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Friday, April 13, 2012

A White Roof: So Simple It's Insane So Insane It Just Might Work

[Edit: Take a look, Wired Online's "Observation Deck: Saving the Planet With Pavement" Has a new take on the issue, just released 06-15-12]

Global warming is a problem.

That being said, we obviously get heat from our sun.

Black absorbs light.  White reflects light.

Consider that urban areas get roofing resurfacing regularly (20-30yrs) and paving rehauls even more frequently (~10yrs)

What if...

You see where this is going.  Absolutely brilliant idea.
  • Simply swap asphalt for concrete.
  • Phase out black roofing.  The new "cool roofs" don't need to be shiny.  White is just fine.
Together, roads and roofs like this one cover about 60% of urban surface area, 
a higher % than I would have guessed.

A hypothetical policy spanning latitudes 45°N-45°S would mitigate global warming extremely effectively.  As AAAS explains:
"Achieving the same amount of cooling by slashing carbon dioxide emissions would require taking every automobile on the planet off the road for about 50 years."

This idea is not brand new by any means, however it's going to need a lot more attention in order for a big change to overcome the status quo.  The New York Times mentions that comedian Jon Stewart even joked about it back in 2009.  A similar policy already enacted, as InHabitat points out, enforces the people of Copenhagen to plant vegetation on their rooftops...  Different... but by no means bad. 

Emerging science is a great catalyst for change.

Precision data, some of the newest available, has allowed for better extrapolations from simulations.  A study out of Lawrence Berkeley National Laboratory shows with significance several changes within the ecosystem of the Mojave Desert (the area of experimentation)  Three sites were maintained: SOL, COOL, and CTRL.  CTRL, as you'd guess, is the control.  At SOL, photovoltaic surfaces (solar panels) were installed.  The third site, COOL, simulated the cool roofing system that could have so much effect on us.

A reflectivity coefficient is referred to as a material's albedo.  Studies of the effects of changed albedo in a given area have been done before, most heavily from 2008 on, but with some mixed results.  It's hard to set up experiments that: A) have an effect on the area large enough to sift out signal from noise, and B) accurately measure the variety of meteorological data necessary for spread out simulations to be truly representative.

Interestingly enough, cool roofing has been seen to affect nearby rural areas in several ways.  Summer afternoon temperature increases, and a correlation with less cloud cover AND lower precipitation emerges.  These possible effects upon implementation of policy could make the situation a little bit hairier.

The idea's simple charm and ease of implementation is a recipe for attention and motivation.  The idea still needs to spread far for international cooperation to come to fruition. Millstein, D., & Menon, S. (2011). Regional climate consequences of large-scale cool roof and photovoltaic array deployment Environmental Research Letters, 6 (3) DOI: 10.1088/1748-9326/6/3/034001
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  1. I've heard about such ideas; this seems like a practical climate mitigation strategy, as well as an energy efficiency strategy, since less cooling will be needed in the summer. I tried to convince my housemates to cover our roof with reflective mylar last summer - they didn't go for it.

    I have also heard of schemes to replace albedo from lost arctic sea ice with floating styrofoam.

    Unfortunately, though this is perhaps the only benign form of solar radiation management I know of, I don't see it preventing ocean heating, which is where most global warming takes place. It also doesn't address ocean acidification, 'the other CO2 problem'

    1. Styrofoam! Very interesting. I like the points you make at the end there. Ocean acidification is very scary to me. It cuts us badly via the bottom of the food chain.

  2. Oh well, sometimes it is the simplest things that can deliver the best results. One way to encourage people to choose a white roof is by providing them with scientific proof that having one truly contributes in our collective efforts to mitigate global warming. Once this scientific basis is established, it is up to the individual homeowners to make the decision and commitment.

  3. Very well said, Terence! Although there are people who believe in benefits of a white roof, others find it hard to believe. Perhaps if people are encouraged to try it for even just once, they would be able to see what you are pointing out here.

  4. You’re absolutely right about the roofing! Asphalt actually costs more as a roofing material than concrete, so concrete is not just eco-friendly, it’s also less expensive. Slate would also be a more eco-friendly and much less expensive alternative for asphalt roofing. Slate roofs are popular because of the vintage/antique look they give homes, and their exceptional resistance to weather, fire and pests. But most of all, slate roofs are the longest-lasting roofing materials, with records of up to 150 years of being fully intact.

    1. The material of roofing may range from banana leaves, wheaten
      straw or seagrass to lamininated glass, aluminium sheeting and
      precast concrete. In many parts of the world ceramic tiles have
      been the predominant roofing material for centuries.

  5. By simply transforming your roof into a white one, you can help preserve the Earth. White roofs reflect the sunlight back into the atmosphere, thus not trapping any harmful gasses inside the house and the atmosphere.

  6. I've heard about such ideas; this seems like a practical climate mitigation strategy, as well as an energy efficiency strategy, since less cooling will be needed in the summer. I tried to convince my housemates to cover our roof with reflective mylar last summer - they didn't go for it plumbers diamond bar ca

  7. I would love to stop by. But, I think it might have to wait until this summer. I did not know that Serlkay had ever expanded its size. I must say that a succesful family owned business in this day and age is a very refreshing sight! As well as this is a very refreshing site! Armor Roofing Nashville


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