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why my heating load is too high than cooling load

asked 2017-07-13 19:57:08 -0500

ben gravatar image

updated 2017-07-14 13:41:57 -0500

house is two storied house with basement on the ground and slope roof on the top .I divided each room of house in zones so I have 10 thermal zones.I used HVACTemplate:Zone:IdealLoadsAirSystem objects. to calculate zone wise sensible cooling and heating load hourly for 8760 hours. All I want is annual hourly based heating and cooling loads,somebody suggested me to use HVACTemplate:Zone:IdealLoadsAirSystem objects. in the same group to calculate hourly heating and cooling load.

I am getting heating load too high than cooling load,the weather file I am using is of Dayton Ohio USA.

please somebody suggest me?

thermal load.PNG

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There could be many reasons for this. You can search the forum for reasons why heating load might be high. You could also share your model so other people can investigate. For a house, look at your assumptions for heating temperature setpoint, infiltration, and wall/roof/window U-values. You may also be providing way more ventilation than is typical.

mdahlhausen gravatar imagemdahlhausen ( 2017-07-13 20:43:57 -0500 )edit

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answered 2017-07-14 09:42:48 -0500

Hi @ben

Using "HVACTemplate:Zone:IdealLoadsAirSystem" would be a right way to assess the heating and cooling loads. I just looked at the weather file "USA_OH_Dayton.Intl.AP.724290_TMY3". The ratio of HDD to CDD appears quite different for the two baseline temperatures which might partly explain your issue.

- 1794 annual (wthr file) cooling degree-days (10°C baseline)
- 1532 annual (wthr file) heating degree-days (10°C baseline)

-  538 annual (wthr file) cooling degree-days (18°C baseline)
- 3197 annual (wthr file) heating degree-days (18°C baseline)

I never worked on a project in this area but if have experience in this area and if you think the ratio of heating loads to cooling loads is too skewed, you should possibly find a way to fix that based on the thermostat set points and thermostat schedules.

I suggest taking a closer look at your thermostat set points and schedules and see if they are correctly modeled. For similar issues, I typically look through the .Zsz file to look at the peak heating and cooling loads (last row in the .zsz file) for each thermal zone to identify if the issue is caused by any particular zone.

Hope that helps!

Raghu

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answered 2017-07-14 09:00:24 -0500

ezeraj gravatar image

an answer - why cant the heating load be larger than the cooling load.Its dependent on the people living inside and the location.I suggest you take it as it is.But its quite a large difference.

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Asked: 2017-07-13 19:57:08 -0500

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Last updated: Jul 14