BIG Energy Upgrade - University of Sheffield · BIG Energy Upgrade programme (aka Energy Innovation for Deprived Communities). The BIG Energy Upgrade is a flagship £14.9 million

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BIG Energy Upgrade:

Environmental burden of insulation materials for whole

building performance evaluation

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Authors

Dr Danielle Densley Tingley Dr Abigail Hathway Dr Buick Davison Publication Date December 2013 Publisher University of Sheffield Copyright © 2013 The University of Sheffield All rights reserved. No part of this report may be reproduced, adapted, stored in a retrieval system or transmitted by any means, including photocopying, recording or other electronic or mechanical methods, without the prior written permission of the publisher. For permission request, please contact: Dr Abigail Hathway [email protected] Dr Abigail Hathway Department of Civil and Structural Engineering Sir Frederick Mappin Building Mappin Street Sheffield S1 3JD United Kingdom

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BIG Energy Upgrade Environmental burden of insulation

materials for whole building performance evaluation

Dr Danielle Densley Tingley Dr Abigail Hathway Dr Buick Davison

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Acknowledgements

This work has been undertaken by the University of Sheffield as a part of the Work-Package 1 of the BIG Energy Upgrade programme (aka Energy Innovation for Deprived Communities). The BIG Energy Upgrade is a flagship £14.9 million programme, part financed by the European Union Regional Development Fund (ERDF) through the Yorkshire and Humber ERDF Programme 2007-13, addressing the priority needs of reduction in carbon emissions and creation of jobs. To address the issues in an integrated approach, the University of Sheffield has brought together a multidisciplinary team of academics who are working alongside Local Authorities, ALMOs, social housing providers and an energy services company in delivering this project.

We would like to thank the Local Authorities that have taken part and provided information for this research, namely: Barnsley MBC, Doncaster MBC, Kirklees Council, Leeds City Council, North Lincolnshire Council and North East Lincolnshire Council.

Our appreciation also goes to their Housing Partners (Berneslai Homes, Kirklees Neighbourhood Housing, North Lincolnshire Homes, Shoreline Housing Partnership Ltd, St Leger Homes, West North West Homes Leeds) and Management Partners (NPS Barnsley, Leeds ALMO Business Centre) who have contributed to the University's work.

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Executive Summary

This report assesses the whole life performance of external wall insulation systems which have been installed to improve the thermal performance of the building fabric of hard to treat homes. Work conducted includes the calculation of the environmental impacts of insulation, estimation of payback periods and discussion of later life cycle stages.

The environmental impact of phenolic foam insulation boards, expanded polystyrene and rockwool boards are quantified and compared. Expanded polystyrene has the lowest environmental impact in the majority of the sixteen categories considered. A wider comparison of embodied carbon also including woodfibre board and PIR boards found woodfibre board to have the lowest embodied carbon by a significant margin – due to carbon sequestration within the wood. The end of life stage was highlighted as an area requiring further work by the industry to ensure that the render and adhesive layers can be separated from the insulation boards once the systems are dismantled so that the insulation can be recycled rather than sent to landfill or incinerated.

Briefing sheets (included as appendices) highlight key information about retrofitting British Iron and Steel Federation (BISF) and Wimpey No Fines homes. Two briefing sheets summarise information on phenolic foam boards and expanded polystyrene boards. A full report on robustness testing can also be found in the appendices.

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Contents

ACKNOWLEDGEMENTS 4

EXECUTIVE SUMMARY 5

1 INTRODUCTION 8

2 STATE OF THE ART 9

3 METHODOLOGY 9

3.1 ROBUSTNESS TESTING 9

3.2 LIFE CYCLE ASSESSMENT 10

4 RESULTS AND ANALYSIS 12

4.1 ROBUSTNESS TESTING 12

4.2 THE ENVIRONMENTAL IMPACTS OF PHENOLIC FOAM 13

4.3 ENVIRONMENTAL IMPACTS OF EXPANDED POLYSTYRENE INSULATION 16

4.4 INITIAL ENVIRONMENTAL IMPACT COMPARISON OF INSULATION MATERIALS 18

5 DISCUSSION 21

6 CONCLUSIONS 24

7 BEST PRACTICE GUIDANCE 25

8 REFERENCES 26

9 APPENDICES I

9.1 DRAWINGS OF RETROFIT MEASURES I 9.1.1 KIRKLEES BISF HOMES I 9.1.2 DONCASTER BISF HOMES II 9.1.3 INSULATION SYSTEMS TO SOLID WALL HOMES, E.G. L2, NL1 & NEL 1 III

9.2 BRIEFING SHEETS IV 9.2.1 BISF HOUSES IV-V 9.2.2 WIMPEY NO FINES HOUSES VI-VII 9.2.3 PHENOLIC FOAM INSULATION VIII-IX 9.2.4 EXPANDED POLYSTYRENE INSULATION X-XI

9.3 REPORT: ROBUSTNESS TESTING OF EXTERNAL WALL INSULATION SYSTEMS XII-XLI

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List of Units Unit Explanation

J Joule – unit of energy

KPa Measure of stress, force/area, Pa = N/m2

W/mK Measure of the thermal conductivity of a material, watts per meter kelvin

W/m2K Measure of thermal transmittance, watts per metre squared kelvin

kg CO2 eq Kg of carbon dioxide equivalents

kg CFC-11 eq Kg of CFC-11 (chlorofluorocarbon) equivalents

CTUh Comparative Toxic Unit - Human

kg PM2.5 eq Kg of fine particulate matter

kg U235 eq Kg of uranium equivalents

CTUe Comparative Toxic Unit - Ecosystems

kg NMVOC eq Kg of Non-methane volatile organic compounds equivalents

molc H+ eq Molecules of hydrogen positive ion (contains more protons than electrons) equivalents

molc N eq Molecules of nitrogen equivalents

kg P eq Kg of phosphorus equivalents

kg N eq Kg of nitrogen equivalents

CTUe Comparative Toxic Unit - ecosystems

kg C deficit Kg of carbon deficit

m3 water eq Volume of water equivalents

kg Sb eq Kg of antimony equivalents

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1 Introduction

This report critically reviews and analyses building fabric retrofit measures that have been installed as part of the BIG Energy Upgrade project, a programme which has retrofitted hard-to-treat homes (i.e. those without cavity walls) throughout the Yorkshire and Humber region. The work focuses on external wall insulation (Figure 1). Across the region this was the main measure installed to improve the energy efficiency of the building fabric. A whole life cycle assessment approach is taken to ensure a full picture of the environmental burdens and possible savings are evaluated. The work therefore assesses the environmental impacts caused by the manufacture of the insulation materials which are the main component of external wall insulation systems. Once installed these materials should improve the thermal performance of the building, thus reducing the heating requirement. Environmental paybacks of the insulation are estimated for a range of internal comfort temperatures as the potential savings will vary depending on the internal temperatures that are maintained.

Figure 1: External wall insulation system build up

In addition, material properties, installation procedures and in-use robustness are examined to identify areas which might cause underperformance of the insulation systems. This includes laboratory testing of a selection of both insulation materials and built up systems, the results of which are summarised within this report; a full report of these tests is also available online and in the appendices (Densley Tingley et al. 2013). A review of two system built houses, Wimpey No Fines and British Iron and Steel Federation (BISF) houses, is also conducted and can be found in the briefing sheets in the appendices. This is utilised in conjunction with post-retrofit performance data to assess why particular house types might underperform.

The work outlined has culminated in a number of best practice recommendations, as summarised in section ‎7. Homes retrofitted as part of the BIG Energy Upgrade project (approximately 1120) form a small part of the retrofit challenge across the UK. Dwellings account for 26% of carbon dioxide emissions (National Refurbishment Centre, 2012). Estimates suggest (Communities and Local Government, 2010) that 5% of English dwellings utilise non-traditional construction, which includes Wimpey No Fines homes and British Iron and Steel Federation (BISF) houses. A further 19% have 9” thick solid masonry walls which will also need additional insulation, either internally or externally. The work outlined in this report is therefore potentially applicable to 24% of the housing stock in England, approximately five million homes (Communities and Local Government, 2010).

Existing Wall

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The unique, whole life cycle approach taken by this project gives insights into the most effective insulation choices to minimise whole life environmental impacts of external wall insulation. These insights, used in conjunction with recommended practices for installation, should result in greater energy savings and reduced environmental impacts from retrofit.

2 State of the art

Discussions around the environmental impact of insulation generally focus on the savings that can be achieved in-use. There are, however, studies emerging (Schmidt et al. 2004; Ardente et al. 2008; Intini & Kuhtz, 2011; Dowson et al. 2012; Zampori et al. 2013) that explore the initial environmental impacts of insulation, predominantly those from manufacturing the insulation. The availability of this environmental impact data is crucial in making an informed choice on which insulation to use. When the scale of retrofit across the UK is considered, the requirement for insulation is large and thus selecting a material with a minimal environmental impact can provide significant savings at the installation stage before the in-use savings are realised.

There is full or partial environmental impact data available for a range of insulation materials, (Schmidt et al. 2004; Ardente et al. 2008; Intini & Kuhtz, 2011; Dowson et al. 2012; Zampori et al. 2013) but there are gaps in this data, particularly for insulation used as part of external wall insulation systems. There is currently no transparent information available for phenolic foam boards, a material that has been used to retrofit many of the Big Energy Upgrade homes. This lack of information has prevented life cycle assessments and payback calculations in other ERDF social housing retrofit projects (Narec, 2013). A key output of this report is therefore to provide environmental impact estimates for phenolic foam insulation boards. Provision of this information will allow environmental impact comparisons of different external wall insulation choices and environmental payback estimates for this and future projects.

3 Methodology

This work evaluates whole building performance of retrofitted homes. It is split into two sections. The main section involves estimating the environmental burden of insulation materials and their environmental payback times. The other, initial section, explores potential reasons for underperformance of the systems, including laboratory robustness testing. The methodology and approach to these sections of work is outlined below.

3.1 Robustness testing

Robustness testing of both insulation samples (Woodfibre Board, Phenolic Foam and Expanded Polystyrene) and external wall insulation systems was conducted. Full systems were subjected to 10J impact tests based on ISO 7892:1988 and ETAG 004 (2008). The results were recorded using a high speed camera, still photographs and measurements of maximum crack diameters and thicknesses. The compressive resistance of insulation samples and built up systems was also tested. Insulation samples were compressed until they reached a 10% deformation (i.e. the sample is compressed by 10% of the initial thickness, e.g. 60mm sample compressed by 6mm to 54mm). In addition, insulation and built up system samples were compressed to 50% deformation. For further details on the robustness tests see Densley Tingley et al. (2013)1.

1 A full report on robustness testing can be found in the appendices to this report

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3.2 Life Cycle Assessment

Life cycle assessment (LCA) is a recognised method of estimating the environmental impacts over the whole life cycle of a product, system or building. A representation of the life cycle of insulation materials is shown in Figure 2. The benefits of insulation in use, principally reducing heating requirements, are often discussed, however it is also important to consider the environmental burden associated with the manufacture of the insulation, the transport of it, installation, maintenance and finally impacts from disposal. Exploring the whole life cycle gives a full environmental picture of the material and can assist in the decision making process when comparing different insulation choices.

Figure 2: Life cycle stages of insulation

This report quantifies the cradle to gate environmental impacts of several insulation materials: phenolic foam, expanded polystyrene and rockwool. A cradle-to-gate study encompasses the environmental impacts from manufacturing the insulation, the scope of which is shown in Figure 3. The other areas of the life cycle are site specific e.g. transport distances of the insulation from the manufacturer to the site and in-use savings which are also dependant on occupant behaviour.

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Figure 3: Cradle to gate environmental impacts

The environmental impacts are quantified across sixteen impact categories: climate change, ozone depletion, human toxicity-cancer effects, human toxicity-non cancer effects, particulate matter, ionizing radiation HH (human health), ionizing radiation E (ecosystems), photochemical ozone formation, acidification, terrestrial eutrophication, freshwater eutrophication, marine eutrophication, freshwater ecotoxicity, land use, water resource depletion, mineral, fossil and renewable resource depletion. These are explained in Table 1. Assessing the impacts over a range of categories gives a representative picture of the environmental burdens of a material. These impact categories, with characterisation factors, are recommended in the International reference Life Cycle Data system (ILCD) from the European Commission-Joint Research Centre – Institute for Environment and Sustainability (JRC-IES, 2011) and so have been selected for use, this should enable the results to be comparable with other studies.

Impact Category Unit Explanation

Climate Change kg CO2 eq

Greenhouse gases that cause climate change added up as CO2 equivalents; uses global warming potentials from the 2007 report from the Intergovernmental Panel on Climate Change (IPCC) over 100 year timeframe.

Ozone Depletion kg CFC-11 eq Ozone depletion potentials (ODPs) from the World Meteorological Organisation used to convert gases to CFC-11 equivalent.

Human Toxicity, cancer effects

CTUh Comparative Toxic Unit for humans used, includes outdoor inhalation, ingestion of drinking water and indirect ingestion of toxins, e.g. those that have built up in plants, animals and fish (Rosenbaum et al. 2011a).

Human Toxicity, non-cancer effects

CTUh Comparative Toxic Unit for humans used, details as above.

Particulate Matter kg PM2.5 eq Intake fraction of fine particles estimated from emissions.

Ionizing Radiation, Human Health

kg U235 eq Includes transfer of contamination to the environment and potential exposure. Some uncertainty associated with the long half life of many radioactive materials.

Ionizing Radiation, Ecosystems (interim)

CTUe Comparative Toxic Unit for ecosystems used, current model focuses on effects in freshwater. Interim category recommended by the ILCD as characterization factors have yet to be outlined in a peer reviewed publication.

Photochemical ozone formation

kg NMVOC eq Emissions that cause increasing ozone concentration in the troposphere are characterised to Non-Methane Volatile Organic Compounds eq. Low level ozone can damage vegetation and cause impacts on human health.

Acidification molc H+ eq Based on accumulated exceedance, this includes atmospheric transportation and deposition of emissions whilst accounting for vulnerabilities of different ecosystems, for more details see Seppala et al. (2006).

Terrestrial Eutrophication

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molc N eq Based on accumulated exceedance, assessment of soil and atmospheric conditions and accounts for sensitivities of biodiversity in different areas (Seppala et al., 2006).

Freshwater Eutrophication

kg P eq Estimates nutrient concentrations that have transferred to a freshwater aquatic environment, focusing on phosphorous.

Marine Eutrophication

kg N eq As above, but focuses on marine aquatic environments, assessing nitrogen equivalent concentrations.

Freshwater Ecotoxicity

CTUe Comparative Toxic Unit for ecosystems used, this accounts for exposure, potential transport and effects on ecosystems (Henderson et al. 2011).

Land Use kg C deficit Assesses the quality deficit of the land occupied, using soil organic matter as a quality indicator.

Water Resource Depletion

m3 water eq Considers water use and relates this to local scarcity.

2 Eutrophication refers to large supplies of nutrients (e.g. nitrogen and phosphorus) to an environmental

system which can cause excessive growth of plants and disrupt ecosystems. For more information on the impacts of eutrophication see Smith et al. (1999).

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Mineral, fossil & renewable resource depletion

kg Sb eq Utilises abiotic (physical, non-biological resources) depletion potential, a ratio between the annual resource extraction and the reserves available. All resources converted to antimony equivalents.

Table 1: Environmental Impact Categories

The results will be shown in two ways (i) tabular quantified environmental impacts for each category and (ii) comparison graphs. In the comparison graphs the material with the greatest impact in a category is shown at 100% impact, the impact of the other materials are then shown relative to this.

4 Results and Analysis

4.1 Robustness Testing

Compression and impact tests were conducted on three different insulation samples: phenolic foam, EPS and woodfibre board. The results are summarised here; for the full report see Densley Tingley et al. 2013. In the impact tests, across all three systems, the base rail detail proved to be a weak point, with cracking occurring to the render around the point of impact and along the base rail. This is an area of concern as repeated impacts to the area could cause the base rail to detach from the system, which would allow significant water ingress, potentially affecting the thermal conductivity of the systems. For the systems with a four board joint, (i.e. phenolic foam and EPS) impact on the joint caused greater compression and cracking than impacts to the centre of a panel. Additional reinforcement mesh at these joint locations might improve the impact resistance. The tongue and groove jointing technique of the woodfibre boards meant that when impacts occurred over a joint the system flexed and the force was spread across the boards at the joint, reducing the potential permanent damage.

The woodfibre boards had the strongest 50% compressive resistance, then the phenolic foam, then EPS. For 10% compressive resistance the order alters, with phenolic foam having the highest, then woodfibre board, then EPS. This is due to the materials properties and the yield points of the insulation. On application of applied stress, when the materials’ yield points are reached permanent damage to the materials occurs. The yield points for the materials were measured as follows, EPS 40KPa, phenolic foam 120KPa, and woodfibre 200KPa, above these points permanent damage will occur. This level of stress, particularly 40KPa and 120KPa, could occur to in-situ systems from projectiles or vandalism.

Permanent visible deformation was observed for the phenolic foam under 50% compressive deformation and on closer examination voids were found within the closed cell structure, suggesting that the thermal conductivity of the insulation might be compromised. In contrast, there was no visible deformation to both the EPS and woodfibre samples; they displayed good bounce back from the maximum level of deformation at 65% and 69% respectively, compared to the phenolic foam at 37%. This correlated with the visible bounce back from the impact tests as captured on a high speed camera.

These results indicate that if the external wall insulation systems are subjected to impacts, permanent damage may be caused. Cracking may allow water ingress to the insulation and this in combination with compression of the materials may affect the thermal conductivity of the systems. It can therefore be concluded that if external wall insulation systems are found to be underperforming they should be checked for impact damage, cracking and compression as this could be a possible cause for underperformance; although the effects will likely be confined to a localised area around the impact.

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4.2 The Environmental Impacts of Phenolic Foam

Phenolic foam insulation is a commonly used external wall insulation material due to its low thermal conductivity, 0.020W/mK, which means, for the same u-value, smaller thicknesses of foam can be applied compared to other insulation materials. The foam has a closed cell structure which resists moisture and water vapour ingress. It is manufactured from fossil fuel derivatives, utilising phenolic resin as its main chemical component.

Due to the lack of available, transparent environmental data for phenolic foam insulation it was necessary to conduct work to provide estimates across the environmental impact categories for phenolic foam insulation boards. The estimates are based on the input chemicals as specified in a recent patent (Kingspan Holding Ltd, 2006). The input chemicals and quantities are summarised in Figure 4. Ecoinvent data from SimaPro 7 was used to estimate the environmental impacts of the majority of the chemicals; although this was supplemented with additional data (Schindler et al. 2010, ELCD 3.0, unknown date) where required. SimaPro 7, LCA software, was used to conduct the environmental impact assessment.

Figure 4: Diagram showing the chemical inputs to make phenolic foam insulation

The contribution to the environmental impact of phenolic foam of each of the input chemicals and key processes is shown in Figure 5. This demonstrates that phenolic resin accounts for the majority of the environmental impact across the categories; this would be expected as it is the main input chemical. The foaming and expanding process also makes a reasonable contribution to all the categories. The input from the remaining chemicals varies significantly depending on the impact category. For example, calcium carbonate has a minimal impact in all categories except for ionising radiation E where it has a considerable impact compared to the contribution from the other chemicals. This graph (Figure 5) only shows the relative impact of each chemical to the overall impact of the phenolic foam not the significance of the impact of each category. Table 2 displays the quantified impacts for each category for 1m2 of 60mm thick phenolic foam insulation.

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Figure 5: Breakdown showing the environmental impact from the components of phenolic foam insulation

Phenolic foam has a reasonably high embodied carbon if compared to other materials, however due to its recognised savings in this category in-use it is not of prime concern. Other categories with high impacts include freshwater ecotoxicity and water resource depletion. If environmental improvements were to be made, it is suggested that these categories be targeted.

Impact category Total Unit

Acidification 0.076 molc H+ eq

Climate change 17.06 kg CO2 eq

Freshwater ecotoxicity 36.03 CTUe

Freshwater eutrophication 0.0047 kg P eq

Human toxicity, cancer effects 7.32x10-7

CTUh

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%%

Environmental Impact Categories

Foaming, expanding

Calcium Carbonate

Aromatic Polyester Polyol

Ethylene oxide

Urea

Phenolic resin

Acids mix

Blowing agent mix

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Human toxicity, non-cancer effects 6.74x10-7

CTUh

Ionizing radiation E (interim) 1.34x10-5

CTUe

Ionizing radiation HH 3.22 kg U235 eq

Land use 6.026 kg C deficit

Marine eutrophication 0.011 kg N eq

Mineral, fossil & ren resource depletion 4.84x10-5

kg Sb eq

Ozone depletion 7.15x10-7

kg CFC-11 eq

Particulate matter 0.0069 kg PM2.5 eq

Photochemical ozone formation 0.085 kg NMVOC eq

Terrestrial eutrophication 0.12 molc N eq

Water resource depletion 0.032 m3 water eq

Table 2: Environmental Impact of 1m2, 60mm (R=3m2K/W) phenolic foam insulation

The significance of the environmental impacts of phenolic foam insulation can perhaps be best ascertained by looking at the environmental payback times from the savings accrued in-use. Table 3 shows the environmental payback times for the environmental impacts of a terraced house retrofit with phenolic foam insulation. The savings are based on the fall in gas use resulting from the reduction in heat loss through the external walls after phenolic insulation is installed. External temperatures are based on a Typical Temperature Year (Department of Energy, 2012) and it is assumed that a constant internal temperature is maintained. The payback times are shown for

three different internal temperatures, 20°C, 18°C and 16°C. This range of temperatures was used as

monitored internal temperatures (within homes in the Big Energy Upgrade project) were found with this level of variation.

Impact category Years Payback, 20°C Years Payback, 18°C Years Payback 16°C

Climate change 0.39 0.48 0.61

Ozone depletion 0.11 0.13 0.17

Human toxicity, cancer effects 1.66 2.03 2.59

Human toxicity, non-cancer effects 1.61 1.97 2.51

Particulate matter 3.10 3.79 4.82

Ionizing radiation HH 3.43 4.19 5.34

Ionizing radiation E (interim) 4.61 5.63 7.17

Photochemical ozone formation 2.02 2.47 3.14

Acidification 1.71 2.09 2.66

Terrestrial eutrophication 1.28 1.56 1.99

Freshwater eutrophication 3.28 4.00 5.09

Marine eutrophication 1.26 1.54 1.96

Freshwater ecotoxicity 6.43 7.86 10.00

Land use 0.25 0.30 0.38

Water resource depletion 11.30 13.81 17.57

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Mineral, fossil & ren resource depletion 2.95 3.61 4.59

Table 3: Environmental payback time for initial embodied impacts of phenolic foam

From the environmental payback estimates it can be seen (Table 3) that there are two categories in particular with long payback periods, freshwater ecotoxicity and water resource depletion. The water resource depletion category is noteworthy, taking between 11-17.5 years to pay back, which is in part due to gas having a low water impact and so the associated savings will be small. However, the water demand in the manufacturing of phenolic foam is not insubstantial. A total of 1.37m3 of water is required to produce the phenolic foam (43m2) to retrofit the terraced house example. This amount of water equates to what the average person would use over approximately 10 days. In contrast, the payback times for the climate change category are short, within a year for all three scenarios.

4.3 Environmental Impacts of Expanded Polystyrene Insulation

Expanded polystyrene (EPS) is manufactured from closed cell plastic beads which are expanded utilising a blowing agent, generally pentane (Hobbs & Ashford, 2012). The beads are fused together in moulds to form rigid boards which are used within external wall insulation systems.

Environmental impact data from the Ecoinvent database (Ecoinvent Centre, 2013) was used to quantify the burdens associated with the manufacture of 1m2, 114mm thick EPS, with a u-value=0.33W/(m2K). The impacts are shown for each category in Table 4. These are calculated for a thickness of insulation to specifically give a u-value=0.33W/(m2K) so that the results can be compared to phenolic foam of the same u-value – this means that the in-use savings would be kept constant. In reality, a specification of 110mm or 120mm of EPS would be required as it is available in 10mm increments.

Impact category Total Unit

Acidification 0.060 molc H+ eq

Climate change 14.38 kg CO2 eq

Freshwater ecotoxicity 17.12 CTUe

Freshwater eutrophication 0.0016 kg P eq


CTUh


CTUh


CTUe

Ionizing radiation HH 1.16 kg U235 eq

Land use 1.69 kg C deficit

Marine eutrophication 0.0087 kg N eq


kg Sb eq


kg CFC-11 eq

Particulate matter 0.0056 kg PM2.5 eq

Photochemical ozone formation 0.079 kg NMVOC eq

Terrestrial eutrophication 0.091 molc N eq

Water resource depletion 0.0056 m3 water eq

Table 4: Environmental impact of 1m2, 114mm thick, (R=3m2K/W) EPS

The environmental impacts of EPS can best be put into context by investigating the environmental payback periods for each category. The methods utilised were identical to those carried out for phenolic foam insulation. The payback time, in years, is shown in Table 5 for the three different internal temperatures. The lower the internal temperature maintained the longer the payback period as less gas is used to heat the property. It can be seen that all the environmental impact

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categories pay back within five years. The two categories with the longest payback periods are particulate matter and freshwater ecotoxicity. It is therefore these categories that should be targeted for reduction if environmental improvements were to be made to EPS insulation boards.

Impact category Years Payback 20°C Years Payback 18°C Years Payback 16°C

Climate change 0.32 0.39 0.50

Ozone depletion 0.07 0.08 0.10

Human toxicity, cancer effects 1.09 1.33 1.69

Human toxicity, non-cancer effects 0.40 0.49 0.62

Particulate matter 2.45 3.00 3.79

Ionizing radiation HH 1.20 1.46 1.85

Ionizing radiation E (interim) 1.20 1.47 1.86

Photochemical ozone formation 1.82 2.22 2.82

Acidification 1.31 1.61 2.03

Terrestrial eutrophication 0.91 1.12 1.41

Freshwater eutrophication 1.08 1.32 1.67

Marine eutrophication 0.93 1.14 1.44

Freshwater ecotoxicity 2.96 3.62 4.58

Land use 0.07 0.08 0.10

Water resource depletion 1.93 2.36 2.99

Mineral, fossil & ren resource depletion 0.76 0.93 1.18

Table 5: Payback times, in years, for EPS Insulation

One way in which to improve the environmental performance of EPS boards would be to use recycled material within the feedstock. EPS can be recycled – either mechanically or chemically (Hobbs & Ashford, 2012); although grinding the material down to be used as new bead feedstock is the most common method. In addition, there is a growing framework of collection points to enable EPS to be recycled (EPS, 2012). With EPS also used for disposable packaging there is potentially a large feedstock of recyclable material.

A comparison has been made to investigate the environmental impacts of different recycled contents of EPS. Three types are compared: typical EPS (0% recycled), 45% recycled EPS and 100% recycled EPS. The environmental impact comparison graph is shown in Figure 6. This demonstrates that 45% recycled EPS has a lower environmental impact across the categories than typical EPS. 100% recycled EPS has a lower impact than both options across all categories except the ionising radiation categories where the 100% recycled content EPS has a higher impact than the 45% recycled EPS – this may be due to the additional regrinding required for 100% recycled EPS. The comparison graph clearly demonstrates the environmental impact benefits of utilising recycled EPS. However, there is currently no published data on what the current recycled content, if any, of EPS insulation is. A first step in specifying EPS with a specific recycled content is the availability of this information. Asking suppliers for the current recycled content of EPS would improve the availability of this information and will thus facilitate the specification of recycled EPS insulation in the future.

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Figure 6: Environmental impact comparison of EPS with different recycled contents

4.4 Initial Environmental Impact Comparison of Insulation Materials

This section utilises environmental impact data discussed in previous sections to conduct an environmental impact comparison of different external wall insulation materials. The quantitative comparison covers the life cycle stages from cradle to gate, this includes the extraction, processing and manufacture of the insulation materials. A discussion of the environmental impacts of the other life cycle stages can be found in section ‎5. A full environmental impact comparison across all sixteen categories is made for EPS, rockwool and phenolic foam; the results can be seen in Table 7 and Figure 7. An expanded embodied carbon comparison (Figure 8) is made with two additional materials, PIR (polyisocyanurate) insulation and woodfibre board. The comparisons are conducted for insulation materials with the same u-value, u=0.33W/(m2K), this means that in-use savings will be the same and the initial impacts can be directly compared. The thermal conductivity and required insulation thickness for the different materials can be found in Table 6.

Insulation Material Thermal Conductivity (W/mK)

Required Thickness for u-value = 0.33W/(m

2K)

EPS 0.038 114mm

Phenolic Foam 0.020 60mm

Rockwool 0.036 108mm

PIR Insulation 0.027 81mm

Woodfibre Board 0.044 132mm

Table 6: Properties of insulation materials

0

10

20

30

40

50

60

70

80

90

100%

Impact Category

100% recycled EPS

45% recycled EPS

Typical EPS

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Comparing the difference thickness requirements of the insulation is a useful step as it may give an indication of the suitability of the insulation for a specific project. For many projects the thickness of insulation applied to the outside of a building will not be an issue. However, for some projects there may be limited space, or difficulties with detailing around openings or eaves if larger thicknesses of insulation are specified. Phenolic foam has the smallest thickness, 60mm, for a u-value=0.33W/(m2K) and woodfibre board the largest, at 132mm.

Impact category EPS Rockwool Phenolic Foam Unit

Climate change 14.38 15.52 17.06 kg CO2 eq


7.60x10-7

7.15x10-7

kg CFC-11 eq


7.49x10-7

7.32x10-7

CTUh


6.77x10-7

6.74x10-7

CTUh

Particulate matter 0.0056 0.014 0.0069 kg PM2.5 eq

Ionizing radiation HH 1.16 3.83 3.22 kg U235 eq


1.16x10-5

1.34x10-5

CTUe

Photochemical ozone formation 0.079 0.052 0.085 kg NMVOC eq

Acidification 0.060 0.14 0.076 molc H+ eq

Terrestrial eutrophication 0.091 0.26 0.12 molc N eq

Freshwater eutrophication 0.0016 0.0055 0.0047 kg P eq

Marine eutrophication 0.0087 0.015 0.011 kg N eq

Freshwater ecotoxicity 17.12 13.57 36.034 CTUe

Land use 1.69 12.90 6.026 kg C deficit

Water resource depletion 0.0056 0.023 0.032 m3 water eq


4.79x10-5

4.84x10-5

kg Sb eq

Table 7: Environmental Impact comparison of EPS, Rockwool and phenolic foam

From Table 7 and Figure 7 it can be seen that EPS has the lowest environmental impact across the categories with the exception of photochemical ozone formation and freshwater ecotoxicity. Therefore, for the full impact comparison, EPS is the recommended insulation choice to minimise the environmental impact of external wall insulation retrofit. Furthermore, the EPS in the comparison has no recycled content; section ‎4.3 has shown that the environmental impact could be reduced by introducing recycled material into the manufacturing feedstock.

Rockwool has the greatest impact across ten of the impact categories, although for some categories this is only by a marginal amount. Phenolic foam has the greatest impact in the remaining six categories (climate change, ionising radiation E, photochemical ozone formation, freshwater ecotoxicity, water depletion and mineral, fossil and renewable resource depletion).

20

Figure 7: Environmental impact comparison graph of EPS, Rockwool and phenolic foam insulation

From the embodied carbon comparison in Figure 8 it can be seen that woodfibre board has the lowest impact, -24.2 kgCO2eq, this is negative because the woodfibre board sequesters carbon within it. Carbon dioxide is absorbed by trees for photosynthesis over their life time, by removing this greenhouse gas from the air wood products are said to store carbon within them, otherwise referred to as carbon sequestration. Woodfibre board is made from waste soft wood, principally offcuts from sawmills and thus sequesters carbon within the boards (EPD-PTX-2010121-D). The embodied carbon estimate for woodfibre boards accounts for greenhouse gas emissions during the manufacture and for those associated with the transport to the UK supply hub.

The other four insulation options have embodied carbon values much closer together, (Figure 8), with the highest value for phenolic foam, 17.1 kgCO2eq, and the lowest for PIR, 12.8 kgCO2eq. EPS and rockwool fall in the middle of these two, with values of 13.9 kgCO2eq and 15.8 kgCO2eq respectively.

0

10

20

30

40

50

60

70

80

90

100%

Environmental Impact Category

EPS

Rockwool

Phenolic Foam

21

Figure 8: Embodied carbon comparison of external wall insulation materials. *The embodied carbon for the woodfibre board insulation includes carbon sequestration and

transport for mainland Europe to a UK hub

The significance of the insulation choice can be best demonstrated by considering a whole house retrofit and then scaling this up to large quantities of homes. The discussion shall focus on two categories in particular, climate change and water resource depletion. The impacts of these categories are easy to understand and climate change reduction is a key driver for the retrofit of homes.

Utilising the terrace home example from earlier sections, where 43 m2 of insulation was required, if EPS was used instead of phenolic foam, 115 kgCO2eq and 1.13 m3 of water eq would be saved. Scaling this up to fifty terraced homes would result in savings of 5758 kgCO2eq and 57 m3 of water eq. Finally if 1000 homes (approximately the number that were targeted for retrofit by the BEU project) were retrofitted with this alternative then 115,153 kgCO2eq and 1131 m3 of water eq would be saved. These savings are significant when considered on this scale, if all UK homes were retrofitted using phenolic foam insulation then there would be a very large water demand for the manufacture. The reduction is CO2eq is also significant; this could be increased if woodfibre board was used as an alternative to EPS, in which case the overall balance would equate to one thousand tonnes of CO2eq being sequestered within the insulation installed.

5 Discussion

The work so far has quantified the initial environmental impact of a number of external wall insulation choices. This focused on the impacts from the manufacture of the insulation and included consideration of in-use savings and payback times. The insulation choices will however have further impacts throughout their life span, arising from transport, construction, maintenance and disposal of the insulation.

All the insulation choices could either be sourced within the UK or in the case of woodfibre boards have had transport to a UK hub included within the environmental impact estimate. Impacts from transport to site will therefore be similar with all products transported by road within the UK. There will be some variability in distances to site but this site specific and would therefore need to be assessed as such.

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

5.00

10.00

15.00

20.00

Em

bo

die

d C

arb

on

(k

g C

O2e

q/m

2)

Insulation Materials

Phenolic Foam

EPS

RockWool

PIR

Woodfibre Board*

22

The environmental impact of the construction process should be similar for all the insulation choices. From discussions with contractors it was ascertained that the systems could be installed onto a typical house with five days labour, one day to erect the scaffolding, three days to install the insulation and a final day to remove the scaffolding. The process and associated energy input are shown in Figure 9.

Figure 9: Construction process for installing external wall insulation

Maintenance to the systems should be minimal over their suggested thirty year life span (WBS, 2013). Minor damage should be removed by hand and patched but more extreme damage would potentially require re-coating of the render system (WBS, unknown date). The environmental impact associated to this will likely occur from on-site diesel usage to power a generator and the environmental impact of the materials that require replacement. The environmental impacts would be less than the original retrofit as application should be to a localised area only. The required maintenance of the external wall systems in different areas would need to be monitored to ascertain how likely and often a high level of maintenance is required.

23

The most problematic issue at end of life for external wall insulation choices is contamination. If the systems are removed from the house, they will be greatly damaged during the removal process and reuse of them would not be an option. The insulation itself will have adhesives, basecoats, mesh and render at least in part still attached to it; this means that the insulation is considered contaminated which can present difficulties for recycling. Incineration with energy recovery is a possibility for all the insulation options discussed although the chemicals released during combustion may require capturing if harmful. End of life scenarios are also specific to a particular insulation type.

It is suggested (Hobbs & Ashford, 2012) that landfill is the most common end of life route for phenolic foam, although incineration is a possibility. Mechanical recycling could be possible if the processes were developed, although waste flows might not be sufficient to support this (Hobbs & Ashford, 2012). Contamination of demolition waste would likely be a problem for recycling, so developing methods to separate the insulation boards from the render build up would be a useful step; this could also be utilised for other insulation types.

EPS can be recycled at end of life and there are collection points across the UK (EPS, 2012) that facilitate this. Although these can be limited for contaminated waste, there are several sites that will take post-construction EPS if they are ‘reasonably clean and uncontaminated’ (Thompsett, 2012). The service is provided free of charge so if the majority of render and mesh can be removed this option would be cheaper than sending the EPS to landfill. The recycling that takes place is generally mechanical, breaking the EPS up, which is then used as the feedstock for new products. Chemical recycling of the polymer is also technically possible (Hobbs & Ashford, 2012). Another alternative at end of life is incineration with energy recovery, EPS can be safely burnt and has a high calorific value, greater than that of coal (Hobbs & Ashford, 2012), and so produces large quantities of heat when burnt, it may however produce greenhouse gases when burnt.

Significant work is being conducted to explore the practicalities of recycling rockwool insulation (WRAP, 2009; eco-innovation observatory, 2011, Rockwool Ltd. 2012). Practically rockwool can be recycled and Rockwool Ltd. is aiming to increase the quantities recovered from the waste stream. Work has largely focused on the feasibility of the collection of rockwool waste because, just as for the other insulation types, contaminated material cannot be recycled so this is a hurdle that must be overcome for external wall insulation systems, otherwise contaminated rockwool will likely be landfilled.

The majority of PIR is currently sent to landfill, although incineration with energy recovery is a viable alternative. Recycling is technically possible but not commonly practiced and will likely lead to the production of alternative products (Hobbs & Ashford, 2012).

Woodfibre board, if untreated, can be recovered and reused again, however, this will not be possible for those used in external wall insulation systems as the render build up will contaminate the material. Contamination may also present a problem for recycling of the material. However, contaminated recovered panels could be used for energy production in incineration plants. In the EPD (EPD-PTX-2010121-D) it is stated that 91 kgCO2eq would be produced during the disposal of 1m3 of woodfibre board; if the initial carbon impacts are also considered the overall balance is -142 kgCO2eq, demonstrating that the woodfibre board sequesters more carbon that is produced as a result of its manufacture and disposal.

The end of life stage is likely to have the most environmental impact of the life cycle stages after manufacturing. In order to minimise the impacts at the end of life of the insulation and to avoid the material being send to landfill, methods to separate the render system from the insulation boards should be developed. If the contamination can be removed from the boards then in some cases (EPS, rockwool and woodfibre) they can be recycled. In addition, the technology and infrastructure

24

may have been developed to recycle phenolic foam and PIR once the systems installed now reach the end of their lives and require disposal.

6 Conclusions This report has examined the whole life cycle performance of external wall insulation systems. There has been a focus on the environmental impact of insulation. By examining the environmental impact of insulation materials over their whole life cycle a better understanding of the materials can be gained and this information should be used when selecting insulation materials.

The environmental impact of phenolic foam insulation has been quantified; this enables insulation comparisons and the estimation of environmental paybacks in this and future studies. The freshwater ecotoxicity and water resource depletion categories were found to have the longest payback periods; these categories should be targeted for reduction if the environmental impact of phenolic foam insulation is to be reduced.

EPS is another common external wall insulation choice, the environmental impact of this has been investigated and it was found that the payback times for all categories were within five years for the three internal temperature scenarios explored. A comparison was also made between EPS with different recycled contents from which it was found that increasing the recycled content reduces the environmental impact of EPS in all categories except for ionising radiation where the 100% recycled EPS had a greater impact than the 45% EPS – this may be due to the regrinding process. It is therefore recommended that EPS with a recycled content be specified were possible and that manufacturers/suppliers are asked what the recycled content is.

A full environmental impact comparison was conducted for phenolic foam, EPS and rockwool insulation with the u-value of insulation choices kept constant at 0.33W/(m2K). The comparison demonstrated that EPS had the lowest environmental impact across the majority of categories. Rockwool has the highest impact in ten categories and phenolic foam in the remaining six. EPS should therefore be the first choice of these three options in terms of minimising the environmental impact of the retrofit. It is acknowledged that this is only one of many factors within the decision making process but it should be considered.

The wider embodied carbon comparison included two other insulation materials, woodfibre boards and PIR boards. Woodfibre boards had the lowest embodied carbon, a negative value, -24.2 kgCO2eq, due to the carbon that is sequestered during the life of the trees that provide the feedstock for the board. The other four insulation options are all synthetic and have similar embodied carbon values, with variation between 12.8-17.1 kgCO2eq. Woodfibre board should therefore be used if the minimisation of greenhouse gas emissions is the main priority.

The environmental impact of the remaining life cycle stages have also been discussed. The key stage which has uncertainties is end of life. There are several disposal options for the different insulation types, incineration with energy recovery is the most practical for contaminated insulation. If methods can be developed to separate the external wall insulation layers, leaving the insulation uncontaminated then current technologies allow EPS, rockwool and woodfibre board to be recycled. Recycling of phenolic foam and PIR is technically feasible but not currently practiced at scale; it may also result in alternative products to insulation board.

On an individual house scale the savings produced from an insulation choice may appear small, but if considered on the scale of retrofit required across the UK the savings become much more significant. Approximately one thousand homes were targeted for retrofit as part of the Big Energy Upgrade. If one thousand terraced homes were retrofitted with EPS instead of phenolic foam, 115

25

tonnes of CO2eq and 1131m3 of water would be saved. If the five million homes that require thermal improvement were retrofitted with EPS instead of phenolic foam then the savings would equate to 575,764 tonnes CO2eq and 5.6 million m3 of water. This is from the retrofit alone; there will be further savings during the use of the material from the reduction in heating requirement. When retrofitting homes to assist the UK in meeting greenhouse gas reduction targets the use of a whole life cycle approach is crucial in order to minimise environmental impacts across the life cycle.

7 Best Practice Guidance

The following list outlines key facts and recommendations found during the course of this work, as outlined in this report and the briefing sheets found in the appendices. These recommendations are designed for those selecting and specifying external wall insulation systems.

1. Consider environmental impact as a key decision making factor when selecting external wall insulation, utilising comparison graphs within this report

2. EPS has the lowest environmental impact across all but two impact categories compared to phenolic foam and rockwool

3. Woodfibre board has the lowest embodied carbon of the five materials compared

4. Specify recycled EPS where possible and ask what the recycled content is

5. Woodfibre board has the highest 50% compressive resistance and is thus least susceptible to impact damage (compared to phenolic foam and EPS)

6. Impact damage to the external wall insulation systems could be a factor if a home is found to be underperforming

7. Air gaps between board joints could also be a factor in an underperforming home

8. Thermal bridging under the base of the external wall insulation system will be an area of heat loss – possibly leading to underperformance of the home

9. For BISF houses integrate an air tightness strategy with the installation of external wall insulation to improve overall thermal performance

10. For Wimpey No Fines homes if gable wall is brick clad this should be insulated too in order to reduce thermal bridging

26

8 References

Ardente, F., Beccali, M., Cellura, M. & Mistretta, M. 2008. Building energy performance: a LCA case study of kenaf-fibres insulation board. Energy and Buildings, 40, pp: 1-10

Communities and Local Government, 2010. English Housing Survey – Housing stock report 2008. Department for Communities and Local Government Publications: London. Available at: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/6703/1750754.pdf [accessed 06/11/13]

Densley Tingley, D., Stocks, G., Hathway, A., Allwood, D. & Davison, B. 2013. Robustness testing of external wall insulation systems. Available in the appendices

Department of Energy, 2012. EnergyPlus Energy Simulation Software, Weather Data, All Regions, United Kingdom. Available at: http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=6_europe_wmo_region_6/country=GBR/cname=United%20Kingdom [accessed 03/12/13]

Dowson, M., Grogan, M., Birks, T., Harrison, D. & Craig, S. 2012. Streamlined life cycle assessment of transparent silica aerogel made by supercritical drying. Applied Energy, 97, pp: 396-404

Eco-innovation observatory. Recycling of Used Rockwool. Available at: http://www.eco-innovation.eu/index.php?option=com_content&view=article&id=406:recycling-of-used-rockwool&catid=55:denmark [accessed 27/11/13]

Ecoinvent Centre. 2013. The ecoinvent Database. Available at: http://www.ecoinvent.org/database/ [accessed 25/11/13]

ELCD 3.0 – European reference Life Cycle Database, Unknown date. Calcium Carbonate. Available at: http://elcd.jrc.ec.europa.eu/ELCD3/resource/processes/6006d87e-ccee-42b1-b203-f67c7c0bad97?format=html&version=03.00.000 [accessed 25/09/13]

EPD-PTX-2010121-D. Environmental product declaration: Pavatex Woodfibre insulation board. Institut Bauen und Umwelt e. V.

EPS, 2012. EPS and the environment – find an EPS recycler. Available at: http://www.eps.co.uk/sustainability/eps_recycler.html [accessed 25/11/13]

Hammond, G. & Jones, C. 2011. Inventory of Carbon & Energy (ICE) Version 2.0. Available at: http://www.siegelstrain.com/site/pdf/ICE-v2.0-summary-tables.pdf [accessed 05/12/13]

Henderson, A.D., Hauschild, M.Z., van de Meent, D., Huijbregts, M.A.J., Larsen, H.F., Margni, N., McKone, T.E., Payet, J., Rosenbaum, R.K. & Jolliet, O. 2011. USEtox fate and ecotoxicity factors for comparative assessment of toxic emissions in life cycle analysis: sensitivity to key chemical properties. International Journal of Life Cycle Assessment, 16, pp:701-709

Hobbs, J. & Ashford, P. 2012. Building Insulation Foam Resource Efficiency Action Plan, prepared by the Resource Efficiency Partnership. Available at: http://www.wrap.org.uk/content/building-insulation-foam-resource-efficency-action-plan [accessed 25/11/13]

Intini, F. & Kuhtz, S. 2011. Recycling in buildings: an LCA case study of a thermal insulation panel made of polyester fibre, recycled from post-consumer PET bottles. International Journal of LCA, 16, pp: 306-315

27

JRC-IES. 2011. ILCD Handbook, International Reference Life Cycle Data System, Recommendations for Life Cycle Impact Assessment in the European context – based on existing environmental impact assessment models and factors. Luxemburg: Publication Office of the European Union.

Kingspan Holdings Limited. 2006. A Phenolic Foam. International Patent Application, No. PCT/IC2006/000096, 8th September

Narec. 2013. ERDF Social Housing Energy Management Project, Final Project Report, October 2013. Available at: http://www.narec.co.uk/narec.co.uk/documents/erdf-social-housing/erdf_social_housing_energy_management_-_final_project_report.pdf [accessed 28/11/13]

National Refurbishment Centre, 2012. Refurbishing the Nation – Gathering the evidence. BRE & Energy Saving Trust. Available at: http://www.rethinkingrefurbishment.com/filelibrary/nrc_pdf/NRC_reportSEP2012web.pdf [accessed 06/11/13]

Rockwool Ltd. 2012. Recycling and waste Handling. Available at: http://www.rockwool.com/csr/committed+to+society/sustainability+reports/recycling+and+waste+handling [accessed 27/11/13]

Rosenbaum, R.K., Huijbregts, M.A.J., Henderson, A.D., Margni, M., McKone, T.E., van de Meent, D. Hauschild, M.Z., Shaked, S., Li, D.,S., Gold, L.S. & Jolliet, O. 2011. USEtox human exposure and toxicity factors for comparative assessment of toxic emissions in life cycle analysis: sensitivity to key chemical properties. International Journal of Life Cycle Assessment, 16, pp: 710-727

Schindler, A., Habel, F., & Baitz, M. PE International. March 2010. Eco-profile of Aromatic Polyester Polyols (APP). Report for PU Europe, Federation of European rigid Polyurethane Foam Associations. Available at: http://www.pu-europe.eu/site/fileadmin/Reports_public/PU_10-204_PU_Europe_project_-_Eco-Profile_of_Aromatic_Polyester_Polyols__APP_.pdf [accessed 25/09/13]

Schmidt, A.C., Jensen, A.A., Clausen, A.U., Kamstrup, O. & Postlethwaite, D. 2004. A comparative life cycle assessment of building insulation products made of stone wool, paper wool and flax, part 2L comparative assessment. International Journal of LCA, 9 (2), pp:122-129

Seppala, J., Posch, M., Johansson, M. & Hettelingh, J.P. 2006. Country-Dependent Characterisation Factors for Acidification and Terrestrial Eutrophication Based on Accumulated Exceedance as an Impact Category Indicator. International Journal of LCA, 6, pp: 403-416

WBS (Wetherby Building Systems Ltd.) unknown date. Silicone & Acrylic, Aftercare & Maintenance. Available at: http://www.wbs-ltd.co.uk/wp-content/uploads/2011/10/silicone_aftercare.pdf [accessed 27/11/13]

WBS (Wetherby Building Systems Ltd.) 2013. System Approvals. Available at: http://www.wbs-ltd.co.uk/wetherby-systems/system-approvals/ [accessed 27/11/13]

WRAP, 2009. Rockwool and Knapzak Trial, Deomstruaction trial report assessing the use of the Knapzak container on site to collect waste mineral wool insulation for recycling by Rockwool Ltd. Available at: http://www.wrap.org.uk/sites/files/wrap/WRAP_Trial_Report_ROCKWOOL%2BKNAPZAK%20%282%29.pdf [accessed 27/11/13]

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Zampori, L., Dotelli, G. & Vernelli, V. 2013. Life cycle assessment of hemp cultivation and use of hemp-based thermal insulator materials in buildings. Environmental Science Technology, 47, pp: 7413-7420

i

9 Appendices

9.1 Drawings of Retrofit Measures

9.1.1 Kirklees BISF Homes

Existing finishes are retained unless corroded or damaged. Different retrofit treatments are applied to the ground and first floor, as shown on the diagrams.

Existing Wall

EPS Filler

60mm Phenolic foam

Render finish

Glass fibre reinforcing mesh

Scrim adhesive

ii

9.1.2 Doncaster BISF Homes

Existing Wall

Render finish

Glass fibre reinforcing

mesh

Scrim adhesive

60mm Phenolic foam

18mm plywood sheet

50mm timber studs

Existing Wall

Render finish

Base coat Structherm system: EPS insulation core with welded wire

cage surround

iii

9.1.3 Insulation systems to solid wall homes, e.g. L2, NL1 & NEL 1

9.2 Briefing Sheets

9.2.1 BISF Houses

9.2.2 Wimpey No Fines Houses

9.2.3 Phenolic Foam Insulation

9.2.4 Expanded Polystyrene Insulation

9.3 Report: Robustness testing of external wall insulation systems

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vi

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viii

ix

x

xi

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Robustness testing of external wall insulation systems

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Authors Dr Danielle Densley Tingley Georgina Stocks Dr Abigail Hathway Dr Dan Allwood Dr Buick Davison Publication Date November 2013 Publisher University of Sheffield Copyright © 2013 The University of Sheffield All rights reserved. No part of this report may be reproduced, adapted, stored in a retrieval system or transmitted by any means, including photocopying, recording, or other electronic or mechanical methods without the prior written permission of the publisher. For permission request, please contact: Dr Abigail Hathway [email protected] Dr Abigail Hathway Department of Civil and Structural Engineering Sir Frederick Mappin Building Mappin Street Sheffield S1 3JD United Kingdom

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Robustness Testing of External Wall Insulation

Systems

Dr Danielle Densley Tingley Georgina Stocks

Dr Abigail Hathway Dr Dan Allwood

Dr Buick Davison

xv

Acknowledgements

We would like to thank Natural Building Technologies and other suppliers for kindly providing us with external wall insulation samples to test; the work could not have been conducted without these and their support is very much appreciated.

The project would not have been possible without funding as part of the University of Sheffield’s SURE scheme, which funded the laboratory tests and our undergraduate student’s time.

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Contents

ACKNOWLEDGEMENTS XV

1 INTRODUCTION XVIII

2 HARD BODY IMPACT TESTS XIX

3 COMPRESSION TESTS XXVI

4 KEY FINDINGS AND RECOMMENDATIONS XXX

5 REFERENCES XXXII

6 APPENDIX XXXIII

6.1 SUPPORTING INFORMATION FOR COMPRESSION TESTS XXXIII 6.1.1 WOODFIBRE BOARD SAMPLES XXXIII 6.1.2 EPS SAMPLES XXXV 6.1.3 PHENOLIC FOAM SAMPLES XXXVII

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Executive Summary

This report presents the results from laboratory-based robustness testing of external wall insulation systems. Two tests were conducted: impact tests and compression tests. These were carried out on three different insulation systems: woodfibre board, expanded polystyrene boards and phenolic foam boards.

In both impact and compression tests the woodfibre samples showed good bounce back (high elasticity) and low relative deformation. The jointing system utilised meant that on impact across two or more boards the woodfibre performed as a system, spreading impact across a larger area, reducing the permanent damage. High stresses (>1000KPa) were required to achieve a 50% deformation of the samples, making it unlikely that high levels of permanent deformation would occur to installed systems.

The phenolic foam samples required the highest stresses to reach a 10% deformation. However, under the higher stresses (>300KPa) that cause a 50% deformation, permanent deformation occurs to the cellular structure of the foam, which will be detrimental to its thermal performance. It is a possibility that this level of force could occur to installed products, through vandalism or hard body impacts.

The EPS samples suffered the greatest initial deformation across the impact tests, although demonstrate good bounce back and low relative deformation. An area of concern for this system is the level of cracking that occurs to the render upon impact. There is significant compression of the insulation on impact, which cracks the render system. This could perhaps be reduced if a render system with more flexibility was used, so it could bounce back after compression with less permanent damage. Due to the low level of stress required (>170KPa), it is likely that some compression and cracking to this in-situ system would occur if it is subjected to even modest impacts.

To improve the robustness of the systems, it is recommended that developments are made to two areas:

The base rail detail of all systems – cracking and metal deformation occurred here in the impact tests of all three insulation systems. This would result in water ingress through the render to the insulation, compromising the performance of the system.

The jointing between four boards for the phenolic foam and expanded polystyrene systems – significant cracking was seen in the impact tests for four board join samples. As above, this would allow water ingress into the systems.

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1 Introduction

The aim of this work was to investigate the robustness of external wall insulation systems. As these systems encase the outside of a house it is important that they can resist impacts from projectiles, skateboards, vandalism and stand up to everyday life (e.g. ladders and bikes may be leant against them) without significant damage. A series of laboratory tests have been conducted to investigate the robustness of external wall insulation systems.

External wall insulation is applied to buildings, usually those with a solid wall, to improve their thermal performance, thus lowering heating requirements and bills, and reducing the environmental impacts associated with heating. These systems are built up of several layers (Figure 10) fixed onto the existing wall mechanically and/or with adhesives. Damage will most likely occur to the outer, rendered layer in the form of cracking. However, significant damage could allow water penetration into the system, and this in turn may affect the thermal conductivity of the insulation. Significant compression to the system could also affect the thermal conductivity. It is therefore important to understand the likelihood of cracking and compression to the systems.

Figure 10: External Wall Insulation System - Layer Build up

Three different insulation systems were investigated, a woodfibre board system, a phenolic foam system and an expanded polystyrene (EPS) system. The specification of these and system breakdowns can be seen in Table 8.

Woodfibre Board System 3

Phenolic Foam System EPS System2

Diffutherm: 100mm thick impact samples

60mm thick compression samples

50mm thick Phenolic foam board for all tests

50mm thick EPS board for all tests

3 Supplied by Natural Building Technologies, http://www.natural-building.co.uk/

Existing Wall

xix

8mm MC55 – multicontact bonding mortar

Primer, Basecoat & Scrim Primer, Basecoat & Scrim

2mm Nanopor Putz Top Coat

1.5mm Silicone Finish 1.5mm Silicone Finish

Table 8: System specification and components of testing samples

The systems were subjected to two tests: hard body impact tests and compression tests. The procedure and results of these are outlined in sections ‎2 and ‎3.

2 Hard Body Impact Tests

All the hard body impact tests were conducted on built up system, rendered, insulation panels. For each insulation type, four different samples were tested: a single panel, a joint between two boards, a joint between four boards (three in the case of woodfibre due to the system utilised) a base-rail detail, and an edge detail for the EPS and phenolic foam systems. More details of these can be seen in Figure 11. Details of where the systems were impacted are also shown in Figure 11, with up to three impacts per sample, each on a different area of the sample.

Figure 11: External wall insulation sample types tested. The ‘X’ marks indicate where the samples were impacted (grey X marks are tests conducted on phenolic and EPS samples only).

Phenolic & EPS samples only tested for four-board join

Woodfibre board tests on three-

board join

Base rail detail

Edge detail, phenolic & EPS samples only

xx

The jointing technique between panels varied across the three systems, as shown in Figure 12. The woodfibre boards lock closely together with little air gap between them, whereas a small air gap can be seen between the phenolic foam and EPS boards.

Figure 12: Jointing between two insulation panels, (a) woodfibre board, (b) phenolic foam board, (c) EPS insulation board

Each of the boards was subjected to a 10J impact. A 1 kg steel ball was dropped from a height of 1.02m to the centre point of impact. A release point was marked on the red frame shown in Figure 13 to ensure the drop height remained consistent. This test set up was based on ISO 7892:1988 and ETAG 004 (2008). Each of the samples was attached to a metal frame (Figure 13); the point of impact was always against the centre steel section piece to mimic the stiffness of a wall. This was kept consistent throughout the tests. Videos of the impacts were taken using a high-speed camera operated at a frame rate of 900 frames per second. Photographs of the impacted surfaces were also taken and crack thicknesses recorded (Figure 14, Figure 15, Figure 16, Table 9, Table 10, Table 11).

(b)

(c) (a)

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Figure 13: Photograph of the test set up for the impact tests, a mark on the red frame was used as a release point for the pendulum, to ensure consistency. The high speed camera which was used to

capture the impacts can be seen in the bottom right corner.

The results for the woodfibre impact tests can be seen in Table 9. Cracking was typically in a circular shape, as can be seen in Figure 14. In Table 9, the Dia. X is the widest diameter the crack extended in the horizontal direction and Dia. Y refers to it in the vertical direction, the greatest crack thickness is also given.

Woodfibre Centre Woodfibre two-board Woodfibre Base Rail Woodfibre three-board

C T B A R M L A R M L A R L A

Dia. X (mm) 38 35 50 41 38 39 42 39.7 50 49 76 58.3 67 43 55

Dia. Y (mm) 44 29 38 37 40 40 45 41.7 19 23 24 22 53 39 46

Max. crack

thickness (mm)

0.3 0.1 0.3 0.23 0.4 0.1 0.1 0.2 0.6 0.2 0.3 0.37 0.5 0.6 0.55

Base rail damage length (mm)

165 165 170 167

Table 9: Crack sizes for woodfibre board impact tests (Note that A refers to the average size crack, the following notations indicate the position of impact on the board, R right, M middle, L left, C

centre, T top and B bottom)

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Comparing the crack sizes for the different woodfibre samples, it can be seen that the greatest crack thickness occurs for the three-board join, although the average diameter of this impact was no larger than that from other tests. The base rail sees the widest crack in a horizontal direction; the impact results in cracks along the base rail on average 167mm in length. From the high-speed camera footage of the three-board join it can be seen that the whole woodfibre board flexes on impact. This is seen to be particularly the case where two or three boards join together. This dissipates the force, reducing the localised compression. The material also visibly bounces back from the maximum compression point. The jointing system of the woodfibre boards appears to facilitate this unified behaviour so that it acts more as a system than an individual board.

Figure 14: Typical impact behaviour of the woodfibre boards, (a) a single board; (b) two-board join; (c) three-board join; (d) base rail impact

The impact results for phenolic foam can be seen in Table 10 and the typical cracking behaviour in Figure 15. The crack thickness and diameter increased the more boards that are joined, suggesting that the junction point between four boards is one of the weakest parts of the system. However, the likelihood of impacts occurring to this specific junction is small. The corner detail when impacted on a straight face performs well, although this might change if impacts were incurred directly to the edge; further testing would be required to ascertain this. The base rail damage, as

(a) (b)

(c) (d)

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with the woodfibre system, extends beyond the impact diameter, with a crack forming along the metal base rail fixture (Figure 15). This result implies that repeated impacts to this area would likely cause extensive damage and might result in the base rail detail becoming detached from the system. More testing would be required to conclusively ascertain the extent of damage that multiple impacts would cause. The high-speed camera footage of the four board join showed that there is a small amount of flex from the whole board upon impact, but the compression is significant and localised to the point of impact. There is some bounce back but a visible impression remains in the surface of the sample.

Phenolic Single Phenolic two-board Phenolic Base Rail Phenolic

Corner

Phenolic four-board

C T B A R M L A R M L A L M R

Dia. X (mm) 40 41 40 40.3 35 40 33 36 163 63 40 88.6 0 27 183 50

Dia. Y

(mm)

33 45 38 38.7 35 37 34 35.3 22 23 24 23 0 17 42 50

Max. crack thickness (mm)

0.06 0.12 0.08 0.09 0.08 0.14 0.12 0.1 0.12 0.1 0.5 0.24 0 15 0.08 0.4

Base rail damage length (mm)

284

Table 10: Crack sizes for phenolic foam impact tests (Note that A refers to the average size crack, the following notations indicate the position of impact on the board, R right, M middle, L left, C

centre, T top and B bottom)

(a) (b) (c)

(d)

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Figure 15: Impact test result for phenolic foam samples, (a) single board, (b) two-board join, (c) four-board join, (d) base rail impact

The impact results for EPS can seen in Table 11 and Figure 16. The results show a similar pattern to those of the phenolic foam, the crack thickness increases the more boards that join together, although the crack thickness for EPS are larger than those for phenolic foam. The impacts to the corner face cause minimal damage, with no visible cracking on two impacts and a fine crack on the third. The base rail impacts show a similar pattern to the other samples, with cracking along the rail and some deflection of the metal. From the high speed camera image of the four board join it can be seen that there is significant compression to the sample on impact. There is substantial bounce back seen, but the initial compression is such that large cracks are formed in the render, with pieces breaking off.

EPS Centre EPS two-board EPS Base Rail EPS Corner EPS four-board

C T B A R M L A R M L A L M R

Dia. X (mm) 45 61 31 45.7 58 46 49 51 71 45 59 58.3 0 0 110 64

Dia. Y (mm) 52 65 38 51.7 45 40 48 44.3 28 22 25 25 0 0 45 55

Max. crack thickness (mm)

0.5 0.4 0.06 0.32 0.2 0.14 3 1.1 0.3 0.3 0.2 0.27 0 0 0.06 1.6

Base rail damage 160 117 107 128

Table 11: Crack sizes for EPS impact tests (Note that A refers to the average size crack, the following notations indicate the position of impact on the board, R right, M middle, L left, C centre,

T top and B bottom)

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Figure 16: Impact test results for EPS boards, (a) Single board, (b) 2 board join, (c) 4 board join, (d) base rail

The woodfibre board systems tested had a greater thickness of insulation, 100mm, compared to the 50mm phenolic and EPS systems so the tests are not directly comparable. However, the material behaviour on impact would likely be similar with different thicknesses of insulation. Across the systems the base rail seems to be a weak point, with cracking occurring along it upon impact. If this were subjected to multiple impacts the damage could become more extensive. Multiple impacts are possible as this detail is close to the ground, so could be kicked or have footballs kicked against it. Exploring means of strengthening this detail in all systems is recommended.

Generally for the phenolic and EPS systems the base rail detail occurs 100mm off the ground, leaving a cold bridge from the end of the insulation to the ground, as seen in Figure 17. Detailing to avoid this cold bridge should be investigated in conjunction with improving the impact resistance.

(a) (b) (c)

(d)

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Figure 17: Thermal image of home with external wall insulation

3 Compression Tests

Small samples of 60mm thick woodfibre board insulation (80x90mm laterally) and 50mm thick EPS and phenolic foam (70x70mm laterally) were placed under compressive loads. Both the built up insulation systems and isolated insulation samples, without render, were tested. Before each test the exact size of the sample was measured; this size was measured again immediately after compression, 1 hour after the compression test and 24 hours later. The amount each sample recovered its thickness after the compression was calculated, as was the relative deformation after 24 hours (Table 12 and Table 14). The relative deformation is a ratio between the change in thickness and the initial thickness ([initial thickness-final thickness]/initial thickness).

The insulation samples were subjected to a compression test, taken to 10% deformation at a rate of 3 mm/min. 10% deformation means that the samples are compressed by 10% of their original size, e.g. a 50mm sample is compressed by 5mm. For each insulation type two samples were tested and the results of these averaged; these can be seen in Table 12. For the woodfibre insulation one of the samples increased in thickness from 59mm to 60mm, the other reduced from 61mm to 60mm. The increase in thickness could be due to the fibres within the samples being displaced from their original position and finding a new equilibrium position once the compression was removed. The average of these suggests negligible permanent deformation of woodfibre board under these test conditions. For the EPS samples, one had no permanent deformation and the other sample a permanent deformation of 2%. Of the three samples, woodfibre insulation has the lowest relative deformation and phenolic foam the greatest, approximately 2.5%, when the samples are subjected to a 10% compression test.

Woodfibre Phenolic Foam EPS

Bounce Back (mm) 6.00 3.85 4.35

Bounce Back, % of max. 101% 76% 90%

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deformation

Relative Deformation %

((initial-final)/initial)x100

-0.05% 2.5% 1%

Table 12: Relative deformation 24 hours after for 10% compression test of un-rendered samples

During the 10% compression tests, the stress on the material was recorded, as shown in Table 13. This was compared to manufacturer’s data and predicted compressive resistance of the material at 10% compression. For the woodfibre board, test 1 shows a very similar strength to those stated in product data (NBT, 2013). In the second test this is reduced by almost 13%. As the samples were mechanically cut into appropriate test sizes it is possible that this process damaged the adhesion between fibres, resulting in a lower compressive strength than expected. Both phenolic foam samples exceeded the minimum compressive resistance as specified by ASTM Standard C1126-12a. As the EPS would be utilised in a wall application with minimal load, it is assumed it is classified as a Type I material for the ASTM Standard C578-12b. A compressive resistance of 69kPa is suggested for Type I EPS at either 10% deformation or at yield, whichever of these first occurs (ASTM Standard C578-12b). It can be seen (Table 13) that neither test results meet this criteria, one by more than 30%. The standard is based on a 25.4mm thick sample but suggests that lower values will result for thicker materials (ASTM Standard C578-12b, 2012). This might, at least in part, explain the lower test results for the 50mm thick samples used here.

Insulation Min. compressive resistance for

10% compression or yield point

(kPa)

Test 1 Result

(kPa)

Test 2 Result

(kPa)

Woodfibre 704 69.8 61.0

Phenolic Foam 1245 162.5 138.3

EPS 696 61.3 46.4

Table 13: Stress at 10% compressive deformation for un-rendered samples

Insulation and the built up systems were also tested under 50% compressive deformation, and as before, two samples of each type were tested and the results averaged (Table 14). All samples at

4 Natural Building Technologies, Pavatex- Technical Specification Diffutherm Data Sheet. Available at: http://www.natural-building.co.uk/systems/new-build/pavawall [accessed 24/10/2013]

5 ASTM Standard Specification for Faced or Unfaced Rigid Cellular Phenolic Thermal Insulation 6 ASTM Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation

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50% deformation were permanently compacted. The rendered woodfibre samples had the lowest relative deformation and the phenolic rendered system the largest.

Woodfibre Woodfibre Rendered

System

Phenolic Foam

Phenolic Rendered

System

EPS EPS Rendered

System

Bounce Back (mm) 20.5 23.5 9.5 9.5 16 17

Bounce Back % of max. deformation

69% 67% 37% 36.5% 65% 62%

Relative Deformation % ((initial-final)/initial)x100

16.5% 14.0% 31% 32.5% 17.0% 19.0%

Table 14: Relative Deformation, after 24 hours, of insulation materials and rendered systems, for 50% deformation

Both compression tests show the same pattern for the material properties. Woodfibre has the least relative deformation, then EPS and then phenolic foam. Woodfibre insulation is a fibrous material, and has an elastic response to the compression. The EPS behaves elastically until it reaches its yield point at 40kPa stress, above which it will undergo permanent deformation. This is reflected in the relative permanent deformation of the EPS samples, which increased significantly from the 10% deformation to the 50% deformation. The phenolic foam also behaves elastically until it reaches its yield point at approximately 120kPa after which permanent deformation occurs to the insulation. Visible permanent compressive deformation can be seen in the sample (Figure 18). Examining this at a cellular level, Figure 19, it can be seen that voids are formed in the closed cell structure. This level of deformation would likely increase the thermal conductivity of the phenolic foam.

Figure 18: Compressed phenolic foam samples showing deformation in the middle of the insulation sample, (a) non-rendered sample, (b) rendered sample with full system build up

(a) (b)

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Figure 19: Phenolic foam samples under optical microscope (a) in virgin state and (b) after 50% compression

It is important to consider at what stress the different insulation samples reach 10% and 50% compression, as this will reflect the likelihood of this occurring to systems once installed on homes. Table 13 shows the stresses that attained a 10% deformation for each of the samples. EPS requires the least stress, 53.9KPa on average, to reach a 10% deformation and phenolic foam the most stress, averaging at 150.4KPa.

The stresses required for a 50% deformation are shown in Table 15, from this it can be seen that the built up systems require a much higher stress for a 50% deformation, which is part of the purpose of the fibre reinforcement and render. EPS has the lowest 50% compressive strength, 136.5KPa, but in contrast to the 10% compressive strength, unrendered woodfibre has the highest 50% compressive strength, 788KPa, whereas phenolic foam requires a stress of 285KPa for 50% compression. This is due the inherent material properties, once phenolic foam’s cellular structure starts to break, its strength is weakened and visible compression occurs, as seen in Figure 18, these are characteristics of brittle behaviour. Whereas, for the woodfibre board, compression pushes the fibres together so they are more tightly packed, making it harder to compress and as such the stress required for a 50% deformation is nearly three times that of phenolic foam and almost six times that of EPS. It should be noted that the woodfibre samples are 60mm thick compared to 50mm thick EPS and phenolic foam samples. This in principle should not alter the pattern of results as the load is continuous through the material structure.

Woodfibre Woodfibre

Rendered

Phenolic Foam

Phenolic Foam

Rendered

EPS EPS

Rendered

Test 1 Stress (KPa)

804 1011 265 318 134 180

Test 2 Stress (KPa)

772 1055 305 286 139 176

Average Stress (KPa)

788 1033 285 302 136.5 178

Table 15: Forces and stresses required to reach 50% deformation of sample

It is important to explore what level of forces could be inflicted on the insulation systems in everyday life in order to understand what level of deformation is likely. In a study of Olympic boxers (across weight classes) the force from a straight/extended punch ranged from 1990-4741N

(a) (b)

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(Walilko et al. 2005). Kicks would likely generate a larger force than this as more mass can be recruited. Impacts of this type in a vandalism context would likely fall into the lower range, but this would be sufficient to cause a 50% deformation in both the EPS and phenolic foam rendered systems, as from the tests conducted a 50% deformation was reached from 875N for the EPS system and 1484N for the phenolic foam system. The area over which the impact occurs is also significant, as the stress increases if the same force is applied over a smaller area. Projectiles with a smaller diameter could potentially cause a higher stress and therefore more damage to the systems than larger projectiles if the impact occurs with the same level of force.

From the tests it can be seen that the level of damage to the system also depends on the material properties of the insulation material. The distinction between the elastic behaviour of the woodfibre board and the more brittle behaviour of the EPS and phenolic foams leads to further conclusions. Permanent damage will occur to these materials when applied stress from impacts exceeds the materials’ yield points. Based on our measurements, EPS and phenolic foam insulation materials have lower yield points, 40KPa and 120KPa respectively, compared to 200KPa for woodfibre boards; the former are therefore more susceptible to this type of damage. The more elastic behaviour of woodfibre board will also most likely lead to a spreading of any applied load over a wider area. This will have the effect of reducing the load experienced by the material and, therefore, reduce the likely damage.

4 Key Findings and Recommendations

From the impact tests it appeared that the woodfibre samples bounced back after impact, leaving little indentation in the sample, but some cracking to the render. This was further demonstrated in the compression tests where the woodfibre samples had the lowest relative deformation of the three samples tested. The render system did not seem to detrimentally affect the bounce back and enabled the sample to sustain a higher level of stress before reaching 50% deformation. The woodfibre boards required the highest loads to reach a 50% deformation.

The phenolic foam appeared to have a small amount of bounce back in the impact tests. This was confirmed in the compression tests. The render system improved the compressive resistance of the foam and did not alter the bounce back. The phenolic foam samples have the highest compressive resistance for a 10% deformation, but under higher loads, visible compression and deformation occurs in the middle of the sample and the closed cell structure is damaged, with voids opening up within it.

The EPS samples consistently have the lowest compressive resistance in the compression tests, although the rendered system did enable higher forces to be resisted. This corresponds with the impact tests where there is visibly more compression to the EPS compared to the other two samples. The visible bounce back is good, and from the compression tests it can be seen that EPS samples had a higher bounce back and lower relative deformation than the phenolic foam samples. This is likely due to air gaps being squashed during compression and the material then expanding again once the loading is released. However, due to the level of the initial compression, large cracks did form in the impact samples; these would likely allow water ingress to the insulation.

In the impact tests, both the phenolic foam and EPS samples had higher crack thicknesses as more boards were joined together. For the woodfibre board samples the three board joint had a greater crack thickness than the single and two board join, but there was no difference between the latter two samples. The jointing technique for the woodfibre boards allows them to act more cohesively, whereas, as can be seen in Figure 12, air gaps are present between phenolic and EPS joins, so the boards will act independently. Strengthening the four board joint in particular is recommended for

xxxi

the phenolic foam and EPS systems. Utilising additional reinforcing mesh over these joints might improve their impact resistance, but this would require further testing to ascertain.

For all three systems the base rail seems a weak point, improving the impact resistance of this is recommended. This is a vulnerable and accessible area of the system so may be prone to vandalism and impacts from projectiles. If repeated impacts cause the base rail to detach this would then allow significant ingress of water, affecting the thermal performance of the systems.

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5 References

ASTM Standard C1126-12a. 2012. Faced or unfaced rigid cellular phenolic thermal insulation. ASTM International, West Conshohocken, PA. 2012. Available at: http://enterprise.astm.org/filtrexx40.cgi?+REDLINE_PAGES/C1126.htm [accessed 24/10/2013]

ASTM Standard C578-12b. 2012. Standard specification for rigid, cellular polystyrene thermal insulation. ASTM International, West Conshohockhen, PA. 2012. Available at: http://enterprise.astm.org/filtrexx40.cgi?+REDLINE_PAGES/C578.htm [accessed 24/10/2013]

ETAG 004. 2008. Guideline for European Technical Approval of External Thermal Insulation Composite Systems with Rendering.

ISO 7892:1988. Vertical building elements – Impact resistance tests – Impact bodies and general test procedures, (Standard reviewed and confirmed in 2012).

Walilko, T.J., Viano, D.C., & Bir, C.A. 2005. Biomechanics of the head for Olympic boxer punches to the face. British Journal of Sports Medicine, 39, pp: 710-719

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6 Appendix

6.1 Supporting information for compression tests

6.1.1 WoodFibre Board Samples

6.1.1.1 Example 10% Deformation Test – non rendered sample

6.1.1.2 Example 50% Deformation Test – non rendered sample

-50

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6.1.1.3 Example 50% deformation test – rendered sample

6.1.1.4 Stress Strain Response of woodfibre samples under 50% deformation

The stress-strain graph is described as a J-shaped curve. As the loading and unloading follow the same curve, the loading should be completely reversible, hence Woodfibre has an elastic response, which correlates with its low relative deformation. The Woodfibre insulation stress-strain graph demonstrates that the material follows Hooke’s Law at the beginning i.e. the stress is proportional to the strain. As this is constant, the modulus of elasticity, Young’s Modulus, can be calculated as 0.9MPa using the Elastic Region Response graph; from this it can be seen that the yield point is at 200kPa.

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0 10 20 30 40 50 60

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]

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-0.1 0 0.1 0.2 0.3 0.4 0.5 0.6

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ess

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)

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6.1.2 EPS Samples

6.1.2.1 Example from 10% Deformation Tests – non rendered sample

y = 884.85x - 27.256

0

50

100

150

200

250

0.09 0.14 0.19 0.24 0.29

Str

ess

(k

Pa

)

Strain

Elastic Region Response

Series1

Linear (Series1)

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Stan

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EPS Board

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6.1.2.2 Example from 50% Deformation Tests – Non rendered samples

6.1.2.3 Example from 50% deformation tests of rendered EPS Samples

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6.1.2.4 Stress Strain Response of EPS samples under 50% deformation

As the strain increases, the strain yield point determines the stress needed to induce plastic deformation in the EPS insulation. The internal cells move to a new equilibrium position. After the yield point, at approximately 40KPa, permanent deformation of the EPS insulation will occur.

6.1.3 Phenolic Foam Samples

6.1.3.1 Example from 10% Deformation Tests – non render samples

-20

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0 2 4 6 8 10 12

Stan

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6.1.3.2 Example from 50% Deformation tests – non rendered samples

6.1.3.3 Example from 50% deformation tests - Rendered Phenolic Foam Samples

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6.1.3.4 Stress Strain Response of phenolic samples under 10% deformation

As the strain increases, the strain yield point determines the stress needed to induce plastic deformation in the phenolic insulation. The internal cells move to a new equilibrium position. The sharp dips in the graph demonstrate cracking within the phenolic foam, breaking the closed cell structure. After the yield point permanent deformation of the phenolic insulation will occur.

020406080

100120140160

0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

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