Hi,I am using Hevacomp V8i to model a residential development. The issue that I am having is with the heat gains. I have modeled the rooms assuming that they will be cooled in the summer to a certain temperature - which you can simply input this temperature. Is there a way to model the rooms to see the effect if there is no cooling in place. Does anyone have any experience on doing this? Thanks in advance Sarah
Duncan Brown
Answer Verified By: Stephen Brown
Hello,
Please post your second question regarding CIBSE Heat Gain to a separate thread and I will try to answer it there.
With regard your question on Summer - The Summer calc uses Operative Temp as defined in CIBSE Guide A5 Section 1.2.2. This equates to Air temperature for the purposes of our calc and comfort conditions.
There is scope in CIBSE to calculate Resultant Temp but the conditions for this are where there is less than 0.4degC between the Operative Temp and Mean Radiant Temp. As such there would be very little difference between an Air or Resultant Temp as Resultant Temp is made up of 1/2 Air and 1/2 Mean Radiant Therefore we do not consider Resultant Temperature for the Summer calc.
Hope that helps.
Regards
Steve
Steve Brown | Bentley Systems
Hi Jose, The two calcs are doing different things. Gain is calculating the cooling load required to achieve a specific a design temperature (Air or Resultant). Resultant is often used for this calc to achieve comfort conditions. Summer is predicting the air temp in the absence of any cooling and therefore the cooling effect on surfaces etc does not come into play. The Air temp would be the worst case and as such is a better predictor of if mechanical cooling is required for a room. Best Regards Steve