Energy consumption for hot water depends less on people’s everyday behaviour and is influenced more by the system technology. This was the finding of an analysis of real consumption data. In a joint study by co2online and Scientists for Future, gas consumption for hot-water production was analysed in almost 700 households.
Technical optimisation more important than behavioural changes
Hot-water circulation systems in particular cause high energy losses. Consumption in single-person households with circulation can be up to three times higher than without it. This shows that the greatest potential for savings lies in optimising technical systems, a one-off step with a long-term effect.
“During the energy crisis, behavioural changes such as taking shorter showers were often discussed. But the analysis shows that the major savings can be achieved through technical optimisation,” says Tanja Loitz, Managing Director of co2online. “Anyone who can do without permanently keeping hot water in the pipes should definitely switch off the circulation system to save energy.”
Small aids such as water-saving shower heads and adjusted user behaviour remain important, but technical improvements offer the greatest potential for long-term savings without requiring constant conscious effort. This disproves the widespread myth that saving energy is primarily a question of behaviour.
Clear recommendations for consumers
In centrally heated buildings, homeowners can insulate distribution pipes and the hot-water storage tank. With circulation systems, it is advisable either to insulate the circulation pipe or, where possible, disconnect and drain it. For smaller households, even switching to decentralised hot-water production, such as instantaneous water heaters, can make economic sense. Energy advisers and specialist tradespeople can help to implement these measures. Measures to optimise energy efficiency, such as renewing the hot-water system or insulating pipes, receive government funding as part of heating replacement or heating optimisation.
“Households in older buildings with poorly insulated hot-water pipes should pay particular attention to optimisation. Losses are especially high here, and technical measures such as insulating the pipes or switching off circulation can deliver substantial savings,” emphasises Dr Hartmut Ehmler, a member of Scientists for Future and author of the analysis.