States that in recent years the application of displacement ventilation systems and chilled ceilings in the office environment has gained popularity in the UK and is increasingly replacing the traditional mixed flow ventilation and cooling strategies. Although displacement ventilation and chilled ceiling systems individually have been used on the Continent for many years, their combined performance and effectiveness has been in doubt. Describes a programme of work undertaken by BSRIA to investigate whether it is feasible to combine displacement ventilation systems and chilled ceiling devices while still maintaining adequate levels of thermal comfort and a predominant upward air movement. The investigations were based on physical measurements and numerical modelling using computational fluid dynamics (CFD) techniques. Supplies and analyses the results of the comparative environmental performance assessment.