Underground Solar Hot Spring

Competition proposal for Architekturwoche Basel, developed in collaboration with Cookies: a seasonal thermal bathhouse powered by renewables in a disused reservoir beneath a parking garage in Basel, Switzerland.

During Architekturwoche Basel, the reservoir would be activated as the Underground Solar Hot Spring. A water-to-water heat pump extracts heat from one basin to create a lively hot spring in the other, demonstrating the potential of water as thermal-energy storage. Powered by local solar production, the installation makes the intermittent, seasonal abundance of a renewable-energy future tangible and social.

Visitors descend from a rooftop gathering space, following exposed orange pipes and the steady sound of the heat pump into a sequence of steaming pools, cold-water curtains, monumental waterfalls, showers and heated daybeds. Beyond the temporary event, the Dreispitz reservoir becomes a case study for treating Basel’s disused reservoirs as district-scale thermal stores and permanent civic infrastructure.

TYPE

COMPETITION PROPOSAL / TEMPORARY INSTALLATION

LOCATION

DREISPITZ RESERVOIR, BASEL

YEAR

2024

THERMAL SYSTEM

100 kW WATER-TO-WATER HEAT PUMP

PROGRAM

3 HOT POOLS / 1 COLD POOL / WATERFALLS / SHOWERS

COLLABORATION

ZEROTH + COOKIES

VISUALISATION

SFTWR