andyro wrote:Andy, I completely agree that it would reduce a lot of input (not 90% however, there is significant input required regarding the shading and heating, I've not checked U-Value and thermal conductivities of elements) however, one of the main reasons that PH is a safer standard is because it uses external dimensions, thus over estimating the heat loss. then, by calculating areas externally, the thermal bridge PSI values tend to be negative, which is essentially a correction factor for overlapping elements.
While I can't speak for Graphisoft, the detailed consideration for vertical (by structure) thermal bridges and lateral (psi) thermal bridge simulation and addition of length parameters (you model every lateral detail, and provide a length multiplier in the structures list view), as well as window installation psi values, appears that EcoDesigner's developers were in fact aiming to align 100% with PHPP. In fact I wrote a blog on this here:
I have yet to complete my PHPP course of study and exam, but it seems GS is 90% of the way towards a completed tool. The PHPP export works (tested to 9.6) but is partial, and Exterior Envelope Area needs to be calculated in 2 ways, for its own calculation methods, but also for PHPP export. This could considerably reduce the PHPP input process if export was consistent and reliable, not to mention well documented.
I have some information that can explain these area discrepancies. But there are parties interested in updating the PHPP export, mapping to the new PHPP. Feel free to write me at email@example.com
Afaik Minh the exterior faces are considered, but the interior surfaces are projected, so the corners are missed, that is the difference between the Evaluation Report's 'Gross Floor Area' and 'Treated Floor Area'. The portions of Window footprints are also subtracted. This is not really a matter of right and wrong, what is needed is a fresh approach to EcoDesigner surface mapping design and export tools. Filling in the gaps is not a Herculean effort. Many more people are trying to do this and failing - those human-hours could be better spent refining the tools at GSHQ 🙂
PS - both PHI and GS are 'wrong'. Heatloss actually starts at the interior surface air film, and ends at the exterior surface air film, if a 'building' is considered as the system boundary. The heatflow calculations should consider the interior area, but the corner conditions should be mapped in a radial manner - neither GS or PHI have bothered to do that so the PH answer is apply heatloss from the exterior surface using an aggregated U value with all psi and chi values applied. Please correct me if I'm wrong, which is 50% of the time easily.