I'been in the HVAC business for 40 years and I always used 50 btuh/s.f. with gas heat and 35 btuh/sf for electric heat. Designed 100's of systems and installed as many also without having one of them not work correctly. These numbers are for conventional construction. Tighter sealed and upgraded insulation like ceilings R38 and walls at R19+ homes and slab insulation would be less of course, guessing about 20% less or 40 for gas and 28 for electric. These nuimbers are strictly for balllpark and check nos. only. Actual Man J calcs should always be ran tyo assure your guesses's are on track or NOT!
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FollowBuilding Envelope Comparisons
It would be great to have a way to make a comparison using different components... say existing conditions compared to adding spray foam. To do this, you could add a Tab to create comparisons. The base system with measurements would be duplicated, then changes made so showcase the effect of different building envelope options. Then in the report, allow for a comparison between the two side by side to show the effect.
On the reports, some things to fix:
-- The sensible & latent cooling should be totaled with a total column.
-- The area total is probably shouldn't be on the same final line as the load cals... confusing. What would be useful is a BTU/Sq/Ft number generated, but again, not on that line unless clearly labeled.
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