Analysis of overheating risk in Passivhaus dwellings during warm season. Focalizing in shadow systems strategies to mitigate it

Resumen

During the last decade, energy consumption in the European Union related to buildings accounts for 40% of the total consumption. In consequence, some strategies and goals have been set up to reduce it, mainly with 2020, 2030 and 2050 targets. To achieve them, one of the main instruments have been the Energy Performance of Building Directive that promotes Nearly Zero Energy Building (nZEB) constructions. According to this directive, many strategies have been adopted to reduce energy demand. A popular certificate it´s the Passivhaus Certificate, creating extremely low-energy demand consumption and airtight buildings. Different norms define the limit of indoor comfort for these constructions (ISO 7730, ASHRAE 55-1992, EN 15251, CIBSE Guide A, CIBSE TM52, CIBSE TM59 and Passivhaus standards). They will be taken into account in this study. As a result of the actual climate change predictions towards a warmer world, multiple studies have focused on the exploration of the actual overheating risk in this type of buildings, especially in multifamily dwellings. They recommend strategies to mitigate it as, for example, solar protection, low insolation materials thickness (roof and wall), hybrid or natural ventilation, passive and low-energy solutions during cooling and intermediate period, active solutions along the heating season, verification of occupancy, shape, activity and orientation, etc. As shown in previous studies, shading systems can provide, not only correct visual comfort but also thermal comfort, permitting solar gains during the cold season while protecting enough to avoid overheating in the warm season. The study will focus on applying shading measures to provide the best applicable solution in this case study, a high-rise residential building in Bolueta, Bilbao, which has already Passivhaus certificate. It will be carried out with different simulations and calculations. Comparing different solutions and make the best combination with other measures, like natural ventilation, to mitigate the overheating risk during the warm season.