Displacement ventilation and cooled ceilings

The performance and effectiveness of any ventilation and cooling strategy depends largely on the method of air distribution and heat removal system. The consequences of poor air distribution and cooling systems are draughts, air stagnation, large temperature gradients and radiation asymmetry. These factors are the chief cause of the occupants' dissatisfaction with their thermal environment, and are major contributors to the so-called 'sick building syndrome'. Cooled ceilings combined with displacement ventilation, sometimes known as 'comfort cooling', has gained popularity in recent years. In the UK, the traditional cooling strategies such as fan coil and vav is now being challenged with static cooling systems in majority of the new and refurbishment projects. The increasing trend towards the use of these systems has led to a number of research programmes to study the air movement, thermal environment and condensation risk of these systems (Alamdari, et al 1993, 1996; Martin et al 1997, Butler 1997). The room air distribution and thermal environment of the combined displacement ventilation and cooled ceiling systems are presented in this paper.