I’m currently heading down to the UKGBC consultation of the development of BREEAM, and thought it would be helpful to review my concerns with the approach to materials and other aspects such as waste and site energy use within BREEAM.
This is drawn from an earlier post written when BREEAM took over CEEQUAL.
So why do I question BREEAM’s scientific methodology in relation to materials? The reason is that the scores for various credits seem to reward some actions in a way which does not reflect the actual environmental impact of the action.
As you can see from the table above, which covers Materials Related BREEAM 2014 credits, weighted for a Fully Fitted Out building, the greatest score can be obtained by using building elements with a Good Green Guide rating. However, some of this score can come from the use of products with Environmental Product Declarations. This might show that the product used is the terrible in terms of environmental impact, but the Mat 01 uplift points will still be awarded.
Where I really question BREEAM however is in the weighting given to construction waste. It is possible to obtain 3.8% of a perfect BREEAM Score by reducing construction waste to exemplary levels (Wst 01). This is excellent, and performance based. But with construction waste being between 2 and 10% of materials used, does it really merit half the BREEAM score from specifying low impact building elements (8.8%)? Additionally, if you recycle exemplary levels of what construction waste you do produce, you are able to obtain a further 1.9%, meaning you can obtain almost as much reward for doing something good with less than 10% of the materials used, compared to the reward for choosing low impact materials in the first place. If BREEAM was scientific, it would not be possible to obtain more than 10% of the Mat 01 score from Wst 01.
Similarly, 1.9% is available by specifying exemplary levels of Recycled Aggregates. Recycled aggregates are already considered within the Green Guide ratings for upper floors, concrete structure and hard landscaping, so this is a double counting of benefit. On top, does the use of recycled aggregate really merit about 30% of the score for specifying low impact materials for walls, floor, roof and hard landscaping?
The same is true for insulation which has 1% compared to 6.8% for the other building elements. Many studies have shown insulation has a tiny influence on the embodied impact of the building – its major effect is in reducing operational impacts – but BREEAM focusses heavily on the embodied impacts of insulation using Mat 04 without any scientific basis.
Hopefully, through the process of consultation as BRE now develop BREEAM, it will be possible to ensure that the credit structure has a more scientific basis. But evidence from BREEAM 2014 shows that credits are more often weighted towards aspects which can be easily measured, or which ensure BRE business from Green Guide ratings and certification, rather than on the basis of impact.