Protocols for planning micro-zones to facilitate occupant-centric control (OCC) to reduce HVAC energy consumption in Indian open-plan offices

Abstract

Micro-Zonal Occupant-Centric Control (MZOCC) saves HVAC energy by creating comfortable virtual micro-zones around occupants and controlling diffusers using occupant centric control (OCC). This is needed in modern open-plan offices with flexible work schedules to avoid energy wasted in air-conditioning unoccupied regions. Despite this, there is no clarity yet on how micro-zones are to be planned within thermal zones. There exist knowledge gaps between established methods of thermal zoning for HVAC design and micro-zoning. Several temporal and spatial factors influence the transient thermal exchanges between virtual micro-zones which increases the complexity of micro-zoning. This study develops protocols for micro-zoning to simplify the process of MZOCC. The study first outlines factors critical in micro-zoning open-plan offices which are identified from literature and survey of Indian offices. Results indicate that Indian open-plan offices are diverse and caters to a variety of activities within each thermal zone. Occupancy survey shows that office spaces are partially occupied, most of the time. The second part delineates protocols for micro-zoning following assumptions derived from literature and survey data. In the third stage, these protocols are used to shortlist the best micro-zonal layouts for MZOCC from numerous possible layouts. The effectiveness of the protocols is confirmed using CFD simulations where it is observed that the shortlisted layouts perform better than others. These layouts act as a starting point, on which airflow control can be strategized to further improve MZOCC. Results also show that planned MZOCC saves 73% energy compared to zone level OCC.