The Texas sun is blazing where I build in Austin, Texas. Let me give you four tips for building an efficient home that will stay cool even during the hottest summer.
Focus on the Lid
The roof on your house is the first line of defense against the summer sun’s rays. Think of your roof like a giant sun hat for your house. I always like to see 2-foot overhangs on a house, and windows with direct south and west sun can benefit from an awning, which will protect the window from direct sunlight (and water). Most roofs on American homes are dark-colored composition shingles. Those dark roofs soak up the heat, and as a result, most attics in the summer are 20 to 40 degrees hotter than ambient air temps. I’m a big fan of light-colored roofs. A 24- or 26-ga silver metal roof is a terrific choice for both efficiency and durability. The light-colored metal will act as a radiant barrier, reflecting the sun’s rays and keeping the attic cooler.
Hot air leaking into your air-conditioned building is a major energy drain for your house. Take measures during a remodel or new build to tighten the envelope of your house as well as your ductwork. Seal all penetrations through your walls with canned spray foam on the inside and tape on the outside. Don’t rely on caulking your siding to air-seal because studies have shown exterior sealing of cladding to be ineffective. I also recommend a blower-door and duct-blast test prior to hanging drywall so you can verify that your house meets current code airtightness standards (or better!).
Duct Inside Your Envelope
Most houses in the South are either concrete slab or pier/beam. Either way, we don’t usually have a full basement in which to install HVAC systems and ducts like northern houses do. As a result, most houses in the South have ducts running in attics or crawlspaces. These attics can easily run upward of 130 degrees on a summer day, and this is a terrible place for your ductwork! Running ducts in the attic also sets your house up for depressurization because those ducts will leak cold air into the attic, and your house will find a way to make up that loss by leaking air back down into the house. It’s a double whammy of inefficiency. Be sure you can locate all your ducts inside your air-conditioned envelope.
Choose Doors & Windows Wisely
A major source of leaks I’ve found in houses is lumberyard doors. Exterior doors from your window dealer are far tighter with respect to air leakage. I recently completed a project with all Marvin exterior doors and they sealed up super-tight. Their multi-point locks and weatherstripping were far superior and well worth the upgrade. Likewise, not all windows are created equal. Look for a tight-sealing window. I like casements because of their inherent air-sealing--the lock mechanism pulls the window in while locking. Talk to your window dealer about glass specifications that will help with cooling in your climate too. In the South, I want the lowest SHGC (solar heat gain coefficient) I can find (I typically use Cardinal’s Low E 366 glass with an SHGC around .20). No matter where in the U.S. you build, also look for a low U-Factor. U is the opposite of R-value. Lower U-Factors mean better-insulating windows.
Follow these four tips and you’ll be well on your way to a very efficient house. I wish you the best in your new build!
Risinger Homes is a custom builder and whole house remodeling contractor that specializes in Architect driven and fine craftsmanship work. We utilize an in-house carpentry staff and the latest building science research to build dramatically more efficient, healthy and durable homes.