A method for quantifying the variability of the heat transfer coefficient due to inter-dwelling heat transfer using a matched pair of test houses

The Heat Transfer Coefficient (HTC) describes the average rate of heat loss (W/K) from a dwelling by transmission through the building fabric and by ventilation. There is increasing interest in measuring the HTC of dwellings to provide an energy rating, to quantify the energy performance gap, to demonstrate build quality, and to identify those dwellings which are most in need of energy efficiency retrofit. Whilst the HTC is generally given as a fixed number, it is hypothesised here to be a variable depending on several factors, yet the magnitude of this variability is unknown. A method for the quantification of one source of HTC variability is considered in this paper: heat transfer through the party wall which affects the HTC and may vary when adjacent dwellings are heated to different temperatures.

This paper describes the adaptation of a matched pair of semi-detached test houses, in a first of its kind experiment, to gain greater insight into the variability of HTC. The test houses were instrumented with calibrated sensors to measure the indoor temperature and the inter-dwelling heat flux. The thermal performance and air permeability of the test houses were measured using co-heating and fan pressurisation tests. This characterisation and the configuration of the test houses enabled the design of experiments to investigate the variability in the measured HTC. The methods presented will be valuable for the development of more accurate thermal characterisation tests.