Workstation design for organizational productivity - National ...

Building maintenance officials establish the outdoor air supply volume for aspace based on the number of occupants. For a healthy volume of outdoor airto be delivered, occupant density should not exceed the ventilation system’soutdoor air supply capacity, and accurate information on office density mustbe given to the professionals setting up and maintaining the system. Changesin the number of occupants must also be reported so that the outdoor airsupply can be adjusted accordingly.Recommended outdoor air supply rates are intended for regular contaminantlevels. When high levels of contaminants occur, the outdoor air supply rateshould be increased. When possible, an outdoor air supply rate of 20 L/s.p(40 cfm) should be used for two to four weeks after renovations or when newcontaminant sources have been added to the office space. (Paint, floorcoverings, office furniture and other materials emit higher levels ofcontaminants when newly installed.) Once contaminant emissions havereturned to normal levels, the outdoor air rate should be reset.Air Delivery: As well as maintaining asuitable outdoor air supply, it isimportant to make sure thatoutdoor air reaches all occupiedparts of the office space. Theplacement and type of supplydiffusers and return air grillesinfluence how air moveswithin the space. Most NorthAmerican offices use supplydiffusers and return grillesmounted on the ceiling, andconfigured so that supply airmixes as thoroughly aspossible with the air in the room.When properly set-up andoperated, this method of air deliverycan achieve acceptable IAQ in thespace. Other air delivery systems, suchas displacement delivery or personal air delivery,I.11I.10Research:Air DeliveryIn COPE lab research,workstation size and partition heighthad little effect on air delivery in anopen-plan office with ceiling-mounteddiffusers and an outdoor air supply rate of10 L/s.p (20 cfm). (The results depend on aproperly configured and operated ventilationsystem, without which poor IAQ is likelyregardless of the office configuration.) TheCOPE field study found that occupants withhigher partitions tended to be less satisfiedwith air quality. This finding is likely to bea psychological effect, with occupantsperceiving that high partitionsinterfere with acceptableairflow.can also provide satisfactory IAQ. As an added benefit, personal air deliverysystems also allow occupants some control over their conditions.To maintain the intended air distribution, diffusers have to remain unblocked.Furnishings should not be placed on top of, or in front of, diffusers, whichmust remain open. The placement and number of supply diffusers and return29