Diane McArdle
Mechanical Option
Skye Laboratories, Inc. Building E
Fort Worth, Texas
September 17, 2002
ASHRAE Standard 62 Ventilation Compliance Evaluation
Skye Laboratories, Inc. Building E is an animal testing research facility. Since ASHRAE Std.62-2001 requirements are intended for human occupancy, the standard is not applicable and does not specify animal holding areas. The laboratories are supplied 100% outside air, therefore; they would meet the requirements for outside air if specified. Two of the ten air handling units condition the chiller plant and the mechanical mezzanine. In view of the fact that Texas has a hot climate and the mechanical equipment is located on the top floor, the supply air is intended to prevent the equipment from overheating.
One out of the ten air handling units services the office area that was evaluated using ASHRAE Std.62-2001. Since some of the spaces were not clearly specified in the standard, assumptions were made. I initially classified the Break Room as a cafeteria since it was adjoined by a space labeled the Kitchen. Since the z values for these areas were over 1.0, I referenced the space layouts in the architectural plans. The kitchen contains vending machines, coffee maker, etc. and the Break Room only had seating for 30 people. I concluded that I could assume the Break Room was an assembly room with 15 cfm required per person. The observation rooms are narrow rooms without furniture that have windows 3.5 ft. from the floor. I estimated one person at 15 cfm for each 2 ft. of window looking into the surgery areas.
The required outdoor air supply rates were calculated using the requirements listed in Table 2 of ASHRAE Std.62-2001. The calculated outdoor air supply rates (Voc ) were divided by the total design supply airflow rates (Vsc ) to determine the Z values. The highest Z value is Zcritical that is used in Equation 6-1. The uncorrected fraction of outdoor air value (X) was determined by dividing the total calculated outdoor air (Von ) by the total design supply air (Vsc). Finally, the corrected fraction of outdoor air (Y) is found by plugging (X) and (Zcritical) into Equation 6-1 ( Y) =X/(1+X-Zcritical) ). The product of the total supply air and the corrected fraction of outdoor air is the required outdoor air flow rate (Vot).
Observation Room G1236 yields Zcritcal= 0.48
X=Von / Vst = 3961 / 35,520 = 0.11
Y= X/ (1+X-Zcritcal)
Y= 0.11 / (1+0.11-0.48) = 0.18
Vot = Y xVst =0.18 x 35,520 = 6272 cfm
Vot< 7000 cfm (designed outdoor air flow rate)
The evaluated air handler unit has the capacity to deliver 35,000 cfm of supply air with 20% outdoor air to the office area. By applying ASHRAE Std.62-2001, 6275 cfm is the calculated requirement for outdoor air quantities delivered to the serviced areas. Since the calculated outdoor supply air is lower than the designed outdoor supply air, the office area of the facility meets ASHRAE Std.62-2001.
Outdoor air requirements vary between the indoor air quality procedure andventilation rate procedure. The outdoor air requirements for indoor air quality procedure requirements are based on the level of contaminants anticipated in the space. The outdoor air requirements for the ventilation rate procedure are based on occupancy levels in the space. The indoor air quality procedure could result in lower outdoor air requirements than the ventilation rate procedureif the space has low contaminant levels. If the space has a significantly high level of contaminants, the indoor air quality procedure would yield a higher outdoor air requirement than ventilation rate procedure.
Currently, the indoor air quality procedure is not widely used. It is hard to implement because contaminant levels have to be estimated before the building is built. With progress in control technology, indoor air quality procedure will be implemented. Control accuracy is needed to measure the varying levels of contaminants in the space. The indoor air quality procedure will reduce the cases of sick building syndrome by providing better indoor air quality than the ventilation rate procedure.