Center for the Built Environment

There is currently no quantitative method for evaluating the effectiveness and efficiency of personal heaters, which are commonly used in workplace situations to achieve thermal comfort. Instead, personal heaters are currently evaluated by their total energy use and heating method. We propose a new index and method of test by which efficiency of personal heaters may be calculated and assessed, taking into account both heating effectiveness and power use. This method was tested on a sample of 12 personal heaters, of various types: conductive, radiant, and convective. Each heater was tested in an environmental chamber, using a thermal manikin to quantitatively determine the amount of heat delivered to a subject. Heater location was standardized across the heaters prior to testing, so that all results are comparable. Results indicated that convective heaters were the least efficient, radiant heaters approximately twice as efficient, and conductive heaters 20 times more efficient than convective heaters. These results could indicate substantial possibilities for plug load savings or lower heating set points in new and existing office buildings.