Some under floor systems make use of central air plant much like ceiling based systems which can maximise the use of “free cooling”. This can be up to 80% of the year during office hours, but differ from ceiling systems in that the ductwork through the work space is reduced and in some cases virtually eliminated. These ductless systems makes use of the floor void itself as a plenum through which the air can flow to variable volume terminals placed in floor panels to suit the space plan and cooling/heating.
The CAM-P system works equally well with central plant and zonal downflow units in both new build and refurbishment. It also offers engineers and designers another option when looking for reductions in system energy consumption and enhanced indoor climate control.
From the time that VAV was first introduced as a solution for energy efficient air conditioning back in the early 70’s, engineers have grappled with the problem of effective air throw from fixed diffusers as the volume is varied. One or two overhead systems produced slot diffusers to create a Coanda effect and overcame the problem of cold air dumping, but never solved the problem of poor air throw at reduced supply air volume. As all systems in the UK normally work at part load – VAV works at an average of 40% or less of full load – this problem often leads to occupant discomfort and complaints.
AET’s new CAM-P system has overcome the problem of discomfort traditionally associated with VAV solutions by introducing its key element, the Air Fixture damper using time modulation control – the new control technique for managing the way conditioned air is introduced into a space. This new device eliminates instances of poor air distribution at part load conditions in fixed slot VAV terminals and improvement in air distribution is immediately noticeable.
The CAM-P system only needs between 7 and 12 Pascals pressure for the Passive Tile Units (PTU) to distribute the air effectively into the room space above the floor. However in part load conditions as the central plant varies its volume, the Air Fixture specially designed damper fitted to the PTUs will start to sequence on/off according to room load demand. These dampers close for brief moments and thus the correct volume of air is introduced in sequence through open grilles in this “Time Modulated” way. The reduced numbers of PTUs operate with full flow thus maintaining the originally designed air throw. The alternating performance of the PTUs is based around a 6 second timing sequence hence ensuring good air distribution in the occupied space is maintained at all times. Extensive testing supports this new concept of Variable Air Volume control.
In addition to the Air Fixture damper, the extensive range of purpose designed VAV supply air floor grilles create a supply of well mixed air in the breathing zone. Some grilles in the range also have personal volume adjustment, so attracting a higher BREEAM score.
Many design engineers have battled with the new Part L codes and the need to reduce fan power to a minimum. With this design approach using free cooling and minimum floor void pressure, the energy calculation is enhanced over fan coils and conventional VAV where far higher external static pressures are required.
The CAM-P system is based on AirFixture technology, visit their website for detailed information