CATEGORY 3 OF THE CODE FOR SUSTAINABLE HOMES

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1 CATEGORY 3 OF THE CODE FOR SUSTAINABLE HOMES Materials Last month we looked at the first two categories of the Code for Sustainable Homes: Category 1 Energy and CO 2 Emissions, and Category 2 Water. We now continue, but remember this account is only an overview. For the fine detail the reader should check out the Code for Sustainable Homes Technical Guide. As described previously, there are nine categories considered within the Code, and within each category a number of issues are assessed. Credits are awarded for each issue, and then the credits are multiplied by a conversion factor to give the points for the category. The sum of the points for all the categories determines the Code Level ranging from Code Level 1 with at least 36 points, to Code Level 6 with at least 90 points (out of 100). There are some mandatory standards for some of the issues, too. Even if a formal Code assessment is not required, the reader may find these articles useful for highlighting the issues that need to be considered in the building of a sustainable new home. CATEGORY 3 MATERIALS Maximum number of credits: 24. One credit converts to only 0.3 points, so the maximum number of points for Materials is a modest 7.2. Three issues are assessed, starting with: Environmental Impact of Materials Aim: To promote the specification of materials which have lower environmental impacts over their life-cycle. Credits available: 15. Mandatory standard at all Levels. For this issue, the five key elements of the building envelope are considered: Roof External walls Internal walls Floors Windows. The specification for each element is given a rating according to the Green Guide to Specification. (See the Endnote for more about the Green Guide. Its ratings for environmental impact range from A+ down to E.) It is mandatory at all Code Levels that at least three of the elements achieve a rating of D, or better. (This mandatory standard seems lax. Two of the building envelope elements can have the worst rating, E, and the other three need be hardly better, at D.) The Green Guide rating for an element determines the credits to be awarded, as in the following table: Green Guide rating A+ A B C D E Credits ½ ¼ 0 CSH CATEGORY 3 1 MAY 2011.

2 Conversion of Green Guide rating to CSH credits Three credits are available for each of the five elements of the building envelope, giving a maximum of 15 credits. (For an official assessment, the online Code Mat 1 Calculator Tool is supposed to be used but this is only accessible to accredited assessors. Likewise, the online Mat 2 and Mat 3 Calculator Tools for the next two issues.) Responsible Sourcing of Materials Basic Building Elements Aim: To promote the specification of responsibly sourced materials. Credits available: 6. The aim is worthy, but defining how to award credits in this complex area takes 15 pages of the Technical manual. (Note that some materials are excluded from the assessment, viz, insulation materials, fixings, adhesives, and additives.) There are several schemes for monitoring the responsible sourcing of materials, the best known being the FSC scheme for timber (run by the Forest Stewardship Council). BRE have a scheme known as BES 6001: Framework standard for the Responsible Sourcing of Construction Product. The scheme sets standards for: Organisational management. Supply chain management. Environmental and social issues. Products are rated as Pass, Good, Very Good, or Excellent. (See Further Info for their Green Book Live website.) For this issue, the basic building elements are defined to be: Ground floor Upper floor(s), if any Roof Frame, if any External walls Internal walls Foundations Staircase (excluding balustrading see Finishing Elements, below). So far, so good. But from here, the methodology becomes complex. Unless you, the reader, are a masochist for detail, I suggest you skip the next few paragraphs! The schemes vouching for responsible sourcing are allocated to one of five tier levels. An excellent scheme such as FSC is in the top Tier Level 1. The SGS scheme ( SGS is the world s leading inspection, verification, testing and certification company ) has been placed in Tier Level 3. Apparently, BRE the producers of the Code do not rate SGS as highly as they rate themselves. Points are available for a material according to the Tier Level of its sourcing scheme. I have put Points in inverted commas, as these are not the same points that we have dealt with previously (obtained by the conversion of credits). In what is CSH CATEGORY 3 2 MAY 2011.

3 possibly a vain quest to achieve some clarity, I have invented the term S-points (where S stands for Sourcing). I hope the following table will shed some light: Tier Level S-points available Examples of compliant sourcing schemes 1 3 FSC, PEFC, BES6001 Excellent and Very Good, Re-used materials. 2a 2.5 BES6001 Good. 2b 2 BES6001 Pass MTCC***, SGS, Certified recycled materials. 4 1 Certified EMS* for manufacture. Points are dependent on the quality of the scheme (ie, its Tier Level) * EMS = Environmental Management System (eg, ISO14001) Note the inclusion of re-used and recycled materials in the above table. What s the difference between them? Consider salvaged bricks. They could be cleaned up and re-used as bricks, or they could be broken up and recycled as hardcore. Of course, for any particular building element a variety of materials will be used, and the likelihood is that the materials will be covered by a variety of sourcing schemes. For each scheme, the S-points potentially available are given by the table above. The tricky part is to allocate one number to represent the S-points of the building element, a number that reflects the mix of the materials and their associated sourcing schemes. I think the best way to show how the Code does this is by an imaginary example, below. (The proportions of materials used are measured by volume, not by weight nor by cost. In the example, the proportions are my guesstimates. I am not an accredited assessor so have no access to the Code Mat 2 Calculator Tool.) Imaginary building element, a roof: Proportion Sourcing Tier S-Points S-points Scheme Level available gained Roof trusses 28% FSC x 3 = 0.84 Battens 7% Bracing (timber) 5% PEFC x 3 = 0.15 Tiles 33% BES6001: Pass Plasterboard 23% EMS (ISO14001) Mortar 2% Slater s felt 2% Sourcing points gained by an imaginary roof 2b x 2 = x 1 = 0.23 TOTAL: 1.88 At least 80% of the materials must be covered by a sourcing scheme for any S-points to be allocated. (If the proportion is less than 80%, S-points allocated = 0.) CSH CATEGORY 3 3 MAY 2011.

4 In the example, 89% of the materials are covered by a scheme (89 = ); so the S-points allocated would be The maximum number of S-points that can be allocated to an element is 3 (ie, 3 x 100%). S-points are allocated for all the basic building elements of the structure. As an illustration, here is another imaginary example a masonry bungalow with the roof described above. S-points allocated Ground floor 1.7 Roof 1.88 External walls 1.5 Internal walls 2.5 Foundations 0 TOTAL 7.58 Sourcing points (S-points) allocated for an imaginary bungalow The average S-points allocated for the five elements is (7.58 5). The average S-points allocated determines the credits to be awarded, as in the following table: Average S-points allocated Credits Conversion of sourcing points to credits for basic building elements So, for our imaginary bungalow, with the average S-points allocated being 1.516, the number of credits gained would be 4, yielding 1.2 points (1.2 = 4 x 0.3.) This fiendishly complex methodology yields, at most, only 6 credits (yielding only 1.8 points). Responsible Sourcing of Materials Finishing Elements Aim: To promote the specification of responsibly sourced materials. Credits available: 3. The finishing elements are defined to be: Balustrading (of staircase) Windows Doors (external and internal) Skirting Panelling Furniture Fascias Any other significant use. CSH CATEGORY 3 4 MAY 2011.

5 Furniture is not the stuff you move into your newly built home, but the units (cupboards, etc) fitted into a kitchen, bedroom, bathroom, etc. The complex methodology is similar to that for the sourcing of the basic building elements, described above. But the maximum number of credits for this issue is smaller only 3 (yielding only 0.9 points). Average S-points allocated Credits Conversion of sourcing points to credits for finishing elements ENDNOTE: The Green Guide Ratings BRE first produced the Green Guide to Specification in 1996, and it is now freely available online. (See Further Info.) The intent has been to produce a simple-to-use listing of common specifications for the basic elements of a building, and to rate each specification from A+ down to E according to the environmental impact of the materials in the specification. Over 1500 specifications are listed. As an example, a popular specification listed for the external wall element is: Brickwork outer leaf Insulation Aircrete blockwork inner leaf Cement mortar Plaster Paint. This gets the top A+ rating. (I ll have more to say about that at a later date.) Many diverse factors are considered by BRE in arriving at a rating for a material (and thence a specification): Climate change Fossil fuel depletion Water extraction Mineral resource extraction Waste disposal Nuclear waste (higher level) Acidification Photochemical ozone creation Stratospheric ozone depletion Toxicity to humans Toxicity to freshwater and to land Eutrophication. (Eutrophication? Pollution of ponds and lakes which results in excessive nutrients for algae, etc. This often leads to a green scum on the surface.) A Life Cycle Assessments of a material (or product) is made for each of the above factors. The impact on the environment is assessed not only for manufacture but also for maintenance, replacement and demolition. And somehow the results are condensed into a single summary rating, ranging from A+ down to E. An unusual specification might not be included in the Green Guide listing. In that case, a rating for the specification needs to be generated by inputting the individual materials into the online Green Guide Calculator. (Unfortunately, at the time of writing, the Calculator can only be accessed by accredited Code assessors.) CSH CATEGORY 3 5 MAY 2011.

6 FURTHER INFO: Code for Sustainable Homes Technical Guide, November 2010 Free download from: Green Guide to Specification Produced by BRE. Available online after free registration. The Green Guide Calculator is not accessible to the public at present. Green Book Live BRE website: The unique reference source for environmental products and services. Includes a list of products approved to BES Available free online: Words: Copyright article by Robert Matthews in SelfBuild & Design magazine, May, CSH CATEGORY 3 6 MAY 2011.