Painted white roof drops house temps 8-10 degrees

lucerne96 · 05-07-12, 10:47 AM

Several years ago, I was involved in a yearlong study of white roof coating. We used a product called Acrymax. We painted all the roofs in an entire city block in Philadelphia. Temperature sensors were installed in various places throughout the block; light poles, roofs, peoples houses, etc to generate data. The same was done in an adjacent city block, whose houses had traditional black tar roofs.

In general, it was found that the white roofs were 50-80 degrees cooler than typical asphalt roofs. The top floor of the homes about 5 to 15 degrees cooler (depending on insulation levels of the houses). This meant that a strategy of summer cooling whole house fans rather than A/C could be used. Average energy reductions were in excess of 30%.

Another interesting point I remember was the average street temp in the height of the summer was 5 degrees LESS that the adjacent (black roofed) street (urban heat island effect).

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A have just recoated my white roofs (over metal roof) with the initial coating lasting about 10 years. Recoating cost about 70 cents sq ft.

05-07-12, 10:47 AM	#11
lucerne96 Helper EcoRenovator Join Date: May 2012 Location: house Posts: 50 Thanks: 3 Thanked 5 Times in 3 Posts	Several years ago, I was involved in a yearlong study of white roof coating. We used a product called Acrymax. We painted all the roofs in an entire city block in Philadelphia. Temperature sensors were installed in various places throughout the block; light poles, roofs, peoples houses, etc to generate data. The same was done in an adjacent city block, whose houses had traditional black tar roofs. In general, it was found that the white roofs were 50-80 degrees cooler than typical asphalt roofs. The top floor of the homes about 5 to 15 degrees cooler (depending on insulation levels of the houses). This meant that a strategy of summer cooling whole house fans rather than A/C could be used. Average energy reductions were in excess of 30%. Another interesting point I remember was the average street temp in the height of the summer was 5 degrees LESS that the adjacent (black roofed) street (urban heat island effect). +++ A have just recoated my white roofs (over metal roof) with the initial coating lasting about 10 years. Recoating cost about 70 cents sq ft.