1. Arizona ranch style homes have low rooflines, with little attic ventilation. This is one type of Arizona home where adding a rigid vent at the peak of the roof slope is probably a good idea. This passive ventilation helps circulate the air out of the attic, without actively sucking your conditioned air from inside the house like a solar attic fan or electric powered attic fan does. I like rigid vents because it may be difficult to add the bird-hole vents along the perimeter of the house and it is not possible to add another gable vent.
Because the attics of Arizona ranch homes get so hot in the summer, it is essential to add at least R-38 insulation to the attic to slow the transfer of attic heat down into the house. R-19 or even R-11 may have been code when the house was originally built, so adding more insulation should be a no-brainer. Another way to help cool the attic temperatures is installing a radiant barrier along the roof slope. Radiant barriers reflect the heat back out of the attic and help keep the ductwork cooler in the summer. You can read more about radiant barriers on our previous blog post.
2. Attic connections into the house are also a common energy deficiency found in Arizona ranch homes. When you walk to the bedrooms, does your ceiling lower because of the metal ductwork running above the hallway? If you put a thermal camera on those interior walls during the hot Arizona summer, you'll find that the walls are a bright orange and red color compared to the other walls of the house. Why?? It's because those walls are directly connected to the attic from missing top plates. You could actually stick a 8 foot ruler down the entire length of the hallway wall from the attic. Those areas need to separated and sealed from the attic.
Some Arizona ranch style homes still have an evap cooler attached to the roof, and many Arizona homeowners love using their evap cooler 2 months out of the year. What these homeowners usually don't know is that their evap cooler is costing them more to keep and use during the hot summer months when the AC is on full blast than what they save during those two months of more temperate weather. During those two months yes, you are saving more money by not using the AC. However, during the 2 months of the dead heat, when 100 degrees looks like a break from the hot weather, you are losing more money because of the leaky ductwork. Check out our video on swamp coolers here.
What about spray foam in the block walls?
I was speaking with the program manager for the Arizona energy audit program about what he thought of spray foaming the block walls of a home and what he said surprised me. He told me that his own home is a ranch style house with block walls and after he insulated the attic, sealed and re-did the ductwork, and air sealed the attic from the house, the only things he has done to his walls was put a trellis with cat's claw vine along his sun struck block wall and his energy bills are not more than $220 on a 2,100 sq ft home.
I verified this with our energy models and while spray foaming your sun struck walls does save money on your energy bills, our models show you get 90% of the savings you would from spray foam wall insulation by simply shading the wall. I have become a serious proponent of spending $400 on a landscaping trellis than $3,000 on spray foaming one wall.
Arizona ranch homes have a number of distinguishing exterior features, including a long, low roofline with have large windows in the living room. However, they also have some pretty distinguishing energy efficiency features that directly causes high energy bills, comfort complaints and poor air quality. Having an APS or SRP approved energy auditor to inspect the home's performance can be the greatest gift you can give yourself, and it'll keep on giving for years to come.
Does my home have enough ventilation?