A building with a 120 ft by 80 ft roof located in Cincinnati

A building with a 120 ft by 80 ft roof, located in Cincinnati, Ohio, has a roof constructed of 1 in. wood with 2 in. R-5.5 insulation and a suspended ceiling. The inside design condition is 78degree F. Determine the net roof cooling load at: (a) September 21 at noon and (b) time of peak roof heat gain. (Use Pita Cooling Load Tables - Table 6.1 for U-value).

Solution

Answer,

From the tables cooling load tables,

For a given condition a building of 120 feet high and aroof of 80feet

Let us consider to be the 8 walls of 10 feet ,

And a 12 feet height of the wall,

Now from the table,

The net roof cooling load can be determined as,

Change in the cooling load temperature difference for roofs,

From the table respective values,

(I) The net roof cooling load for the September 21 noon ,

@noon the value is 16,

(II) the time of peak roof gain is 28-16= 12

Thetotal net roof cooling load time 16-12 = 4