The old red waterworks building on Sct. Kjelds Gade at Nørresø is an important part of the Danish city Viborg's history, as it housed the city's first water treatment plant, which ensured the supply of clean drinking water to the people of Viborg in the early 1900s. Now the former water treatment plant is being reused for a combined city park, heating plant and rainwater basin, promoting the green connection between water, the environment and energy.

Søværket (The Lake Plant) conveys its own history through the preservation and (re)use of both the old water treatment building and a subsequent clean water tank. The waterworks building houses a heat pump system that supplies the area's district heating consumers by extracting heat from the old wells.

Playful presentation of both history and technology

A phosphorus purification system has been installed in the clean water tank for use in heat production, while a play and recreation area has been created on top of the tank. Here one can experience both the area's historical function as a water treatment plant and its new heat-producing and rainwater-handling functions. This is demonstrated through the use of water pipes in the design of tables and benches.

A basin covering most of the area of the lake works has been created around the seating area of the clean water tank, which can hold 5,500 m3 of rainwater. The basin cleans rainwater from the catchment area, which is separately drained, before discharge into Lake Nørres. In this way, the Søværket will contribute to urban life, energy supply and water quality in the future, while strengthening the historical narrative.

The project is a multidisciplinary collaboration between Energi Viborg Vand A/S, Viborg Varme, Viborg Municipality and C.F. Møller Architects. The Søværket project demonstrates the potential of reusing old technical facilities in innovative ways, to the benefit of both the environment and residents.