Unexpected values for Thermal Gains & Losses

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1

I am seeing unexpected results in the breakdown of thermal gains and losses. The attached script demonstrates the question with a simple text box model:

Unexpected Thermal GainsLosses.gh (666.0 KB)

Often, when I make one simple change (in this case changing only the wall insulation value), I see changes in other thermal gains + loss categories that do not make sense. Usually People Gain, Equip Gain, Lighting Gains, and Solar Gains remain as expected (when modifying parameters that should not affect these), but a number of the losses (such as Infiltration, Roof, Floor and Window transmission) show modified values when these parameters should not be affected by the change.

See below for the results of a Baseline run (using R-30 walls) and a second run (with the only change being R-10 walls). The highlighted values are all ones that should not be affected by this change but show increases or decreases in energy.

Any ideas why this would be happening?

Thank you!

Thermal Gains + Losses
Thermal Gains + Losses1772×813 230 KB

2

Hi @molly,

The results don’t look strange to me. Energyplus is a dynamic energy simulation program. So if you make one surface less heat resistant, it has effect on all the values. If you look at the losses due to infiltration, you can see that these are less. This is probably because temprature setpoints are not met in the same way as they were met in the previous simulations. So I think the avarage tempratures are lower in this new simulation. This means less heat transmission through other surfaces.

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3

Hi @Erikbeeren, Thank you for your reply! That makes sense, it’s good to know that this is not an error.

4

Hi @molly

For understanding the results of your simulations it is good to look at the room tempratures. They tell you a lot about what is going on.

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