Visualizing Thermal Environments: Before and After. FLIR Systems’ thermal cameras are very useful in making important decisions during renovation and construction.

Providing a comfortable living environment is the value that the housing industry offers to its customers. Infrared (IR) images allow the industry to provide advice for improving the living environment. We asked Dr. Masayuki Mae, an associate professor at the Faculty of Engineering at the University of Tokyo, for vital points.

Since 2008, Dr. Mae has worked on a wide variety of research subjects, including air conditioning, ventilation, hot-water supply, and the use of natural light, all in attempt to realize a true eco house. He believes that the prerequisites for a comfortable eco house are “high insulation and airtight performance, and vertical temperature evenness from head to toe.” In around 2010, he started to use FLIR Systems’ thermal cameras to visualize and evaluate the thermal insulation and airtightness of residential buildings. He values FLIR Systems’ thermal cameras by saying, “When I used them for the first time, I was impressed that IR images apparently showed the difference in comfortability. They help people having no construction expertise understand the importance of a thermal living environment. Adding intuitively recognizable visual information to conventional textual and speech advice for living environment improvement can significantly contribute to establishing trust with users.”

Thermal cameras can even visualize comfortability.

As using thermal cameras makes thermal insulation deficiencies easily identifiable via the difference in color, you can check if the construction provides the performance as intended. You can also verify the airtightness. Airtightness is an important factor for comfortability because it relates to the effectiveness of air conditioning and temperature evenness. International standards (ISO7730) recommend that the temperature difference from head to toe should not exceed 2˚C, which is the temperature evenness that is essential to comfortability. A lack of airtightness causes the inflow of cold and heavy outdoor air from the ankle level, increasing the vertical temperature difference. Images 1 and 2 show the temperature profiles of temporary houses constructed by different constructors. Image 1 is for a steel framed, highly insulated house with double sash windows. While a certain level of insulation is achieved, the vertical temperature difference due to low airtightness is apparently significant.

A steel-framed, emergency temporary housing with double sash windows; while a certain level of insulation is achieved, the temperature difference from floor to ceiling due to low airtightness is significant.

A wooden temporary house constructed by a local builder; thanks to airtightness, the temperature difference from floor to ceiling is kept small.

Image 2 is for a temporary wooden house that is highly insulated and airtight. As you can see, the temperature difference between the ankle level and the ceiling is small. IR images make the differences in indoor thermal environments and comfortability recognizable at a glance. Careful construction work is required to ensure airtightness, and airtightness is often seen as less important compared to thermal insulation.

The necessity of large-scale testing for the strict analysis of airtightness may have been an obstacle to the widespread recognition regarding the importance of ensuring airtightness. When constructors can easily check airtightness by using thermal cameras, it is expected that construction accuracy will be enhanced and airtightness will be improved.

Making the Most of Thermal Cameras and Exploiting their Power so as to Ensure Maximum Communication of Conditions

- Camera technique greatly impacts the effectiveness of communication: Tips on taking advantage of thermal cameras -

1. Determine composition according to your intended message.

First of all, clarify your message, and then determine the shooting angle based on that. For example, point a camera upward to express the coldness of the floor (Image 3). To check heat leakage, take images from the outside (Image 4). When you want to express the comfortability of a house, include two elements (i.e., a person and a room) in a subject to contrast room and body temperatures. IR images are also useful in expressing the airflow of an air conditioner. Although a thermal camera itself cannot visualize the airflow, it can visualize how the ambient temperature is changed by the warm or cold air from an air conditioner. It can be quite an effective tool if carefully utilized.

In a poorly insulated residential building with low airtightness, it is difficult to warm up an entire room, resulting in heavy dependence on warming devices such as heaters.

To check heat leakage, take an image from the outside at night so as to avoid the effects of sunlight.

2. Set the temperature range to 5–30˚C when shooting rooms in winter.

When comparing the indoor environments of different buildings, it is important to use the same temperature scale. Based on our experience, we think a temperature scale ranging from 5–35˚C is best in the winter heating season. In this setting, the comfortable temperature range of 20–25˚C is displayed in yellow, which visualizes the comfortability. In the summer cooling season, we recommend a temperature range of 10–40˚C by taking a seasonal change of clothing into account.

3. Take images when effects are easily recognizable.

There are appropriate periods of time and seasons for shooting buildings with thermal cameras. To view thermal insulation performance, take images in the winter during the nighttime instead of the daytime. This is because shooting in the daytime can be affected by sunlight. In contrast, to express the heat generated by sunlight in summer, take images in the daytime when the sun shines. When comparing different buildings, take images at the same period of time and under similar weather conditions. Although it is difficult to completely match the conditions, taking images under conditions matched as closely as possible is important for making them convincing.

4. Use the appropriate camera according to the intent. 

While a lens with a field of view (FOV) of 45° is enough to find thermal insulation deficiencies, a wide-angle lens of 80° is ideal for visualizing the thermal environment of an entire room. This type of lens enables you to capture IR images that make the state of an entire house recognizable at a glance. If no wide-angle lens is available, you can use image composition software.

5. Use IR images for improving the comfortability.

To make the most of thermal cameras, it is important to take a large number of IR images. As you gain experience, you will surely learn something. By verifying the images that you capture and by identifying what is different from your expectations, you will deepen your understanding of thermal insulation performance and comfortability. Consider acquiring basic knowledge in thermodynamics such as radiation, convection, and conduction, as needed. IR images are the best educational tool for visually checking thermal insulation and airtightness.

Thermal cameras can also be used to give advice on living.

The way of living changes in different thermal environments. IR images enable you to visually recognize the thermal characteristics of a cold house. Architecture experts need to make more effort to communicate the values of high-performance buildings (Images 5 and 6). Better building performance means more comfort and easier living for the residents. Having them understand the design concept and live more comfortably and easily is as important as constructing. IR images are thus an optimum tool for disentangling and communicating the way of living in a high-performance residential building. They help users understand the importance of the thermal environment, and they allow you to build trust with them.

Room of a highly insulated, airtight residential building; the IR image enables the intuitive understanding of a comfortable living space.

External appearance of a highly insulated residential building; the amount of heat leakage is low.