Heating cost accounting for actual living space

The #BGH recently decided that in the context of the heating cost account, which is according to the legal defaults of § 556a BGB in connection with § 7 BetrKV, it it depends on the actual floor space. There is nothing to the contrary, even in terms of the rental agreement. The BGH's ruling that a #rent reduction only comes into effect in the event of a deviation of 10 % of the contractually agreed total living space of the business entity, but is not transferable to the #heating costs, since it would depend on the objective residential value and not the subjective quality agreement. (BGH, Decision of 30.05.2018 - Az.: VIII ZR 220/17)