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.
This weighting system is defined in greater detail within the BRE Global Core Process Standard (BES 5301) and it’s supporting procedural documents. These form part of the over-arching BREEAM Standard and the Code for a Sustainable Built Environment. The same ranking of impacts used in BREEAM underpins the scoring mechanisms in the BRE Green Guide to Specification and the BRE Environmental Profiling Method for construction materials. BREEAM FCO provides a means of adapting these weightings to produce weightings specific to the region or country of assessment.
Table 3 below outlines the weightings for each of the nine environmental sections included in the BREEAM New Construction scheme:
|Health & Wellbeing||15%|
|Land Use & Ecology||10%|
Each of the above environmental sections consists of a differing number of assessment issues and BREEAM credits (as described below and defined in detail in the technical sections of this Scheme Document). As a result, each individual assessment issue and credit varies in terms of its contribution to a building’s overall score. For reference, Appendix H contains a breakdown of individual assessment issues by building type for this BREEAM scheme, and lists the maximum percentage available under each issue to contribute towards the overall BREEAM score.