Energy-Efficient Envelope Design for Apartment Blocks—Case Study of A Residential Building in Spain

Buildings are known to be responsible for about a third of energy consumption in developed countries. This situation, together with the fact that the existing building stock is being renovated at a very slow pace, makes it crucial to focus on the energy retrofitting of buildings as the only way to reduce their contribution to these energy consumptions and the consequences derived from them in terms of pollution and climate change. The same level of insulation and the same type of windows is usually proposed for all dwellings in a building block. This article shows that since the improvements required by each dwelling in the same block are different, the proposed solution must also be different. The methodology is proposed for a practical case consisting of an apartment block in Cádiz, a demonstration building of the European RECO2ST project. To achieve the optimum solution for each case, a multi-objective optimization problem is solved: to minimize the annual heating demand of the building and the standard deviation of the annual demand of the different dwellings. Thanks to the use of the proposed methodology, it is possible to bring the building to a Nearly Zero Energy Building (NZEB) level, while avoiding excessive insulation that causes overheating in summer.