Discussion in 'General Discussion' started by CdnShockwave, Aug 8, 2010.
New anti-warming tool: white roofs - Los Angeles Times
Why do we use the materials we use now? Is there a cost benefit or increased structural integrity?
I mean, I see his win-win-win points, but there has to be a downside to using concrete instead of asphalt or we'd be using concrete now.
Yes, most materials in construction are selected on the basis of cost, using limiting criteria in terms of structural properties. I think asphalt gets used now (in terms of residential buildings) because they're primarily made of wood, and concrete would be too heavy, whereas asphalt functions as a useful sealant for the roof.
This article seems like its exaggerating, but reflective roof surfaces could have benefits, even if they're not "anti-warming", by decreasing the need for air conditioning, which would reduce power consumption. I'm also a big fan of solar panels being installed on roofs, now that solar technology is getting more affordable, which would also be a "reflective" material, albeit a more expensive one.
...This article is from 2008 -_-
Still true though.
Thanks for posting this, I wasn't aware that something so simple could have such a profound effect.
I've heard that the ice sheets work in a similar way. As global warming increases and the ice sheets melt, less heat will be reflected and more will be absorbed, which in turn will accelerate global warming further.
The white roof policy seems a very sensible inclusion for building codes, but replacing roofs on all existing buildings and changing road materials in 100 cities is unlikely to happen.
Living in a house that can be both uncomfortably hot in summer and freezing cold in winter, it'd be ideal if we could have roofing that could change colour dynamically to regulate temperature by reflecting or absorbing heat.
I just had a new roof put on my house. Its brown. Take that environment!
My guess is that the opposition will raise the three usual arguments against a white/reflective roof initiative: cost, practicality, and aesthetics. It would be expensive and impractical to convert every outdoor surface to high-reflection material (although even just a coat of white paint would probably do the trick), but I think this is a cost effective and practical way to go in terms of building codes so that new buildings have reflective surfaces. This could be coupled with some kind of longer term initiative to phase out dark rooves in existing buildings. So if you want to replace your roof you'd have to use reflective material, but wouldn't have to tear down your existing roof right away. That seems practical and cost effective in my opinion.
The other "problem" is the aesthetics factor. I can just see people complaining that white/reflective rooves are ugly and an eye sore. This seems to be a big argument in the opposition of wind turbines. To this I would reply, I think we've passed the point where we can have everything exactly the way we want it. Given the enormous benefits of reflective surfaces I think the benefits greatly outweigh the aesthetics factor.
Are solar panels reflective? They've all appeared to be dark in colour which you'd think would absorb more heat... but then again the surfaces are rather glossy so I could see it being reflective in that sense. Solar panels are rather big in Australia. I see a lot of houses that use them, primarily to heat water.
Interestingly enough, there are solar farms in Canada. I always thought they'd be rather impractical considering the long winters we get. The biggest one is set to be built in Sault Ste Marie. I would have thought that places like Nevada and Arizona deserts would be ideal of large scale solar farms given consistent daylight hours year round, few clouds, and being rather desolate landscapes it wouldn't really offend anyone's view.
I've also heard that concrete roads deteriorate faster in environments that experience cold winters. Not sure how credible that is though. I just heard it somewhere.
That's exactly how ice sheets keep the planet cool. The idea makes pretty good sense. Given the number of square meters of roofing there are in the world by making those rooves reflective you essentially mimic the effect of glaciers. And, by reflecting more heat, it slows the melting of glaciers and thus mitigates the amount of melt water going into the oceans. I agree that the white-roof building code policy is a good way to go. Even though it's impractical to have every roof converted to a reflective surface by tomorrow afternoon, it still seems like an effective addition to the environmental arsenal.
In terms of keeping your house cool/warm, I don't think that having a reflective roof would mean your house would be harder to heat in the winter. The sun doesn't get very high in the sky in winter so the amount of sunlight probably has a minimal impact on how warm/cold your house gets via your roof. Houses are heated internally so proper insulation would be the determinative factor. But a reflective roof would probably have a noticeable effect in summer due to long days and the sun getting very high in the sky, not only by lowing the amount of heat directly absorbed by your individual roof but also by the cumulative effect of other houses and buildings reflecting heat.
Im all for it. Who gives a shit about the color of their roofs anyway?
May cost more , but worth it overall.
Yes, most solar panels are "reflective". The final layer in the panel is usually a reflective surface in order to send the sunlight back up through all the semiconductive layers in order to effectively double the chances of an interaction (and thus, increase the electricity generated) so while it's not a truly reflective surface in the way a mirror would be, I think it still counts, compared to something like tarred shingles. Even if it does absorb heat, it generates power, which would hopefully be a net gain in terms of energy consumption and "warming" potential.
Concrete roads, bridges, and other major structures do tend to deteriorate faster than asphalt ones, not only due to expansion and contraction with seasonal temperature (that's one of the reasons why you have expansion joints in bridges), but due to normal stress and strain through load application and fatigue. Concrete is stronger than asphalt, but not as flexible, meaning cracks tend to propagate faster once they start, and may be harder to fix than asphalt, which just requires patching with additional asphalt or, in some cases, rubber composite.
You're also right that in winter, reflection isn't really going to hurt your ability to keep your house warm, as the heat lost through poor insulation is going to be a much bigger factor anyway, as you mentioned.
Going on a tangent: a popular counter-argument to white roofs is that by reducing heat gain in the summer, they're also reducing it in the winter when you'd actually want it. While this is true, there is significantly more sunlight to reflect in the summer months than there is to absorb during winter; it's not a symmetrical situation.
Insulation is still way more important to maintaing a comfortable environment.
I have a wireless thermometer in my attic. In the summer right now with an outside temp of 100 it's 145 F. In the winter months this same attic, with my dark shingles mind you, barely gets above the outside temperature. I can't see where having a white roof would make a hell of a difference to me in heat loss in the winter. However, in the summer months...
I've seen a demo of this stuff, it's insane how much heat it reflects away. The attic went from 135f to 98f with the same temp outside during the same time of day. It was ugly as sin from the outside, but I'll be damned if it didn't work really well. I'm thinking about doing it just to save on cooling costs.
It'll never happen, too expensive.
Debatable in Minnesota. But if the greenies around here find that white roofs are practical for our climate, I fully expect this to be crammed down my throat and mandated eventually.
Chances are, if they made it mandatory, it would only apply to renovations and new construction until it became more urgent. If.
I have an NYC building code binder on by desk; there are already so many rules and guidelines you probably wouldn't even notice if another was thrown in.
Oh, I'd absolutely expect a grandfather clause. Agreed.
I wish they'd been more forthright about putting forward such measures years ago. There's always going to be opposition. It's an extra cost up front, but a long-term saving. It's unlikely it would ever get much further than become a requirement for new construction anyway, but in so many areas the building boom has largely fizzled out and they're not going to be building much more any time soon, so the effect it would have now is going to be far more limited.
Think about all the new homes that were built in the last ten years that could've been more energy efficient.
One of the ways you hear about dealing with this kind of situation(without forcing people to change their building) is by channelling carbon taxes into grants for implementing things like this. It benefits the home owner, and provides work for all those unemployed construction workers. It also indirectly benefits all of us, because (aside from global warming), the more you lower the demand for energy, the less energy inflation there will be. People will definitely notice the cost of carbon taxes, but the less obvious effects should reduce fuel inflation which will go some way towards balancing things out.
Having white rooves would be an excellent way to reduce warming. It would have really no effect on your heating in the winter, if it does, then something is wrong with your insulation and that can always he rectified.
Sadly, it would be far too unrealistic to implement on a large scale. Even for just new construction, there would be too many changes to make in every level of the roofing industry from raw material to finished product. Not to mention, the small ratio of white/coloured rooves would prove to be barely effective in the short time span that we are purportedly dealing with.
I'd like to see it tho, I could make a lot of money from it.
The fact that retrofitting all existing rooves with reflective surfaces could be expensive seems like an awfully short-sighted argument. The effects of global warming will cost trillions of dollars (drought, floods, forest fires, severe storms/hurricanes, interior climate control costs (hotter summers = bigger air conditioning bill), rising sea levels, and so on). Given the tentative fact that fitting all/most rooves with reflective surfaces would, per year, offset the affects of more carbon dioxide that humanity generates in a year, is an enormous plus. Given the benefit (preventing trillions of dollars in damage) the cost (which would be nowhere near a trillion dollars) seems rather insignificant.
In my opinion, it would be stupid not to do this. This is an enormous benefit for a comparatively minor cost. In terms of carbon-emitting industry, fitting rooves with reflective surfaces would mean that carbon reduction targets would not have to be as tough on industry (basically at the very least we could keep on pumping out carbon at the same rate and still significantly offset the effects of that). Basically what I'm getting at is that people scream that going green is too expensive (such as replacing carbon-emitting equipment such as coal fire generators and gas driven cars with wind turbines, solar, nuclear, ect). By making reflective rooves, there would be less of a need to go green. Basically, we could keep on doing what we're doing now.
Ideally I'd love to see the end of human use of fossil fuels and a totally green human way of life (coupled with reflective rooves and all the other green initiatives such as recycling, sustainability, ect). But continuing to pump out carbon BUT initiating a large scale reflective roof policy seems like a fairly good compromise.
I have to ask.
What are a Rooves?
Separate names with a comma.