A conventional system supplies conditioned air from high level, in this case ducted to high level from a remote air handling unit. In order to maintain conditions where it is needed, i.e. where the people are at lower level, the whole space must be conditioned. Also, supply air does battle with the warmer return air which is also extracted at high level. This is what we term Thermal Lift.

An Underfloor Air Conditioning System, in contrast, supplies air in the same direction as thermal lift, i.e. from low level to high level. This means that the occupied space receives the air at the optimum temperature and with the highest volume of fresh air.

With an underfloor system we are only interested in conditioning the space that is actually occupied by personnel – i.e. up to head height. The area above this height is allowed to rise in temperature, which has the advantages as follows:

•        Higher Inlet temperature onto AHU – increasing AHU efficiency or even allowing smaller AHU’s is careful design consideration is made.

•        Another advantage of only conditioning the occupied space entails that a smaller fresh air content can be used (as long as the fresh air is input into the area as a function of the underfloor system – i.e. not from high level). This entails that the maximum content of fresh air can be delivered to the space where it is required, with minimal wastage be directly re-circulated.