Here are some very important specifications to include in your document that are critical for a contractor to determine cost. If everyone gets a spec sheet with these variables defined, your final bids will be more accurate and should be more consistent.
- Room Classification, either Fed Std or Iso spec should work here.
- Temperature specification and tolerance. Example: 68 +/- 5 Deg.
- Humidity specification and tolerance. Example: 50 +/- 10% RH. Let the bidder know if the temperature and humidity specifications are process critical or operator comfort. If humidity control does not affect your product, leave it out. It is the most costly specification to control for the HVAC system.
- Amount of process exhaust in CFM. This is relevant since both outside air to generate room positive pressure and air removed from the cleanroom by the process has to be accounted for.
- Process heat load in kilowatts (KW). Are there ovens, large process machines, or just operators in the cleanroom? If you are not sure about this item, list the connected electrical voltage and current draw (amps) to start with. This will ensure some A/C tonnage is dedicated to this specification.
- Number of operators. This affects temperature and to some degree, humidity.
- A brief definition of the manufacturing process or product in the cleanroom may also help.
- A description of the host building is helpful since this may affect where the HVAC equipment can be placed.