This study presents an investigation into efficiency and operation of an under-floor HVAC system at an office complex in London against a number of KPIs. Energy consumption of different system components was monitored for seven months together with time log graphs of room temperature and carbon dioxide levels at each floor.

Thermal comfort and ventilation control of the system was assessed against performance criteria specified in ASHRAE standards. Energy consumption of the system was compared to a conventional over-head VAV system and an air-conditioning system at an office complex in Singapore. User experience was assessed by analyzing questionnaires completed by building occupants. Whole Life-Cycle Costing of under-floor HVAC system was compared to VAV, VRF, FCU and CC systems available on the market today.

Carbon Footprint

Carbon footprint analysis showed that annual carbon footprint of WMProtek under-floor HVAC system is 197 tonnes of CO2; with 0.54tonnes/person. Typical AC system has an annual carbon footprint of 1.125 tonnes/person, which is 52% higher. Annual savings in carbon emissions of the under-floor system are equivalent to 211 trees planted or 132 cars taken off British roads.

From above the two main conclusions can be drawn:

• WMProtek under-floor HVAC system is good at achieving the objectives it was designed to achieve.
• The under-floor AC system is more flexible, energy efficient and cheaper than a conventional overhead VAV system.
• Therefore, based on the results of this study, it can be concluded that the WMProtek under-floor HVAC system is likely to perform better than an over-head VAV system.

Study by
Jekaterina Rusakova
New Hall College
Department of Engineering, University of Cambridge, UK