New method for measuring the heat loss from buildings

Research project The project will contribute to a new method for measuring the heat flux on the building envelope. To better measure the energy performance would significantly improve the quality and contribute to energy efficiency measures.

The project goal is to develop thermography into a method for imaging measurement of the heat flow rate (W/m2) from the building envelope surface. The method enables on site measurement of the heat energy loss (kWh) from the envelope, and its thermal transmittance (U-value). Presently, only single point measurement of the heat flow rate is possible, while no reliable imaging method exist. For this reason, field measurements are rarely performed, and instead one relies mainly on computer simulations. It is well known that computed and measured results often differ significantly.

Head of project

Thomas Olofsson Professor

+46 90 786 67 10

Project overview

Project period:

2015-01-01 – 2017-12-31

Participating departments and units at Umeå University

Department of Applied Physics and Electronics, Faculty of Science and Technology

Research subject

Building technology, Energy engineering

Project members

Anders Ohlsson Senior research engineer

Email

+46 90 786 52 19

Ronny Östin Associate professor

Email

+46 90 786 63 37

Project description

With conventional thermography obtained a picture of the temperature on the surface of eg the building's envelope. This Technology has since the 1970s been used frequently in the construction sector to quickly get an indication of the place on the walls and ceilings as heat energy leaking out. Some research groups has recently started the development of technologies designed to directly measure the flow of heat energy through thermography. The image of the building would not show the surface temperature (° C), but instead the heat flux (W / m2) at each point on the surface. This opens up two possibilities:
(I) By summing the heat flow of e.g. a lot of wall all parts, you get a measure of the flow of lost heat energy (W) from the wall surface. For example, an energy-saving measure concerning an entire housing stock thus be evaluated by measuring the energy loss before and after the action, and the effect expressed directly in the saved amount of energy (kWh).
(Ii) Given that the difference between indoor and outdoor temperature is determined, as a value of the wall thermal transmittance (U-value) measured. The technology thereby enables the measurement of energy losses in existing buildings, such as measurement of a building element insulation properties.