Presents energy use characteristics of systems incorporating personal environmental control (PEC) in open plan offices compared with conventional designs, through the use of computer simulations. States the primary reason for incorporating PEC is to increase worker productivity through improved thermal comfort and air quality conditions. To analyse the economics associated with the installation of a PEC system, it is necessary to know the installation costs, the operating and maintenance costs and the cost savings associated with improved worker productivity. States the study shows that the effects of PEC systems range from 7% savings a 15% penalty in building lighting and HVAC electrical use compared with conventional systems. With current energy and labour costs, only about an 0.08% annual increase in productivity associated with PEC is necessary to offset a worst-case penalty of 15%. States research is required to quantify the relationship between worker productivity and individual comfort control.KEYWORDS: Controls, offices, open plan spaces, buildings, productivity, comfort