I am working on a project where the mechanical specification allows for a 2degC temperature rise but when I try to apply this parameter in the CIBSE Gains Design Data Tab the project freezes at 0%.
I can make other design parameter changes but this one.
Hi Grant, my first thoughts would be that this could possibly be related to your room design and cooling supply air temperatures, however I can't be certain without seeing the project - could you please forward it? Upload link here.
Shane Regan | Senior Building Performance Support Engineer
Hi Shane, I've uploaded the project to the above link.
Thanks for your reply, the SI units in my project are metric so not sure why imperial are being shown your end.
Reading through the documentation I believed that the supply air temperature should only be lower than the room temperature when "a central all air system" is used (page 84 of manual).
Hi Grant, that part may be referring to the temperature of Fresh Air loads. The relevant part about the supply air temperature can be found below.
Hi Shane, this is the passage I was refering to.
How would I setup the poject if no temperature rise was allowed, my indoor design temperature was 22degC and my AHU supplied fresh air at 22degC?
Here is the project I am trying to produce, what should be in the blank "Supply Air Temperature" cell?
The system is a 4-pipe FCU not a all air system as highlighted above.
The guidance on using Fresh Air Loads in the following article should assist.
Calculations - Using Fresh air loads in Design Database
Primary Fresh Air assumes there is also local cooling in the room via a fan coil. The Supply Air Temp is for that fan coil and so should be lower than the room design.
The following should also be of interest:
CIBSE Gain calculation - Allowing temperatures to rise