In situ U-value measurements for today's Cypriot houses

Abstract

The present work aims to establish the thermal characteristics and actual thermal behaviour of typical residential houses in Cyprus under real weather conditions. For this purpose, a wireless web-based monitoring system has been deployed covering 44 different houses, geographically spread all over Cyprus. Construction materials varied amongst each house, resulting in a theoretical U-value range of 0.467–1.389 W/m² K. Calibrated temperature sensors were installed and measurements were conducted at 30-min intervals for each individual house. The indoor air temperature of each house, the outside (ambient) air temperature, and the internal and external wall surface temperatures have continuously been monitored for a period of 15 months. Processing the above-mentioned data has led to the establishment of the mean indoor air temperature of the typical Cypriot residence and calculation of the U-value for each individual wall, facing north, south, east and west, including the roof, comprising the building envelope. Variations of the calculated U-value of up to 25% for each wall orientation were observed, even though construction materials of each wall remain the same. Furthermore, deviations of up to 30% from the theoretical U-value calculation were also observed.