LCA Boundary Condition

My understanding is that you are supposed to compare buildings with similar thermal performance. This is necessary to avoid making the baseline with extra materials that would make its life cycle worst than the designed building. That said, this credit evaluates the envelope and structure materials of the building, the energy used during building operation is evaluated under the Energy and Atmosphere credits.

Hi Thanyatorn, To build upon Dionisio's contribution, I would like to add that the flexibility on the creation of the baseline is an opportunity to help design teams seek these credits at different project stages: concept, schematic, and/or detailed design stages. The early you start, the more opportunities of improvement you will have at lower cost as you have not committed to a design/material option. At any stage there is the possibility of a) looking for materials that have lower impacts or b) make a more efficient use of materials, and thus lower the impacts. Yet, this still leaves the question on how/when to define that baseline. So, when you work this credit with the "Minimum energy performance" requirements, you could use the proposed design with the achieved improved energy performance as your LCA baseline (this is not required, but I think can work nicely as I will explain). Then, as you well pointed out, the materials that make the U-value of your envelope are part of the material quantities that you will use for your whole building LCA. Don't forget that the structure of the building is not normally included in the energy model but is an important (and required) contributor of the LCA scope. Afterwards, you can develop your Improved building from an LCA perspective by looking for materials with low impact for both the envelope (that maintain the same U-value of your envelope and building energy performance) and structure. Working with both credits through this strategy is a great opportunity as you not only are aiming at reducing operational energy consumption and its carbon footprint but also the embodied carbon of the materials that make up the building.