Hello,
we have a SHGC that we are inputting however it doesn't seem to be making any changes to the Heat gain simulation we are running.
we did some playing about with the env. average, env.cyclic light and env cyclic hvy when we change these it makes drastic changes is there something we are doing wrong or are we changing the wrong cell for the G value?
Hi Kyle,
I assume you're doing a CIBSE calculation which uses the Solar Gain Factors and U-Value for it's calculations. Shading coefficient and SHGC are not used in that calculation. More info can be found in this Wiki.
Best RegardsSteve
Steve Brown | Bentley Systems
Answer Verified By: Kyle Pawlaczyk
Hi Stephen,
We are running CIBSE heat gains under the design data base.
We had previously read the article you provided a link to, prior to submitting our post. We have been using the glazing property box, under the glazing constructions i.e the area highlighted in green on the wiki page.
As i am sure you will appreciate, we are provided with G values from manufacturers & Architects, which represents total solar energy transmittance. If we alter the SHGC figure it does not change the solar gains in the results, but if we change 'env. average', 'env.cyclic light' and 'env cyclic hvy' this effects the resulting solar gains.....
Which box do we enter the G value into? I was told years ago (circa 13 years ago), that it was the SHGC figure, but it appears to do nothing when altered!
Looking forward to your response.
As per my previous reply the CIBSE method does not use G Values or shading coefficients. It only uses Solar Gain Factors. If the manufacturer can provide both longwave and shortwave shading coefficients then you can calculate Solar Gain Factors by following the equations in this Wiki which is mentioned in the original link I sent, under the Data for Design Database Calculations section.