World’s whitest paint, claimed to eliminate/reduce air conditioning needs
trigonman3
| Posted in Green Products and Materials on
I eagerly await the testing and results as I am about to start building a house in north Texas (climate zone 3).
Any comments? It doesn’t seem like this is “insulating paint” that we know is bogus.
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Replies
You can't beat the zeroth law of thermodynamics. While it certainly may help reduce cooling loads in warm climates, it can't do anything about heat from convection and conduction. Its probably a case of over hyped results making their way into the media. It won't replace insulation, or air-conditioning, but it may help reduce the need for both.
Reduce? Sure. There's already places where it's common to use lighter-colored roofing materials to reduce solar gain and A/C needs. Making the coating even more reflective would reduce heat gain even further. The "eliminate" part is overhype though -- there's more than just solar radiation at play, and if you have any windows they're still a major source of solar gain (unless you paint them white too!) I could see this stuff being sold for use on commercial roofs in hot climates though.
I wonder how much cleaning or other work is needed to maintain the reflective and emissivity properties?
The press release from Perdue's site says the paint "can potentially handle outdoor conditions", so sounds quite a long way from something that can reach commercial production.
Still falls into the "pretty neat stuff made in a research lab" category.
Maybe don't turn this into an exterior finish spec on that new home quite yet.
I have actually done this on a commercial building and measured the results. There IS improvement in reduced solar gain, and it IS measurable. It’s not a massive improvement though, but it did make financial sense in our application (a datacenter that runs a massive amount of cooling all day all year long and has an electric bill around $100,000/month).
We didn’t use fancy paint though. We used the cheapest white paint we could find that was rated for use outdoors. We applied it with a sprayer over a pitch roof to change it from the dark gray of the gravel to a fairly bright white. We would repaint about every 3-4 years or so. Nothing fancy or high tech, and you probably get 90+ percent of the benefit of the fancier coatings at maybe 10-15% of the cost. We actually considered some fancy ceramic coatings too and ruled them out due to cost.
Bill
One wonders how the reflectivity of corrugated aluminum or other metal
roofing compares with this paint - it's probably worth checking.
If you want to investigate various materials, use their Solar Reflective Index (SRI).
A rough idea of the effect: "a 93-square-metre (1,000 sq ft) white roof will offset 10 tons of carbon dioxide over its 20-year lifetime". That's about $500 worth of carbon.
The very best materials go below ambient, so they are providing some cooling.