[Bldg-sim] HVAC Equipment Sizing

[Michael A. Eustice]

My best guess would be the pull-down cooling load.  If you're modeling the 12-hr building as 12 hours occupied and 12 hours unoccupied.  The software may let the building temperature float way up outside of setpoint during the unoccupied hours.  Then, when your occupied hours start, the equipment needs extra capacity to pull down the thermal lag of the building to meet setpoint in a reasonable timeframe.  Make sense?  Are you modeling it that way?

Michael

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sandeep Kachhawa
Sent: Wednesday, February 16, 2011 9:33 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] HVAC Equipment Sizing

Dear all

I am comparing the epuipment sizing of a day time and a 24 hr office building on EnergyPlus. When I simulate the two while autosizing the hvac equipment, the Nominal Cooling Capacity (W) of the 24 hr building comes less than the day time building. Though the total energy consumption, as expected, of the 24 hr building is more than the 12 hr building, why the cooling capacity (equipment size) of the 24 hr building is lower than the 12 hr building. In my particular case, for a conditioned area of around 1600 m2, the cooling capacity for day time and 24 hr building is coming around 146 kW and 128 kW, respectively.
What could be the possible reasons for such behaviour?

Thanks
Sandeep Kachhawa

________________________________
The information contained in this message is intended only for the personal and confidential use of the recipient(s) named above. If the reader of this message is not the intended recipient or an agent responsible for delivering it to the intended recipient, you are hereby notified that you have received this document in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify HT Lyons immediately, and delete the original message.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20110216/8c02366b/attachment-0001.htm>