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

why is CDD50 used in ashrae90

asked 2022-04-08 23:26:08 -0500

yongqingzhao's avatar

updated 2022-04-10 10:01:37 -0500

Hi, everyone

A question was confused me for a long time, so have to the email to ask you, which is why CDD50 is used in Ashrae 90, CDD50 is defined as following:

cooling degree-day base 50°F (CDD50): for any one day,when the mean temperature is more than 50°F, there are as many degree-days as degrees Fahrenheit temperature difference between the mean temperature for the day and 50°F. Annual cooling degree-days (CDDs) are the sum of the degree-days over a calendar year.

However, I am very confused why 50°F is used as the threshlod between cooling and heating? That means when the outdoor air temperature is more then 50F, the cooling starts to work?In chinese standard, 26℃ is as the base of CDD.

edit retag flag offensive close merge delete

1 Answer

Sort by » oldest newest most voted

answered 2022-04-09 06:34:08 -0500

rgleason's avatar

I think it is because a good approximation for the balance point of buildings is often taken as 50 degreesF although a given building based on its design is likely different.

edit flag offensive delete link more

Your Answer

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

Add Answer

Training Workshops

Question Tools



Asked: 2022-04-08 23:26:08 -0500

Seen: 139 times

Last updated: Apr 09