[EnergyPlus_Support] Heating well down on what was expected

[Sam Roose <sam@xxxxxxxxxxxxxxxxxxxxx>]

Hi all,

I have just uploaded a file to EnergyPlus Support Files/ Problem Submittals/
Sam Roose called 40_radiant_lights. After doing a degree-day calculation to
check the validity of the annual heating energy, I have found that the
resulting kWh/yr.m2 predicted by the design day calculation for each of the
building zones is almost always 5-10 times that which EnergyPlus predicts
for the building, even taking into account the COP of each heating pump.

The design day calculation involved inverting the R value of each exterior
element and multiplying it by that elements area (to get UA). This was then
multiplied by the design days for Wellington above the heating setpoint
(1917 for an 18 degree setpoint - same as the Wellington weather file I
have) to get total heat loss through an element in Watt days/yr. The element
losses are then summed and converted to kWh/yr (*24 hr/1000 W), then divided
by the area to get the final kWh/yr.m2 for each zone.

Example: "24 hr" zone uses about 150 kWh/m2.yr/ COP 3 compared to
EnergyPlus's prediction of 9.4 kWh/m2.yr. I have no idea why this is and
would appreciate help in finding any file (or maybe formula) problem which
causes this difference. Thanks in advance

Sam Roose



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