Commissioning of the HVAC-plant in a large office building designed with an underfloor ventilation system including input into what should be emphasized when evaluating the total system is to be done.

The following paper presents HVAC system commissioning activities, highlighting the most critical techniques and features to consider when commissioning the underfloor air distribution (UFAD) system. UFAD systems are non-standard and unique and therefore a special attention is needed to some issues and situations specific only for UFAD installations, e.g. coordination of the raised access floor, carpet and furnishings, temperature stratification etc. Some of the most important tests to be performed during commissioning of UFAD systems, are the air leakage, air stratification and thermal decay testing. In order to achieve successful operation of UFAD, the active participation of all involved parties, e.g. architects, interior designers, HVAC designers, contractors etc. is needed since the very beginning of the project. Commissioning of UFAD just requires a discipline, structured approach and commitment from all participants involved. The practical study involved assessment of expected UFAD performance at the Sparebank kvartalet office building complex in Trondheim, Norway. The underfloor plenum was not properly sealed, creating a significant risk of future energy waste. The openings in the raised access floor construction also lead to the dust and dirt accumulation in the plenum. This in its turn would not only impair indoor air quality, but could also lead to the malfunction of mechanical equipment installed in the plenum. Trying to seal the plenum after laying down the carpet was found to be difficult, costly and time consuming. Even though relatively good air distribution in the entire floor was achieved, some diffusers (automatically controlled) are located too close to the workstations and it will be probably needed to rearrange their layout in order to avoid draught complaints by occupants. The easier commissioning and better performance of UFAD in Sparebank Kvartalet could actually be achieved in a less time consuming and costly way if the commissioning would start early in the pre-design phase, with a well established commissioning plan