4.5 How to specify required conditions for a contractor

It is often difficult to specify clearly to a builder or air-conditioning specialist the requirements for a storage environment. Merely stating the target temperature parameters may not produce a successful outcome. It is suggested that the following parameters be considered.

  • Set point for temperature and humidity
  • Tolerances expressed in values above and below the set point
  • Frequency of change (the period of cycle between high and low)
  • Rate of change (the gradient of the cycle)
  • Amount of fresh air expressed in percentage of cycled air
  • Air cleanliness expressed in terms of percentage, or the quality of filter necessary to remove that content
  • Air flow throughout the room
  • Number of sensors and their placement, and the means of determining the overall conditions
  • Energy consumption under a range of conditions

An alternative to the standard supply contract is a performance contract in which the performance is defined in terms of given standards or approaches, but the supplier is commissioned over a given period of time to maintain and manage the system so that it continues to meet those standards. This is likely to be more expensive, but provides a strong incentive for the supplier to meet the specified conditions in the long term.