Enhancing non-domestic Passivhaus auditoria ventilation design for improved indoor environmental quality

Enhanced energy conservation strategies often involve tightly controlled ventilation flow rates. However, stra-tegies that don't carefully consider ventilation rates can, in certain contexts, result in inadequate ventilation, with increased risks of poor indoor environmental quality and user acceptance. These design challenges are often exacerbated in non-domestic buildings with highly dynamic occupancy patterns. This study used computational fluid dynamics, supported by field measurements, to investigate the relationship between zonal supply air strategies and thermal comfort in the George Davies Centre, Leicester University, which is the largest non -domestic certified Passivhaus building in the UK. Ventilation strategies involving mechanical ventilation oper-ating with heat recovery turned on and off, and natural ventilation systems were investigated in relation to their ability to maintain thermal comfort in an auditorium space characterised by high internal heat gains and tiered seating. The results show that, depending on the selected thermal comfort criterion, a thermally comfortable environment could be achieved when incoming air is in the range of 9-26 degrees C for mechanical ventilation with heat recovery and 17-29 degrees C for natural ventilation. These temperatures are referred to as 'limiting operating tem-peratures' in the paper. The work showed that in a temperate climate, thermal comfort could be maintained, for up to 80% of the year, using mixed mode ventilation, without space conditioning, in combination with intelligent design and control strategies. Operating in natural ventilation mode also provided increased fresh air supply capacity, a finding which is particularly relevant in the context of mitigating airborne viral transmission.