2025-08-17
This time we talk about estimating building -values and in-situ measurements.
Papers
When it comes to building the -value—i.e. thermal conductivity—measures the walls ability to conduct heat. In general, a lower -value is a good thing for a building. However, measuring this value on site is difficult due to environmental conditions, weather, building use, or age of the infrastructure. Thus, determining this value is a difficult but important problem.
Most works use a heat flux meter (HFM) to estimate this value (for example Cesaratto et al). Such sensor need to be put on the wall which might not always be easily accessible and there is a push to use thermography instead. Two usual assumptions are either long data collection campaigns or steady-state condition during the measurement (Fokaides et al). Thermography has been used to estimate building defect (Fox et al) but more rarely to estimate directly because the thermal images are even more sensitive to environmental conditions than HFM. Danielski et al showed that, given enough measurements, the -value could be estimated, under non-steady state, using a linear regression.
Interestingly, most methods are more often limited by the data collection step than the science for estimating . We know how to estimate conductivity, but we cannot easily collect data to do it.