While many assume that the thermal comfort of an individual is dependent on the air temperature of a space alone, there are actually six variables involved in maintaining optimal thermal comfort.  These are air temperature, relative humidity, air motion, radiant temperature, the individual's clothing insulation value, and the individual's metabolic rate.

According to the American Society of Heating, Refrigerating, and Air conditioning Engineers (ASHRAE), the optimal humidity level for an office environment is between 30% and 60% to avoid skin and sinus irritation, discomfort, and mold growth.  Air temperature should be kept between 20ºC and 28ºC, with temperature slightly lower in the winter to account for the increased clothing insulation value of individuals.  Air motion is also an important consideration, as rapidly moving air from ventilation results in the feeling of discomfort from draft exposure.  It is recommended that air motion be kept below 0.1 m/s for optimal satisfaction in cool weather, and slightly faster in warmer weather when cool breezes can increase individual satisfaction (1). 

Strategies for thermal comfort are most successful if implemented during the building process.  These strategies may include: (i) the installation of a controllable HVAC system which can be adjusted as necessary, (ii) providing humidification and dehumidification to maintain optimal humidity levels, (iii) providing optimal but not excessive circulation, (iv) installing good quality, operable windows, and (v) preventing overheating from radiant solar heat

Sources:
¹ Charles, K., Reardon, J.T. and Magee, R.J., 2005. Construction Technology Update #64: Indoor Air Quality and Thermal Comfort in Open-Plan Offices.  NRC Institute for Research in Construction.