What type of weather conditions and what time of day are required for a thermal imaging survey?

Planning for a thermographic survey is critical and often misunderstood (sometimes by thermographers too).

The answer is “it depends”. It depends what the goals of the survey are. To keep it simple, here is a summary of key considerations for typical kinds of surveys.

Weather Conditions Required for a Heat Loss Thermal Imaging Survey.

The key here is to achieve stable heat flow through the fabric of the building. Therefore, this type of survey should generally (in the UK) be conducted when it is cold outside and when the building is warm inside. It should not be too windy and the building should be dry. The standard usually referred to is BS EN 13187.

What is also important is that there must be no direct or residual energy from the sun in the building. Many people have surveys conducted an hour or so after sunset and this is normally fatally flawed.  Whilst there are exceptions and subtleties to this, as a rule, there will be solar load in the building for many hours after sunset. Therefore, we have learnt the hard way over many years that heat loss surveys should generally be conducted in the early hours of a cold morning, before the sun can fall on the building.  It is almost impossible to conduct these types of heat loss survey during summer months when the ground temperatures and surrounding buildings are at high temperatures for months on end. Even at midnight!!

Therefore we only conduct heat loss surveys during the colder months and in every case, we will look at the details to plan an acceptable survey not only compliant with BS EN 13187 but industry best practice. This does mean the opportunities can be at a premium to do this – many competitors cut corners here in order to maximise the number of times they can survey – more money for them and less useful results for you!

We have produced a guide on how to prepare for a thermal imaging heat loss survey which can be downloaded from here (please contact us if you don’t have a password).

Weather Conditions Required for Other Thermal Imaging Surveys.

Different types of survey have widely differing requirements. In some cases we can do they survey almost any time of day, any day of the year. Some are summarised below.

• Underfloor heating surveys – almost any time. More information here.
• Roof surveys – it depends on the roof design – contact us to discuss – normally after rain.  More information here.
• Pipe leak tracing – almost any time. More information here.