Thermographic survey of buildings
According to the Technology Strategy Board, in the UK, the built environment accounts for 45% of total carbon emissions (27% from domestic buildings and 18% from non-domestic). Much of this is wasted, through: inefficient operation; inefficient equipment, appliances, machinery and plant; and losses through the building fabric. Findings from the PROBE studies (Post Occupancy Review of Buildings and their Engineering) demonstrated that actual energy consumption in buildings will usually be twice as much as predicted.
Losses through the building fabric might be the result of poor design, low-quality materials, poor workmanship, poor maintenance, or changes that have been made since completion. These losses can go unnoticed as the problem may be hidden within the building fabric.
Thermographic surveys can help identify problems, using infrared cameras to reveal differences in surface temperatures. They locate areas of the building fabric that may be hotter or colder than surrounding areas, suggesting that there are specific losses in that area. The visual and immediate nature of the survey results can offer a relatively inexpensive and non-invasive way of helping clients and other stakeholders to understand the significance of problems that might otherwise be difficult to conceptualise.
Thermographic surveys can be qauntitative, but because of the complexities of material properties and environmental conditions, they are more commonly qaulitative. They can be internal or external surveys.
In relation to thermal losses, a thermographic survey can help identify:
- Whether the design and specification has been complied with.
- Whether there is continuity of insulation.
- Wet insulation.
- Problems with cladding.
- Structural defects.
- Air leakage and air infiltration.
- Problems with heating, cooling and ventilation systems.
- Problems with glazing, doors and seals.
- Cold bridging.
- Whether the quality of materials and workmanship is consistent.
It might also be used to:
- Locate under-floor or underground pipes.
- Identify problems related to moisture penetration.
- Locate blockages in flues.
- Locate insect infestations.
- Locate electrical problems.
- Illustrate improvements made after a retrofit programme.
Whilst thermogaphic surveys may be relatively inexpensive, the problems identified can be very costly to rectify as they may involved deconstructing elements of a building, or may be issues that repeat throughout the building (for example incorrectly installed glazing).
A thermographic survey might be undertaken for a single building, several buildings, a site or an organisation, and might be carried out for commercial or domestic clients. It might be undertaken as an isolated study, or as part of a wider energy audit undertaken to assess total energy use and propose measures to reduce consumption and costs. See Energy audit for more information.
NB Only materials with a high emissivity provide a reliable reading. This is because materials with a low emissivity have a tendency to reflect the temperature of surrounding objects. Typically, materials such as bricks and plaster have a high emissivity, while metals and glass have a low emissivity. Thermographic surveys also require certain environmental conditions, for example an external survey should be carried out when there is no direct solar radiation. See Thermography for traditional buildings for more information.
NB From December 2015, energy audits will be required every four years for all large enterprises with more than 250 employees or a turnover exceeding €50m. See Energy Savings Opportunity Scheme (ESOS) for more information.
 Related articles on Designing Buildings Wiki
- Air permeability testing.
- Air tightness in buildings.
- Cold bridge.
- Conventions for calculating linear thermal transmittance and temperature factors.
- Draughts in buildings.
- Energy audit.
- Energy Savings Opportunity Scheme.
- Performance gap.
- Site inspection.
- The history of non-domestic air tightness testing.
- Thermography for traditional buildings.
 External references.
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