“WLC tool users are doing their best to pick the most appropriate generic impact factors, but differences in which factors and reference points are available in different tools, as well as varying training and experience, are likely feeding into this inconsistency we have seen historically for similar house types. Within the new homes sphere, we need to agree to use the same set of defaults and assumptions where product-specific EPDs are not available. The conventions provide a ‘wrapper’ in terms of input assumptions and output scope to ensure that new homes WLC assessments can be compared like-with-like.” - Adam Graveley, Future Homes Hub