A U-value is a measure of thermal insulation. It defines how well a building element keeps the heat inside a building. Another relevant parameter for thermal losses is convection, also known as air leakage and air flow. A third parameter is relevant mostly during summer; thermal radiation. These three are factors are the fundamental parameters for evaluating energy consumption. Unfortunately, there’s one parameter besides these three, one that is fully unpredictable. The behavior of the residents.
Why you should measure U-values
To know the true physical heating demand of a building, one needs to know both air leakage and U-values for various parts of building envelopes. Air leakage or air tightness can be measured according to a standard but until now affordable instruments allowing in situ measurements of U-values haven’t been available. Because of this, experts have had to make estimations based on calculations. These estimations are often far from the truth.
- Average measurement time: 60 min
- Minimum heat flow: 3 W/m2
- Maximum heat flow: 100 W/m2
- Error: typically less than ± 8 % or 0.07 W/K*m2
- Devices calibrated with known wall structures (hot box analysed U-values)
- Data analysis with advanced excel template
- Ten instruments in weatherproof case