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iii
Contents Foreword Acknowledgements Introduction Why this book? Information presentation within The Green Guide Environmental issues covered in The Green Guide How Green Guide ratings are assessed Summary ratings Weighting the importance of environmental impacts Sources of LCA information Recycling Reclaimed or recycled materials Embodied energy Costs Replacement intervals How the elements were chosen Using The Green Guide to Housing Specification Timber External walls Framed wall construction Cavity and solid masonry wall construction Roofing Pitched roof construction Flat roof construction Ground floors Concrete ground floor construction Suspended timber ground floor construction Upper floors Windows Internal walls Internal partitions Party walls Kitchens Worktops Cupboard units Refurbishment: external and internal wall insulation Bespoke timber cladding systems Dry cladding systems Insulating render Internal wall insulation Polymer-modified cementitious render systems Polymeric coating systems Traditional render Insulation Landscaping Boundary protection External surfacing: hard and soft Appendix 1 Life-cycle assessment Appendix 2 Environmental issue categories Contacts and further information Key references
v vi 1 2 3 3 3 4 4 4 5 5 5 6 6 6 6 7 8 8 10 12 12 14 16 16 18 20 22 24 24 25 26 26 27 28 29 29 29 29 29 29 29 30 32 32 34 35 35 37 37 39 39
v
Foreword
This publication has been developed to provide house builders and housing designers with a simple reference guide to the environmental impacts of the construction materials most commonly used in house building. The BRE method of Environmental Profiling has been adopted as the basis for the approach, which means that for the first time, housing designers will have a simple method available for comparing the environmental performance of one construction type with another. This will enable informed choices to be made in relation to the materials used to build our new homes, as well as raising awareness of these important environmental issues. There is growing global pressure to ensure that construction is ‘sustainable’ and practical guidance and information are required. This Guide, together with the companion new environmental standard for homes, EcoHomes, fills that gap and represents a valuable contribution. NHBC has been pleased to support their development. Christopher Mills, NHBC Director, Technical Services
vi
Acknowledgements
The first version of The Green Guide, looking at specifications used in The Post Office’s property portfolio, was developed by Nigel Howard and David Shiers of Oxford Brookes University as a private publication for The Post Office in 1992. Following great interest in the publication, which had been circulated widely amongst The Post Office’s design consultants, a second version was published by BRE with The Post Office in September 1998. This version was linked to BREEAM 98 for offices and was used to assess credits for materials specification. The production of this version of The Green Guide, specifically relating to the materials used in housing has been generously sponsored by NHBC. Its production would not have been possible without the work which had gone before on the earlier versions; in particular, thanks are due to David Shiers of Oxford Brookes University. We wish also to acknowledge the contribution made by the following individuals and organisations: Neil Smith, NHBC Deborah Brownhill, BRE Suzy Edwards, BRE Matt Thomas, BRE Susheel Rao, BRE Alan Yates, BRE Paul Evans, FBE Management Ltd Helen Fairmaner, AFH Shaw Sprunt Francis Maude, Donald Insall Associates Andrew Upton, Anchor Trust
1
Introduction
This third version of The Green Guide contains over 150 specifications commonly used in housing. The guide contains typical wall, roof, floor and other constructions listed against a simple environmental rating scale running from A (good) to C (poor). Twelve different environmental impacts are individually scored, together with an overall Summary Rating, information on recycling and typical costs. The Summary Ratings enable users to select materials and components on their overall environmental performance over the building’s life. Because ratings are also given for individual environmental issues such as climate change, the specifier can alternatively select materials and components on the basis of personal or organisational preferences or priorities, or take specification decisions based on the performance of a material against a particular environmental parameter.
Why this book? A typical house uses almost 150 tonnes of material in its construction.
All figures in this report, unless otherwise referenced, have been derived, either directly or through analysis carried out by BRE in research for this and other projects, from the publications listed in Key references at the back of this Guide.
UK energy consumption 1995
The environmental impact of housing is considerable. Each year in the UK, domestic energy use accounts for around 30% of energy consumption, and the materials used in house construction account for 10% of mineral extraction and 1% of climate change. Whilst energy efficiency initiatives over the last 30 years have reduced the energy needed to heat a typical house considerably, the development of initiatives to reduce the impacts arising from construction materials has been comparatively slow. Of the written information available to date, most has lacked practical guidance and has proved difficult for designers and their clients to interpret. This handbook provides a ‘green’ guide to specification of construction materials for housing which is both easy to use and soundly based on Life Cycle Assessment (LCA) studies of the environmental impacts of different materials.
Building operation
UK waste generation
Industry (including building materials manufacture) Quarrying
Industry - building materials Demolition and construction Other industry Agriculture Agriculture
Transport - other freight
Colliery China clay Sewage sludge
Transport - building materials Dredged spoil Transport - people
Municipal and commercial waste
2
The Green Guide to Housing Specification Information presentation within The Green Guide
Whilst specifications are generally comparable, there are inevitably instances where comparisons are not exactly like-forlike. Some internal walls are loadbearing whilst others are not: windows, although all double-glazed, may have differing thermal efficiencies.
Materials and components have been arranged into construction categories or ‘elements’ such as External wall construction, Internal walls, Upper floor construction, etc. (see pages 8–34), so that designers and specifiers can compare and select from comparable systems or materials specifications. It is meaningless to compare the environmental performance of say, concrete floors and a particular type of paint and therefore ratings are based only on a specification’s performance within each respective element. To ensure that credible, like-for-like comparisons are made, a ‘functional unit’ of comparison has been defined for each element. In the case of external walls for example (page 8), the functional unit is 1 m2 of wall that satisfies building regulations — so the environmental impacts of 1 m2 of each external wall specification listed have been assessed and compared with each including sufficient insulation to give a U value of 0.45 W/m2K. Using functional units for comparing specifications means that variables such as the mass of material needed to fulfil a particular function, for example structural stability, are taken into account. This is important because a comparison of the environmental impacts of, for example, one tonne of structural steel and one tonne of structural concrete would be misleading as less steel is needed to perform the same function.
Environmental issues covered in The Green Guide The environmental issues against which building materials and components are judged, reflect the generally accepted areas of concern related to the production of building materials used in the UK. They are listed in the box, below. Further information about these environmental issues is given in Appendix 2. Environmental issues and production of building materials concerns
Climate change: Fossil fuel depletion: Ozone depletion: Freight transport: Human toxicity: Waste disposal: Water extraction: Acid deposition: Ecotoxicity: Eutrophication: Summer smog: Minerals extraction:
Global warming or greenhouse gases Coal, oil and gas consumption. Gases which destroy the ozone layer Distance and mass of freight moved Pollutants which are toxic to humans Material sent to landfill or incineration Mains, surface and ground water consumption Gases which cause acid rain, etc. Pollutants which are toxic to the ecosystem Water pollutants which promote algal blooms, etc. Air pollutants which cause respiratory problems Metal ores, minerals and aggregates
Introduction
3
High environmental impact
How Green Guide ratings are assessed C rating
B rating
A rating
Low environmental impact
Environmental impact of specification
The specifications in this book are based on commonly found components, assemblies and materials selected to reflect the best available data and provide a representative range of specifications. The ratings compare a square metre of each specification over a 60-year building life and therefore take account of maintenance and refurbishment over the building life, and demolition at the end of its life. For each specification, information was gathered on the constituent materials, for example the relative quantities per m2 of each material and its expected life before replacement. Using Life Cycle Assessment (LCA) studies which show the environmental impacts of the manufacture of a tonne of materials, the specifications were then analysed over the 60-year building design life to give the total environmental impacts for each specification, where necessary taking account of the expected replacement of components during the building’s life. Although this study is underpinned by extensive LCA data, it was felt that listing the actual values for each environmental issue for each specification would significantly increase the complexity of the Guide, make comparison more difficult, and would be of interest only to specialists. The Environmental Profiles have therefore been presented in a straightforward way, to enable specifiers to make meaningful comparisons between materials and components. The A B C rating system, where ‘A’ denotes the best environmental performance, is quick and easy to use and understand. The way A B C ratings were calculated is shown in the diagram, left. For each element category, eg roofs, the range of numerical results for each issue was arranged in order of environmental impact, and the range from highest to lowest divided into three equal bands. Specifications within that category with impacts in the band with the lowest environmental impact were assigned an ‘A’ rating, specifications with results falling in the middle band were assigned a ‘B’ rating, and specifications with results in the band with the highest environmental impact were assigned a ‘C’ rating.
No environmental impact
Summary Ratings
0
Although some specifiers will be happy to make a choice based on their own assessment of the importance of each environmental impact, there is also a demand for a Summary Rating, reflecting overall environmental performance. The Summary Rating was determined by firstly assigning a relative importance or weighting factor to each issue. Secondly, the impacts for each issue were multiplied by the respective weighting factor and the resulting values summed for each specification to give a single figure. These summary results were then assigned A B C ratings from their position within the band of summary results for each element in exactly the same way as the issue ratings were calculated.
4
The Green Guide to Housing Specification
Groups consulted as part of the weighting exercise: ● ● ● ● ● ● ●
Weighting the importance of environmental impacts
local government, central government, materials producers, construction professionals, environmental activists and lobbyists, academics, and environmental researchers.
Weighting of environmental issues Issue % weight Climate change
36.0
Fossil fuel depletion
11.4
Ozone depletion
7.7
Freight transport
7.4
Human toxicity
6.7
Waste disposal
5.8
Water extraction
5.1
Acid deposition
4.8
Ecotoxicity
4.1
Eutrophication
4.1
Summer smog
3.6
Minerals extraction
3.3
Environmental Profiles have been used to assess the following materials: ● Aggregates ● Aluminium ● Brick ● Gravel and sand ● Limestone ● Granite ● Ground granulated blast furnace slag ● Aerated blocks ● Clay roof tiles ● Concrete roof tiles ● UK consumed softwood ● Rock wool ● Glass wool
The weighting factors used in this Guide were determined from an extensive BRE research programme that included consultation with more than 60 professionals representing seven different groups (see box, left). A surprising degree of consensus regarding the relative importance of different environmental issues was found across the groups. From this consensus, it was possible to weight the different issues covered by The Green Guide and hence to derive the Summary Ratings. The relative weightings are given in the Table, left.
Sources of LCA information Information is required on materials for their whole life cycle. A major source of data is the BRE Environmental Profiles scheme, which was developed with support from DETR and UK Materials Producers. The Environmental Profiles scheme enables environmental assessment of construction materials by using a common ‘level playing field’ methodology. This allows direct comparison of the environmental impacts of functionally equivalent products. Environmental Profiles are life cycle assessment (LCA) data derived from the UK industry. Wherever permission to use Environmental Profiles has been given by manufacturers, BRE has used this data within this Guide. However, the BRE Methodology was only launched in June 1999, and some materials have still not been assessed in this way. Where assessment has not occurred, or permission to use derived Environmental Profiles has not been obtained, BRE has referred to other sources of data. These sources include LCA data in the public or private domain and overseas studies, such as the LCA databases compiled by IVAM at the University of Amsterdam, PRé product ecology consultants based in the Netherlands and other well respected LCA providers. Where possible, these sources have been listed in the Key references, page 39. When necessary, BRE has adapted these studies to take account of differences between UK and overseas practice, in energy mix and in methodology, and improvements in production techniques where older LCA studies have been used.
Recycling Recycling has not been included as a separate environmental issue within the Environmental Profiles scheme, however the BRE Methodology and generated Environmental Profiles do take account of the actual levels of recycled input, and the current fate of materials at the end of their life cycle. By taking account of current recycling practice, BRE is emphasising the importance of today’s decision making in delivering sustainable construction — however it is recognised that specifiers might wish to take account of the potential for recycling that exists for construction materials. Specifiers should be aware of the ongoing debate concerning the merits of recycling and should adhere to best environmental practice when considering waste disposal and use of recycled material. We have tried to reflect the complexity of this argument by separately identifying and assessing four key aspects of recycling for each material or component. ● Recycled input The percentage (by mass) of recycled or waste material contained within a product. ● Recyclability The percentage (by mass) of material capable of being recycled or reused at end of life of the product. ● Currently recycled The percentage (by mass) currently being recycled or reused in the UK.
Introduction ● Energy saved by recycling
5 A comparison of the energy required to recycle and/or reuse the products compared with the energy required to produce similar products from primary resources based on current practice.
The information on recycling has been presented as A B C ratings calculated in the same way as those for environmental issues, with an A rating representing good performance.
Reclaimed or recycled materials Maximum transport distances for reclaimed materials Material Distance (miles) Reclaimed tile
100
Reclaimed slate
300
Reclaimed bricks
250
Recycled aggregates
150
Reclaimed timber
1000
(eg floor boards) Reclaimed steel products
2500
Reclaimed aluminium
7500
Reclaimed materials are materials that are directly reused, or reused with very little processing, for example, bricks that have been cleaned of mortar. Recycled materials are materials that require reprocessing to be reused, for example, aggregates that are made of crushed concrete demolition waste. From an environmental point of view, repair is generally preferable to reuse, reuse to recycling and recycling to disposal. The low impacts of reclaimed materials can be increased if they are transported very long distances compared with new materials. The Table, left, shows the maximum distance a reclaimed material can be transported by road before it will have a greater impact than a new material manufactured locally. For example, reclaimed bricks from up to 500 miles away would have less environmental impact than new bricks from a factory 250 miles away.
products
Embodied energy Many products with minimal energy use in their production can still have considerable impacts on mineral extraction, waste generation and water usage. In addition, the consequential impacts of energy use can vary greatly depending on which type of fuel or electricity generation is used; for example, comparing wind with coal-fired electricity generation. Therefore, BRE believes that embodied energy, a measure of the total energy used, does not always constitute a good model for overall environmental impact. Instead, the BRE Methodology takes account of energy use by tracing the impacts resulting from energy use, such as climate change, acidification and fossil fuel depletion. BRE recognises that embodied energy is still used by many as a proxy for environmental impact; however the Summary Rating, which reflects eleven weighted environmental issues, gives a much more accurate picture of overall environmental impact.
Costs Cost ranges are based on Spon’s Architects’ and Builders’ Price Book 1999 at a Davis Langdon & Everest Tender Index of 325.
Although primarily a ‘green’ guide, this handbook also provides data on initial capital cost, maintenance and durability to ensure that environmental issues are considered within a wider context of specification choices. Indicative asbuilt costs are provided for each material or component as a cost range in £/m2. All costs are inclusive of materials, labour and plant. Readers are reminded that these costs do not include any allowance for maintenance, repair or replacement (whole life costs) over the chosen 60-year life of the building.
6
The Green Guide to Housing Specification Replacement intervals
The specifications are assessed over a 60-year building life, taking account of maintenance and refurbishment over the building life, and its demolition. For an internal wall with ‘tongue and groove’ (t&g) boarding, repainting occurs every 5 years and the t&g boarding has a typical replacement interval of 35 years. The impacts of the paint will therefore be increased to reflect the 11 subsequent repaintings and the impacts of (tongue and groove) boarding increased to reflect its replacement after 35 years.
Environmental impacts from the materials use of a typical house over 60 years
External walls Roof
Replacement intervals indicate the typical replacement life of the major components of each element. It should be recognised that these replacement intervals are not always representative of durability, but take account of other factors such as ‘fashion’ which may have a greater influence, for example, in the replacement intervals for kitchen fittings. Replacement intervals are given in years for the most frequently replaced major component; for the example, left, the replacement interval for the tongue and groove boarding is given. The replacement intervals stated in this Guide should be used for general guidance only.
How the elements were chosen BRE initially considered the common specifications for elements used in typical house construction. A simple analysis was then undertaken to identify those elements that contributed most to the overall environmental impact of house construction over a 60-year life. The chart, left, illustrates the contribution of each element to the overall environmental impacts for a typical house. Generally the external walls, upper floors and roof of a typical house can account for over 50% of the total building mass, with a further 20% contained within the sub-structure and ground floor. Because of this high mass, these elements have the potential to produce the greatest relative impact of all the elements that make up a house. They can require the highest energy levels for extraction, production and transport, use the largest amounts of raw material, produce the highest emissions and generate the largest amounts of waste, especially after demolition. Elements which have been excluded from this Guide include: ● elements over which most housebuilders have no control (eg carpets), ● elements which make a contribution to the impact of a typical house, but where the impacts of the different specifications are very similar, ● elements which make very little contribution to impacts of a typical house.
External surfacing Ground floor Internal walls Windows Upper floors Boundary protection Kitchen worktops Kitchen cupboards Other
Using The Green Guide to Housing Specification Whilst all specification choices are important, designers may wish to give particular attention to the selection for the building elements which have the potential for the greatest environmental impact. As a quick guide, the table of ratings for each element includes a pie chart displaying that element’s typical contribution to the impacts of a house. However, specifiers should note that when A-rated specifications have been chosen for the major elements, the impacts from the minor elements become more significant to the overall impacts of the house, particularly when C-rated minor element specifications have been chosen. Designers and specifiers should note the following in their use of the table of ratings. ● The A B C ratings are relevant only within an element. An A rating in one element for a particular issue is not equivalent to an A rating in another element for the same issue. ● In most cases, the distinctions between specifications are significant. For some elements, however, specifications with a similar impact may fall into different A B C bands, for example one specification may have the worst impacts for an A rating whilst a specification with very similar impact may be a top performing B rating. Equally, specifications with the same rating may have quite different impacts if one lies at the bottom of ‘A’ whilst the other lies at the top. However, actual impacts are used when calculating Summary Ratings so these similarities or differences will be reflected in the overall Summary Rating.
Introduction
7
● The A B C ratings have been used to distinguish between impacts for an issue even when the impacts may all be close to zero. This is particularly true for ozone depletion ratings where the impacts from most element specifications are zero, or very close to zero. However, the Summary Rating will reflect the small contribution from these low impacts to the element profile. ● Many houses will in practice last much longer than the assumed 60-year life and hence the value of low maintenance and design for longevity are underestimated in the ratings. For temporary or short-life buildings these aspects will be over-estimated. The ratings have been assigned using the best available information at the time of writing and will be updated as BRE’s knowledge evolves.
Timber The Environmental Profiles for timber in this Guide have been based on timber sourced from sustainably managed forests. Where possible, designers should give preference to timber products obtained from well-managed, sustainable sources, independently certified under schemes such as the Forest Stewardship Council, the Finnish National Certification Scheme or UK Woodland Assurance Scheme. Where independently certified timber is not available, designers should give preference to timber from suppliers who have adopted a formal Environmental Purchasing Policy, such as the Forests Forever Environmental Purchasing Policy, or through the 95+ Group, and who can provide evidence of commitment to that policy. The organisation, Forests Forever, can advise on issues regarding the sourcing of timber. The Environmental Profiles for timber also take account of typical transport based on current patterns of imports and home production. The transport impacts of locally sourced timber are therefore likely to be better than those shown within this Guide. The use of timber preservatives in situations where timber, left untreated, would be likely to decay, greatly extends the life of the timber (with modest additional initial environmental impact), thereby reducing replacement intervals and its total impact over a 60-year life. Factory application of preservatives both ensures their efficacy and minimises any risk of environmental damage. The use of wood preservatives is strictly regulated under the Control of Pesticides Regulations.
8
External walls
Functional unit: 1 m2 to satisfy building regulations, in particular a U value of 0.45 W/m2K.
A B C ratings have been assessed across all External walls specifications. However for ease of use, this element has been split into two sections: ● framed construction, and ● cavity and solid walls.
Summary Rating
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Cost
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
External walls
A
A
A
A
A
A
B
A
A
A
A
A
A
£50–£70
60
C
A
A
A
A
A
A
A
A
A
B
A
A
A
A
A
A
£50–£68
60
C
A
A
A
Canadian Cedar weatherboarding, timber B
A
A
A
C
A
A
A
A
A
A
A
A
£52–£72
30
C
B
B
B
A
A
A
B
A
A
A
A
A
A
A
A
A
£60–£79
60
C
A
C
A
A
A
A
A
A
A
A
B
A
A
A
A
A
£67–£81
60
C
A
C
A
A
A
A
A
A
A
A
A
A
A
C
C
A
£43–£62
30
C
B
C
B
C
C
C
C
A
C
A
A
C
C
A
A
A
£57–£82
30
C
C
C
C
A
B
A
A
A
B
A
A
B
A
A
A
A £155–£220 30
A
A
A
A
Framed wall construction Brickwork outer leaf, insulation, steel frame, plasterboard, paint Brickwork, timber frame with insulation, plasterboard, paint frame with insulation, plasterboard, paint Clay tiles, battens, timber frame with insulation, plasterboard, paint Concrete tiles, battens, timber frame with insulation, plasterboard, paint Painted, pre-treated softwood weather boarding, timber frame with insulation, plasterboard, paint PVC weatherboarding, timber frame with insulation, plasterboard, paint Terracotta rainscreen cladding, aluminium framework, insulation, aerated blockwork wall, plasterboard/plaster, paint
External walls
9
Framed wall construction Using more insulation to achieve better ‘U’ values will reduce the impacts from domestic heating. Over a 60-year life, this will far outweigh the small increase in impacts from manufacturing the additional insulation material.
Due to their lightweight nature, framed structures generally score better than their masonry counterparts. A ratings can be achieved using all conventional cladding materials (with the exception of PVC weatherboarding). The PVC weatherboarding performs badly because of the comparatively high impacts of PVC manufacture compared with other cladding materials. The timber and tile clad options, except for the cedar weatherboarding, perform very well, mainly due to their lightweight nature. Although containerised transport by sea is a very efficient method of transporting freight in comparison with road transport, the cedar is imported from the west coast of Canada, giving the freight transport impacts that cause it to get a B rating. Insulation used in framed construction
Improving the insulation to reduce the building’s energy consumption will not affect the ratings of any element.
Specifiers should pay particular attention to the comments and ratings contained in the section on Insulation on pages 30 and 31. However, because of the small mass of insulation needed to satisfy Building Regulations compared with the heavy mass of materials used in framed construction, the ratings are not sensitive to the insulation selected, as long as the insulation does not use ozone-depleting chemicals. If an ozone-depleting insulation is specified, then the resulting increased climate change and ozone depletion impacts will affect the Summary Rating for the specification. For example, an A Summary Rating will move to a B Summary Rating, a B to a C, and a C would perform so badly, a D rating would be appropriate. Use of reclaimed materials
Both reclaimed bricks and tiles can be used in framed external wall constructions. The Table on page 5 shows the distance reclaimed bricks and tiles can be transported before the impact of transport becomes greater than the impact of manufacturing a new brick.
10
The Green Guide to Housing Specification
Summary Rating
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Cost
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
External walls
B
B
A
A
A
B
B
B
A
A
A
A
A
£49–£71
60
B
A
A
A
A
A
A
A
A
A
B
B
A
A
A
A
A
£49–£71
60
C
A
A
A
B
A
A
A
A
A
C
B
A
A
A
A
A
£51–£67
60
C
A
A
A
C
C
C
C
A
C
A
A
C
C
A
A
A
£55–£86
30
A
B
B
B
A
A
A
A
A
A
B
B
A
A
A
A
B
£44–£72
60
A
A
A
A
B
A
A
A
A
A
C
C
A
A
A
A
B
£49–£65
60
C
A
A
A
A
A
A
A
A
A
B
B
A
A
A
A
B
£28–£40
60
C
A
A
A
B
B
A
A
A
B
B
B
A
A
A
A
B
£45–£64
60
A
A
A
A
A
A
A
A
A
B
B
B
A
A
A
A
B
£38–£55
60
A
A
A
A
A
A
A
A
A
A
C
C
A
A
A
A
C
£97–£109 60
C
A
A
A
Cavity and solid wall construction Brickwork outer leaf, aerated blockwork inner leaf, plasterboard/plaster, paint Brickwork outer leaf, insulation, aerated blockwork inner leaf, plasterboard/plaster, paint Brickwork outer leaf, insulation, dense blockwork inner leaf, plasterboard/plaster, paint PVC weatherboarding, insulation, aerated blockwork wall, plasterboard/plaster, paint Rendered aerated blockwork cavity wall, plasterboard/plaster, paint Rendered dense blockwork cavity wall, insulation, plasterboard/plaster, paint Rendered dense blockwork outer leaf, insulation, aerated concrete blockwork inner leaf, plaster/plasterboard/plaster, paint Rendered lightweight blockwork outer leaf, insulation, aerated blockwork inner leaf, plasterboard/plaster, paint Rendered solid aerated blockwork, plasterboard/plaster, paint Stone outer leaf, insulation, dense blockwork inner leaf, plasterboard/plaster, paint
External walls
11
Cavity and solid masonry wall construction The high mass of materials used in masonry construction leads to poorer environmental performance than comparable framed alternatives. However, the use of aerated blocks, which are both lightweight and provide insulation, improves performance. Brickwork, as a result of the energy required to fire the brick, performs less well than other masonry, but used with cavity wall insulation and aerated blocks or framed construction, can still obtain A ratings. It should be noted that brickwork and masonry walls will typically last much longer than the assumed 60-year life used by this Guide, Although the masonry options generally perform well in terms of recycling, they are normally only recycled into lower grade ‘fill’. The use of easily removable lime mortars greatly increases the ease with which bricks, can be reused. Insulation used in cavity wall construction Increasing the insulation to reduce the building’s energy consumption will not affect the ratings of any element.
Specifiers should pay particular attention to the comments and ratings contained in the section on Insulation on pages 30 and 31. However, because of the small mass of insulation needed to satisfy the Building Regulations compared with the heavy mass of materials used in cavity walls, the ratings are not sensitive to the insulation selected, as long as the insulation does not use ozone-depleting chemicals. If an ozone-depleting insulation is specified, then the resulting increased climate change and ozone depletion impacts will affect the Summary Rating for the external wall specification, so that an A Summary Rating will move to a B Summary Rating, a B to a C, and a C would perform so badly, a D rating would be appropriate. Use of reclaimed materials
Reclaimed bricks can be used in masonry walls. The Table on page 5 shows the maximum distance reclaimed bricks can be transported before the impact of transport becomes greater than the impact of manufacturing a new brick.
12
Roofing
Functional unit: 1 m2 of roof area (measured horizontally), to satisfy building regulations, particularly a U value of 0.25 W/m2K.
A B C ratings have been assessed across all Roofing specifications. However for ease of reference, this element has been split into two types: ● pitched roofing, and ● flat roofing.
Summary Rating
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Cost
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
Roofing
A
A
A
C
B
A
A
A
A
A
A
A
A
£32–£67
60
C
A
C
A
A
A
A
A
B
A
A
B
A
A
A
A
A
£28–£54
60
C
A
C
A
B
A
B
A
B
B
A
A
B
B
A
B
A
£50–£77
30
C
A
C
A
C
C
C
A
C
C
A
B
C
C
C
C
A
£36–£69
35
C
C
C
C
A
A
A
A
C
A
C
A
A
A
A
A
C
£51–£143 60
C
A
A
A
Pitched roof construction Clay tiles, battens, sarking felt on timber roof structure with insulation between rafters Concrete tiles, battens, sarking felt, battens on timber roof structure with insulation between rafters Fibre cement slates, battens, sarking felt on timber roof structure with insulation between rafters Polymer resin bonded slates, battens, sarking felt on timber roof structure with insulation between rafters Slates, battens, sarking felt on timber roof structure with insulation within rafters
Roofing
13
Pitched roof construction The ‘room in the roof’, where attic rafters are used to provide habitable space within the loft, is becoming popular with housebuilders, who can provide extra living space for little extra cost. The additional timber needed to construct the attic trusses is offset by the general reduction in material used per unit of living area.
Traditional roof materials score well here, with replacement materials, polymer resin bonded slates and fibre cement slates, scoring less well than their traditional counterparts. Trussed rafters, a modern innovation, use almost 30% less timber than traditional cut rafters, reducing the environmental impact of the roof structure. The contribution of the structure to the roof ’s overall environmental impact is small though, so the ratings given are applicable for either type of timber roof structure. Use of reclaimed materials
Reclaimed tiles are likely to be more brittle than new tiles, leading to shorter replacement intervals than virgin materials. However, like reclaimed slates, they can still be transported long distances without losing their environmental benefits — the Table on page 5 shows the maximum transport distances before the impact of transport becomes greater than the impact of manufacturing new slates or tiles. Insulation used in pitched roof construction
Specifiers should pay particular attention to the comments and ratings contained in the section on Insulation on pages 30 and 31. However, because of the small mass of insulation needed to satisfy the Building Regulations compared with the heavy mass of materials used in pitched roofing, the ratings are not sensitive to the insulation specified, as long as the insulation does not use ozone-depleting chemicals. If an ozone-depleting insulation is specified, then the resulting increased climate change and ozone depletion impacts will affect the Summary Rating for the specification, so that an A Summary Rating will move to a B Summary Rating, a B to a C, and a C would perform so badly, a D rating would be appropriate.
14
The Green Guide to Housing Specification
Summary Rating
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Cost
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
Roofing
A
A
A
A
A
A
A
A
A
A
A
B
A
£43–£58
30
A
B
C
B
A
A
A
A
A
B
A
A
A
B
B
B
A
£60–£88
35
C
C
C
A
A
A
A
A
A
A
A
A
A
A
A
B
A
£60–£87
30
C
B
C
B
A
A
A
A
A
C
B
C
A
B
B
A
B
£78–£118 35
C
A
B
A
A
A
A
A
A
B
B
C
A
A
A
A
B
£79–£117 30
C
A
A
A
B
A
A
A
A
C
C
C
A
B
B
A
C
£65–£100 35
C
A
A
A
A
A
A
A
A
B
B
C
A
A
B
A
C
£55–£62
C
A
A
A
Flat roof construction Chipboard or OSB decking on timber joists with insulation, polyesterreinforced bitumen felt Plywood decking on timber joists with insulation, asphalt, chippings Plywood decking on timber joists with insulation, polyester-reinforced bitumen felt Precast concrete slab, insulation, asphalt, chippings Precast concrete slab, insulation, polyester-reinforced bitumen roofing felt, chippings Reinforced concrete flat slab, insulation, asphalt, chippings Reinforced concrete flat slab, insulation, polyester-reinforced bitumen felt, chippings
30
Roofing
15
Flat roof construction Because insulation and timber decking often have to be replaced when roofing membranes are replaced, the lifespan of the roofing membrane is of great importance to the environmental profile of flat roofs. Increased resource consumption in constructing a roof that will last longer will be offset by the reduction in materials used later in repairs and refurbishment. Concrete roof structures, with their greater resource consumption, perform relatively well because they remain intact when the roofing membrane needs to be replaced. In terms of the impacts of roofing membranes, asphalt generally has higher impacts than the lightweight reinforced bitumen felts and elastomeric polymers (eg ethylene propylene diene monomer (epdm)) which have similar impacts. Insulation used in flat roof construction
Specifiers should pay particular attention to the comments and ratings contained in the section on Insulation on pages 30 and 31. However, because of the small mass of insulation needed to satisfy the Building Regulations compared with the heavy mass of materials used in flat roofs, the ratings are not sensitive to the insulation specified, as long as the insulation does not use ozone-depleting chemicals. If an ozone-depleting insulation is specified, then the resulting increased climate change and ozone depletion impacts will affect the Summary Rating for the specification, so that an A Summary Rating will move to a B Summary Rating, a B to a C, and a C would perform so badly, a D rating would be appropriate.
16
Ground floors
Functional unit: 1 m2 ground floor to satisfy building regulations, in particular a U value of 0.45 W/m2K.
A B C ratings have been assessed across all Ground floor specifications. However for ease of reference, this element has been split into two types: ● concrete ground floors, and ● timber ground floors.
Summary Rating
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Cost
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
Ground floors
C
C
C
C
A
C
A
A
C
C
C
C
A
£42–£70
20
C
A
A
A
B
C
C
C
B
B
A
A
C
C
B
B
A
£30–£44
20
A
A
A
A
A
B
A
C
B
B
A
A
A
C
B
A
A
£44–£61
25
B
A
A
A
B
B
B
C
A
C
A
A
B
C
C
B
A
£55–£75
25
C
A
A
A
C
A
A
A
A
C
C
C
A
A
B
A
C
£43–£60
60
C
A
A
A
C
B
A
A
B
C
C
C
B
A
C
A
C
£71–£166 60
C
A
A
A
Concrete ground floor construction Chipboard or OSB decking on insulation on precast concrete planks Chipboard or OSB decking on timber battens with insulation, on beam and block flooring Plywood decking on timber battens with insulation, on beam and block flooring Plywood on insulation on precast concrete planks Screeded in-situ concrete slab, over insulation on polyethylene dpm laid on blinded subbase Screeded in-situ reinforced concrete slab, over insulation on polyethylene dpm laid on blinded sub-base
Ground floors
17
Concrete ground floor construction Concrete ground floors can use large amounts of concrete and hardcore and this results in high impacts, in particular for mineral extraction. Beam and block floors and precast plank floors do not require oversite concrete and this reduces their materials usage and consequent impacts. The performance of the beam and block floors also reflects the low mass of the blocks. The choice of floor decking, because of its low mass/m2 in comparison to the ground floor structure, makes only a small contribution to the overall impacts. The section on upper floors on pages 20 and 21 contains more information. Use of reclaimed materials
The use of local recycled aggregate, both for hardcore and within concrete, will improve the environmental profile of any relevant specification. The Table on page 5 highlights the maximum distance it can be transported before its impacts exceed virgin aggregate. If in-situ demolition or construction waste can be crushed and utilised as recycled aggregate, this is the best option, both in terms of the profile of the new construction, and the demolition of the old. Insulation used in ground floor construction
The choice of insulation for ground floor construction is often determined on the basis of resistance to crushing or moisture rather than simply conductivity. Specifiers should pay particular attention to the comments and ratings contained in the section on Insulation on pages 30 and 31. However, because of the heavy mass of materials used in floors and the small masses of insulation needed to satisfy Building Regulations, the ratings are not sensitive to the insulation selected, so long as it is does not use ozone-depleting chemicals. If an ozone-depleting insulation is specified, then the resulting increased climate change and ozone depletion impacts will affect the Summary Rating for the specification, so that an A Summary Rating will move to a B Summary Rating, a B to a C, and a C would perform so badly, a D rating would be appropriate. Substructure
It was not possible to prepare meaningful elemental comparisons of substructure design. However, cellar and basement construction can contribute significantly to an environmental profile of a house. This is due to the high mass of the materials often used to withstand the levels of lateral loading from the surrounding ground and water pressure, in addition to the loads imposed by the building.
18
The Green Guide to Housing Specification
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
B
C
C
C
A
B
A
A
C
C
C
C
A
£31–£67
20
A
A
C
A
B
C
C
C
A
A
A
A
C
C
C
C
A
£37–£73
20
C
C
C
C
A
B
B
C
A
B
A
A
B
C
C
B
A
£45–£84
25
C
A
B
A
A
B
A
C
A
A
A
A
A
C
C
B
A
£52–£95
25
C
C
C
C
A
A
A
A
C
A
A
A
A
A
A
A
A
£39–£75
60
C
A
B
A
A
A
A
A
C
A
A
A
A
A
A
A
A
£40–£77
60
C
C
C
C
Cost
Summary Rating
Ground floors
Suspended timber ground floor construction Chipboard or OSB decking on timber joists with insulation, over 100 mm oversite concrete Chipboard or OSB decking on timber joists with insulation, over 50 mm oversite concrete on polyethylene dpm laid on 50 mm sand Plywood decking on timber joists with insulation, over 100 mm oversite concrete Plywood decking on timber joists with insulation, over 50 mm oversite concrete on polyethylene dpm laid on 50 mm sand Tongue and groove softwood boards on timber joists with insulation, over 100 mm oversite concrete Tongue and groove softwood boards on timber joists with insulation, over 50 mm oversite concrete on polyethylene dpm laid on 50 mm sand
Ground floors
19
Suspended timber ground floor construction Due to their low mass and resource consumption, timber suspended ground floors perform well; however, the requirement to provide oversite concrete beneath suspended timber ground floors means that all the specifications include a substantial mass of concrete. This increases their impacts, particularly for mineral extraction. The timber specifications have all assumed that the concrete or sand blinding has been laid directly onto the ground, with no hardcore base. Use of virgin aggregates for hardcore in these specifications will have an adverse affect on the Summary Ratings. The environmental impacts of carpets and other floor coverings such as tiling or linoleum can be significant, particularly as they may be replaced relatively frequently. However housebuilders are generally not responsible for the specification or installation of floor covering, so it has not been included here. Generally, natural materials such as wool, cork and timber do better than their synthetic counterparts, and the use of natural or recycled underlays for carpets is also advantageous. The choice of floor decking, because of its low mass/m2 in comparison with the ground floor structure, makes only a small contribution to the overall impacts. The section on upper floors on pages 20 and 21 contains more information. Use of recycled materials
The use of local recycled aggregate, both for hardcore and within concrete, will reduce resource consumption and will improve environmental performance. The Table on page 5 highlights the maximum distance recycled aggregate can be transported before its impact exceeds that of virgin aggregate. If in-situ demolition or construction waste can be crushed and utilised as recycled aggregate, this is the best option, both in terms of the profile of the new construction, and the demolition of the old. Insulation used in ground floor construction
Specifiers should pay particular attention to the comments and ratings contained in the section on Insulation on pages 30 and 31. However, because of the heavy mass of materials used in ground floors and the small masses of insulation needed to satisfy the Building Regulations, the ratings are not sensitive to the insulation specified, as long as it is does not cause ozone depletion.
20
Upper floors
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
C
C
C
B
C
B
A
A
C
B
C
C
A
£24–£28
20
A
B
B
B
C
B
B
B
C
B
A
A
B
B
C
B
A
£25–£40
25
B
B
A
B
B
A
A
A
C
B
B
B
A
A
B
A
B
£24–£33
60
B
A
A
B
C
B
A
A
C
C
C
C
B
A
C
A
C
£40–£80
60
C
A
A
B
C
C
C
C
A
B
A
A
C
C
C
C
A
£21–£47
20
A
B
C
C
B
B
B
C
A
B
A
A
B
C
C
A
A
£22–£34
25
C
C
B
C
B
C
C
B
B
A
A
A
C
B
C
C
A
£21–£47
20
A
B
C
B
A
B
A
B
B
A
A
A
A
B
B
B
A
£22–£34
25
C
C
C
C
A
A
A
A
C
A
A
A
A
A
A
A
A
£29–£56
60
C
C
B
C
Cost
Summary Rating
Upper floors
Upper floor construction Beam and block flooring, chipboard or OSB decking on timber battens, plasterboard ceiling Beam and block flooring, plywood decking on timber battens, plasterboard ceiling Screeded beam and block flooring, plasterboard ceiling Screeded in-situ concrete slab, plasterboard/plaster ceiling Steel joists, chipboard or OSB decking, plasterboard ceiling Steel joists, plywood decking, plasterboard ceiling Timber joists, chipboard or OSB decking, plasterboard ceiling Timber joists, plywood decking, plasterboard ceiling Timber joists, tongue and groove floorboards, plasterboard ceiling
Upper floors
21
Upper floor construction Functional unit: 1 m2 of upper floor to satisfy building regulations.
The results for upper floor construction follow a similar pattern to those for ground floor construction, with timber floors of all kinds showing a smaller impact than heavier and more resource intensive alternatives. Of the concrete floors, the beam and block flooring again performs slightly better than the insitu slab because of its comparatively lower mass. Floor decking
In contrast to ground floors, the mass/m2 of floor decking in comparison to structure is higher, and can have significant bearing on the impacts of upper floors. Chipboard and OSB both utilise waste timber from other processes, however they require greater proportions of energy intensive resins and processing than plywood. Plywood is often produced from tropical hardwoods, and care should be taken to ensure that these have been sustainably grown. Tongue and groove softwood floorboards have comparatively little processing and perform well.
22
Windows
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
PVC-U frame, double glazed
C
B
C
C
A
B
A
A
B
C
A
A
B £150–£530 25
C
C
C
C
Pre-treated softwood frame,
A
A
A
A
A
A
A
A
A
A
A
C
A
£70– £320 25
C
A
B
A
B
A
A
A
C
A
A
A
A
B
B
A
A £130– £355 35
C
A
A
A
C
C
C
A
A
C
A
C
C
A
A
A
A £270–£360 30
A
A
A
A
C
C
C
A
A
C
A
C
C
A
A
B
A £275–£370 35
A
A
A
A
C
A
C
A
A
C
C
A
A
C
C
A
C £185–£420 25
C
A
B
A
Cost
Summary Rating
Windows
double glazed, painted inside and out Durable hardwood frame, double glazed, painted inside and out Powder coated aluminium frame, double glazed Aluminium faced timber composite frame, double glazed, painted inside Glass block window
Windows
23
Windows Functional unit: Double-glazed window of approximately 1 m2 in area with one fixed and one opening casement.
Despite their comparatively low mass, windows can make a significant contribution to the environmental impacts of a house. PVC-U windows perform poorly due to the high intensity of the materials manufacture and the shorter lifespan. PVC-U windows have no recycled input; however, the industry is taking steps to encourage the recycling of PVC-U windows. Primary aluminium manufacture is also very intensive, though much less energy is needed to process recycled aluminium. But although aluminium used in construction contains amongst the highest percentage of recycled inputs of any construction material and is also extensively recycled, the high impacts of primary aluminium manufacture still results in high overall environmental impacts for the aluminium window. Made from a renewable material requiring low energy in manufacture, softwood timber windows perform well. As with all timber products, specifiers should ensure that the timber is sustainably grown. This is particularly relevant for hardwood windows, which perform less well than softwood windows because the timber is typically transported much longer distances. Locally grown hardwoods will have similar impacts to the softwood windows. The aluminium faced window, which has a sacrificial aluminium extrusion on the external face, has a performance similar to that of the aluminium window. Glazing
The glass within a typical double glazed window accounts for less than 10% of the environmental impact of the window.
The choice of glazing (single, double or triple) will not affect the Summary Rating of the window, although it will have a significant effect on the heat loss through the window over its life. Like the use of additional insulation, the energy used to manufacture the extra sheet of glass in double glazing will be far less than the energy lost through the window over its life. The use of coatings on glass (to improve thermal performance, etc.) will also make very little difference to the environmental profile of the window.
24
Internal walls
Summary Rating
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Cost
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
Internal walls
A
A
A
A
A
A
A
B
A
A
A
C
A
£26–£41
60
A
B
B
B
Brickwork, plasterboard/plaster, paint
B
B
B
A
B
A
C
B
B
A
A
C
B
£35–£50
60
C
A
A
A
Dense blockwork, plasterboard/plaster,
B
A
A
A
B
A
C
C
A
A
A
C
A
£37–£50
60
C
A
A
A
Fairfaced brickwork
B
B
A
A
B
A
C
B
A
A
A
A
B
£22–£27
60
C
A
A
A
Glass block wall
C
C
C
C
A
C
B
A
C
C
C
A
C £185–£420 40
C
A
C
A
Lightweight blockwork partition,
C
C
A
A
C
A
C
B
A
A
A
C
A
£33–£39
60
A
A
A
A
A
A
A
A
A
A
A
A
B
A
A
A
A
£150–200 60
C
A
C
C
Steel stud, plasterboard, paint
A
A
A
A
A
A
A
A
A
A
A
C
A
£36–£44
60
C
C
C
C
Timber studwork partition,
A
A
A
A
A
A
A
A
A
A
A
C
A
£27–£30
60
C
C
C
C
A
A
A
A
A
A
A
A
A
A
A
C
A
£32–£44
35
C
B
C
B
Internal partitions Aerated blockwork partition, plasterboard/plaster, paint
paint
plasterboard/plaster, paint Softwood framed safety glass — single glazed
plasterboard, paint Timber studwork with tongue and groove boarding to one face, plasterboard to the other, paint to both sides
Internal partitions Functional unit: 1 m2 of internal wall. It should be noted that these specifications may not be comparable in terms of load-bearing capacity, fire resistance, acoustic performance or transparency and hence may not be suitable in every situation.
Generally, the lightweight framed partitions perform better than their heavier masonry counterparts. Aerated blocks are much lighter and use less material per m2 than dense blocks and lightweight blocks. This gives a better environmental performance than other blockwork, even though the manufacturing is more intensive. The extraction and transport of raw materials for the lightweight blocks, which use low density aggregates such as pumice, requires more energy than dense blocks, which generally use more locally sourced aggregates. The choice of plaster or plasterboard makes little difference to the profile of relevant specifications. Plasterboard does have higher processing energy and wastage than plaster, but it can contain up to 100% recycled material from processes such as emission scrubbing within coal-fired power stations.
Internal walls
25
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
A
A
A
A
A
A
A
A
A
A
A
A
A
£32–£44
60
A
B
A
B
C
B
C
A
A
B
C
B
C
A
B
C
A
£54–£66
60
C
A
A
A
A
A
A
A
B
A
C
C
A
A
A
A
A
£57–£75
60
C
A
A
A
C
C
A
A
C
B
B
A
B
A
B
C
A
£30–£50
60
A
A
A
A
A
A
A
C
A
A
A
A
A
C
A
C
A
£48–£60
60
C
C
C
C
C
A
A
A
A
C
C
C
C
A
C
A
C
£78–£99
60
C
A
A
A
C
B
C
A
A
B
C
B
C
A
B
C
B
£50–£63
60
C
A
A
A
A
A
A
A
A
A
B
B
A
A
A
A
A
£37–£44
60
C
A
A
A
B
A
A
A
B
B
C
C
A
A
B
B
A
£36–£44
60
C
A
A
A
Cost
Summary Rating
Internal walls
Party walls Aerated blockwork cavity wall with isolated plasterboard panels Brickwork cavity wall, plasterboard/plaster Dense blockwork cavity wall, plasterboard/plaster Lightweight blockwork cavity wall, plasterboard/plaster Plasterboard lined timber framing, plywood structural sheathing with absorbent material (mineral fibre) Reinforced concrete wall, plasterboard/plaster Solid brickwork wall, plasterboard/plaster Solid dense blockwork with isolated plasterboard panels Solid dense blockwork, plasterboard/plaster
Party walls Functional unit: 1 m2 of party walling to satisfy building regulations, in particular the provision of acoustic separation between dwellings.
Party walls containing air spaces (in the form of cavity walls or isolated panels or timber frameworks) to provide acoustic separation tend to have lower environmental impacts than those which use solid mass. Again, the aerated blockwork, when built in accordance with Approved Document E of the Building Regulations (England & Wales), performs better than the other masonry options because of the low mass of the construction.
26
Kitchens
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
Glazed tiles on chipboard base
B
A
A
A
A
A
C
A
A
A
A
A
A
£70–£100 20
B
A
C
A
Hardwood laminated blockboard
A
A
A
A
A
B
A
A
A
C
C
A
A
£60–£70
20
C
C
C
C
A
B
A
A
A
A
A
A
A
A
A
A
A
£30–£45
20
A
A
C
A
Slate tiles on chipboard base
A
A
A
A
A
A
A
A
A
A
A
A
A
£70–£100 20
C
A
B
A
Slate worktop with timber supports
C
A
A
C
C
A
C
A
A
B
A
A
C £170–£147 20
C
A
A
A
Solid hardwood worktop
A
A
A
A
A
B
A
A
A
C
C
A
A
£60–£75
20
C
A
B
A
Stainless steel worktop on chipboard
A
A
A
A
A
A
A
A
A
A
A
A
A
£40–£80
20
A
A
C
A
Stone worktop with timber supports
B
A
A
C
A
A
A
A
C
B
A
A
A £140–£160 20
C
A
A
A
Synthetic stone worktop
C
C
C
A
A
C
A
C
A
A
A
C
A £200–£300 20
C
C
C
C
Cost
Summary Rating
Worktops
worktop Melamine laminated chipboard worktop
base
Worktops Functional unit: 1 m2 of worktop plus any additional support needed to fit standard kitchen units.
These ratings could also be used to judge worktops used in other places such as bathrooms.
Although the impact of kitchen fittings within the typical house is small, less than 5%, the range of environmental performance from the common specifications gives housebuilders the opportunity to make significant reductions in environmental impacts through ‘green’ specification. Synthetic stones, using mineral dust in an acrylic resin, have greater environmental impacts than their natural counterparts. Stone worktops, despite their minimal processing, do not perform particularly well because of their high mass. Slate, because of the large amounts of wastage associated with its finishing, does less well than other stones. Glazed tiles, because of the energy required to fire and glaze them, do not perform well. The solid hardwood worktop performs very well, with the laminated blockboard performing slightly less well due to the glues used. Chipboards with both melamine laminate and stainless steel also have good performance.
Energy saved by recycling
Currently recycled
Recyclability
Recycled input
Cost
Minerals extraction
Summer smog
Eutrophication
Ecotoxicity
Acid deposition
Water extraction
Waste disposal
Human toxicity
Freight transport
Ozone depletion
Fossil fuel depletion
Climate change
Summary Rating
Cupboard units
Typical replacement interval
27
Beech veneered chipboard doors
B
B
B
A
A
B
B
A
B
B
C
A
A £126–£141 20
A
A
C
A
Lacquered MDF doors
B
B
B
A
A
A
B
C
A
B
A
C
A
£94–£105 20
A
A
C
A
Lacquered MDF and glass doors
B
A
A
C
A
C
C
B
A
C
C
A
C
£94–£105 20
C
A
C
C
Melamine laminated chipboard doors
C
C
C
A
B
B
C
A
C
B
B
C
A
£82–£97
20
A
C
C
A
Solid hardwood doors
A
A
A
C
A
C
A
A
A
C
C
A
A £130–£145 20
C
A
A
A
Solid softwood doors
A
A
A
A
C
A
A
A
A
A
A
A
A £114–£130 20
C
A
A
A
Solid softwood glazed doors
A
A
A
B
C
C
B
A
A
B
C
A
C £140–£155 20
C
A
C
C
Cupboard units Functional unit: 1 m2 of kitchen cupboard frontage, with standard chipboard carcass.
As with the worktops, the timber specifications perform very well because of their low climate change impacts. MDF, chipboard and melamine all use highly processed resins that adversely affect their profiles. The low mass of glass used in the glazed cupboards does not greatly affect their profiles and their overall performance is similar to that of solid doors of the same frame material.
28
Refurbishment: external and internal wall insulation
Functional unit: 1 m2 of internal or external wall insulation with protective cladding where necessary to upgrade the thermal performance of a solid 9 inch masonry wall to provide a U value of 0.45 W/m2K. In all cases, we have assumed that the internal wall surface was sound, and that the external surface required rendering or some other form of protection.
Specification of insulation
Compared with external wall construction, the mass of insulation used within external and internal wall insulation is greater in proportion to that of the other materials. The choice of insulation is therefore significant to the impacts of the chosen cladding system. For this reason, specifiers should select both the cladding type and the Summary Rating of the chosen insulation (using the Summary Ratings for insulation given on page 30) in order to check the ratings for the given cladding system. If an ozone-depleting insulation is specified, then the resulting increased climate change and ozone depletion impacts will affect the Summary Rating for the specification and make it worse than a system using a C-rated insulation. To obtain a Summary Rating for a system using an ozonedepleting insulation, the Summary Rating for a system using a C-rated insulation should be made a rating worse. For example, a polymer-modified cementitious render using an ozone-depleting insulation would move from a B Summary Rating to a C. Specification of cladding
Generally, minimally processed cladding systems, internal wall insulation and traditional renders perform well. Claddings such as timber and fibre cement require much less processing than epoxy resin laminates or aluminium boards with a thermoplastic core and they have correspondingly lower impacts. Relevant information on Canadian Cedar cladding is given in the section on framed external walls (page 8). Internal insulation systems perform well because the framework needed to support the insulation and plasterboard can be much lighter than external systems as they do not need to withstand wind loading, etc. Traditional render, with minimal processing and a longer typical replacement interval, performs well. Polymer-modified cementitious renders using small quantities of highly processed synthetic material and having shorter typical replacement intervals have correspondingly higher impacts. And polymeric renders, which contain a much higher proportion of synthetic material, will again have higher impacts. The insulating lime render is one of the poorest environmental performers, because of the thickness and resulting mass needed to obtain the required thermal performance.
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Typical replacement interval
Recyclability
Currently recycled
Energy saved by recycling
A
A
A
A
A
B
A
A
A
A
A
A
A
A
30 C
A
B
A
BC
B
A
A
C
B
B
A
A
A
B
C
A
A
30 C
A
B
A
ABC
A
A
A
A
A
A
A
A
A
A
A
C
A
30 C
A
B
A
ABC
B
B
A
A
A
C
A
B
A
A
A
A
A
40 A
B
A
B
Recycled input
Summary Rating
Refurbishment: external and internal wall insulation
29
Insulation used in Specification (Rating from Insulation section)
Refurbishment: external and internal wall insulation
Bespoke timber cladding systems Canadian Cedar cladding, timber framework Timber cladding, timber framework
Dry cladding systems Aluminium/plastic board, aluminium framework Aluminium/plastic board, steel framework Epoxy resin laminate board,
A
A
A
A
A
A
B
A
A
A
A
A
A
A
40 B
B
A
B
BC
B
B
B
B
A
C
A
A
B
B
B
A
A
40 B
B
A
B
ABC
C
C
C
A
A
B
B
B
C
A
A
C
A
30 C
C
B
C A
aluminium framework Fibre cement board, aluminium
AB
A
A
A
A
A
B
A
C
A
A
A
A
A
40 A
B
A
framework
C
B
B
B
A
A
B
A
C
B
A
A
A
A
40 A
A
A
A
Terracotta rainscreen cladding,
A
A
A
A
A
A
B
A
B
A
A
A
A
A
30 A
B
A
B
BC
B
B
A
C
A
C
A
B
A
B
C
A
A
30 B
B
A
B
—
C
B
B
A
C
A
C
A
A
A
A
A
C
30 C
A
A
A
ABC
A
A
A
A
A
A
A
B
A
A
A
A
B
60 C
A
A
A
AB
A
A
A
A
A
A
B
B
A
A
A
A
B
25 C
A
A
A
C
B
B
B
A
A
A
A
B
B
A
A
A
B
25 C
A
A
A
aluminium framework
Insulating render Insulating lime render
Internal wall Insulation Steel framework, plasterboard
Polymer-modified cementitious render systems Polymer-modified cementitious render, glass wool mesh
Polymeric coating systems Polymeric coating, glass wool mesh
A
B
B
B
A
A
B
A
A
B
A
A
B
A
20 C
C
C
C
BC
C
B
C
C
A
C
A
A
B
C
C
A
A
20 C
C
C
C
ABC
A
A
A
A
A
A
B
C
A
A
A
A
C
30 C
A
A
A
Traditional render Sand/cement render, glass wool mesh
30
Insulation
Recyclability
Currently recycled
Energy saved by recycling
C
£14–£17
C
A
A
A
A
A
£2–£10
C
C
C
C
B
B
A
£11–£15
C
C
C
C
A
A
A
A
£1–£15
B
C
C
C
A
A
B
C
C
£15–£30
B
C
C
C
A
B
C
C
A
A
£7–£8
C
C
C
C
A
A
A
A
A
A
£2–£4
A
C
C
C
B
B
A
A
C
A
A
A
A
A
A
A
A
Expanded polystyrene (EPS)
A
A
A
A
A
A
A
A
A
A
A
A
Extruded polystyrene (XPS)
C
C
C
A
A
A
A
A
C
A
A
A
Foamed glass insulation
B
A
A
A
B
A
A
A
A
A
A
Glass wool insulation with density
A
A
A
A
A
A
A
A
A
A
A
B
A
A
A
C
B
B
C
A
A
A
A
A
A
A
A
A
A
A
B
A
A
A
A
B
C
A
B
B
B
C
A
C
A
A
A
A
A
A
A
A
Corkboard insulation with density
Cost
A
Minerals extraction
C
Summer smog
C
C
Eutrophication
C
C
Ecotoxicity
C
C
Acid deposition
C
£10–£12
Water extraction
£5–£7
A
Waste disposal
A
Human toxicity
C
Freight transport
C
Ozone depletion
A
Fossil fuel depletion
C
Climate change
£7–£11
Summary Rating
Recycled input
Insulation
120 kg/m3
(HCFC free) with density less than 40 kg/m3
160 kg/m3 or less Glass wool insulation with density over 160 kg/m3 Mineral wool insulation with density 150 kg/m3 or less Mineral wool insulation with density over 150 kg/m
3
Polyurethane insulation (PU) (HCFC free) Recycled cellulose insulation
Insulation
31
Insulation Functional unit: 1 m2 of insulation materials to provide a common thermal performance, equivalent to 50 mm of expanded polystyrene (EPS).
Insulation is generally a material with very low density and only small masses are needed to provide high levels of insulation. For this reason, the contribution of the insulation to the impact of elements is generally small. However, for external and internal wall insulation (page 29) where the mass of insulation is significant in comparison to the mass of other materials, and when the selected insulation causes ozone depletion, the choice of insulation will have a significant impact on the Summary Rating of an element. Ozone-depleting insulation
Relative ozone depletion and climate change impacts* of various blowing agents Ozone Climate depletion change CFC-11
1
3400
HCFC-142b
0.06
1600
HFC
0
300
Pentane
0
0
Carbon dioxide
0
1
* Ozone depletion and climate change impacts are explained in more detail in Appendix 2.
One of the most important issues today relating to the environmental impacts of insulation materials is the use of hydrochlorofluorocarbons, known as HCFCs, to blow some foamed insulation products. These gases are used because they reduce the conductivity of closed cell foams and therefore increase their thermal efficiency. They have replaced chlorofluorocarbons (CFCs) which were used for the same reasons, but which have been phased out under the Montreal Protocol because of their effect on ozone depletion. However, as can be seen from the Table, left, HCFCs still deplete ozone and are also very strong greenhouse gases. Because of this, the environmental impact of foams which use these gases are over three times greater than foams which use alternative blowing agents such as pentane or carbon dioxide. Because these ozone-depleting foams are so environmentally damaging, to include them within the specifications for Insulation in the Table above would completely skew the results: HCFC-blown foams would get C Summary Ratings and all the other insulation would achieve A Summary Ratings. If HCFC-blown foams were assessed using the Category range as used in the Table, left, they would typically achieve E, F or G Summary Ratings. Impacts of insulation
The conductivities of the insulation materials used are those which would be expected shortly after installation where good construction practice has been followed. There is growing evidence to suggest that actual thermal performance can vary considerably, due to, for example: ● poor construction practice such as overcompression, leaving gaps, etc., ● the escape of HCFCs from closed cell foams over very long timescales, ● moisture penetration, ● compression or contamination over time by dust and dirt, particularly in lofts.
Until better information is available, however, we are unable to consider these variables.
Low-density mineral wool, expanded polystyrene (EPS), corkboard and recycled cellulose are all good performers due to their minimal processing energy. Lower density mineral wools should be used in preference to denser mineral wools where possible as the environmental impact increases proportionally with their weight, particularly as their conductivity is relatively unaffected by density. Polyurethane (PU) and extruded polystyrene (XPS) are both very highly processed, but as polyurethane foams have lower conductivity, less foam is required to provide similar thermal resistance, resulting in a better environmental profile.
32
Landscaping
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
Brickwork wall, 1 brick thick
C
C
C
A
C
C
C
C
C
A
C
A
B £160–£200 45
C
A
B
A
Brickwork wall, 1/2 brick thick
B
B
B
A
B
B
B
B
B
A
B
A
A
£90–£159 30
C
A
B
A
Drystone walling
A
A
A
A
A
A
A
B
A
A
A
A
C £111–£230 60
C
A
C
A
Galvanised steel post and wire strung
A
A
A
A
A
A
A
A
A
A
A
A
A
£8–10
20
C
A
A
B
Galvanised steel railings
B
B
B
B
A
C
A
A
C
C
B
A
A
£90–100
45
C
A
A
B
Galvanised wire chainlink fence with
A
A
A
A
A
A
A
A
A
A
A
A
A
£10–£12
30
C
A
A
B
Hedging or any living barrier
A
A
A
A
A
A
A
A
A
A
A
A
A
£16–£44
60
A
A
C
A
Perforated concrete blockwork wall
A
B
A
A
B
A
A
A
A
A
A
A
A
40
A
C
C
A
Plastic coated chainlink fence with
A
A
A
A
A
A
A
A
A
A
A
A
A
£11–£13
20
C
C
A
C
A
A
A
C
B
A
A
A
A
A
A
C
A
£16–£20
20
C
B
C
A
A
A
A
A
A
A
A
A
A
A
A
A
A
£14–£16
20
C
B
C
A
A
A
A
A
B
A
A
A
A
A
A
A
A
£25–£27
20
C
B
C
A
A
A
A
A
A
A
A
A
A
A
A
A
A
£8–£12
20
C
B
C
A
A
A
A
A
A
A
A
A
A
A
A
A
A
£24–£26
15
C
B
C
A
B
A
A
A
A
A
C
B
A
A
A
A
C £112–£190 60
C
A
C
A
Cost
Summary Rating
Landscaping
Boundary protection
at 1 ft intervals
steel posts
metal posts Pre-treated timber close boarded fencing Pre-treated timber palisade or picket fencing Pre-treated timber post and panel fencing Pre-treated timber post and rail fencing Pre-treated timber post and trellis fencing Stone and mortar wall
Landscaping
33
Boundary protection These ratings can be applied to boundary protection up to 2 m in height and where the specification is appropriate, to balustrading.
The perimeter of many gardens is long enough for the area of fencing or other boundary protection to be comparable with the area of external wall of a typical house. Boundary protection can therefore make a significant contribution to the overall impacts of a typical house. As with many elements, performance generally reflects the mass of material used. Stone walls, with low impacts from processing, still have the highest impacts in terms of mineral extraction. The waste generated at the end of life for the brickwork and stone and mortar walls is also high. The metal chainlink and wire fences, despite metals having high impacts from processing, still perform well because such low masses of metals are used. The railings, which need a relatively higher mass of metal, have higher impacts. All the timber used in these specifications has been pre-treated, ensuring good protection against decay. Untreated timber could be used, with slightly lower initial impacts; but it will have a shorter life and thus worse overall performance over a 60-year life. Living barriers, such as hedging or willow, are one of the best performers, even taking account of a rigorous electrical trimming regime. In addition, they will provide a very good environment for wildlife.
34
The Green Guide to Housing Specification
Summary Rating
Climate change
Fossil fuel depletion
Ozone depletion
Freight transport
Human toxicity
Waste disposal
Water extraction
Acid deposition
Ecotoxicity
Eutrophication
Summer smog
Minerals extraction
Cost
Typical replacement interval
Recycled input
Recyclability
Currently recycled
Energy saved by recycling
Landscaping
Asphalt paving over prepared sub-base
C
C
C
A
A
C
B
A
C
C
C
A
A
£12–£17
30
C
B
B
A
Brick pavers laid over prepared
B
C
C
A
B
A
B
A
B
A
B
A
B
£41–£48
30
C
A
A
A
A
A
A
A
B
A
A
A
A
A
B
C
A
£4–£8
5
C
B
B
B
C
C
A
A
A
B
C
B
B
A
C
A
C
£65–£77
25
C
A
A
A
B
A
A
A
B
A
B
B
A
A
B
A
B
£19–£27
30
C
A
A
A
B
A
A
A
C
A
C
B
A
A
B
A
B
£16–£23
25
C
A
A
A
A
A
A
A
A
A
B
A
A
A
A
A
A
£10–£20
10
B
A
A
A
External surfacing: hard
sub-base Chipped wood or bark over prepared sub-base In-situ concrete laid over prepared sub-base Concrete pavers over prepared sub-base Concrete paving slabs laid over prepared sub-base Glass aggregate made from waste over prepared sub-base Granite setts over prepared sub-base
B
A
A
A
A
A
B
B
A
A
A
A
B
£67–£72
40
C
A
A
A
Gravel over prepared sub-base
A
A
A
A
A
A
B
A
A
A
A
A
B
£6–£9
10
C
B
B
B
Pre-treated softwood timber decking
A
A
A
A
C
A
A
A
A
A
B
B
A
£30-60
20
C
A
B
A
Proprietary grass concrete paving
B
A
A
A
B
A
B
C
A
A
B
A
B £115–£159 30
Stone paving flags over prepared
B
A
A
C
A
A
B
A
A
A
B
A
B
Bark or wood chipping mulch
A
A
A
A
A
A
A
A
A
A
A
B
Glass aggregate made from waste,
A
A
A
A
C
A
B
A
A
A
B
A
Grass turf (includes mowing)
A
A
A
A
B
A
A
B
A
A
A
Gravel or stone chipping mulch
B
A
A
A
A
A
B
B
A
A
A
Low maintenance planting
A
A
A
A
A
A
A
A
A
A
River pebbles
A
A
A
A
C
A
A
A
A
A
on concrete foundations C
A
A
A
£73–£86
40
C
A
A
A
A
£1–£3
5
C
C
C
C
A
£8–£15
10
A
A
A
A
A
A
£4–£7
30
B
A
A
A
A
B
£1–£3
10
C
A
A
A
A
A
A
£8–£17
15
B
A
A
A
B
A
A
£2–£5
30
C
C
C
C
sub-base
External surfacing: soft
used as mulch
Landscaping: external surfacing Functional unit: 1 m2 of external surfacing
This element has been split into two types: hard landscaping — suitable for a drive or pathway, and soft landscaping — suitable for areas with little traffic. However, the ratings are given for surfacing overall. The areas of driveways, paths and landscaping completed by housebuilders can be comparable to the areas of external walls for some houses. The choice of specification of these areas can therefore significantly affect the overall impacts of a typical house. Planting does particularly well, even allowing for maintenance such as grass mowing and watering. As with most of the elements involving heavyweight materials, the materials with low impacts from processing such as stones tend to perform better than the more processed materials such as asphalt.
35
Appendix 1
Life-cycle assessment Life-cycle assessment (LCA) is a method used to measure and evaluate the environmental burdens associated with a product system or activity, by describing and assessing the energy and materials used and released into the environment over the life-cycle of the product. The LCA method can be broken down into three stages. ● Methodology definition ● Inventory analysis ● Impact assessment Methodology definition
The first step in an LCA study is to consider the product system in question, and define the methodology, functional unit and boundaries for the study. This Guide uses the approach described in the BRE Methodology for Environmental Profiles of construction materials, components and buildings (Howard et al 1999). This Methodology is the result of a four-year project funded by DETR and UK construction materials manufacturers. The industry actively supported this work because they recognised that a single, ‘level playing field’ methodology was necessary for the great range of products and types of materials used in UK construction. The Methodology defines a common basis for comparison as a square metre of construction element, eg alternative specifications for an external wall, satisfying building regulations, and built using good workmanship with good maintenance. In LCA jargon, these are known as ‘functional units’ and they are equivalent in their role in the building. The Green Guide uses the BRE Methodology’s Cradle to Grave boundary. In other words, the data used incorporates the impacts from the cradle, ie extraction (and including planting, where appropriate), manufacturing, transportation, construction, maintenance, repair and replacement over a 60-year building life, demolition, and finally to landfill or incineration, ie the grave. Inventory analysis
Inventory is a list of all the burdens: the inputs and outputs or emissions from a process. Using the BRE Methodology, inventory analysis takes account of any recycled input, any recycling or reuse of products after use, and allocation of environmental burdens to any co-products from product systems, such as the co-production of sodium hydroxide when manufacturing chlorine or the slags from metal refining. Impact assessment
Once the Inventory has been produced for a product system, the burdens can be classified, ie they are assigned to the relevant environmental issues to which they contribute. For example, the emission of methane contributes to
36 Examples of how environmental impacts are ‘characterised’ and ‘normalised’ Using the United Nations’ Intergovernmental Panel on Climate Change’s 100-year Global Warming Potentials, compared with carbon dioxide (CO2), methane has an effect 21 times greater for the same mass of emission. The units we use to measure global warming are kilograms of CO2 equivalent (kg CO2 eq100 years) so a classified emission of 1 tonne CO2 and 1 tonne methane would be characterised to 1000 kg CO2 eq100 years and 21 000 kg CO2 eq100 years, respectively. The total climate change impact for the UK is approximately 721 million tonnes of CO2 eq100 years. Divided by the UK population (approximately 65 million), this gives climate change impact for one UK citizen of around 12 300 kg CO2 eq100 years. The normalised impact of the emission of 1 tonne methane described above would therefore be 21 000/12 300 = 1.7.
The Green Guide to Housing Specification both global warming and summer smog. When all the burdens have been classified, they are then characterised. For each environmental issue, the characterisation process evaluates the strength of the classified burdens using a common unit. Because each issue has its own unit, it is still hard to compare the different issues. The characterised impacts for each issue are therefore compared with the corresponding impacts of a ‘norm’ — the Environmental Profiles Methodology uses the impacts of one UK citizen. This process is known as normalisation. Each impact is now a dimensionless proportion of the corresponding impact for one UK citizen and constructions can now be analysed by comparing their normalised impacts in the selected environmental issue categories.
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Appendix 2
Environmental issue categories Climate change Nine out of the 10 hottest years on record occurred between 1983 and 1998.
‘Global warming’ is associated with problems of increased desertification, rising sea levels, climatic disturbance and spread in disease. It has been the subject of major international activity, and methods for measuring it have been presented by the Intergovernmental Panel on Climate Change (IPCC). Gases recognised as having a ‘greenhouse’ or global warming effect include CFCs, HCFCs, HFCs, methane and carbon dioxide. Their relative global warming potential (GWP) is calculated by comparing their global warming effect after 100 years to the simultaneous emission of the same mass of carbon dioxide. Fossil fuel depletion
UK oil reserves are estimated to provide 33 years’ consumption at current rates.
This issue reflects the depletion of the limited resource that fossil fuels represent. It is measured in terms of the primary fossil fuel energy needed for each fuel. Ozone depletion
Under the Montreal Protocol, CFC manufacture is banned after 2000 and HCFCs will be phased out by 2015.
Ozone-depleting gases cause damage to stratospheric ozone or the ‘ozone layer’. There is great uncertainty about the combined effects of different gases in the stratosphere and all chlorinated and brominated compounds that are stable enough to reach the stratosphere can have an effect. CFCs, Halons and HCFCs are the major causes of ozone depletion. Damage to the ozone layer reduces its ability to prevent ultraviolet (UV) light entering the earth’s atmosphere, increasing the amount of harmful UVB light hitting the earth’s surface. Freight transport
The movement of freight causes congestion, noise, and discomfort to those local to transport routes such as roads, ports or flight paths. All transport modes are included with the same weighting, and the issue takes account of both the distance travelled and the mass carried. This issue does not reflect the impacts of energy use or emissions from each type of transport, which are accurately accounted for within other relevant categories, eg fossil fuel depletion. Human toxicity
The emission of some substances such as heavy metals can have impacts on human health. Assessment of toxicity has been based on tolerable concentrations in air, air quality guidelines, tolerable daily intake and acceptable daily intake for human toxicity.
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The Green Guide to Housing Specification Waste disposal
This issue reflects the depletion of landfill capacity, the noise, dust and odour from landfill (and other disposal) sites, the gaseous emissions and leachate pollution from incineration and landfill, the loss of resources from economic use and risk of underground fires, etc. Water extraction
This issue reflects the depletion, disruption or pollution of aquifers or disruption or pollution of rivers and their ecosystems due to over abstraction. Acid deposition
Acidic gases such as sulphur dioxide (SO2) react with water in the atmosphere to form ‘acid rain’, a process known as acid deposition. When this rain falls, often a considerable distance from the original source of the gas, it causes ecosystem impairment of varying degree, depending upon the nature of the landscape ecosystems. Gases that cause acid deposition include ammonia, hydrochloric acid, hydrogen fluoride, nitrous oxides and sulphur oxides. Eutrophication (or ‘over-enrichment of water courses’)
Nitrates and phosphates are essential for life, but in increased concentrations in water, they over-encourage the growth of algae, reducing the oxygen within the water leading to increasing mortality of aquatic fauna and flora and to loss of species dependent on low-nutrient environments. Emissions of ammonia, nitrates, nitrous oxides and phosphorus to air or water all have an impact on eutrophication. Ecotoxicity
The emission of some substances such as heavy metals can have impacts on the ecosystem. Assessment of toxicity has been based on maximum tolerable concentrations in water for ecotoxicity. Summer smog (or ‘low-level ozone creation’)
Because the reactions depend on sunlight and are common in polluted atmospheres, this issue is known as ‘summer smog’. In atmospheres containing nitrogen oxides (a common pollutant) and volatile organic compounds (VOCs), ozone creation occurs under the influence of radiation from the sun. Different VOCs, such as solvents, methane or petrol, react to form ozone at different rates. Although ozone in the upper part of the atmosphere is essential to prevent ultraviolet light entering the atmosphere, increased ozone in the lower part of the atmosphere is implicated in impacts as diverse as crop damage and increased incidence of asthma and other respiratory complaints. Minerals extraction
This issue reflects the total quantity of mineral resource extracted. This applies to all minerals, including metal ore, and applies to both UK and overseas extraction. The extraction of minerals for building in the UK is a high profile environmental topic but the minerals themselves are not considered to be scarce. Instead, this issue is a proxy for levels of local environmental impact from mineral extraction such as dust and noise. It assumes that all mineral extractions are equally disruptive of the local environment. Further information
Further information on these issues, and the way they have been measured and assessed is included in the BRE Methodology for Environmental Profiles of construction materials, components and buildings.
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Contacts and further information
● For further information on the environmental assessment of housing read: Rao S, Yates A, Brownhill D & Howard N. EcoHomes: the environmental rating for homes. Garston, CRC, 2000. ● For further information on the BREEAM portfolio of environmental assessment tools for buildings, contact the BREEAM Office, Tel 01923 664462 or visit http://products.bre.co.uk/breeam ● For further information on Environmental Profiles, visit www.bre.co.uk/envprofiles ● For further information on software tools offering more detailed analysis of building designs, including operational impacts of a building, visit www.bre.co.uk/envest ● For further information on the sourcing of sustainable timber, contact Forests Forever, Tel 020 7839 1891 or visit www.forestsforever.co.uk ● For further information on green specification for offices, read Howard N & Shiers N with Sinclair M. The Green Guide to Specification. Garston, BRE, 1998. ● For further information on sourcing of reclaimed and recycled materials, visit the Materials Information Exchange at www.bre.co.uk/waste The following publications offer useful advice on the environmental impacts of individual materials: ● Green Building Digest, issued by Department of Architecture, Queens University Belfast. Tel: 028 9033 5466 www.qub.ac.uk/arc/research/gbd ● Woolley et al. Green Building Handbook. London, E & F N Spon, 1997 (compendium of the first 12 editions of Green Building Digest). ● Woolley et al. Green Building Handbook. Volume 2. London, E & F N Spon, 2000 (compendium of editions 13 to 20 of Green Building Digest). ● Anink, Boonstra & Mak. Handbook of Sustainable Building. London, James & James, 1996.
Key references All figures in this report, unless otherwise referenced, are derived from the following publications, either directly or through analysis carried out by BRE in research for this and other projects. Association of Plastics Manufacturers in Europe and the European Centre for Plastics in the Environment. Plastics in perspective. Brussels, APME, August 1991. http://lca.apme.org BRE. The BRE Database of Environmental Profiles, www.bre.co.uk/envprofiles British Geological Survey. United Kingdom minerals yearbook 1996. British Geological Survey. 1997. Construction Industry Research and Information Association. Environmental impact of building and construction materials. London, CIRIA, June 1995: ● Volume B Mineral products,
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The Green Guide to Housing Specification ● Volume C Metals, ● Volume D Plastics and elastomers, ● Volume E Timber and timber products, ● Volume F Paints and coatings, adhesives and sealants. Department of Energy. Energy use and energy efficiency in UK manufacturing industry up to the year 2000. Volume 2. London, The Stationery Office. 1984. Department of Energy and Department of Industry. Energy Audit Series. London, The Stationery Office. ● Glass Industry, No 5, June 1979. ● The Cement Industry, No 11, July 1980. ● The Iron and Steel Industry, No 16, April 1982. Department of the Environment. Housing and construction statistics 1988–1998. London, The Stationery Office. Department of the Environment and The Welsh Office. The Building Regulations 1991, Approved Document E, 1992 edition. London, The Stationery Office, 1991. Department of the Environment and The Welsh Office. The Building Regulations 1991, Approved Document L, 1995 edition. London, The Stationery Office, 1991. Department of Trade and Industry. The digest of UK energy statistics. London, The Stationery Office, 1998. Department of Transport. Transport statistics of Great Britain 1995. London, The Stationery Office, 1995. E & F N Spon. Spon’s architects’ and builders’ price book 1999 (Tender Index 325). London, E & F N Spon, 1999. Ecobilan. European ecolabel for paints and varnishes. Pilot project carried out by the Ecobilan for the Ministry of Environment in France. Environmental Toxicology International. All fired up-burning hazardous waste in cement kilns. Seattle (USA), Environmental Toxicology International Inc. EUMEPS, Syndicat National des Plastiques, Alveolaires (SNPA). Expanded polystyrene and the environment. Paris, Syndicat National des Plastiques, Alveolaires (SNPA), 1990. Eyre N J & Michaelis L A. The impact of UK electricity, gas and oil use on global warming. Strategic Studies Department, Energy Technology Support Unit, 1991. Forests Forever/TTF. Directory of national forest policies. London, Forests Forever/TTF, 1997. Friends of the Earth. The good wood guide. Friends of the Earth Handbook. Friends of the Earth, 1996. Government Statistical Service. The digest of environmental statistics, No 20. London, The Stationery Office, 1998. Howard N, Edwards S & Anderson J. The BRE Environmental Profiles Methodology for construction materials, components and buildings. Garston, CRC, 1999. Institution of Mining and Metallurgy. Minerals, metals and the environment. Oxford, Elsevier Applied Science, 1992. Metallgesellschaft AG. Metal Statistics 1981–1991. 69th edition. Frankfurt-am-Main, Metallgesellschaft AG, 1992. NETCEN. UK greenhouse gas emission inventory, 1990–1995. Salway, NETCEN, 1997. Norman C K. UK Year Book of Timber Statistics 1983–85. London, Timber Trade Foundation, 1987. Norsk Hydro AS. PVC and the environment. Oslo, Norway, Petrochemical division, Norsk Hydro AS, September 1992. Ove Arup. Occurrence and utilisation of mineral and construction wastes. London, Arup Economics and Planning, 1991 UK Iron and Steel Statistics Bureau. UK Iron and Steel Industry Annual Statistics 1991. West J M. The reduction of carbon dioxide emission and energy consumption in the manufacture of cements: a review. Garston, BRE, April 1991.
Also available from BRE EcoHomes: the environmental rating for homes S Rao, A Yates, D Brownhill and N Howard BR389 2000 EcoHomes, the housing component of the BREEAM portfolio, permits housebuilders and designers to have their home designs assessed, considering key issues such as energy efficiency, transport facilities, security and materials selection. It is structured so that the assessment can be carried out at specification, house type and site specific stages of development. There are credits under EcoHomes for choosing a specified proportion of major building elements with an overall ‘A’ summary rating from The Green Guide to Housing Specification.
