[Bldg-sim] Supply air temperature reset and economiser

Chris Yates chris.malcolm.yates at gmail.com
Fri Nov 26 04:59:52 PST 2010


Dear Bldg-sim,

I am having some difficulty with the definition of outdoor air reset 
temperatures.
Clause G.3.1.3.12 of A90.1 (2007) states:
/The air temperature for cooling shall be reset higher by 2.3degC under 
the minimum cooling load conditions./
Question 1: We are not using DOE2 or EQuest. How are the "minimum 
cooling load conditions" decided?

Question2: During non-occupancy and cold external conditions, what SA 
temperature setpoint should be used? For example, if the air handler 
cycles during night to meet Zone heating setpoints, the SAT setpoint 
must be close to the RAT otherwise the system will first cool (possibly 
by increasing cold outdoor air) and then reheat the air in the zones.

Question 3: For the sake of comparison we generated a file similar to 
our model using the E+ example file generator but when we queried it, it 
appeared to operate the economiser via a differential enthalpy. A90 
appears to stipulate a fixed Dry Bulb shutoff (G3.1.2.7). Is the example 
file in error here?

Best regards

-- 

Chris Yates C Eng MCIBSE

/Building Physics Consultant/

Tel:+447960731576

Email: chris.malcolm.yates at gmail.com

Skype: christopher.m.yates

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20101126/9321ed42/attachment.htm>


More information about the Bldg-sim mailing list