Thermal Comfort in Offices – Natural Ventilation vs. Air Conditioning

Based on both subjective and objective data, a study was carried out in order to identify differences in the perception of thermal comfort of office workers in naturally ventilated and air-conditioned buildings. The analysis of the interviews shows that occupants of naturally ventilated office buildings are significantly more satisfied with their thermal environment than occupants in air-conditioned buildings. Several perceived parameters influence thermal comfort: lighting, draughts, temperature variations, acoustics, olfactory quality, glare and perceived control as well as for air which is perceived as stale and dry. The impact of these parameters depends on the type of ventilation and the perception of the indoor temperature (hot or cool). The closest agreement between predictions and subjective perception of thermal comfort for air-conditioned offices is achieved by Mayer’s modification of the PMV-Model. For naturally ventilated offices the ASHRAE approach shows the best match.