Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Cooling load is not changing when I change Window to Wall Ratio

asked 2019-01-03 23:53:41 -0500

updated 2019-02-05 00:31:17 -0500

I am facing problem to get cooling load for difference Window to Wall Ratio(WWR). When I am changing WWR for the same model there is no change in cooling load.I found the same cooling load for 5% or 80% and above. Now need to know how can I solve this problem? I am using Open Studio (1.14.0) , Sketch Up make(2016), Energy Plus(8.6) version.

1 2

edit retag flag offensive close merge delete


Which value are your looking at exactly? Do you have absolutely the same value? What about total EUI? Can you show at least a picture of your model?

Julien Marrec's avatar Julien Marrec  ( 2019-01-04 02:58:30 -0500 )edit

I am looking for changing my cooling load value with changing WWR. Theoretically, for 5% window to wall ratio the cooling load is not same with the cooling load for 20% WWR. But in my model I found the almost same value of cooling load. Total EUI for 5% WWR = 1866.29 kBTU/ft^2 and for 20% WWR = 1853.07 kBTU/ft^2, which is almost similar.'s avatar  ( 2019-01-05 00:32:12 -0500 )edit

Given how simple your model is, do yourself and everyone who might want to help a favor and just share your OSM and EPW (upload them somewhere and add the link in your question).

Julien Marrec's avatar Julien Marrec  ( 2019-01-22 02:38:13 -0500 )edit

I am using Open Studio and Sketch up from few days only. That's why I am facing to calculate the cooling load in this simple model. I will be grateful if you help me to find the answer. In OSM file, i give the 20% and 65% wwr cooling load calculation which is not match with theoretical results. I am adding my EPW file also for your refernce.'s avatar  ( 2019-01-23 01:36:51 -0500 )edit

I am trying to solve the above problem but I don't find any solution. On that note I need your help to find the answer. 1.Why my cooling load value is not changing with different WWR? 2. I want all the data in hourly basis instead of monthly.

I am eagerly waiting for your response.'s avatar  ( 2019-02-01 23:53:03 -0500 )edit

1 Answer

Sort by ยป oldest newest most voted

answered 2019-02-05 11:25:17 -0500

The single-zone building has a >> 1,000 kBtu/sf EUI. You aren't seeing a large % change in cooling energy use, because your heating and fan energy use is so high. This is because the model assumes a 1,271 cfm/person ventilation rate in your Design Specification Outdoor Air. Typical values are ~20 cfm/person.

Also, the model has both Milan and New Delhi design days. Remove New Delhi design days.

edit flag offensive delete link more


Thanks for replying. I got your point but I want to know why this cooling load become same all the time whether i change my window to wall ratio. In normal condition if we increase the window size there will be more heat inside the room but in my design the cooling load is same if I change the window size. I designed a building with 40% and 90% window to wall ratio but both case i found the cooling load is same. In addition my U value of the glass is equal with a clear glass. Eagerly waiting for your answer.'s avatar  ( 2019-02-09 02:58:16 -0500 )edit

Can you specify which values you referring too as cooling load? And do you mean "similar" or literally identical? The values you give in the comments above are cooling energy use intensity, not cooling load. The EUIs have a ~13 kbtu/sf-yr difference which quite a lot for a typical office building. You aren't seeing a big difference in cooling coil load, because 95%+ of the load on the coil is cooling ventilation air with your ventilation rates.

mdahlhausen's avatar mdahlhausen  ( 2019-02-09 16:05:13 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer


Question Tools


Asked: 2019-01-03 23:53:41 -0500

Seen: 403 times

Last updated: Feb 05 '19