Thermal comfort assessment of an office building served by under-floor air distribution (UFAD) system – A case study

• Assessment occupants' thermal comfort was performed for building using a UFAD system.
• Many assessment tools were used to evaluate occupants' satisfaction.
• Most of occupants (80%) complained from 'slightly cool' to 'cool' conditions.
• Problems were mainly caused by non-optimal UFAD system operation.
• The methodology used can be used for other HVAC and air distribution problems.

The occupants' thermal comfort in an office building served by an under-floor air distribution (UFAD) system has been assessed using a number of different methods: field survey, physical and subjective measurements, and computational fluid dynamics (CFD) analysis. Results show that for rooms conditioned by UFAD systems, the Predicted Mean Vote (PMV) index was misleading, whereas the Air Distribution Performance Index (ADPI) was more indicative of the relative level of occupants' thermal comfort in the room. The CFD model search for the best operating conditions that maximize the occupant's thermal comfort resulted in a 90% improvement in the ADPI compared to the existing conditions. This was accomplished by setting the supply air temperature to 21 °C and inlet velocity to 1 m/s.