Design approaches for retrofiting offices to reach nearly zero energy: A case study in the Mediterranean climate

Currently, feasible construction practices are not enough to reach zero energy buildings, therefore, European Union (EU) legislation states that new buildings and renovations should be designed as nearly zero energy buildings (nZEB); however, design alternatives need to be carefully considered and selected before implementation. This study aims to investigate the effect of building facade elements and energy-efficient building systems on reaching nZEB with two different design approaches (DAs). These approaches are investigated through the case of a selected office building's facade retrofit options in terms of energy efficiency and thermal comfort. In the first DA, different design variables of a double skin facade (DSF) are investigated and optimized in order to decrease the total amount of consumed energy, and the best parameters are used in the design of the south facade. In the second DA, the building retrofit aims to meet nZEB criteria by redesigning the south building facade via genetic algorithm optimization, while providing thermal comfort in all months and reducing the number of discomfort hours. The investigation is carried out via building energy simulation (BES) of a selected office building, validated by indoor and outdoor measurements. The results show that the parameters of the building facade can play a significant role in decreasing the energy consumption of the building, and both DAs decrease total energy consumption while utilizing currently feasible and common building technologies. Yet, in the second DA not only is the energy consumption lower but, it also significantly decreases discomfort hours. (C) 2020 International Energy Initiative. Published by Elsevier Inc. All rights reserved.