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[EnergyPlus_Support] Comparing EnergyPlus with steady state simulation

Hi

I'm comparing models of three domestic houses in EnergyPlus and with the steady state simulation appropriate for the UK - Standard Assessment Procedure (SAP).

I wonder if anyone out there has tried anything similar, as I find that I'm getting alarmingly different results in terms of summary heating energy requirements...

For three "standard" dwellings, I've taken the u-factors as reported by EnergyPlus in the envelope summary (as yet I'm not entirely sure how the film resistances are generated) and entered these in a spreadsheet implementation of SAP to get the fabric heat losses, infiltration has been set to broadly match the air-change rates determined by SAP by setting the site:heightvariation wind speed profile exponent value to 0; SAP has specific heating schedules which are emulated using an ideal loads air system to provide heat, ground temperatures are set at a constant 12C (the slab program produces temperatures which are higher than are found in the building suggesting reversed heat flow!).  Solar gains in SAP neatly correspond with EnergyPlus's reported window heat gain.  There are no casual gains.

The differences are that EnergyPlus models range between 80% and 50% of the overall heat energy demand than is calculated by SAP.  Unless I'm doing anything particularly stupid.  If anyone is interested and would like to correspond I'd be grateful to hear from you!

best regards
j.



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