Indoor environmental quality benchmarks for air-conditioned offices in the subtropics

Indoor environmental quality (IEQ) of air-conditioned offices could be benchmarked by the occupants' acceptability. This study proposes a five-star IEQ benchmarking system based on an expression of the occupants' overall IEQ acceptance on thermal comfort, indoor air quality and aural and visual comfort. By using an earlier proposed IEQ index, the occupants' adaptive response of clothing adjustment for the perceived thermal environment was reported in order to determine the overall IEQ acceptance. The benchmarking parameter of a star rating system and the IEQ index were applied to express relative IEQ performance of air-conditioned offices in Hong Kong. The IEQ performance of some recommended environmentally sustainable policies for ''Excellent'' and ''Good'' offices was evaluated and compared with the existing offices. The probable IEQ in some Hong Kong offices were determined by Monte Carlo simulations from reports of surveyed studies. Among the existing office stock, results have shown that in offices which are renovated to the ''Excellent'' and ''Good'' IEQ criteria recommended by some policies, the IEQ acceptances for 5-star IEQ benchmarked offices are namely 0.95, 0.94, and 0.92, while for 3-star IEQ benchmarked offices, they are 0.89, 0.89, and 0.67 accordingly. The proposed star rating system would serve as a quantitative measure of IEQ for air-conditioned office environment in Hong Kong and given selected model parameters, it would be a useful reference for similar environments where the evaluation of an occupant is expected.