Importance of Solar Reflectance Index (SRI)
So I’m looking to do a re-roof of my house in Huntington Beach, CA (US Climate Zone 3, CA Climate Zone 6) and I’m wondering if its worth it to upgrade from a standard asphalt shingle with an SRI of 17 to a concrete tile with an SRI of 49. Will I see a big reduction in my attic temperatures by focusing on the SRI of the roofing material? Or will the money be better spent on more insulation?
BTW, I would love to do a metal roof, but its not very common here and is also way over my budget.
Edit: After some reading I think it is important to mention that my attic is unconditioned and vented. And my air ducts are in the attic with the air handler in the living space. The insulation in my attic is poor right now, but I plan on removing the existing insulation and installing at minimum R-38 of new insulation (probably blown-in cellulose).
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Insulation/air sealing (including the ducts) is more important. But somewhat higher SRI asphalt shingles (25?) might be worth it.
My only gripe with going with a higher SRI asphalt shingle is that over time the granules will come off, and the granules is what gives the asphalt shingle its high SRI rating. Essentially, every time it will rain, or there are high winds, or if someone walks on the roof the SRI of the asphalt shingle will drop. LOL
Yes, the concrete tile would keep your attic cooler than asphalt, and it would be a worthwhile upgrade considering longevity alone. I'm surprised it's cheaper than metal.
It terms of aesthetics, I love the look of standing seam metal roofs. But the price is $13/sqft for a standing seam roof vs. $0.46/sqft for lightweight concrete tile vs. $0.31/sqft for mid-tier asphalt.
Also the concrete tile that has an SRI of 49 is not the best looking color in my point of view. If I get it will purely be for the SRI rating only.
Depending on how close to the beach you are, the climate is very moderate there. You won't see much reduction in energy cost for a higher reflectance roof. Definitely spend money on sealing the ductwork and adding attic floor insulation though.
I am about 3 miles from the beach. Most of the year we have a moderate climate. It just seems like every year the number of hot days keeps increasing. We recently had a heatwave that lasted about a week and my local temperature reached 100°F one day, which is very rare for us. This is what is driving me to get a more efficient roof. Perhaps a simple "cool roof" would do. My existing asphalt shingle roof is worn out so really any new roof will be an improvement.
How much are you going to spend for a few days a year? You should consider the payback. Then again, concrete roofs are durable and fireproof. That's looking more important these days.