Detection and Visualisation of Air Infiltration and Exfiltration Adequate air exchange is essential for the occupants’ health and safety, but most buildings have a far higher rate of air exchange than is necessary. The root cause is often poor design and/or construction which allows air leakage from the inside of outside of the building, or the opposite. The leakage pathway is often complex and, without thermal imaging, extremely difficult to visualize. This also allows the contractors to quickly identify and repair the problem areas to stop the energy loss immediately.
Thermographic Home Inspections
Energy auditors may use thermography—or infrared scanning—to detect thermal defects and air leakage in building envelopes.
How They Work 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 conditions. 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.
Infrared scanning will allow you to check the effectiveness of insulation in your home. 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. A thermographic scan performed by a certified technician is usually accurate enough to use as documentation in court proceedings.
Preparing for a Thermographic Inspection To prepare for an interior thermal scan, the homeowner should take steps to ensure an accurate result. This may include moving furniture away from exterior walls and removing drapes. The most accurate thermographic images usually occur when there is a large temperature difference (at least 20°F [14°C]) between inside and outside air temperatures. In northern states, thermographic scans are generally done in the winter. In southern states, however, scans are usually conducted during warm weather with the air conditioner on.