How not to ‘Live Your Life in a Jumper’ legacy of HVAC and the curious case of Comfort in Passivhaus

Since the 1970s, the comfort model has experienced a major paradigm shift from PMV/PPD to the ‘adaptive comfort’ model (de Dear et al., 2013). As opposed to considering buildings as ‘environmental capsules’ with centrally controlled HVAC (Heating, Ventilation and Air Conditioning), the core concept of adaptive comfort resides in the idea of harmonizing the outdoor and indoor environment with natural ventilation, and to widen the comfort range of the occupants by increasing adaptive opportunities, to achieve comfort with less energy intensive practices. Passivhaus as a new sustainable housing typology shares features of both a naturally ventilated building, and a mechanically controlled building. It is designed on the premise that occupants are to accommodate its passive features, and adapt their perception of comfort into a more sustainable mean. The result however is far from ideal. Case study analysis of a diverse range of Passivhaus projects in the UK, argues that fundamentally Passivhaus principle is against the principle of adaptive comfort. The legacy of half a century’s application of HVAC has already changed the occupants’ expectations of comfort, which are now based as much on a normality of controlled environment as on seasonal and climatic variations. Many Passivhaus occupants are satisfied with or actively pursuing a narrow-ranged temperature setting (20±1˚C) that was promised by Passivhaus system throughout the whole year. Increased sensitivity to temperature change is experienced in a few cases, which seems to affect the occupants’ demand for a rigid comfort zone in other scenarios. The study also shows the Passivhaus system is in danger of engaging more energy intensive technology for cooling with the escalation of global warming. To re-accommodate the adaptive comfort into the Passivhaus system, more attention needs to be paid from an architectural perspective rather than relying on spread sheet calculation and mechanical solutions.