Roof Surface Temperature

Measured and calclrlated heat flow for a clolrdy day 3 april follo vi g a day with fairly clolrdy conditioirs.

Roof surface temperature. This fsec study didn t look at shingle lifetime but i think that adding 9 degrees to a temperature of 150 degrees won t make much difference. A cool roof under the same conditions could stay more than 50 f cooler and save energy and money by using less air conditioning. Overall the plywood sheathing in black shingled roof systems tended to be 10 f to 15 f 5 c to 8 c warmer dur ing the midafternoon of a sunny day than the plywood in comparable white shingled roof systems. Cool roofs can be made of a highly reflective type of paint a sheet covering or highly reflective tiles or shingles.

Most of the roughly 2 percent of the earth s land surface covered in urban development suffers from some level of urban heating. The darker the surface the more the heating. Fresh asphalt reflects only 4 percent of sunlight compared to as much as 25 percent for natural grassland and up to 90 percent for a white surface such as fresh snow. Standard or dark roofs can reach temperatures of 150 f or more in the summer sun.

On roof summer temperatures for asphalt shingles 10 76 c about 50 f to 170 f research on shingle durability tests asphalt shingles at temperatures typically up to a maximum of about 170 f well below the temperatures that occur during manufacture of the product. The average temperature difference through the day was about 2 degrees f. Different sources report different temperatures. 138 145 but feels hotter to the touch than a black roof.

If the roof considered in figure 2 had a white instead of black surface i e. On a hot sunny day the temperature on the surface of a traditional black roof can be more than 50 degrees fahrenheit 10 degrees celsius warmer than the surrounding air temperature source. A comparison of hourly values given in figures 3 and 4 for cloudy and clear days respectively indicates a greater discrepancy for clear days. What kills shingles isn t so much the temperature.

Department of energy. Up to 68 degrees cooler than black roofs. The difference between the maximum temperatures of black and white vertical surfaces is about 50 f degrees compared with 60 f degrees for horizontal surfaces. An approximate equation for the sol air temperature ts of the outside surface of a given wall or roof is.

Ts to a id is hso a absorption coefficient of outside surface id direct solar radiation on surface.