Equitable decarbonization of heat supply in residential multi-apartment rental buildings: Optimal subsidy allocation between the property owner and tenants

•Equitable decarbonization of heat supply in residential rental buildings.•Fair financial governance support strategy between property owner and tenants.•Equitable switch is possible but with massive public subsidy payments.•Heat pump alternative is not competitive compared with district heating.•Allocating the costs of inaction between governance, property owner, and tenants.