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cafe heating/cooling load skylight

cafe heating/cooling load skylight

cafe heating/cooling load skylight

(OP)
skylight 25x25, with 16 bronze tinted skylights. will be a cafeteria underneath for 10-15 people. 14 ft high walls. constant volume system.

With U=1.0 and SC=0.73 for a singele 1/4" coated skylight, the cooling load comes to ~ 10 tons (4500 cfm) with Trace 700.

What is good estimate of U-value, SC.
Is 4500 Cfm too high? total area is 600 sf. almost 8 cfm/sf? what is good tonnage estimate?  

pic attached.  

RE: cafe heating/cooling load skylight

(OP)
Project in washington dc. interior space with its own interior walls.

RE: cafe heating/cooling load skylight

Single pane glass? If so, SC = 0.8 is not a bad number, U = 1.1.

25"x25" or some other unit?

10 tons / 600 sqft = 60 sqft / ton.... which is pretty high. Typical cafe numbers would be 200-400 sqft/ton (from rules of thumb).  

RE: cafe heating/cooling load skylight

(OP)
25 FT X 25 FT. THE WHOLE  CAFE IS 25 FT X 25 FT AND ENTIRE ROOF IS MADE OF SKY LIGHTS. A GRID OF 4X4- EACH ONE IS 6 FT X 6FT WITH ALUMINUM FRAME SO 6X4=24 FT PLUS ALUM MAKES IT 25FT X 25 FT. IT HAS BROWN TINT AND IS 3/16" THICK. AT 200 SF/TON = 3 TON WOULD BE LOW. 7-8 TONS SOUNDS BETTER??

7 TONS X 400 CFM/TON = 2800 CFM. ABOUT 5 CFM/SF.

IS 5CFM/SF TOO HIGH?

RE: cafe heating/cooling load skylight

A typical house rule of thumb is about 1 ton/600 sq ft, but even that's overkill, at least, for Orange County in California.  We're running 1 ton/700 sq ft with no problems, here.  

You're essentially wanting to put about 6-7 times the capacity of what a typical house might need.  I could see going 1 ton/200 sq ft, because of the humidity and higher body and equipment load.  

Are you thinking you need to freeze everyone so that the turnover is higher?

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: cafe heating/cooling load skylight

Any higher solar loads. Most houses don't have glass roofs.
 

RE: cafe heating/cooling load skylight

True enough, but we do have skylights and our roof is essentially drywall, whatever's left of the original  blown-in insulation, plywood, and aluminum.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

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