Thermal Imaging - Explained 

WHAT DOESN'T THERMAL-IMAGING DO?

1.     It cannot "see" through any surface or material. It is not "X-Ray" vision

2.    It cannot automatically diagnose a building defect. In untrained hands it can lead to           some misleading and potentially wasteful findings.

3.    It doesn't harm the building fabric or any personnel. Infra-red is not harmful.

4.    It doesn't work in all weathers and all temperature conditions.

5.    It doesn't mean that every user is knowledgeable about building construction and               building defects. Learning how to use a thermal-imager does not compensate for               decades of building construction experience and knowledge. This is where we as               Chartered Building Surveyors have an advantage.

WHAT DOES THERMAL-IMAGING PROVIDE?

1       In the hands of an experienced RICS Chartered Building Surveyor it can assist                     greatly in producing a holistic Condition Survey or Energy Audit of a building.

2.     INDOORS: Enables detection of moisture, cold spots, overheating pipes and                        electrics.
                           
3.    OUTDOORS: It checks for thermal-bridging, heat-loss, air-filtration, incorrectly                     installed double-glazing or thermal insulation, uninsulated roofs, wall cavities and                leaking flat roofs.

4.     SERVICES: A thermal-imager can detect overheating and subsequent fire risks in                 electrical intakes and consumer units, electrical pumps, etc.

5.    UNDER-FLOOR-HEATING: Enables a heat scan to show any irregularities in the                    hidden pipework, locates where the pipes are in order to avoid accidental damage.


WHY DO I NEED A CHARTERED BUILDING SURVEYOR?

There are courses for certifying Thermographers and these are useful and beneficial. However in the hands of a person with inadequate building construction knowledge a thermal-imager is just another tool in the box and could be worse than not having one.
At ALBION we have been using thermal-imaging since 2010.  As building surveyors we have over 35 years experience of construction and building inspections. 

THERMAL CONSIDERATIONS (for Geeks):

If everything in the scan is the same or very similar temperature this will cause what is known as "Thermal Blindness". In other words the scanner cannot differentiate and you end up with a mono-coloured, bland scan. For an external scan there must be a temperature difference between the outside and inside of 10 degrees C minimum, as well as the right weather conditions, see below. We use a professional-level scanner for high resolution results.

Emissivity: How much infra-red a surface emits is critical to a worthwhile scan. Metallic, shiny surfaces are too reflective and will render a scan useless - unless we apply some black tape onto the surface. A competent thermographer will set the camera to the correct emissivity setting for the material being scanned. Carpeted floors are another no-no as the temperature of the surface below is distorted.

Weather effects: There is no point in trying to scan a building facade on a windy or rainy day. The surface temperature(s) will be distorted and totally misleading. A sun-baked facade or one partially hard-shaded will also make the scan meaningless. Solar loading is the term used to describe a heated-up facade.

Angular variations: The angle of the thermal imager to the surface has an effect. Most thermographers agree that being perpendicular to the target is best, but some manufacturers say otherwise. We try both for the best result. 

Reflective surfaces: As stated above these are unlikely to give off meaningful readings. Aluminium cladding, stainless steel, etc are examples of reflective surfaces that will mean thermal scanning is pointless. A solution is to apply tape or paint to dull the surface as and when practicable.

Focus: Everything scanned by the imager can be adjusted back as base apart from the focus. If this is blurred it cannot be corrected after the event. 

WHAT ELSE DOES A THERMOGRAPHER NEED TO KNOW?

1.  How a building "works", how it is built, how to recognise the different types of walling,       the basic construction and where problems are likely.

2. Heat transfer basics, such as convection, conduction and radiation.

3. The limitations of the thermal-imager: "trust but verify" as President Ronald Regan said.

4. Is it damp or is it cold air?  Both would have the same colour on the scan. A moisture meter can help diagnose one from the other. However, moisture meters have their own limitations.

5. How to inspect a property is a basic surveying skill. Looking for clues pre-scan to see        when and how to plan the survey. Being methodical and taking images and ensure            they are recorded before leaving site. Make sure the imager focus is spot on.