I don’t buy into it making that much difference. I think your money would be better spent making sure you have the right insulation and attic ventilation.
Not sure whether the power savings will amount to 10-15% but there’s definitely a difference in the temperatures inside the home due to difference in tiling color. There’s no doubt about that.
Very minimal if any. Tile in itself can insulate and vent a house much better than metal and comp,regardless of color. There is an airspace between the tile and sheathing and when installed over elevated battens it is able to breath under the roof itself. People often ask me about lighter colors and reflectivity but they very rarely are going to go white. It looks terrible.
Thank you all for the response. I finally took a decision and went for the cool roof. I didn’t choose the white tile.
Cool shingles have a higher solar reflectance index than regular shingles, but not by much. It might make your attic a bit cooler, thus reducing the cooling load in the summer. Where it really makes a difference is when you get into white metal roofs, giving you an attic that is virtually sitting at ambient temperature. I know because I have one, and despite already good insulation and an air-sealed ceiling, I still feel the benefits clearly. So, yes, the lighter the color, the less your roofing material will heat up. However, to really have a noticeable benefit you’ll have to go to full white (which isn’t possible for regular asphalt shingles).
I disagree that white roofs look bad. I think they look great, but that is subjective.
While good insulation is important, I disagree that it is the only solution to reducing heat transfer. Air-sealing the ceiling to attic line is just as important. Also, insulation is only retarding the movement of heat into your living space, it won’t prevent it, while a cooler roofing material prevents heat transfer into your attic in the first place.
Why is white not possible for asphalt shingles? They are made by several manufacturers
There’s lots of shades of “white.” While white asphalt shingles appear white, they are only required to have an initial solar reflectance index of 0.25. The whitest whites for metal panels reach up to 0.90 of initial solar reflectance (i.e. up to 90% of the sun’s energy is reflected upon impact, so to speak). It’s not just the color that influences the SRI but also surface structure and reflective particles in high quality paint.
I don’t know if a manufacturer could make an asphalt shingles with a higher initial SRI. They probably could. However, they also have to keep in mind that roofs get dirty and then look very unpleasing. Asphalt shingle roofs don’t clean up as easily as smooth metal panels due to their gritty surface structure.
I personally think that white shingles don’t offer as much of a cooling benefit over regular lighter colored shingles, especially if they come at a surcharge. Metal cool roofing is a whole different category.
The asphalt or sbs that the shingle is made of is a heat sink.
Over the course of the day it will heat up (the asphalt/sbs) regardless of the type of reflective material or scheme employed, this heat will then be released over time into the night.
Here in Texas, Austin tried to make black shingles illegal. That failed. Now they have on the website exactly what axiom said. Austin blames the city not cooling down, on warm summer nights, because of dark color roofs that are remaining hot, long after sundown.
I know a true white roof will reflect more heat than a black roof regardless of what data might say. The guys behind the desk can come up with whatever data they want but I have sat on, handled and worked around both colors for decades and dark shingles will always be hotter. Beyond that there are white shingles that qualify for energy star certification.
Tileman, I’d argue that the guys behind the desk (or in the testing lab) would not disagree with you. However, before installing a product it is important to look at those numbers, because that is usually the performance you’ll get in the field. I am just a homeowner, but I’ve never met anyone who would make their roofing choice based on anything other than mere aesthetics (or cost, for that matter). People often aren’t fully aware of the consequences.
Based in Texas myself, I can attest to the black shingle frenzy around me. It’s nuts. People in my neighborhood (older spacious ranches from the 1960s and 1970s with large roof surfaces) pay a ransom to cool their houses, heated up by the huge heat sink above their heads. The initially affordable black roof shingle now turns into a financial burden that easily adds hundreds of dollars to your summer utility bill.
If people were more prudent, they’d choose roofing made for their climate zone. Shingles as black as the night aren’t it in Texas. They also deteriorate rapidly under these conditions (which can include rather large temperature swings).
Yes a white roof will reflect more infrared and be cooler than a dark roof but over the course of the day the heat will build up in the asphalt/sbs of the shingle regardless of color.
A piece of low slope membrane doesn’t have the same mass or heat retaining characteristics as your basic shingle and low slope membrane is commonly installed over insulation.
This is why the thick expensive shingles tend to dry out and get brittle and I suspect this is why the thin Owens Corning 3-tabs last so long.
In my climate (Northern Michigan) there are negligible differences between light & dark roof coverings with a dark roof being more desirable in most cases.
The answer to all of it is to install a cold roof, and super insulate the living area
You do have a point here that whites will look dirty over a period of time. Do other colors can have the same reflective score of 0.9 solar reflectance as pure white ?
The short answer would be: No. No other color will have the same high reflectance as a pure white.