Should white roofs be required in cold Montreal?

For borough mayor, white roofs are a no-brainer

The mayor of Rosemont-La Petite-Patrie hopes a new bylaw requiring white roofs on homes and commercial buildings will make his the coolest borough in Montreal, literally.

François Croteau says his proposed bylaw, which will require all new roofs in the borough to be white - or of a colour or material that reflects rather than absorbs heat - just makes environmental and economic sense.
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Akbari said the roofing industry is slow to embrace the cool roof materials, since they cost 10 to 25 per cent more than traditional materials. But in the long run, the building owner will reap more than the difference in energy savings, and have a longer lasting roof.
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Akbari sees cool roofs as a key tool in fighting climate change. To make his point, he calculated the cooling effect on the planet of replacing every black roof in the world with a white, or cool one.

"This could delay global warming by one and half years, which is equal to taking all the cars in the world off the road for the next 20 years."

Nation & World | U.S. suggests white roofs to curtail climate change | Seattle Times Newspaper

There is also the winter problem: In a cold climate, a dark roof can lower heating costs by soaking up the winter sun.

Montreal - Wikipedia, the free encyclopedia

Montreal's summers are warm, but often muggy with average high temperatures of 26°C (79°F) and low of 16°C (61°F), temperatures frequently exceed 30°C (86°F). Winter in Montreal usually brings very cold, snowy, windy, and at times, icy weather, with an average high temperature of -9°C (23°F) and lows of -16°C (9°F). However, some winter days are with milder temperatures, and others below -20°C (-4°F)

2008: City close to breaking snow record

So far this winter, 347 centimetres of snow has fallen in Montreal. The city needs another 37 centimetres of snow to break the record of 383 centimetres of snowfall set in 1971.