Most older homes are sieves; they leak air all over. Homes built before the 1980s often have up to 2 air changes per hour (ACH), which means the home exchanges its entire volume of air with outside air every 30 minutes. In contrast, a new production home exchanges ½ ACH per hour. Air sealing is something most contractors never think about, so starting there is not only relatively simple but has immediate results. The blower-door test conducted during the energy audit will pinpoint where air leakage occurs and provide a roadmap of where to start.
The energy audit should provide a prioritized list of retrofit projects. As a team with an energy auditor, ABC Construction learned what the audit means and how to cost out each of the efficiency projects. Each house is different but the typical order of priority is as follows:
- Air seal: Heating a house is like trying to fill a balloon full of pinpricks. Air sealing typically starts from the top down. Warm air rises, so the attic is the place where most warm air is lost. The floor between the conditioned area and the attic is the place to start. In many cases, there are only batts laid between the ceiling joists. Move or remove the batts and caulk, seal and foam all penetrations in that surface. High-temperature sealants will be necessary around flues.
- Weather strip doors and windows: In older homes it is not unusual to see daylight around doors, and closed windows can be very drafty. The simple approach is to weather strip around moving parts as directed by the manufacturer. More complex projects require removing indoor casing (very carefully) or exterior trim to determine whether the space between the rough opening and the window frame has been sealed. In the past, fiberglass insulation was “chinked” into that space. It is more effective to spray low-expansion foam to completely fill the area. Then replace the trim (very carefully).
- Add attic insulation: Very few homes in America are sufficiently insulated to meet the energy price increases that are inevitable in this country. If you have removed attic insulation to air seal, then replace the insulation with blown cellulose to an R-value roughly 50 percent above code requirements. Energy-code requirements are rising; protect your homeowner’s comfort with high R-value attics—typically R-50 or higher.
- Inspect the basement/crawlspace: There are a number of upgrades that can be done in a basement or crawlspace, and you may locate even more issues while you’re there. Consider the following:
- Insulate the water heater: Water-heater tanks are only insulated to R-7 and are often located in one of the coldest areas of the house. In California, code requires an R-15 tank. Insulated jackets are very inexpensive and can double the insulating quality of the tank.
- Insulate hot-water pipes: The previous comments also are true for hot-water pipes except typically they are not insulated at all. Wherever you can access hot-water pipes, wrap them in foam pipe insulation. This often means crawling through the crawlspace to get to the farthest reaches.
- Inspect for water intrusion or damage: While insulating pipes, carry a flashlight and inspect the perimeter of the crawlspace for signs of water intrusion at the foundation. If there is water intrusion, this typically has been a chronic problem and sill plates or joists may be moldy or rotten. This is also an opportunity to identify plumbing leaks from supply pipes or drains and make repairs.
- Insulate under the kitchen and first-floor bathroom: If the basement or crawlspace is uninsulated, install unfaced batt insulation under the kitchen floor and bathroom floor. This will keep feet warmer in winter.
- Test for radon: Radon is insidious no matter what part of the country in which you practice. It is a gas that follows the path of least resistance from deep underground to the surface. If a house is on that path, radon will seep into the foundation and often into the house. Test for radon with an inexpensive test kit from your local hardware store. Leave it in the lowest space of the home for five days. The kit will turn a different color or you can send it in for analysis. The U.S. Environmental Protection Agency has great retrofit details on its Web site, EPA.gov/radon/pubs/mitstds.html, about how to address radon if it is found.
- Upgrade windows: Window technology is changing rapidly. Typical single-glazed windows are the equivalent of R-1. Most double-glazed windows are up to R-2. There are windows on the market now that are as high as R-11 for fixed glass and R-7 for operable windows. Window-replacement economics change dramatically if you can improve the R-value that much.
- Inspect roofing and siding: As houses age and potentially settle, the cladding that protects the envelope can develop cracks or just wear out. When inspecting the exterior, keep in mind that exterior insulation can be installed before the new siding or roofing is applied.
- Upgrade wall insulation depending on age and style of house: Blowing in insulation in existing walls has potential problems depending on the construction employed when the house was built. The exterior felt paper may have disintegrated allowing water into the wall cavity. If there is no insulation now, any water that gets behind the siding can just evaporate in the wall and exit out as water vapor. If you fill the wall with insulation it will trap the moisture and can cause mold and rot to grow out of sight. Find an unobtrusive spot and cut a hole in the interior wall to see what the condition of the wall cavity is. Then make a determination about how to proceed.