Energy Audits 101: What You Need to Know


energy-audit-2“Why are the Benefits of a Home Energy Audit? What Will I Learn?
“What happens during an Energy Audit?”
“What is Zero Energy’s Experience with Energy Audits?”
“What are Blower Door and Infrared Diagnostic Tests?”


“Why are the Benefits of a Home Energy Audit? What Will I Learn?”

A home energy checkup helps you by determining where your house is losing energy and money – and how such problems can be corrected to make the home more energy efficient and comfortable. An energy audit is a wise first step to any energy project –since you can’t be energy smart until you know where your home’s performance can be improved! By planning improvements wisely, possible benefits include:

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  • Lower energy bills
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  • More environmentally-friendly practices
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  • Improved air quality
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  • Improved comfort

“What happens during an Energy Audit?”

When Zero Energy performs an energy audit, we customize the process depending on the building, your goals, usage patterns, types of energy used. Most often, our energy auditors run a number of tests on your home, including checking for leaks, examining insulation, inspecting the furnace and ductwork, performing a blower door test and using an infrared camera. We provide feedback about your air conditioner, ductwork, building envelope (for air leaks), and insulation — and can identify causes of indoor air pollution, mold and mildew.

Armed with this information, Zero Energy Associates (ZEA) can help you create a plan of action regarding fixes and upgrades to your energy systems. Solar PV, Solar Thermal, HVAC and Zero Energy projects typically come after the efficiency work has been done, which not only saves energy, but lowers the overall cost of the project since the solar and HVAC system sizes can be reduced.

What is Zero Energy’s Experience with Energy Audits?”

Zero Energy has been assessing and monitoring energy usage since 2004 when the company really began combining heating pumps and solar electric systems and measuring the inherent performance. Zero Energy Associates was also the project design team for the second LEED for homes project ever built in 2006. More recently they participated in the Pilot Program and several committees for what is now called Energy Upgrade California EUC.

“What are Blower Door and Infrared Diagnostic Tests?”

These are two assessments Zero Energy usually includes in an energy audit because of their ability to diagnose whole home performance:

blower-door-testBlower Door Test

A blower door test is designed to measure building leakage, often referred to as air infiltration. This is done by depressurizing the home using a large fan inserted into a nylon mat, installed in a doorway of the home. A sensitive device called a pitot tube measures the amount of air the must be forced out of the house to maintain a set pressure gradient. A nanometer records the pressure difference and the cubic feet per minute of air which is being pulled through the house from points of infiltration into the attic and crawlspace.

While we understand that ventilation is generally good, we also know that unintended air infiltration can be bad. It introduces contaminants that may reside in the attic, underfloor and outdoors.  Controlled ventilation allows us to filter the outdoor air and control the flow so that we are not losing the precious conditioned air that we paid to heat or cool.

infrared-testingInfrared Diagnostic

Thermal imagery or infrared diagnostic photography can further help us understand what is happening out of sight and can allow us to pinpoint points of infiltration that may not be visible to the naked eye. By sensing temperature differences, images are captured of air leaking into the home or business around light fixtures, baseboards and outlets. We are also able to detect insulation performance and placement behind sheetrock. This type of diagnosis can be instrumental in tracking and amending home performance issues which may have otherwise gone unrecognized.

Report and Computer Analysis

Once a home or building has been audited all the collected data and measurements need to be compiled into a useable and easy to understand report.

Minimum Health and Safety Requirements

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  • When air sealing, enclosed cavity insulation representing 15% or more of the total building shell area, or sealing of the ducts outside the thermal envelope are recommended, the work scope must include pre and post-installation blower door tests.
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  • Whenever blower door tests are required, the results must be compared to the Building Airflow Standard to verify compliance with ASHRAE 62-89 requirements for ventilation. If natural ventilation is inadequate according to the ASHRAE standard, mechanical ventilation must be installed or recommended as part of the work scope to increase the ventilation to required levels (refer to page 6 for specific requirements).
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  • A preliminary and post-installation safety inspection of all combustion appliances must be completed whenever changes to the building envelope and/or heating system are part of the work scope.
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  • The combustion appliance safety inspection includes all of the following: carbon monoxide test, draft measurement, spillage evaluation, and worst-case depressurization of the combustion appliance zone.
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  • In homes with natural gas/propane service, the gas line must be inspected thoroughly and all leaks repaired.
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  • Combustion safety test results must be acted upon appropriately according to the Combustion Safety Action Level Table.
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  • Whenever an appliance fails any of the combustion safety test, appropriate repairs must be completed or specified in the work scope according to the requirements listed (refer to tables on page 13).
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  • Appropriate inspection and diagnostic tests must be included in the workscope when attic insulation and/or ventilation are specified.
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  • Whenever air sealing or other shell-tightening measures are recommended, leakage paths to the attic must be given highest priority on the work scope.

Combustion Safety and Carbon Monoxide Protection

A preliminary and post-installation safety inspection of all combustion appliances must be completed whenever changes to the building envelope and/or heating system are part of the work scope. This inspection includes all of the following tests: carbon monoxide (CO) measurement at each appliance, draft measurement and spillage evaluation for atmospherically vented appliances, and worst-case negative pressure measurement for each combustion appliance zone (CAZ). Combustion safety test results must be acted upon according to the Combustion Safety Action Level table.

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  • Carbon Monoxide Testing of appliances and Ambient Carbon Monoxide Testing
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  • Spillage and Draft Testing of Appliances
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  • Worst Case CAZ Depressurization
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  • Gas Supply Safety

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