PU Passive House, Evere: Evaluating the thermal performance of the building fabric

The PU passive house was designed as a quasi zero energy building and therefore requires a highly insulating building fabric. The KU Leuven - University of Leuven was asked to evaluate the overall performance, energy use and indoor comfort of the PU passive house. In a first step the overall heat loss coefficient of the house was evaluated to verify whether the products used in the envelope and the installation quality really achieves the calculated performance levels.

To this end, KU Leuven performed a so-called co-heating test on the empty building. During this test the indoor environment is heated to a constant elevated temperature (e.g. 25°C). By measuring the heat input necessary to keep the house at this temperature and plotting the energy use against the indoor-outdoor temperature differences, an estimate of the heat losses through the building fabric can be made. This test is almost the only way to evaluate the real insulation quality of a building.

Top: schematic overview of the co-heating test. By expressing the heat input Qh necessary to keep the house at the elevated indoor temperature Ti as a function of the indoor- outdoor temperature difference ∆T, the overall heat loss coefficient H of the house can be determined. The last term at the right hand side of the equation refers to possible additional heat gains due to solar radiation.
Bottom: the measurement equipment installed in the PU passive house in Evere. Due to the high thermal quality of the building envelope an elevated temperature of 25° could be achieved by a few IR-bulbs distributed over the dwelling.

The analysis of the data yielded an estimated heat loss coefficient of 60.0 W/K, with a standard deviation of 3.0 W/K. This indicates that the thermal performance of the building fabric meets its very high standards, and is in line with the high design levels of a passive house.

For more information please contact:

PU Europe

Vanessa Pereira

Av. E. Vannieuwenhuyse 6

BE – 1160 Brussel

Tel : +32 2 676 72 06