The thermography of building envelopes is by far the fastest application of the concept of thermography. This is largely informed by the rising costs of energy, Carbon emission reduction targets, and building regulations.
Our intention is to let you know of the many options of building thermography and also confer a comprehension of the various benefits and limitations of each option. This will let you determine the kind of survey they need to meet their unique outcomes.
Qualitative vs. Quantitative
These options may be placed into two main categories. These are the qualitative and the quantitative respectively.
Qualitative approaches depend largely on the experience and the knowledge of the thermography and the building science to note any potential issues that might arise in a building envelope.
This approach does not make use of the temperature measurements but instead on the differences on the levels of radiosity i.e. the differences in the colors that are shown on the thermal imaging to determine those portions which experience excessive heat losses.
Notwithstanding the fact that quantitative approaches employ the same methodology in identifying the defects, they do take the extra step and use the temperature readings to find out how heat is getting dissipated.
The preferred kind of approach depends largely on what your goal is. If you are attempting to identify the defects that may exist within the building envelope, you will have to rely on the qualitative survey as it delivers the best results.
If however, you are identifying the potential cost savings or carbon dioxide reductions, you have the quantitative approach for your consideration.
External vs. Internal Surveys
Next, you want to choose between the internal or external surveys. Generally speaking, the internal survey is by far the simplest to implement. That is because the approach is relatively straightforward for capturing the thermal images of the building envelope.
On the same note, those images that are captured internally also require that the walls be cleared of any furniture, pieces of equipment, and pictures for the survey to be credible. At face value, an external survey would be the better option under this circumstance.
Such a survey may be simple but not reliable to convey the best results. Moreover, it is very much affected by the external environmental conditions during the survey duration.
These include such factors as the clear night skies and the windy conditions which have the attendant impact of making any quantitative survey quite inaccurate.
Depending also on the nature of the building construction, not all the building defects may be noticeable from the images that are captured externally.
For instance, a poorly lit loft insulation in the house that has a pitched roof is only detectable with an internal survey.
On the contrast though, an internal survey is less impacted by external environmental conditions. This is because the air temperature and the convective currents stay relatively constant which results in more accurate measurements.
Internal surveys are a bit time consuming though. It requires the capturing of numerous images given the high number of rooms or floors and the limited power of the lens angle.