Put Your Home to the Test with a Home Performance with ENERGY STAR® Assessment

During a Home Performance with ENERGY STAR® assessment, your Trade Ally will conduct several indoor environmental tests. These tests reveal things like hidden air leaks, missing insulation in attics and walls and improper ventilation for combustion gases from appliances, furnaces and water heaters. The report generated from these tests will help you to spend your home improvement dollars strategically and effectively.


Air leakage can increase heating and cooling costs more than 30 percent and contribute to comfort, health and home durability problems. Finding hidden air leakage sites is the key to solving your home’s energy performance issues. Home Performance with ENERGY STAR requires a blower door test be performed during the energy assessment and post-assessment to help determine a home's airtightness. Below are a few reasons for establishing the proper building tightness.

  • Reducing energy consumption due to air leakage
  • Avoiding moisture condensation problems
  • Avoiding uncomfortable drafts caused by cold air leaking in from the outdoors
  • Ensuring that the indoor air pollution and the home’s air quality is acceptable

How They Work

A blower door is a powerful fan that mounts into the frame of an exterior door. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through the home’s unsealed cracks and openings. The Trade Ally may use a smoke pencil to detect air leaks.

Blower doors consist of a frame and flexible panel that fit in a doorway, a variable-speed fan, an airflow manometer used to measure the pressure differences inside and outside the home and hoses for measuring airflow.

Preparing for a Blower Door Test

The following steps should be taken to prepare your home for a blower door test so accurate data can be recorded:

  • Close windows and open interior doors
  • Turn down the thermostats on heaters and water heaters
  • Cover ashes in wood stoves and fireplaces with damp newspapers
  • Shut fireplace dampers, fireplace doors and wood stove air intakes.

Following the test, the Trade Ally enters the data collected into a software model and produces a report indicating where improvements can be made in the home to reduce air leaks and improve the home’s comfort for its residents. 



Vented combustion appliances such as gas and fuel oil water heaters, furnaces, boilers, and even fireplaces need to exhaust all of their combustion by-products outside the home, all the time. One of these combustion exhaust by-products is carbon monoxide, and it is especially dangerous because it is odorless, colorless, tasteless and quite toxic. If there are no combustion appliances or the appliances are sealed-combustion, there shouldn’t be any issues. However, if any of the appliances are atmospherically vented, have induced draft, or are power-vented, combustion safety testing will reveal if conditions in the home can create back drafting. Back drafting is combustion exhaust rolling out of the intended exhaust pathway and into the home.

Testing Process

The combustion safety test is actually a series of combustion tests. The simplest of these, and often the first test conducted, is the worst case CAZ (combustion appliance zone) test. What is the worst case? Basically, the Trade Ally will turn on every device in the home that can create negative pressure in the room or space in which the combustion appliance is located, and then compare that pressure to the outside. Pressure-changing household devices include: bath exhaust fans, kitchen hood, clothes dryer, laundry room exhaust fan, attic exhaust fan or HVAC air handler.

The test requires two pieces of equipment – a manometer (pressure gauge) and a smoke source such as a smoke pencil.

After surveying the home for combustion appliances and exhaust fans, the Trade Ally will:

  • Seal the house, closing all exterior windows and doors.
  • Turn off all combustion appliances.
  • Close all interior doors.
  • Measure the baseline pressure. This is the pressure relationship between the combustion space and the outside with no exhaust fans on.
  • Turn on all the fans and measure the worst-case depressurization. If the test results are within program standards, back drafting should not be an issue in the home.

If the test results exceed program standards, the Trade Ally will make recommendations on how to solve the issue. 



Thermography testing is used to identify areas of air leakage and cold spots located in the home’s walls or ceilings. This optional test can be conducted either on the interior or exterior of the home. Interior scans are most common, because warm air escaping from a building does not always move through the walls in a straight line. Heat loss detected in one area of the outside wall might originate at some other location on the inside of the wall.

Windy weather or similar exterior and interior temperatures may provide inconclusive results because the technology relies on temperature differences to detect issues. For this reason, thermography testing is optional in the program and at the discretion of the Home Performance with ENERGY STAR® Trade Ally.

If the Trade Ally decides the conditions are correct, the testing equipment used is an infrared camera or infrared video. The equipment creates images or thermograms. These thermograms show surface heat variations and will help the Trade Ally detect heat loss and air leakage in building envelopes and ensure the insulation has been installed correctly.

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