The effective measurement of heat flow through exterior walls is important for understanding the energy consumption and thermal efficiency of buildings. Environmental conditions, building design, structural conditions, and construction materials can all contribute to heat loss, influencing energy efficiency and operating costs.
Large differences can occur between expected and actual energy loss through heat transfer. These differences can reveal weak points, flaws, or areas for improvement in the building
envelope.
The EKO HF-01S heat flux sensor is used to measure heat flux from or towards a surface of interest. By measuring real-world heat transfer, the HF-01S helps evaluate actual insulation performance and supports decisions for energy efficiency improvement.
The HF-01S can be installed on building surfaces where heat transfer rate needs to becdetermined, including façades, interior and exterior walls, floors, roofs, doors, windows, and
glazing surfaces.
Heat flux data can be used to evaluate the insulation condition of a wall or other building component. High heat flux can indicate inadequate insulation and higher energy loss, while low heat flux can indicate better insulation performance.
When used together with two temperature sensors, the HF-01S can support in-situ determination of thermal resistance R-value and thermal transmittance U-value, following ISO
9869 and equivalent ASTM methods.
Heat flows from a point with higher temperature towards one with lower temperature. The amount of heat flow per unit area is called heat flux. The HF-01S measures voltage in relation to the heat flux passing through the sensor. This voltage is converted into heat flux using the sensitivity value from the calibration certificate.
q = V / S
Where q is heat flux, V is sensor output voltage, and S is sensor sensitivity. For example, if the measured voltage is 0.37 mV and the sensitivity is 55 μV/(W/m²), the heat flux is 7.4 W/m².
Reliable measurement starts with correct sensor installation. Select a representative measurement location on the wall or building component. Clean the surface and make sure it is smooth, dry, and free from dust, moisture, grease, and oil.
Apply suitable thermal contact material between the sensor and the surface. For temporary installation, use removable materials such as thermal adhesive pads, carpet tape, thermal
paste, or thin film conductive liquid. For permanent installation, use adhesive with suitable thermal conductivity and keep the adhesive layer as thin as possible.
Avoid air gaps between the sensor and the measured surface. Poor thermal contact can create local hot spots or cold spots and lead to inaccurate measurement results.
To keep similar infrared radiation and heat convection on the sensor and surrounding surface, cover or paint the sensor with a thin layer of material that has similar surface properties.
Masking tape or paint can be used to match the sensor surface with the measured surface. Connect the HF-01S to the data logger and confirm the correct wiring and polarity. Record the sensor voltage together with temperature data from both sides of the wall or building component.
Convert the measured voltage into heat flux using the calibration sensitivity. Use averaged or integrated values over a suitable measurement period rather than relying only on instantaneous readings.
The measured heat flux can be used to compare different locations, identify high heat-loss areas, and evaluate the actual thermal performance of the building envelope.
The HF-01S is designed with low thermal resistance and a built-in guard structure to reduce
measurement uncertainty caused by the sensor installation.
The HF-01S provides a practical method for measuring heat flux through building surfaces and
evaluating actual insulation performance. It helps identify high heat-loss areas, compare building
envelope performance, and support energy efficiency improvements.
When combined with temperature sensors, the HF-01S can support in-situ R-value and U-value
measurement of walls, façades, roofs, floors, doors, and windows. Use QRU-100 for the easy
plug and play experience of data collection for this application.
Ready to enhance your thermal monitoring? Contact our team for assistance or to request a quote.
How it works
