Hourly Data From CBECC-Com

asked 2016-06-29 00:04:58 -0500

Hi All,

I have a technical question regarding viewing the hourly data from Title 24 simulation from CBECC-Com (essentially E+).

After the simulation, I opened HourlyResults.csv file to view the hourly data. It is basically showing only couple days in a year, I have cooling/heating/lighting/equipment energy use. Except those days, the hourly data are all just "0". This is a little bit odd to me. I assume it has something to do with the internal load schedule because it is not only for HVAC but also happens to lighting and equipment. But, isn't Title 24 use default schedule for all the internal gains (even if I don't assign any schedule to the space, it will still use the default)?

Have any of you ever ran into this problem before? Please advice if there is something I should check.

Thanks!

answered 2016-06-29 10:46:58 -0500

aparker

8107 ●4 ●18 http://www.openstudio.net/

From the T24 2013 NonRes ACM Ref. Manual

2.6.2 Sizing Equipment in the Standard Design

For cooling capacity sizing, compliance software shall use the **OnDay schedule from Appendix 5.4B for occupant, lighting and equipment schedules, respectively. For heating capacity sizing, compliance software shall use the OffDay schedule from Appendix 5.4B for occupant, lighting and equipment schedules, respectively.

I haven't used CBECC-Com, but based on your description it sounds like what you are seeing is hourly results from the design days (several days per year). For winter (heating) design days it is common practice to assume that all of the internal loads are turned off (always 0) because this represents a worst-case scenario where they don't contribute heat and the heating system needs more capacity. On the flip side, for summer (cooling) design days it is common practice to assume that all of the internal loads are turned on (either following the normal schedule or always 1), which will increase the amount of cooling capacity needed. Based on the reference above and your description, it appears that CBECC-Com follows this practice.

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Thanks for your help! I agree with all what you suggested about the design day issue. I was also able to get some help from CBECC-Com team. Actually what happens is that I was using "Quick Analysis" to run the simulation, and this option only runs four weeks in a year, one week per season to minimize the difference compare to a normal 8760 hours simulation. The option just allows people to run the simulation and detect errors quickly, I forgot to uncheck this when I run a normal simulation. I appreciate your help!