Comfort control and improved thermostat location in conference rooms and academic working spaces

Abstract

The challenge of comfort control within commercial and academic spaces was explored in an attempt to determine what would be the optimum location and type of measurement over different occupancies and different seasons of the year. A computational fluid dynamic (CFD) simulation using Reynolds-averaged, RNG k – ε turbulence model was set up. It was verified by physical measurements of temperature and flow behavior within a commercial conference room containing a large external window and that was conditioned by an active chilled beam. Experimental measurements, supplemented by simulation, indicated a large, seasonal-varied deviation between the temperature measured by a wall-mounted thermostat and the average comfort conditions around occupants of the room. CFD results and post-processed predicted mean vote (PMV) values showed that having the thermostat located near the humans in the middle of the room (over a table in this case) improved the thermal comfort conditions compared to having it on a wall opposite the external window (PMV of 1.1 as compared to 1.8 for an Andover, MA summer scenario, respectively).The major causes of the deviations were the convective and infrared heat transfer from the window surface as well as the solar gains to the room interior. The wall thermostat errors could be moderated by including temperature measurements at the window surface as an additional input in the control algorithm. This conclusion was confirmed by experiments in a dormitory room and a large shared academic workspace.