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Environmental section weightings

Environmental weightings are fundamental to any building environmental assessment method as they provide a means of defining, and therefore ranking, the relative impact of environmental issues. BREEAM uses an explicit weighting system derived from a combination of consensus based weightings and ranking by a panel of experts. The outputs from this exercise are then used to determine the relative value of the environmental sections used in BREEAM and their contribution to the overall BREEAM score.

Table 7: BREEAM Environmental section weightings for common project types

Environmental sectionWeighting
Non-residentialSingle residential dwellingsMultiple residential dwellings
Fully fitted outShell onlyShell and corePartially fittedFully fittedPartially fittedFully fitted
Management12%13.5%13%11.5% 15% 12.5% 12%
Health and wellbeing14%8%8.5%14.5%15%15%15%
Hazards1%1.5%1%1% 1% 1%1%
Energy19%19.5%19%19.5% 22.5%18.5%20%
Transport8%11%8.5% 8%6.5%8.5%8%
Water6%3%6.5%4.5%6.5% 4.5%5.5%
Materials12.5%16.5%13.5%13.5% 9% 13% 12.5%
Waste7.5%8.5%8%7%6%7%6.5%
Land Use and Ecology10%13%11% 11% 8.5%10.5%10%
Pollution6.5%1%7%5.5%6%6% 6%
Surface water run-off3.5%4.5%4%4%4%3.5%3.5%
Total100%100%100%100%100%100%100%
Innovation (additional)10%10%10%10%10%10%10%

Each of the above environmental sections consists of a differing number of assessment issues and BREEAM credits (as described elsewhere and defined in detail in the technical sections of this scheme document).

Adaptation of weightings for local conditions

In order to provide weightings that are adapted for local conditions, the weightings are reviewed for the first project that registers for assessment in a country or region. These weightings are then set as appropriate for that project and all other projects thereafter in that country or region for the life of the current BREEAM International version. The development of these weightings is based on robust and independent information forwarded from 'local experts' who have an understanding of local conditions. This may be a member of the design team if they can demonstrate sufficient knowledge of the environmental conditions of the region or country, or another individual or organisation with the relevant expertise.

The required information is compiled by the BREEAM Assessor using the 'BREEAM International Weightings' form (available from the BREEAM Assessor Extranet). It is the assessor's responsibility to correctly complete the 'Environmental Weightings' and submit the form to BRE Global, who use the information to develop appropriate weightings for that country or region.

The weightings are tailored based on the ten technical categories, with categories being considered 'Global' or 'Local'. Global categories are those defined as having a universal impact, independent of the local context. Local categories are those defined as being variable locally, due to social, environmental, political or economic factors. BRE Global will take account of these factors when determining the relative importance of the technical sections.

Influence of hazards

In the case of the Hea 07 Hazards and the Flood Risk criteria within Pol 03 Flood risk management and reducing surface water run-off, these issues are separately weighted from the remainder of their respective technical sections. BRE Global considers the Heath & Wellbeing and Pollution sections to be predominantly 'Global' categories; however, given the local importance of addressing natural hazards (including flood risk) these issues are 'Local'.

The influence of location

As well as having an impact on the weightings attributed to BREEAM sections and assessment issues (see Adaptation of weightings for local conditions above), the culture, economy, climate and work practices can also affect the development of criteria and the method of assessing certain BREEAM issues.

One example involves the opportunity for rainwater recycling in BREEAM issue .Wat 01 Water consumption. In this instance the higher performance benchmarks vary according to amount of precipitation available. The assessor can determine the precipitation zone in which the building is located using the map inFigure 4 (and other information below) and consequently use this climatic zone to establish the appropriate water consumption benchmark for a building in that location.

The map below highlights the Earth's climates zones according to the Köppen-Geiger climate classification method. They are defined according to maximum and minimum temperature ranges, as well as the total and seasonal distribution of precipitation.

For the purposes of BREEAM, the climatic zones (refer to Figure 3 ) are defined as:

  1. Equatorial - tropical climates where temperatures remain above 18°C
  2. Arid - dry climates (semi-arid and desert climates)
  3. Warm temperate - mid-latitude climates (warm, dry summers with cool, wet winters)
  4. Snow - temperate, is generally between -3°C and 10°C (subarctic or temperate alpine areas and low precipitation)
  5. Polar - permafrost or tundra climates

For the purposes of .Wat 01 Water consumption, the precipitation zones (refer to Figure 4 ) are defined as:

  1. Precipitation zone 1: corresponds to Appender’s precipitation regions f (fully humid) and m (monsoonal)
  2. Precipitation zone 2: corresponds to Appender’s precipitation regions s (summer dry) and w (winter dry)
  3. Precipitation zone 3: corresponds to Appender’s precipitation regions S (steppe) and W (desert)

Advice and guidance on how to carry out a classification can be found at: http://www.physicalgeography.net/fundamentals/7v.html

World map of KÖppen-Geiger climate classification

Figure 3 : World map of Köppen-Geigerclimate classification

World map of BREEAM precipitation zones

Figure 4 : World map of BREEAM precipitation zones

BREEAM International New Construction 2016
Reference: SD_TBD – Issue: 0.0 (draft)
Date: 23/12/2015
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