Energy efficient homes often perform well below their stated efficiency goals. The reasons for this are varied; at times cutting-edge technology is not installed correctly or components are added in a piecemeal fashion and don’t work as a combined system. Building construction has to be flawless as gaps or cracks in the building envelope will undermine insulation efforts. You can measure the energy efficiency of any building to ensure that it is performing as intended. This helps identify areas where insulation is insufficient, air sealing needs a tweak or mechanical systems are not functioning as they should.
Once tested, your home will get a HERS rating. Traditional homes score over 100 on the HERS rating scale. An energy efficient home should score around the 50 mark while a net zero home has a score of 0.
Blower door test
The purpose of a blower door test is to ascertain the airtightness of the building envelope and to identify leakage points. A blower door is a large fan which is held in an expandable frame and sealed into a door jamb. Air is then exhausted from the house until the house is under a negative pressure of 50 pascals. There are two main readings that blower-door tests produce; airflow at a pressure difference of 50 Pascals (cfm50) or air changes per hour at a pressure difference of 50 Pascals (ach50). Smoke sticks are then used to identify leaks in the building envelope. In new homes, this test should be conducted before the dry wall is hung to expedite remediation.
The energy audit
An energy audit consists of several components that measure every aspect of your home. Your HVAC system is measured for efficiency with a duct blaster test. The duct blaster test checks that ductwork is sealed effectively. Here a device is used to pressurize ductwork to ascertain the amount of air leakage through pressure loss. EnergyStar appliances require less than 6% air leakage to perform optimally.
Doors and windows should be checked for a good seal during the blower door test utilizing a smoke stick. An infrared camera test can help to highlight areas where air is escaping. Thermal imaging cameras identify the heat-loss patterns invisible to the naked eye.
Check caulking on the exterior of your home and weather stripping around your doors and windows. Fill in any gaps or cracks with a reliable sealant. The Earthworks Group claim that cracks in the average home can add up to a 9 square foot hole in the wall.
Having an energy audit conducted on your home is a really great way to find problem areas. The tests are conducted by qualified contractors who can make recommendations for improvements that could save you thousands of dollars a year. Governments provide incentives for homeowners who conduct energy audits which usually involve tax credits or refunds (see Canadian rebates here.) Testing your home for efficiency will help you to identify the weak points and improve the efficacy of your building envelope. You can also make a more effective plan for retrofits and save fistfuls of money on your annual utilities bill.