the proliferation of house dust mites, condensation, damp and mould.

Current LegislationThe Building Regulations 2000: 2006 Edition

Part L:Insulation

Current LegislationThe Building Regulations 2000: 2006 Edition

Part F: VentilationIn general terms, the requirement may be achieved by providing a ventilation system which:

• extracts, before it is generally widespread, water vapour from areas where it is produced in significant quantities (e.g. kitchens, utility rooms and bathrooms);

• extracts, before they are generally widespread, pollutants which are a hazard to health from areas where they are produced in significant quantities (e.g. rooms containing processes or activities which generate harmful contaminants);

• rapidly dilutes, when necessary, pollutants and water vapour produced in habitable rooms, occupiable rooms and sanitary accommodation;

• makes available over long periods a minimum supply of outdoor air for occupants and to disperse, where necessary, residual pollutants and water vapour. Such ventilation should minimise draughts and, where necessary, should be reasonably secure and provide protection against rain penetration;

• is designed, installed and commissioned to perform in a way which is not detrimental to the health of the people in the building; and

• is installed to facilitate maintenance where necessary.

Current LegislationGovernment Acts & Initiatives

Fitness StandardsThe Housing Fitness Standard was a part of the Housing Act 1985. It applied to all types of accommodation and included:

– the structural stability of the property; – disrepair such as leaking roofs, dangerous wiring or faulty windows; – rising or penetrating damp; – providing a hot-water supply and suitable facilities for preparing and

cooking food, including a sink; – suitable lighting, heating and ventilation; – providing toilets, a bath or shower, and a wash-hand basin with hot and

cold water; and – an effective drainage system.

Research found that the Standard was inadequate as a mechanism for identifying dwellings which are in the worst condition, whether for targeting grant-aid or for determining where enforcement action should be concentrated.

The Housing Act 2004, which came into effect in April 2006, replaced the Fitness Standard with The Housing Health and Safety Rating System (HHSRS).

Current LegislationGovernment Acts & Initiatives

The Housing Health and Safety Ratings System (HHSRS)

The New Act

Current Housing Act Fitness RegimeHousing Health and Safety Rating System

The System of Assessment

Under the Landlord and Tenant Act, 1985, landlords are obligated to keep the structure and exterior of the property in a good state of repair. Landlords are responsible for ensuring, amongst others, that the following areas are safe and fit for use, as well as effecting repairs when necessary to restore them to a fair condition:

– The structure and exterior of the property. – Ensuring an adequate provision of lighting, heating and ventilation. – Treating of any health-threatening damp that occurs (not to be confused with condensation, a

more common but less serious problem caused mostly by poor ventilation).

Current LegislationGovernment Acts & Initiatives

Landlord & Tenants Act 1985

“If the house falls into disrepair through fair wear and tear or lapse of time, or for any reason not caused by him, then the tenant is not liable to repair it.”

- Lord Denning

Current LegislationGovernment Acts & InitiativesThe Environmental Protection Act 1990

• The EPA defines ‘statutory nuisances’ - threats to health in terms of a "threat of disease, vermin or the like".

• Specific cases have defined premises with mould growth to internal surfaces as being a statutory nuisance because of their adverse health effects. This case reiterated widely accepted research on chronic and acute health effects following inhalation of mould spores.

• Many EHOs have been involved in deciding whether mould growth in social housing is a statutory nuisance. This has normally followed action by the tenant against a local authority under section 82 of the EPA. Indeed, the most common cause of statutory nuisance in premises is mould growth to internal surfaces, caused by condensation.

• To discharge his duty under the act, a landlord needs to abate the statutory nuisance and take reasonable action to prevent the same problem in the future, given reasonable actions by the occupant.

Current LegislationGovernment Acts & Initiatives

Duty of Care“You must take reasonable care to avoid acts or omissions which you can reasonably forsee would be likely to injure your neighbour.

Who then is my neighbour?

The answer seems to be persons who are closely and directly affected by my act [or omission] that I ought reasonably to have them in contemplation as being affected when I am directing my mind to the acts or omissions which are called into question.”

Lord Atkin

Defective Premises Act 1972

A landlord who is under a repairing obligation:-

“owes to all persons who might reasonably be expected to be affected by defects in the state of the premises a duty to take such care as is reasonable in all the circumstances to see that they are reasonably safe from personal injury or from damage to their property caused by a relevant defect.”

Current LegislationGovernment Acts & Initiatives

Thermal Comfort

Heating, insulation and ventilation are not mutually exclusive and must work together in a balanced system.

The objective of a good ventilation strategy is to provide a balance between energy efficiency and indoor air quality.

Prolonged relative humidity levels (>60%) lead to condensation and mould growth. The solution is to control relative humidity levels to between 40 – 60%. This can be achieved by installing suitable ventilation systems:

- Local extract fans

- Heat recovery room ventilators

- Mechanical supply ventilation

- Passive stack ventilation

- Whole-house mechanical ventilation and heat recovery

Heat Recovery VentilationAdvantages

• Heat recovery ventilation systems recycle heat content in the exhaust air ejected out of a house need by using it to pre-warm the incoming fresh air, thereby relieving the load on the central heating system.

• Controlling the level of relative humidity in a dwelling not only minimises condensation, dampness and mould growth (CDM) but also the energy required for space heating.

• HRV can reduce household energy consumption by 9% to 21%

• Results revealed that HRV bears positive contributions toward energy saving and also control of relative humidity in dwellings.

• Heat recovery ventilators are seen to sustain humidity levels around 50% whereas extract fans allow relative humidity to rise.

• Keeping all other variables constant, HRV effect on boosting internal temperatures is clearly evident.

Heat Recovery Ventilation: Energy Efficiency And Health In UK Homes (Bernard Willis)

• Allergens derived from house dust mite faeces have been known to play a major role in allergic ailments, including asthma.

• In 2002 a study confirmed that hygrothermal conditions do impact on health by either exacerbating or hampering the growth of house dust mites. Raising bedroom temperatures from 16 to 18°C without reducing ventilation results in a factor 10 reduction in mite numbers. A reduction from 0.5 to 0.4 ach increases mite populations by factor 100.

Report on Health Benefits Feasibility Study (Tom White)

• This report presents the analysis of a survey regarding the benefits of Single Room Heat Recovery Ventilators (SRHRVs).

• 30 properties in Leicester were fitted with Single Room Heat Recovery Ventilators (SRHRV’s). The survey

was carried out after installation to ascertain the views of the recipients and to test whether the work had been successful.

• The houses were targeted specifically to include occupants who had breathing difficulties, including asthma.

• ‘Through the wall’ Heat Recovery Ventilator units were installed.

• Condensation, damp and mould growth is associated with other ailments including nausea, breathlessness and other respiratory problems, nerve damage and even death.

• Preventing an increase in the mite population and reducing condensation, damp and mould is an important issue when considering the health and well-being of the residents.

Heat Recovery VentilationHealth Benefits

Heat Recovery VentilationEnvironmental Benefits

Report on Health Benefits Feasibility Study (Tom White)

• Traditional extractor fans represent a potential waste of energy, an associated increase in carbon emissions, and an extra cost on the fuel bill of the home owner.

• Heat recovery ventilation reduces heat loss whilst providing good hygrothermal conditions.

• Overall, 76% of respondents changed the way they heated their houses after the new SRHRV’s were installed, of which 79% stated that this change was solely due to the presence of the new SRHRV’s.

Heat Recovery Ventilation: Energy Efficiency And Health In UK Homes (Bernard Willis)

• A study in the USA considered various ventilation strategies, including heat recovery, and their influence on the overall energy consumption bill of thermally insulated houses. Results indicated that total energy consumption can be reduced by 9 to 21% by using heat recovery systems.

• A Swiss study showed that current HRV met temperature efficiency of above 78% at very low electrical input.

Heat Recovery Ventilation

• There was only one type of heat recovery unit installed under the EEC 2002-2005.

• The heat recovered per kWh of electricity used by the unit was 8.5kWh.

• Ofgem considers that a 20% improvement in energy efficiency at the same operating conditions would demonstrate a significantly greater improvement in energy efficiency for these units.

Energy EfficiencyEnergy Efficiency Commitment 2005-2008

Innovative Action

Energy EfficiencyThe Energy Savings Trust (EST)

• In 1993, UK Government established The Energy Saving Trust and set a target for reducing UK emissions of carbon dioxide (CO2), one of the greenhouse gases responsible for climate change, by 20 per cent of 1990 levels by 2010.

• The Energy Saving Trust is a non-profit organisation, funded both by government and the private sector. They were set up to address the damaging effects of climate change. The aim is to cut emissions of carbon dioxide (CO2) by promoting the sustainable and efficient use of energy.

• The trust encourages individuals and organisations to commit to saving 20% of their own energy, through using low energy light bulbs, walking instead of driving, and washing clothes at 30°C, among other ideas.

• Part of the initiative involves publishing a best practice standard, to which housing professionals are encouraged to adhere.

• Of particular interest is the publication, ‘Energy efficient ventilation in dwellings – a guide for specifiers’, which details Heat Recovery Ventilation as part of best practice.

http://www.energysavingtrust.org.uk

Energy EfficiencyCarbon Trust

• The Carbon Trust is a private company set up by Government in response to the threat of climate change.

• “Our mission is to accelerate the move to a low carbon economy by developing commercial low carbon technologies and working with business and the public sector to reduce carbon emissions.”

• The Climate Change Levy (CCL) was set up to encourage the business and public sectors to improve energy efficiency and reduce emissions of greenhouse gases through a price based signal on energy usage.

• In order to protect the competitiveness of energy intensive sectors subject to international competition, Climate Change Agreements (CCAs) were introduced alongside the levy which provide an 80% discount on the levy if challenging targets are agreed and met for improving energy efficiency or reducing greenhouse gas emissions.

http://www.carbontrust.co.uk

• Condensation is a symptom of an excessively humid dwelling.• Excess humidity encourages the proliferation of house dust mites,

the exacerbation of allergy symptoms, and the emission of particles from building materials.

• Condensation provides standing liquid water, which is a potential breeding ground for harmful toxic moulds.

• Condensation can cause damage to building materials, which requires expensive repair.

• Effective ventilation dissipates moist air to the exterior of the dwelling, reducing humidity and its resulting problems.

• The benefits of this include better health and lower building maintenance expenses.

• Effective heat recovery ventilation encompasses these benefits, and adds energy efficiency, thus reducing expenditure on energy.

ConclusionThe Hazards of Condensation and the Benefits of

Ventilation