Mechanical, natural and hybrid ventilation systems in different building types: Energy and indoor air quality analysis

Ventilation is fundamental for providing good Indoor Air Quality in buildings. Nevertheless, it involves considerable energy consumption. In this paper, a co-simulation approach was applied to two case studies, a residential and an educational building, to evaluate different control strategies for hybrid ventilation systems in terms of annual energy demand and risk mitigation. The simulations were performed using TRNSYS and CONTAM and successively applying the Wells-Riley model to estimate the airborne infection risk. The analysis is performed for three climates, Venice, Rome and Helsinki. Results for the apartment show that different control strategies do not lead to significant variations in the overall heating demand for a given climate. In contrast, increasing natural ventilation hours during the cooling season produces savings in both sensible (up to 31% in Venice) and latent demand (up to 30% in Rome). Fan absorption in the heating season is reduced by 40% and 86% in Rome for the flat and classroom, respectively and by 84% in Venice for the apartment in the cooling season. Moreover, a control strategy enhancing natural ventilation is promising in reducing the infection risk. Therefore, if well-regulated through a suitable control strategy, the hybrid ventilation system seems promising in maintaining healthy indoor environments while reducing energy consumption.