Non Intrusive U Value Metering

Abstract

The significance of U values in buildings' shell energy performance is well known in the scientific community as well as in the construction sector. In addition, conducting a validation of the energy performance of a building often requires the knowledge of real U value figures, since their theoretical peers may deviate considerably from the real ones. The theoretical U value of a shell element may be calculated using complex material and surface related information, while its practical validation is conducted usually by equipment that requires tedious installation and constant contact with the examined element. Aim of this paper is to introduce an easily deployed, plug and play, contact less technology, able to provide a reasonable approximation of the building element U value and its variation with external air speed as well as an accurate estimation of the U value change in case of a shell (wall or window) retrofit.

A Novel Approach for U-Value Estimation of Buildings’ Multi-layer Walls Using Infrared Thermography and Artificial Intelligence

“…Two other non-invasive methods, namely: Heat Flux Meter (HFM) method and Infrared Thermovision Technique (ITT), are limited to be performed in winter only, as they require over 10°C temperature gradient between indoor and outdoor environment [4,5]. Another approach of estimating U-value from external and internal wall temperatures is by using noncontact infrared sensors; this technique shows better performance over HFM method; however, it is restricted to use during night only and it requires the measurement to be conducted over a few days [6]. The reliable estimation of in situ U-value is difficult in real buildings because of many constraints such as, installing instruments, extended period of monitoring time, dependency on season, dependency on weather condition and presence of sunlight [4][5][6].…”

“…Another approach of estimating U-value from external and internal wall temperatures is by using noncontact infrared sensors; this technique shows better performance over HFM method; however, it is restricted to use during night only and it requires the measurement to be conducted over a few days [6]. The reliable estimation of in situ U-value is difficult in real buildings because of many constraints such as, installing instruments, extended period of monitoring time, dependency on season, dependency on weather condition and presence of sunlight [4][5][6]. Furthermore, nonlinear and complex relationship among different parameters need to be considered for accurate estimation of U-value.…”