Mixed mode is better than air conditioned offices for resilient comfort : adaptive behaviour and visual thermal landscaping

This work investigated future building resilience, regarding thermal comfort, energy, health, and accommodating user behaviours and individual requirements by comparing mixed mode (MM) and fully air conditioned (HVAC) offices. Recently, offices are designed, as a fully HVAC sealed-box, while no particular guidelines or standards cover MM buildings. Although providing adaptive opportunities was demanded by occupants and predicted as an important asset for future offices; recently, centrally-operated systems are replacing them. In this work, MM and HVAC offices were compared using field studies of thermal comfort on 13 office buildings with overall 4,776 datasets in three countries: Japan, Sweden and Norway. Statistical analysis was applied on the Japanese datasets, while visual thermal landscaping (VTL) on the Swedish and Norwegian offices. The MM building had 16% higher overall comfort, 32% satisfaction and health conditions, as compared to the HVAC building. However, extra care is needed in designing MM buildings and user-friendly thermal controls, as they have the potential to be energy efficient by using natural ventilation and a variety of adaptive opportunities to achieve comfort. Overall, MM buildings were found more resilient regarding thermal comfort, energy, health, coping with future pandemics (e.g. COVID), and accommodating individual needs, as compared to HVAC buildings.