Hey there, time traveller!
This article was published 19/7/2009 (2500 days ago), so information in it may no longer be current.
The Winnipeg Free Press recently published an opinion article titled, Cool way to save the planet -- paint the town white (July 16.) This article repeated claims made by proponents of white roofing that painting all roofs white would reduce greenhouse emissions.
This article and others like it fail to note other key facts in this debate that refute or diminish these claims, especially in cold weather regions such as Manitoba.
I represent the association of EPDM (ethylene propylene diene monomer rubber) roofers in the United States. The EPDM Roofing Association is the trade association for the manufacturers of the EPDM roofing membrane and their suppliers. EPDM is usually sold as a dark membrane. I should point out that the manufacturers of EPDM also manufacture white roofing products, so their main goal is for customers to use the most appropriate product for their needs.
The initial study upon which the claims about white roofing have been made was conducted by the Lawrence Berkeley National Laboratory, which found that the benefits of white roofing would be felt in warm weather climes. As the report stated, its proposals for energy savings were based on colouring "63 per cent of the roofs white in 100 large cities in tropical and temperate areas worldwide."
I don't think I need to point out to you that Manitoba would not qualify as a tropical or temperate area.
Currently, the Cool Roof Rating Council acknowledges a "winter penalty" when cool roofs are installed in northern climates, which means these regions will not affect the energy savings as warmer regions do. But even that penalty is limited to winter months, and does not consider the impact of autumn and spring conditions in those climates.
For example, Winnipeg averaged 5,777 heating degree days per year, compared to 186 cooling degree days, from 1971 to 2000, according to data from Environment Canada, which can be found at http://www.ccme.ca/assets/pdf/cind_people_htng_clng_e.pdf.
That means the demand for heating buildings is 30 times greater in Manitoba than the demand for cooling them. That also means that any benefit found from decreased use of air conditioners in the summer would be next to meaningless compared to the ongoing demand to heat buildings in the rest of the year.
This doesn't even consider the fact that the only way to get the benefits of white roofs is if they stay white. It also doesn't consider that additional research by the Berkeley Laboratory found that roofs play a much more significant role in the heating of a building as compared to cooling it.
Because of data like this, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has divided North America into regions within its ASHRAE 90.1 Energy Code, to provide the most relevant guidance for specific sections. This approach is much more effective than the broad brush thinking that "everything should be painted white."
In order to achieve the goals of reducing the energy demand on our planet, we will need to enable government and regulatory bodies to make better decisions and help achieve the goal we all support, the reduction of greenhouse gases.
The Free Press and other papers like it can play their part by providing a more detailed, balanced and factual study of this topic than what was contained in this article.
You can find out more about ERA by going to www.epdmroofs.org.