Solar exposure

[AUTOKAD]

Hello everyone, I'm new to the forum and new to the hvac world. My question is, How do you calculate glazing solar exposure, say in a commercial retail space, without using a software. We have a software in the office that does the heat/ loss calc. and part of it is the solar calculation. But I'm just thinking how to do it without the software. I know for glass we have glass sq ft x .61 x T, for heat and then glass sq ft x .61 x sensible T. But how do you get the solar? Please advice. Thank you.

 

[KLH]

Get a copy of ASHRAE GRP158, "Cooling and Heating Load Calculation Manual."

 

[sprinkler1000]

For calculating heat gains through glass, you have heat transfer between outdoor air temp and indoor design air temp., plus solar heat gains.For this take into account the U factor of the glass (W/m2ºC)
You should consult some hvac design handbook and get the values for solar radiation heat depending on the orientation of the window and the geographical location of your building. This solar heat gain must be reduced if the glass has some kind of protection film or is coloured (see Solar Heat Gain Coefficient and Shading Factor concepts)

 

[cdxx139]

I havent done cooling calcs by hand, but from what Ive read, you do the cooling calc, then you pick a couple of days or times in the year where your experience tells you would be the max cooling (now we have software that does all 8000+ hours of the year)

Look into the ASHRAE CLTD method for cooling. I believe that was that last cooling calc they provided that could still be done by hand (but you still needed some tables to look up)

knowledge is power