Development of a user-friendly Indoor Environmental Quality (IEQ) calculator in air-conditioned offices

Abstract

The assessment of indoor environmental quality (IEQ), would be used as an environmental performance indicator for environmental diagnosis in workplaces to explain reported occupants’ concerns in comfort, odour and working performance. Expressions of the occupants’ overall IEQ acceptance on thermal comfort, indoor air quality, aural and visual comfort are developed and the assessed environment is benchmarked by a 5-star rating system of IEQ performance for an indoor environment in Hong Kong. This rating system is a validated expression for indicating the relative performance of a service package, where a 5-star and 1-star award is respectively given to the best and the worst 10% samples. However, for assessing the IEQ in workplaces, it requires sophisticated instrumentation together with an intensive questionnaire. This study develops a user-friendly 5-star IEQ calculator incorporates market available sensors for measuring essential physical parameters, which focusing on five indoor environmental parameters including air temperature (oC), relative humidity (%), carbon dioxide (CO2 ) concentration (ppm), horizontal illumination level (lux) and sound pressure level (dBA). The calculator predicts occupant’s acceptance for thermal comfort, indoor air quality, illuminance, noise levels and the overall IEQ acceptance. Together with the input physical parameters and the additional subjective parameters including activity level (Met), and clothing value (clo), the calculator calculates (i) the predicted thermal perception (Hot, Warm, Slightly Warm, Neutral, Slightly Cool, Cool, Cold), (ii) the predict indoor air quality (IAQ), lighting and sound level acceptance (Dissatisfactory, Acceptable, Good) and (iii) the relative IEQ acceptance performance using the star rating expression (1 to 5 star) This user-friendly IEQ calculator not only provides an easy method for the assessment of the indoor environment but also can be used as a tool for professionals to evaluate the relative IEQ performance of air-conditioned workplaces, and allows early diagnosis of IEQ problems.