knightian

Hello everyone, I've just started building a large "extension". We've knocked down about 2/3rd of an old timber frame bungalow and are rebuilding it with a Potton timber frame building. This won't be Passiv Haus levels, but will exceed the new Part L for insulation and air tightness. The rebuilt section will be its own thermal envelope and have underfloor heating from a biomass boiler and MVHR. I'm struggling to find an installer that applies the same analytical rigour as Heat Geeks. The installers I've contacted so far have ignored my SAP calculations and used rules of thumb based on the area of the building and end up proposing cooling systems that seem far too large. Does anyone have any recommendations of installers (ideally in the South East) that will read a SAP or at least conduct their own thermal modelling first, taking into account the fabric, glazing, orientation etc? Thanks!