About Energy Performance Testing

Blower Door Tests

Professional energy auditors use blower door tests to help determine a home’s airtightness.

These are some reasons for establishing the proper building air tightness:

  • Reducing energy consumption typically caused by air leakage.
  • Avoiding moisture condensation problems
  • Avoiding uncomfortable drafts caused by cold air leaking in from the outdoors
  • Making sure that the home’s air quality is not too contaminated by indoor air pollution.

How it Works

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 all unsealed cracks and openings. The auditors may use a smoke machine to detect air leaks. These tests determine the air infiltration rate of a building.

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

There are two types of blower doors: calibrated and uncalibrated. It is important that auditors use a calibrated door. This type of blower door has several gauges that measure the amount of air pulled out of the house by the fan. Uncalibrated blower doors can only locate leaks in homes. They provide no method for determining the overall tightness of a building. The calibrated blower door’s data allow the auditor to quantify the amount of air leakage and the effectiveness of any air-sealing job.

Duct Blower Testing

Energy auditors perform duct blower testing because leaky ducts can significantly increase air conditioning and heating bills, dramatically reduce equipment capacity and performance, as well as result in potentially dangerous indoor air quality problems. In fact, duct leakage is responsible for many of the comfort complaints experienced by homeowners today.

Leaks in forced air duct systems are now recognized as a major source of energy waste in both new and existing houses. Studies indicate that duct leakage can account for as much as 25% of total house energy loss, and in many cases has a greater impact on energy use than air infiltration through the building shell. Just as important, duct leakage can prevent heating and cooling systems from doing their job properly, resulting in hot or cold rooms, and humidity problems. Worse yet, duct leaks can create air quality problems by pulling pollutants and irritants directly into the house.

Here are just a few of the problems resulting from duct leakage:

  • Leaks in the supply ductwork cause expensive conditioned air to be dumped into the attic, crawlspace or garage instead of into the house.
  • Return leaks pull outside air (hot in summer, cold in winter) into the duct system reducing both efficiency and capacity. In humid climates, moist air being drawn into return leaks can overwhelm the dehumidification capacity of air conditioning systems causing homes to feel clammy even when the air conditioner is running.
  • Heat pumps are particularly susceptible to comfort complaints from duct leakage, especially during the heating season. Duct leaks can cause the air coming from heat pumps to feel luke-warm or even cold during the winter. In addition, leaky ductwork has been found to greatly increase the use of electric strip heaters in heat pumps during the heating season.
  • Leaks in return ductwork draw air into the house from crawlspaces, garages and attics bringing with it dust, mold spores, insulation fibers and other contaminants.
  • Household depressurization from duct leaks and imbalanced duct systems can cause spillage of combustion products (from furnaces, water heaters and fireplaces) into the house.

How it Works

A duct blower test involves pressurizing the duct system with a calibrated fan and simultaneously measuring the air flow through the fan and its effect on the pressure within the duct system. The tighter the duct system, the less air you need from the fan to create a change in duct system pressure. Testing procedures can be set up to measure only duct leaks which are connected to the outside, or to measure total duct leakage (i.e. leaks connected to the outside and inside of the house). Duct leakage measurements are used to diagnose and demonstrate leakage problems, estimate efficiency losses from duct leakage, and certify the quality of duct system installation.

Source: The Energy Conservatory

Infrared Scanning

Energy auditors may use thermography - or infrared scanning – to detect thermal defects and air leakage in building envelopes. Thermal imaging can also be used to detect electrical hot spots, plumbing leaks, roof leaks, and other building deficiencies.

How it Works

Thermography measures surface temperatures by using infrared video and still cameras. These tools see light that is in the heat spectrum. Images on the video or film record the temperature variations of the building’s skin, ranging from white for warm regions to black for cooler areas. The resulting images help the auditor determine whether insulation is needed. They also serve as a quality control tool, to ensure that insulation has been installed correctly.

A thermographic inspection is either an interior or exterior survey. The energy auditor decides which method would give the best results under certain weather condition. Interior scans are more 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. Also, it is harder to detect temperature differences on the outside surface of the building during windy weather. Because of this difficulty, interior surveys are generally more accurate because they benefit from reduced air movement.

Thermographic scans are also commonly used with a blower door test running. The blower door helps exaggerate air leaking through defects in the building shell. Such air leaks appear as black streaks in the infrared camera’s viewfinder.

Thermography uses specially designed infrared video or still cameras o make images (called thermograms) that show surface heat variations. This technology has a number of applications. Thermograms of electrical systems can detect abnormally hot electrical connections or components. Thermograms of mechanical systems can detect the heat created by excessive friction. Energy auditors use thermography as a tool to help detect heat losses and air leakage in building envelopes.

Infrared scanning allows energy auditors to check the effectiveness of insulation in a building’s construction. The resulting thermograms help auditors determine whether a building needs insulation and where in the building it should go. Because wet insulation conducts heat faster than dry insulation, thermographic scans of roofs can often detect roof leaks.

In addition to using thermography during an energy audit, you should have a scan done before purchasing a house; even new houses can have defects in their thermal envelopes. You may wish to include a clause in the contract requiring a thermographic scan of the house.

The energy auditor may use one of several types of infrared sensing devices in an on-site inspection. A spot radiometer (also called a point radiometer) is the simplest. It measures radiation on spot at a time, with a simple meter reading showing the temperature of a given spot. The auditor pans the area with device and notes the differences in temperature. A thermal line scanner shows radiant temperatures viewed along a line. The thermogram shows the line scan superimposed over a picture of the panned area. This process shows temperature variations along the line. The most accurate thermographic inspection device is a thermal imaging camera, which produces a 2-dimensional thermal picture of an area showing heat leakage. Spot radiometers and thermal line scanners do not provide the necessary detail for a complete home energy audit. Infrared film used in a conventional camera is not sensitive enough to detect heat loss.

Fox Energy Specialists' certified energy auditors use high tech thermal imaging cameras.

Carbon Monoxide Testing

Carbon Monoxide is a lethal gas produced in normal amounts whenever you use an appliance which burns a combustible fuel. Combustible fuels include gas, oil, kerosene, charcoal and wood. When proper ventilation of appliances becomes blocked, carbon monoxide concentrations build up inside your home and become deadly.

Because carbon monoxide is invisible, tasteless and odorless, its victims may never know there is something wrong until it’s too late. It often takes the lives of whole families. Children and the elderly are the first to be overcome along with pets. Over 2,500 people in the United States will die each year of carbon monoxide poisoning and over 10,000 will be hospitalized.

Most victims who lose consciousness may be left with permanent brain damage, mental and speech disorders, vision and hearing impairments, seizures, coma or death.

How it Works

Fox Energy Specialists' certified energy auditors use a Bacharach carbon monoxide test to test your water heater, stove, oven, gas furnaces and any other gas appliances. They test to ensure that concentration of CO in the air of your home is at a safe level below 50 parts per million (ppm) by taking multiple air readings around your home and appliances. We will also use a Bacharach combustible gas leak detector to check for any gas leaks from connectors at gas appliances.

Low E Window Testing

Low-emissivity (Low-E) coatings on glazing or glass control heat transfer through windows with insulated glazing. Windows manufactured with Low-E coatings typically cost about 10%-15% more than regular windows, but they reduce energy losses by as much as 30%-50%.

A Low-E coating is a microscopically thin, virtually invisible, metal or metallic oxide layer deposited directly on the surface of one or more of the panes of glass. The Low-E coating reduces the infrared radiation from a warm pane of glass to a cooler pane, thereby lowering the U-factor of the window. Different types of Low-E coatings have been designed to allow for high solar gain, moderate solar gain, or low solar gain. A Low-E coating can also reduce a window’s visible transmittance unless you use one that’s spectrally selective.

To keep the sun’s heat out of the house (for hot climates, east and west- facing windows, and unshaded south-facing windows), the Low-E coating should be applied to the outside pane of glass. If the windows are designed to provide heat energy in the winter and keep heat inside the house (typical of cold climates), the Low-E coating should be applied to the inside pane of glass.

Window manufacturers apply Low-E coatings in either soft or hard coats. Soft Low-E coatings degrade when exposed to air and moisture, are easily damaged, and have a limited shelf life. Therefore, manufacturers carefully apply them in insulated multiple-pane windows. Hard Low-E coatings, on the other hand, are more durable and can be used in add-on (retrofit) applications. The energy performance of hard-coat, Low-E films is slightly poorer than that of soft-coat films.

Although Low-E coatings are usually applied during manufacturing, some are available for do-it-youselfers. These films are inexpensive compared to total window replacements, last 10-15 years without peeling, save energy, reduce fabric fading, and increase comfort.

How it works

An energy auditor will use a Low-E contact meter to test to see if the windows have a Low-E coat of film on the windows and if they are applied correctly for the climate zone.

The back side of the meter contains four non scratch nickel-plated pads. These pads are used to contact the coating or glass substrate that is being tested. If the pads are touching the conductive Low E coating, the indicator will light yellow or red depending on which side the coating is on. The indicator will light up green if there is no coating on either side.