Occupant Environmental Satisfaction in a Semi-Outdoor Workspace versus Air-Conditioned Offices in Singapore

Kajima Technical Research Institute Singapore, Kajima Corporation, 489690, Singapore

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Abstract

In Singapore, the hot and humid climate has made air conditioning the default design strategy for commercial office buildings. However, it comes at a cost with cooling demand up to 60% of total electricity consumption. Strategy of higher temperature setpoints combined with elevated air speed has been shown to improve both energy efficiency and occupant comfort in tropical conditions. Yet, the central question remains: is it possible to work without air conditioning in a modern workspace? This study investigates occupant satisfaction with environmental conditions in a purpose-built semi-outdoor, naturally ventilated workspace in Singapore. A Post-Occupancy Evaluation (POE) survey was used to assess occupants' satisfaction across 19 environmental parameters. These parameters include temperature, humidity, air movement, overall thermal comfort, air freshness, scent, overall IAQ, lighting, light color, window views, overall visual comfort, noise, privacy, communication, furnishings, available space, personal control, cleanliness, and overall environment. Thereafter, satisfaction performance of 14 common parameters from the semi-outdoor workspace were compared against thirteen conventional air-conditioned (AC) offices extracted from the literature. The findings were unexpected. The semi-outdoor workspace showed either higher satisfaction or lower dissatisfaction with temperature, air freshness, scent, window view, available space, and noise level when compared with AC offices. This outcome suggests that occupant expectations in semi-outdoor settings could be different from those in fully controlled indoor environments. The results also indicate that maintaining optimal air speed is a key factor in achieving higher overall thermal satisfaction in semi-outdoor workspaces. On the other hand, satisfaction with humidity, lighting, personal control, cleanliness, and privacy was lower than in AC offices, largely because of the dynamic and less controllable outdoor weather conditions. These results based on user feedback demonstrate that semi-outdoor workspaces are not an impossible option in tropical climates. The study offers valuable insights that can inform the design and operation of future naturally ventilated workspaces in the tropics. By adopting appropriate design strategies, it is possible to reduce energy-intensive reliance on air conditioning while maintaining acceptable levels of occupant satisfaction.