This is a theoretical study based on the theory of collective goods from microeconomics. If a MU-dwelling building have supply water temperature control SWTC and heat metering HM the collective indoor temperature will be 21.7 degrees C. If two identical buildings share HM and both have their own SWTC then the indoor temperature in both buildings will be 22.5 degrees C since the marginal cost of temperature for the collectives is halved. If the two buildings have less than 15 dwellings each one HM and one SWTC can be used for both buildings. The difference in temperature between the buildings will probably be less than 1 degrees C. If they are bigger it is profitable to invest in one HM and one SWTC for each building to avoid the low indoor temperature from the unbalance in heat demand.