A general model for the optimization of energy supply systems of buildings

In this paper, a general model for the optimization of the energy supply systems of buildings is proposed. The model is based on a general superstructure that allows to include all the existing and future technologies, covering heating, domestic hot water, cooling and electricity. The model is linked to a Mixed Integer Linear Programming (MILP) problem that allows the selection of equipment and its operation, enabling the minimization of the annual cost for a set of constraints imposed by the designer, such as a Non-Renewable Primary Energy (NRPE) consumption limit. The model has been applied to a case study consisting of a domestic building located in Bilbao (Northern Spain). 13 different technologies were taken under consideration together with the specific conditions of the Spanish context. Three different objectives were determined: (i) the optimal cost; (ii) the Zero Energy Building (ZEB); and (iii) the ZEB′, an alternative ZEB where the whole electricity consumption is considered for the calculation of the NRPE. The 3 cases were compared and analyzed and, finally, a parametric evaluation was carried out, setting the aspects that limit the feasibility of low energy buildings: economic feasibility and physical constraints such as roof availability for renewables. •A model for the optimization of energy supply systems for buildings is presented.•The model covers both design and operation optimization.•The model is applied to a case study building located in Northern Spain.•The designs are limited by the roof availability and economic feasibility.•The model can be used for fast design and policy making.