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Thermographic Survey Requirements 2017-02-13T11:22:18+00:00

Thermographic Survey Requirements

The following are thermographic survey requirements in accordance with the recommendations of BS EN 13187:1999. As such, if any of the conditions above are not met before undertaking a thermographic survey, the conclusions and outcomes within our reports may not be fully accurate or actionable.

1. Temperature Difference

To ‘see’ heat loss (or gain) at least a 10°C temperature difference between the inside and outside must be achieved for a minimum of 24 hours prior to the survey if occupied, or 72 hours for a ‘dead’ building. If the building has no operational heating system, temporary direct heaters (such as space heaters) may be required.

2. Dry Surfaces

Prior to the start of a survey, building surfaces must be dry so that artificial cooling from moisture evaporation does not skew the results. For heavy building fabrics such as brick it’s highly recommended that the surface has been dry for at least 24 hours. For lightweight buildings, a minimum of 12 hours is recommended.

3. Full Access

Full access must be granted before any thermographic survey in order to analyse external elevations from inside of the thermal envelope. The building fabric must be kept free from obstructions such as furniture and building materials, as we cannot move anything during the survey and it takes at least an hour for the local temperature conditions to stabilise.

4. No Solar Radiation

Building surfaces must be free from solar radiation for a ! minimum of 2 hours prior to the start of the survey – longer if the building consists of a heavyweight fabric. This is to allow for the effect of external heat gain in the wall to dissipate. Typically, surveys can be expected to start at 00:00 during summer and 20:00 during winter.

5. Low Wind Speed

The wind speed during the survey should not be greater than 5m/s (18kph). This is in order to stop the cooling effect from exceeding recognised compensation values.