Providing enough ventilation without draft in the occupied zone of office buildings is one of the main purposes of air conditioning. Recently, an underfloor air-conditioning system (UFAC) with outlets for supply air mounted in raised floor panels has been introduced as a system that is able to obtain both efficient ventilation and prevent draft in the occupied zone of new generation office buildings. Although there are some underfloor air-conditioning systems, few studies on thermal comfort with those systems have been investigated so far. This paper deals with the subjective experiments utilising a UFAC system. Twenty-six subjects (10 males and 16 females) participated in the experiments. The airflow characteristics that can provide comfortable conditions without any draft were found for the occupied zone of offices.

KEYWORDS: thermal comfort, underfloor, air conditioning, ventilation, offices, air flow.