Simulate the cooling needed in the morning through Cibse Gain, after having turned off the plant operation

Question

Hello, 
 I am using Cibse Gain to simulate the cooling loads in a office building. After the weekend or in each morning, I would like to know the cooling (or heating) needed (pulldown load). The only way that I&acute;ve seen to do it is, in the "Building Data" screen, set the "Cooling Plant Operation" hours, for example being ON from 6:00 to 18:00 (I don't know if I can use the Plant Profiles, I haven't seen where). When I calculate the loads using Cibse Gain, there's no values between 18:00 and 6:00 in the morning, but those are precisely the values I want to get when the plant is turned off. 
 Thanks in advance for the help. 
 Jose

Stephen Brown · Answer

Hello Jose, 
 
The results you see are the calculated cooling loads for the plant operating period. To see what the cooling load would be before the building is occupied you would need to extend the plant on\off times and you would get appropriate results for an occupied weekday where plant is on during the day. 
However remember the CIBSE method is a 24 hour calculation made up of a mean component and the hourly swing from that mean over an isolated 24 hour period. As such there is no consideration for a weekend with plant turned off. For this you would need to look at our Dynamic Simulation software. 
 
Regards 
Steve

Stephen Brown · Answer

Hi Jose, 
 
If your ventilation rate is the same during the plant on and plant off times then you could include that in the Room Data as the Summer a/c rate. It would be included for the full 24 hours. If you only wanted the night ventilation for a set period or at a different a/c rate then this isn't possible. What you are looking is achievable in the Dynamic Simulation software. 
 
Regards 
Steve