Sol-Air Temperature 1

[biddu]

Hi Friends

Iam reviewing the heat load calculations submitted by one of our suppliers. In the calculations I have noted that they have calculated the heat gain for exposed walls/Roof as follows

1. Heat gain due to transmission (using temperature difference based on outside and inside temperature)
2. Heat gain using Sol Air temperature.

My question is

Is it correct to calculate separately the heat gain due to conduction by difference of outside and inside temperature and again by using temperature difference between inside and sol-air

My understanding is that when we use SOL-AIR temperature it combines the effect of radiation and transmission of heat and therefore there is no need to calculate heat gain from conduction separately

Please advice. Any link on web with sample problem will be appreciated.

biddu

 

[lilliput1]

Yes you are right. The straight transmission loss should not be added bcause the sol-air temperature - room temperature already combines radition & transmission. What should be added is solar heat gain through windows.

 

[lilliput1]

And also internal heat gains = lights, people, equip,equipment

plus system heat gains = supply fan heat, return fan heat, duct heat gain and outdoor air load.

 

[biddu]

Thanks Lilliput1

Is it possible to get some references or some worked examples on web. I need something to show to the supplier as well as client that what we are saying is correct. Any reference material etc. would be a great help. I tried to search on net (and ASHRAE handbooks) but I could not find any reference where it is stated that sol-air temperature covers the heat transmission due to conduction as well as radiation.

 

[chicowater]

Try looking on this site, they have information on heat gain/loss calculations:
Manual J