Energy savings from domestic zonal heating controls: Robust evidence from a controlled field trial

Domestic zonal heating controls enable hydronic systems to heat rooms to different temperatures at different times. The first credible evidence known to the authors, of the in-use energy savings of such controls, is reported. The results and research methods are globally relevant. The energy demands and room temperatures in 68, gas-heated, owner-occupied, semi-detached homes, in the English Midlands were monitored for a year before zonal controls were fitted in 37 of the homes prior to the second year of monitoring. The other homes retained the existing heating controls and so provided a matched (control) group. Surveys and questionnaires characterised the dwellings, heating systems and households. In two thirds of the homes with zonal controls the annual gas demand decreased, in one third it increased. Overall, the mean gas demand decreased by 3.5% relative to the homes that retained their existing controls. Savings were achieved primarily by reducing bedroom temperatures, especially in the evenings. Wireless, digital zonal controls are unlikely to provide an acceptable payback through reductions in energy bills at today's prices, but they offer households the flexibility to react to time-of-use energy pricing. A matched (control) group is essential for the reliable calculation of energy demand changes arising from interventions in occupied homes.