Exploratory analysis of the operation of a MHRV system in an overheating nZEB apartment in Spain

Abstract

Abstract This article investigates the operation of a Mechanical Heat Recovery Ventilation (MHRV) system in an overheating nZEB apartment in Spain. The building, an apartment tower, was found to have a moderate to severe issue of overheating during extensive parts of the year. The study focuses on a flat located on the top floor of the Bolueta tower I in Bilbao, Spain, which is the world’s tallest Passivhaus building. Temperature and relative humidity data loggers were placed in various locations inside and outside the flat, as well as an amperemeter to monitor the operating regime of the MHRV unit’s fans. The study covered a period of 18 months and consisted in an exploratory analysis of the data obtained. The results show that the dwelling and its ventilation system partially correspond to the expected performance during the cold season but deviate from the usual design assumptions considered for the warm periods. The MHRV unit may have difficulties entering bypass mode and providing sufficient free cooling to maintain adequate indoor temperatures due to its placement. These findings provide insight into the thermal performance of the building and operation of the MHRV system and can inform future research.