Home Audit and Air Seal the Dryer Vent
Home Energy Audit – Better Air Seal the Dryer Vent!
by Don Ames
A home energy audit that includes a blower door and a duct blaster will provide valuable information when your working to save power and lower your power bills.
I prefer a cold clear day to a warm rainy day. Just moving the audit equipment from the vehicle to the home can be stressful in the rain. If I forget my hat and my nearly bald head is exposed, the rainy day is even more stressful. This home is a double wide manufactured home built in 1996 with about 1404 sq ft of living area. It’s an all electric home, electric furnace with a heat pump. No natural gas in sight.
A Mother with a school age child live here, the living room, kitchen, master bedroom and bathrooms are neat and clean. The kids room is hurricane Matilda. Unfortunately, the water heater is in the closet in the kids room.
- After a quick look around, I notice a few things about this home:
- The whole house fan in the ceiling of the hallway is running.
- Four windows are foggy and have moisture between the panes of glass.
- Several floor heat register covers are missing.
- Has a nice Honeywell thermostat that is not programmable.
The water heater was replaced several years ago, appears new and the water lines that go down through the floor have been well sealed. The water temperature is a little high at 131 degrees. Appliances are all newer and all energy star rated. The range hood is also newer but is not vented outside. Mounted on an interior wall, the range hood simply sucks air in the bottom side over the range and then blows the air back into the kitchen just over your head. A great fake range hood. Nicely mounted but it does not take the moisture created by cooking and put that moisture outside.
The blower door and duct blaster is set up and put to the test.
Home air ventilation rate is 680 cfm ( cubic feet per minute ). This is actually a little low, a cfm per sq ft is a rule-of-thumb. A rate around 1,400 is going to be closer to a healthy air exchange rate.
Total duct leakage is 540 cfm. Total duct leakage is all the air that leaks out of the heating ducts. Includes the air that leaks back into the home and the air that leaks to outside of the home.
Duct leakage to the outside is 190 cfm. This is just the air that leaks to the outside of the home. Interesting, more of the air that leaks out of the heating ducts is leaking back into the house tha
n out into the great outdoors.
Leaving the blower door fan running and then walking around the house is a good way to identify places where outside air is leaking into the home. I have my infrared camera fired up and start looking at the usual infiltration places. Around the front door and the light switch by the door are guilty. Windows that are sliders and the plumbing pipe penetrations under the sinks are guilty. The surprise finding is where the dryer duct cuts through the wall on it’s way outside. A nice big square hole was cut for a small round duct. Big air problem.
The homeowner actually trusted me in her house. She let me in and then went back to work. Hope I didn’t take anything. I have all the gear packed up and then turn to leaving her the paperwork that has the recommpendations for her and her home.
- Teach daughter that a clean room can really be the way to go. A clean room takes very little energy and is definitely more efficient.
- Turn down the water heater temperature to 120 degrees.
- Install a fresh furnace filter and change filters every month.
- Install a programmable thermostat.
- Have the heat pump and furnace serviced once a year.
- Air seal the plumbing penetrations under the sinks and air seal the dryer vent hole.
- Replace four windows. In this case, I would choose to replace the whole window instead of just the window glass.
- Have a duct sealing contractor seal the heating ducts. If they can reduce the leakage by 50% to the outside, the local power company will pay for the work.
- Suggest that the whole house ventilation fan in the hallway be turned off. If they need fresh air, open a window.
I will guess that all these measures and a slight lifestyle adjustment will result in a 10% savings on the old power bill. Throw-in a reduction in carbon production and a more comfortable home and you have a winner. And really folks, I don’t care how long it takes you to pay for the new windows with your power bill savings. Really I don’t. Instead of return-on-investment, I think of it as more of a gift – a gift for us, a gift for the earth, and a gift for everybody’s future.
Happy New Year…Don Ames