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Dark colored asphalt roof shingles (C) Daniel Friedman Roof Color - what is the best color for a roof?

  • ROOF COLOR RECOMMENDATIONS - CONTENTS: Choices of roofing color & effect of roof color on building cooling or heating costs. Effect of roof color on energy usage. Effect of roof color on life of roofing material. Roof color choice depends on climate and amount of sunlight. Table shows roof colors and effect on cooling load & cooling costs. Effects of roof color & reflectance on cooling energy costs for buildings with low slope roofs.
  • POST a QUESTION or READ FAQs about choosing the color for a roof and the effect of roof color on building cooling load
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Roof color choices vs. energy efficiency in heating or cooling:

This article describes the effect of roof color on shingle (or other roofing material) life and the effect of roof color on building cooling load. We provide a table of the effects of various roof colors on building cooling loads and costs.



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Choices of Roof Color & Effect on Energy Use & Roof Shingle Life

Snow on a northern roof - Rhinebeck NY (C) Daniel FriedmanThe question-and-answer article about the effects of roof color on building temperature and on roof life discussed here quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

Roof Shingle Color Advice for Northern Climates Compared with Hot High-Sun Climates

Question: what is the best color for a roof?

What is the best color for a building roof? In Iowa a well-insulated roof has snow on it for most of the winter, so using dark shingles to absorb solar energy won't work.

In the summer a light colored roof will stay cooler.

So in our hot Iowa summers, when we have to air-condition, is it not better to use light-colored roofs, despite the trend toward dark roofs? -- Victor Gibson, Waterloo IA

[Click to enlarge any image]

Answer: Roof Color for Iowa-like Climates

Our photo (above left) shows heavy snow-cover on an asphalt shingle roof in Rhinebeck, NY.

In the absence of specific research [back in 1985] on the subject, we polled several roofing experts.

They agreed that roof color alone has a minor effect on the overall energy balance of a well-insulated house in your area (Iowa), winter or summer.

The attic insulation level and under-roof ventilation rate are the most important factors. So for a house in your climate, choose whatever color strikes your fancy.

Roof Color Suggestion for Hot Climates

White roof shingles (C) Daniel Friedman

In very hot climates (Florida, Texas, Arizona), however, roof color definitely affects the cooling load of a house.

Roof color choice also may affect shingle life in those climates.

For instance, an attic under a black-colored roof can be 30 degF. hotter than a white-roof attic in Florida, according to the Florida Solar Energy's Phil Fairey.

Light colors would be in order there.

Roofing Color Effect on Cooling Costs

Table 2-18 Roof color and cooling Loads (C) J Wiley, S Bliss

As explained in Best Practices Guide to Residential Construction, chapter on BEST ROOFING PRACTICES:

Tests at FSEC also indicate that simply switching from dark to white asphalt shingles in a cooling climate can reduce peak cooling loads by 17% and seasonal loads by 4%.

The greatest savings resulted from using white metal roofing (see Table 2-18 shown at left.)

[Click any image or table to see an enlarged version with more detail.]

-- Adapted with permission from Best Practices Guide to Residential Construction.

Effects on Energy Costs of Highly-Reflective Low-Slope Roofs

Cooling cost reduction from roof coatings - ORNL graph

The U.S. Department of Energy and Oak Ridge National Laboratories have studied and reported on the effects of roof coatings that help deal with building heat load by improved solar reflection.

The graphic shown here, [published by Oak Ridge National Laboratories at ornl.gov/sci/roofs+walls/roof/coatings.html] illustrates that a fresh-coated roof can reduce the annual cooling energy in a low-slope-roofed building by as much as 43% (uninsulated roof)

And remarkably, notice that the uninsulated but fresh-coated roof performed almost as well as a roof with two-inches of insulation. (Of course, two inches of insulation isn't much.).

Roof color effects on building energy costs: research citations

Ribbon slates, Poughkeepsie NY (C) D Friedman

The link to the original Q&A article in PDF form immediately above was expanded/updated by the preceding online version of this article.

Reader Comment: Roof color vs energy savings study in Canada & the U.S.D.A. Shingle color

(Apr 5, 2012) JD Leatham said:
The Canadian Steel Building Institute looked directly at roof color in relation to energy savings in 4 Canadian cities (Toronto, Windsor, Vancouver and Winnipeg - very different summer - winter conditions). Their findings revealed that(in comparison to black)a 55% Al/Zn coated steel roofing provided the best energy savings irrespective of climate.

The high reflectivity reduced cooling costs in the summer months and the low emissivity allowed the roof to retain heat in winter lowering heating costs.

Reply:

Thanks JD.

Similarly, a U.S.D.A. study found that for most locations tested, roof sheathing temperature below black roof shingles were 10-15 degF. higher than the same sheathing material under white shingles on a sunny day. One might think that benefits solar gain in a heating climate - at least when the roof is not snow-covered. But the same study found that the black roofs also loste heat faster than the white roofs, more or less evening the score - at least when measuring sheathing temperature changes.

Overall the U.S.D.A. study found that roof color, at least for asphalt shingle roofs, is the dominating factor in determining the peak or highest roof temperature during sunlight hours.

Most roofing experts seem to agree that

Lighter coloured roofs gain less heat in sunny weather

Darker coloured roofs gain more heat in sunny weather and may help speed snow-melt in snow-climates

If your home is in a climate where heating costs are about equal to cooling costs for your building, then a neutral or gray coloured roof may be the best Choice - Ed.

Roof Color vs Energy Cost Studies

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Continue reading at ASPHALT SHINGLE LIFE / WEAR FACTORS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see ENERGY SAVINGS in BUILDINGS - home

Or see COOLING LOAD REDUCTION by ROOF VENTS where we describe the effects of various factors together such as roof venting, radiant barriers, and roof color. This website provides un-biased articles about many common roofing materials, installations, inspection, defects, roofing repairs, and products.

Or see ROOFING INSPECTION & REPAIR - home

Or see SLATE THERMAL MASS for SOLAR HEAT STORAGE

Or see WHITE ROOF COLOR BENEFITS

Or see WARRANTIES for ROOF SHINGLES

Suggested citation for this web page

ROOF COLOR RECOMMENDATIONS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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