Andrew Pollard, Nikki Buckett.
Data from the Papakowhai Renovation Project and the Waitakere NOW Home are used to assess the clawback from the water heating and space heating services in ten New Zealand homes.
Increased energy efficiency of the hot water and space heating services in domestic buildings in New Zealand should reduce the cost of providing these services. However, the phenomenon of ‘clawback’ – where occupants use the improved heating system to increase comfort, can alter the effect of energy efficiency upgrades.
In the Waitakere NOW Home, clawback of water heating service occurred over the two years of monitored data, resulting in a 25% increase in demand.
In the Papakowhai Renovations, occupants of homes which are heated in winter to lower temperature levels are more likely to clawback increased service levels as comfort. Extensive upgrades to the thermal envelope are more likely to result in large improvements in indoor temperatures and reductions in space heating energy use, irrespective of whether clawback occurs. Solar hot water systems had similar or reduced water heating demand after their installation, and could therefore be considered as effective energy efficiency intervention with little or no clawback.