Cohaus Grey Lynn

Cohaus is an innovative cohousing community in Auckland designed with sustainability and energy efficiency at its core. The development consists of 20 households, all benefiting from a centralised hot water system powered by STIEBEL ELTRON’s innovative heat pump technology. By integrating renewable energy solutions, Cohaus has significantly enhanced energy efficiency, reduced carbon emissions, and maximised available living space for residents.

To meet the community’s hot water needs, Cohaus implemented a centralised heat pump system featuring two WPL 25 ACS air source heat pumps and two SBS 1001W hot water cylinders. The system is integrated with solar PV, using the hot water cylinders as thermal batteries to store excess solar energy. This solution supplies hot water efficiently to all 20 households while optimising energy use by leveraging renewable energy sources.

Benefits and Performance
The centralised heat pump system required an initial investment of approximately $100,000, which was $50,000 more than installing individual conventional hot water heaters. However, the additional capital cost is offset by substantial energy savings, achieving a full return on investment in less than three years. Annual operational savings are estimated at $15,000, with an expectation that these savings will increase over time.

By opting for a centralised hot water system, over 20m² of floor space was saved across the apartments. With an estimated built floor space value of $100,000, the system delivered instant payback purely from space optimisation.

The hot water heating set point can be increased when excess solar electricity is available, effectively using the hot water cylinders as thermal batteries. This approach enhances renewable energy self-consumption and further reduces reliance on the grid.

The Cohaus community demonstrates the value of investing in a centralised heat pump hot water system for multi-residential developments. By integrating STIEBEL ELTRON’s WPL 25 ACS heat pumps and SBS 1001W hot water cylinders with solar PV, Cohaus has achieved significant energy savings and reduced operational costs. The approach has optimised living space within each household while enhancing sustainability through renewable energy integration.