Center for the Built Environment

Mixed mode (MM) buildings open up a new arena for energy efficient design. Zoned MM buildings are the most common, particularly in the developing world where only some areas in a building are air- conditioned (AC) based on programmatic requirements while the rest of it is naturally ventilated (NV). Occupants in the NV zone frequently visit the AC zone and are well aware of the conditions there. The unanswered question in such a MM building is whether occupants in the NV zone have similar adaptive behaviour and thermal comfort opinions as those in purely NV buildings or are they possibly influenced by higher expectations created from the AC zone visits.

A transverse (cross-sectional) study was conducted between April 2011 to July 2013 in the hot and dry climate of Jaipur, India, including 2869 total survey responses, out of which 604 were from zoned type MM buildings. Mixed mode observations were available only during summer (April-August 2011). Occupants were asked about their ‘right-now’ opinion of indoor environmental quality variables such as thermal and humidity sensation, air movement and comfort. Simultaneous physical measurements of air and radiant temperature, relative humidity and air speeds were also recorded. We analyse the results examining the physical conditions and thermal comfort responses in both the zones, and adaptive actions exercised in the NV zone. We compare the observations from the NV zone to three adaptive comfort charts to evaluate whether comfort in the NV zone in a MM building can be modelled as a purely NV building.