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/m 2 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.

Energy class dependent residential battery storage sizing for PV systems in Cyprus

“…In order to calculate the total thermal resistance of the house to ambient ( R h‐a ), the wall, roof, and floor thermal resistance were considered. The thermal resistances were calculated by considering both the convection and conduction mechanisms for heat transfer [4, 5]. The heat capacitance of the whole structure ( C structure ) was ignored deliberately because the simulation time is 24‐h and hence there is not enough time for the structure ( C h > 25 × 10 6 J/K) to change temperature since several days are required.…”

A Model Calibration Approach to U-Value Measurements with Thermography

“…E.g., Li et al conclude that "the mean U-value of English solid-walled properties is significantly lower than the CIBSE Guide A value" and that "the distribution of U-values is so large that the on-going use of a single mean cannot be justified when assessing individual properties" [3]. Xeni et al find deviations of up to 30% between measured transmittances and theoretical design values [4]. In addition, for many old buildings the design values are not known.…”