Variation in Indoor Thermal Environmental Parameters in an Open Space Office

Abstract

Building energy modelling is an indispensable component of today’s design method. However, as per research findings, real-life buildings could utilize almost twice the amount of their ideal energy performance. Thus, it is important to understand the variation in the thermal environmental and thermal sensation parameters in the office buildings during real-life operation. Currently, the design of the indoor environment in buildings is performed based on the appropriate national and international standards. Based on thermal comfort requirements for mechanically conditioned buildings, the temperatures are held within narrow limits, and it is expected that the new and existing buildings adhere to them very strictly. Naturally, the question arises, instead of keeping indoor thermal conditions constant, could it be healthier to make it dynamic. A more dynamic thermal environment that goes beyond the boundaries of comfort zones may be able to provide occupants with thermal comfort, along with instances of thermal delight and positive stimulation.
To this objective, physical measurements were carried out in open office space in Lausanne, Switzerland. Data showing the overall variation of the thermal comfort parameters in space and in time have been presented. The ranges of thermal environment parameters, i.e., operative temperature, relative humidity, air speed, and local discomfort factors consisting of horizontal and vertical radiant temperature asymmetries, vertical temperature differences are discussed. Also, thermal sensation indicators, i.e., PMV and PPD are calculated from the measured values. These values are then compared with the limits specified in the standard ISO 17772. The thermal environmental parameters, particularly operative temperature, mostly lay in the Category II and III. Local discomfort factors did not exceed the limits of Category I. Thermal sensation calculation showed that the conditions were more on the cooler side since PMV was in the range of -0.2 to -1 and, the PPD was between 10-20%.