Building thermography:
Making thermal bridges and air leaks visible

Building thermography shows temperature patterns on surfaces, making thermal bridges, missing or damaged insulation and indications of air leaks visible quickly. Reliable conclusions require suitable conditions, such as a sufficient temperature difference, little wind and no direct sunlight, and results should be assessed within the workflow “find → verify → document”, not in isolation.

What does thermography reliably show in buildings?

What becomes reliably visible above all is the temperature distribution on surfaces: cold zones at thermal bridges, uneven surface patterns caused by insulation problems and characteristic patterns caused by air leaks. However, thermography does not automatically replace root-cause analysis. Depending on the situation, areas of concern should be confirmed with additional tests, such as humidity/temperature measurements or an airtightness test, before renovation decisions are made.

Thermal imaging camera for building thermography

Typical measurement tasks in building thermography

Thermal bridges

Thermal bridges often occur at geometric and structural transitions, such as window reveals, ceiling connections, roller shutter boxes or balcony connections. Thermography helps locate these zones quickly and document their patterns.

Thermal imaging cameras for building diagnostics

Locating thermal bridges with a thermal imaging camera

Air leaks

Air leaks often appear as localized cooling or flow-related patterns at connections, around sockets, on sloping roofs or at transitions. It is important to note that these patterns depend heavily on wind, pressure differences and use, such as ventilation and doors.

Thermal imaging cameras for HVAC

Detecting air leaks with a thermal imaging camera

Signs of mold risk

Thermography can reveal surface areas that are significantly colder than their surroundings. Such zones may indicate an increased risk of mold because condensation is more likely to occur there. The result should be treated as an indication of risk and, if necessary, checked against humidity and indoor-climate data.

Recognizing mold risk

Detecting mold risk with a thermal imaging camera

Conditions: when thermography provides reliable results

Indoor/outdoor temperature difference

Good contrast usually requires a significant temperature difference between indoors and outdoors. Without this “driving force”, patterns are less pronounced and harder to interpret.

Wind, rain and solar radiation

Wind and rain cool surfaces through convection and evaporation and can create patterns that must not be confused with insulation quality. Direct sunlight, including sunlight shortly beforehand, can heat surfaces and distort thermograms. Practical rule: document the conditions and choose the measurement time deliberately.

Humidity, convection and usage effects

Damp components, airflows and user behavior, such as heating and ventilation, influence surfaces. Context information, including weather, indoor climate and use, is therefore part of the measurement documentation.

Practical workflow: from image capture to decision

Screening: finding areas of concern

Consistent scale logic and accurate focus help identify areas of concern. The goal is a “map of suspected areas”, not a final diagnosis.

Verification: confirming areas of concern

Depending on the question, areas of concern are confirmed by comparing several perspectives, carrying out additional temperature/humidity measurements or performing an airtightness test. This helps prevent reflections, weather effects or snapshots from leading to false conclusions.

Documentation: ensuring comparability

For traceable results, document measurement points, viewing direction, distance, scale values and conditions. This makes images comparable over time, for example before and after a measure.

Typical sources of error and how to avoid them

Scale changes: automatic scales can “dramaticize” or “smooth” images – always document the scale values.
Sun/wind: the measurement time and weather conditions are part of the measurement result.
Misinterpretation: thermography shows the surface; the cause may need to be checked.

Building practical guide

Outdoor checklist: what to check before capturing images

Sunlight: direct sun or sun shortly beforehand can heat surfaces (choose the measurement time deliberately).
Wind/rain: convection and evaporation cool surfaces and change patterns (document the weather).
Temperature difference: without a sufficient indoor/outdoor difference, contrast decreases.
Humidity/use: ventilation, damp components and airflows influence surfaces.
Documentation: record scale values, viewing direction, distance and conditions.

Next steps: fundamentals and instrument selection

Reliable building thermography benefits from combining fundamentals (ε/RTC/IFOV), practical application guidance and a camera offering sufficient resolution and focus for typical object sizes and distances.

Back to fundamentals (ε/RTC/IFOV)

Resolution, NETD, FOV & focus

Selecting & comparing thermal imaging cameras