Thermography

Thermography - Thermography is an imaging technique that uses an infrared camera to visualize the surface temperatures of a building. This allows for the reliable detection of energy-related weaknesses such as thermal bridges, drafty windows, or missing insulation. Thermography is an indispensable tool in building diagnostics - both prior to renovation planning and when inspecting newly constructed buildings.

How does a thermographic inspection work?

In building thermography, an expert uses a thermal imaging camera (infrared camera) to capture images of a building’s exterior or interior surfaces. The camera detects the infrared radiation emitted by the surfaces and converts it into a color-coded image. Warm areas appear in shades of red and yellow, while cold areas appear in shades of blue and violet.

Precise conclusions about the energy efficiency of the building envelope can be drawn from these temperature differences. Typical findings include:

• Thermal bridges at floor slab connections, balcony overhangs, lintels, and soffits
• Uninsulated roller shutter boxes - a classic weak point in older buildings
• Leaky window frames and poor connections between window frames and masonry
• Areas with missing or damaged insulation in the facade
• Moisture-saturated building components - since moisture increases thermal conductivity, damp spots appear distinctly different in the thermal image compared to dry areas of the same material

For meaningful results, exterior thermography should ideally be performed during the cold season-preferably when outdoor temperatures are below 5 °C and there is a temperature difference of at least 15 °C between the interior and exterior. Calm nights or early morning hours without direct sunlight provide the most reliable images, as sunlight selectively heats the facade and causes measurement distortions. Interior thermography is also possible under more moderate conditions and is particularly suitable for locating air leaks at window joints, electrical outlets, or ceiling penetrations.

Combining Thermography and Blower Door Testing

We recommend combining thermography with a blower door test. In a blower door test, a calibrated fan is installed in an exterior door, creating a negative pressure of 50 pascals inside the building. Leaks through which outside air enters are thus amplified and can be visualized particularly clearly via thermography-since the incoming cold air cools the affected surfaces.

This combination not only reveals heat loss due to inadequate insulation but also convection losses caused by air leaks-such as at skylight connections, electrical outlets in exterior walls, junctions between wooden beam ceilings and masonry, or pipe penetrations through the exterior wall. This combined test is particularly insightful, especially for older buildings in Nuremberg that were constructed without vapor barrier foil.

The cost of a thermographic inspection ranges from 150 to 500 euros, depending on the building’s size and the scope of the documentation. An accompanying blower door test adds another 300-600 euros to the bill. This makes the combination a very cost-effective investment: The identified weak points can be specifically addressed, which significantly increases the efficiency of the renovation measures-and prevents costly misinvestments (e.g., facade insulation when the actual problem is leaky window connections).

Thermography Before Buying a Property

Thermography is not only of interest to current property owners but also to prospective buyers. A thermographic inspection prior to purchase clearly reveals which energy-related defects exist and what renovation costs the buyer can expect. This information serves as an important basis for purchase price negotiations: Identified thermal bridges or missing insulation can be backed up with concrete cost estimates and used as an argument for a price reduction.

Sellers who have a thermography inspection conducted before the sale and disclose the results create transparency and trust-this can accelerate the sales process and justify higher prices if the results are favorable.

Practical Tip for Nuremberg and Franconia

Especially in Franconia’s building stock-from Wilhelminian-style houses in Nuremberg’s Südstadt to post-war buildings in Fürth and Erlangen-thermography often reveals significant energy-related defects. Many of these buildings were constructed with little or no thermal insulation, and retrofitting without a prior assessment often results in measures that miss the actual weak points.

Anyone looking to buy or renovate a property in the Nuremberg metropolitan region should plan for a thermographic inspection before purchasing: It provides insight into the actual renovation needs and helps calculate costs realistically. The best time of year in the Nuremberg region is November through February-that’s when temperature differences are large enough to yield meaningful images. The Energy Agency of Northern Bavaria and various trades businesses in Middle Franconia that are certified under the Central Innovation Program for SMEs conduct professional thermographic inspections. Upon request, we can connect you with suitable experts from our network.

Frequently Asked Questions

When is the best time for a thermographic inspection?

Exterior thermography yields the best results during the winter months between November and March, when the temperature difference between the interior and exterior is sufficiently high. Ideally, there should be at least a 15 °C difference (e.g., 20 °C indoors, 5 °C or less outdoors). Taking images at dusk or under overcast skies prevents distortions caused by direct sunlight. You should wait at least 24 hours after heavy rain, as wet facades can distort the thermal image.

Can I have a thermographic inspection performed on a condominium unit?

Yes, this is generally possible. For a condominium unit, indoor thermography is usually preferred, as the exterior scan covers the entire building and the unit owner only has exclusive ownership of their specific unit. For an exterior thermography of the entire apartment building, it is recommended to organize the process through the homeowners’ association and split the costs proportionally-this is more cost-effective than individual contracts and systematically covers all residential units. A motion at the homeowners’ association meeting for a joint thermography inspection is usually approved by a majority vote.

Does thermography replace the energy performance certificate?

No, thermography does not replace an energy performance certificate. It is a supplementary diagnostic tool that identifies specific weak points and visually illustrates where heat loss occurs. The energy performance certificate, on the other hand, documents the calculated energy demand or consumption of the entire building in a standardized format and serves as a comparable benchmark between buildings. The energy performance certificate is required by law for purchases, sales, and new leases; thermography is voluntary but often more valuable for renovation planning because it enables specific recommendations for action.

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