Video Series: A Home Energy Audit
THE BEST WAY TO LOCATE AIR LEAKS IN AN EXISTING HOUSE IS WITH A BLOWER DOOR
Although many homeowners assume that the most significant air leaks in their home are around windows and doors, hidden leaks in a basement or top-floor ceiling are usually more significant. To find these hidden leaks, air-sealing contractors use a blower door.
To find out whether his own house was leaky, GBAGreenBuildingAdvisor.com managing editor Dan Morrison invited John Jennings, an energy consultant from Steven Winter Associates, to bring a blower door to Dan's Cape Cod house. Once the blower door was installed and operating, technicians checked for air leaks in every room of the house.
Other Home Energy AuditEnergy audit that also includes inspections and tests to assess moisture flow, combustion safety, thermal comfort, indoor air quality, and durability. Videos:
1. Blower door testing a home
2. New dormer insulation options
3. Identifying existing insulation
4. Garage workshop insulation
5. Upgrade your old boiler?
The leaks that matter are up high and down low
Air sealing work usually begins in the attic. (During the winter, the stack effectAlso referred to as the chimney effect, this is one of three primary forces that drives air leakage in buildings. When warm air is in a column (such as a building), its buoyancy pulls colder air in low in buildings as the buoyant air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season. pushes indoor air into the attic through unsealed cracks, while pulling outdoor air into the basement or crawl space.)
The existing attic insulation is temporarily peeled away, exposing the partition top plates. Sealing the gaps between the partition top plates and the drywall cuts down on air leaking into the attic. These gaps are sealed with spray foam. While the insulation is pulled back, workers also seal around plumbing vents and electrical cable.
Down in the basement, it's important to seal air leaking through cracks around the mudsill and rim joist.
After obvious cracks have been sealed, a second blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas. is performed, to measure the leakiness of Dan's newly tightened house.
For more information on blower-door testing, see "Blower Door Basics."
Mar 9, 2010
9:53 AM EST
9:53 AM EST
Energy Audits
by Chaz Steffen
A complete Energy Audit should have three parts to it. The first part is the actual inspection and testing of the home. This should include but is not neccessarily limited to Combustion gas testing to determine not only the efficiency of the equipment but to detect potential safety concerns (such as carbon monoxide), A Blower door to determine the volume of leakage and location of leakeage using zonal pressure testing, A duct blaster if there is a forced air distribution system for heating or air conditioning to determine both total duct leakage and leakage to outside of conditioned space, A visual inspection of all systems within the house, temperature and humidity levels recorded, and if available a complete thermal scan both prior to the blower door and after the blower door has been running for at least twenty minutes. The second phase of the audit is to perform computer modeling work. The homes dimensions, type of equipment, the levels of insulation, the air infiltration rate, the ventilation rate if equiped with mechanical ventilation will cause the software to run a series of scenarios of the currant state of the home and how it is performing compared to the energy standards of today. The computer model can be checked to the utility bills of the homeowners to verify the accuracy of the model. The software can also run a number of improvement analyses of the home where it actually looks at specific improvements and the effect that they would have on energy consumption. The third phase of the audit is the education of the homeowner, sitting down and discussing the report that was generated after the first two phases of the audit to explain concepts and answer question. Anything less than this is just an ennergy consultation and not a complete diagnostic energy audit.
Comments