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Dark colored asphalt roof shingles (C) Daniel Friedman White Roof Color
Benefits of white / light colored roofing

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Choosing a white roof color:

Roof color can have a positive or negative impact on building energy efficiency, the service life of the roof, and on the environment.

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



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White Roof Color & Effect on Energy Use & Roof Shingle Life

White roof paint or sealant (C) InspectApediaMatt Smith Arizona Roofing Systems

White Roof Effect on Building Heat Gain

A white roof surface or a white painted-on roof coating has a very high solar reflectance index (SRI), as high as 90 %.

Another important aspect is the thermal emittance of white roofing: white roof surfaces emit 100 % of the absorbed heat, helping to maintain a more-stable, cooler temperature inside the building.

By emitting un-wanted solar heat gain, a white roof will increase the building's energy efficiency, reduce roof surface temperatures, reduce energy cost and utility bills and extend the roof's service life.

In a neighborhood where most building roof surfaces are black or dark in color, the collective heat collection results in an urban heat island that affects the local climate. In contrast, where most roofs are light in color, the urban heat island effect is reduced. (Grimmond 1994).

In some climates, lower heat-island temperatures reduce the level or frequency of smog. (Akbari 2005)

The albedo of a city may be increased at minimal cost if high-albedo surfaces are chosen to replace darker materials during routine maintenance of roofs and roads. (Akbari 2001)

To the extent that a white roof reduces the transmission of heat to the building interior, in a cooling climate a result is a decreased usage of air conditioning. In turn that lower cooling cost cuts the building's energy cost and also reduces its carbon footprint.

Discussing their Shasta White ENERGY STAR® rated shingles, Owens Corning points out that the actual energy savings will vary depending on the geographic location of your building as well as on individual building characteristics. (Ownes Corning 2017).

White Roof Life & Warranty

Roof stain or lichens or moss caused by trees (C) Daniel FriedmanIn my experience and opinion, with all other conditions such as installation details, roof slope, climate, exposure, and ventilation are the same, white roofs should have a longer life than dark roofs of the same material - perhaps twice as long.

However roof shingle warranties, more recently often called not a warranty but a "declaration of performance", are issued by manufacturers by specific shingle product or type, not by shingle color. The words "white" or "color" do not appear in shingle warranties that we examined. (Owens Corning 2017).

See WARRANTIES for ROOF SHINGLES

Reader note: Bretz, writing with Akbari (1998) point out that

Since incoming solar radiation has a large non-visible component, solar-reflective materials can also be produced in a variety of colors.

Those authors also tell us that even dark colored roofs can include solar-reflective materials to obtain part of the environmental and cooling cost benefit of white roofs - Editor.

Watch out: stains on white roofs reduce their effectiveness at reflecting un-wanted heat, particularly in the urban environment. (Cheng 2012)

While trees close to a building may benefit its cooling cost by their shade, if trees drop leaves and debris onto a roof leading to its stain or discoloration, there may also be a loss of roof solar heat reflection in other seasons. Further, debris on roofs reduces shingle life.

More about these concerns is at DEBRIS STAINS on ROOFS.

Research on The Benefits of White Roofing

white shingles on low slope (C) Daniel Friedman

The author

Matthew Smith, content editor for Arizona Roofing Systems, Mesa, AZ 85203 USA, Tel: 480 218-8888 Website: https://www.azroofingsystems.com/ Email: azroofingsystem@gmail.com

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Continue reading at ROOF COLOR RECOMMENDATIONS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see ASPHALT SHINGLE LIFE / WEAR FACTORS

Or see DEBRIS STAINS on ROOFS

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 SLATE THERMAL MASS for SOLAR HEAT STORAGE

Or see WARRANTIES for ROOF SHINGLES

Suggested citation for this web page

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

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING ENERGY SAVINGS

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