Energy-efficient gas-heated housing in France: predicted and observed performance

Abstract This report presents selected results of an analysis of data collected by GdF, the gas utility of France, during a project to monitor the performance of energy-efficient gas-heated houses and apartments in France. The data base includes the performance predicted at the design stage, as well as supplementary information obtained by questionnaire from the residents. 220 residences yielded sufficiently complete and reliable data to permit weather correction to be carried out by PRISM software. The results show, on average, fairly close agreement between the observed consumption C tot, obs and the consumption C tot, the (predicted according to the French procedure), although with some tendency towards overconsumption (or underprediction), C tot, obs being 6% higher than C tot, the . Among individual consumers there is much scatter, especially for apartments. Characterized in terms of the r.m.s. variation of the ratio C tot, obs / C tot, the , the scatter is 0.3 for single-family residences and 0.5 for apartments. The scatter appears to be mostly due to behavioural effects, as suggested by the large variation (almost 2 to 1) between highest and lowest consumption in a group of six identical row houses. A detailed comparison between predicted and observed PRISM parameters (heating slope, base level and balance temperature) is presented for a subset of 82 single-family houses where the uncertainties are sufficiently small. Most of the overconsumption arises from differences between predicted and observed values of the base level (hot water and cooking), whereas for space heating prediction and observation agree within one percent. An attempt to correlate the ratio C tot, obs / C tot, the with data from the questionnaire has remained inconclusive for the most part.