Shower heat exchanger: reuse of energy from heated drinking water for CO₂ reduction

Abstract. The heating of drinking water in households contributes significantly to the emission of greenhouse gases. As a water utility aiming to operate at a climate neutral level by 2020, Waternet needs to reduce its CO₂ emission by 53 kton yr⁻¹. To contribute to this ambition, a pilot project was carried out in Uilenstede, Amstelveen, the Netherlands, to recover the shower heat energy with a shower heat exchanger from Dutch Solar Systems. An experimental setup was built in the Waternet laboratory to evaluate the claimed efficiencies. The energy recovery efficiency observed in the lab was 61–64 % under winter conditions and 57–62 % under summer conditions, while the energy recovery efficiency observed in Uilenstede was 57 % in December 2014. Based on the observations, 4 % of the total energy consumption of households in Amsterdam (electricity and gas) can be recovered with a shower heat exchanger installed in all households in Amsterdam, which also means a 54 kton year⁻¹ CO₂ emission reduction can be achieved.