May 31, 2009

Chu's White Paint Brush

This past week the Obama administration’s energy secretary, Steven Chu, suggested that one solution the nations of the world should take to reduce global warming is to paint roofs and roadways white. The premise being that white colored roof would reflect insolation whereas a darker colored roof would absorb it. Chu elaborates further

If you look at all the buildings and make all the roofs white, and if you make the pavement a more concrete type of colour rather than a black type of colour, and you do this uniformly, it's the equivalent of reducing the carbon emissions due to all the cars in the world by 11 years.

Sounds like a sweet deal. A little white paint here, a little more over there and before you know it, all the cars in the world suddenly have no effect on global warming because their emissions will be offset. Does this mean someone that paints their roof white will get a carbon tax exempt card for being a good soldier in the fight against global warming? Does it even matter that painting one’s roof white will only reduce cooling costs when it’s hot outside? What about when it’s not hot and sunny? What good is your white roof doing when it’s snowing or when it’s cloudy, cool and damp?


There’s a long list of problems that white roofs have and there’s good reasons why most roofing surfaces across much of the country are darker colours. For example, a white roof would be a detriment to comfortable indoor air temperatures on a cold, cloudy windy day in the winter. Did the energy secretary figure increased energy costs to heat one’s home in the winter due to their new white roof? Here in the Northeast, where winters are famously cold, windy and snowy, the preferred way of heating one’s home is oil. Each hour longer that one would have to run their oil burners to make up for the loss in heat from the sun is the equivalent of leaving a diesel truck idling on the road for that same time. Hardly seems we’re making any dents in the equivalent numbers of cars being taken off the road.

The problems doesn’t only extend to extra oil consumption in the winter, there’s other risks as well. For example, a lighter colored roof allows more snow to build upon its surface as a darker roof would absorb more heat, melting some of the snow off throughout the winter. This extra added weight of snow might leave some roofs vulnerable to collapse! We’ve seen problems with collapsed roofs during the winter of 2007-08 in New England when continuous snowstorms left a 2-4 foot snow cover on top of many roofs leading to failure, especially as spring approached when the full season of accumulated snow of roofs would absorb much of the water from spring rains. If less snow is allowed to melt off during sunny winter days the percentage of roofs vulnerable to collapse would rise, even in winters that don’t deliver crippling amounts of snow. In addition to potential roof collapse, the slower melting of the snow could also lead to moisture/water problems from leaks that may present from something as simple as sagging paint or a slow drip from the ceiling or, much worse, mold and mildew problems, which can be toxic!

Generations of home builders in the Northeast have recognized these problems very early and made adjustments to how homes were built to account for these climatic caveats. Deciduous trees were planted on the southwest and southeast corners of homes to shade them in the summer and allow sunlight through in the winter. As these trees grew older they would shade the roof, a much better solution to having one that’s white, nipping sunlight in the bud before reaching the roof of the house. Windows weren’t installed along the north facing side of the house and conifers were plants to act as a wind block. Unfortunately, these building practices become a lost art as more and more pre-designed homes, made to all look the same as part of housing associations, became the preferred way of housing development.

As with homes, roadways are also expected to be a light shade of colour under Chu’s plan and this also presents its own set of problems. The winter season is just as harsh on roads as it is on roofs. Darker coloured roadways absorb just enough insolation during the winter to keep road surfaces a few degrees warmer than the ambient ground temperatures, helping to prevent them from freezing over when working in tandem with salt during winter storms. This same logic also applies on nights when the temperature is close to freezing and black ice formation could arise. The extra heat absorbed by dark coloured roadways may be the difference between a wet road and an icy one. The colour of a road also plays a role in problems with sun glare when the sun is low in the sky. The extra light reflecting off these new lighter roadways when the sun is low in the sky in mornings and evenings would play havoc on east-west routes.

All rationality appears to be lost by those that are scrambling to ‘stop global warming’ and ‘save the planet’. Our safety must be put at risk by paving glaring roads and driving around in glorified golf carts that crumple like tin cans. We’ve seen individuals nearly drive themselves to death from hypothermia trying to reach the North Pole to bring attention to global warming. The media continues to regurgitate green movement talking points without any questioning of the data that continues to show irregularities and anecdotal evidence pointing towards opposing conclusions. Any loon with a claim of climate disaster or wacky geo-engineering project is given open forum to the world. The hundreds of climate conferences that take place each and every year in which thousands of delegates are flown in from all over the world and given world-class cuisine surely emit more greenhouse gas than many of the developing nations they’re claiming to aid combined.

Chu’s advice isn’t all bad, however. In tropical areas where it’s warm year-round with the sun nearly overhead having a white roof would be advantageous. Conversely, as explained above, having a white roof in northern climes would work to one’s disadvantage so broadbrushing the issue simply won’t cut it. A more intelligent approach must be made with weight given to the climatic regime of each region of the country if one wants to implement a global warming building code for the exterior of one’s home.

1 comment:

  1. Joanne at Blue Like You has some pics of white roofs in Canada yesterday.