WKO — underground heat-cold storage — how it works + your rights
WKO stores summer heat underground for winter use via heat pump. Often collective in new-build areas — watch fixed monthly fee AND maintenance costs.
WKO uses the soil (60-150 m deep) as seasonal storage: in summer warm groundwater is pumped up for cooling, in winter cold water is pumped up + heated by heat pump. Many new-build areas have collective WKO — mandatory connection, monthly fixed cost + consumption part. Resident rights: (1) under Wcw 2025 affordability test for collective heat networks (NMDA principle); (2) right to transparent billing — fixed cost specified; (3) complaints to operator → Geschillencommissie Energie. Risks: higher monthly costs than promised, maintenance fees on top, reduced capacity after 15-20 years soil saturation. For developer/HOA: maintenance contract with operator essential + annual yield evaluation. Versus all-electric heat pump: WKO more efficient but higher investment and collective dependency.