CI-81-01-3 -- Dynamic Response through Computer Control

A computer is programmed to dynamically respond to load changes and reset control points to operate equipment in an economical manner while maintaining defined comfort conditions in an 11-story divisional headquarters building. This paper will describe that building, the equipment and the control strategies.

A computer room and a cafeteria each occupy one floor while the balance is primarily office environment.

The central HVAC facilities that are computer controlled to maintain comfort conditions are 4 constant volume perimeter and 2 variable air volume interior air handlers, 2 chilled water systems (one, of which, is a heat pump to cool the computer room and reclaim heat for the balance of the building during winter), a 2-cell cooling tower, and an electric water heater.

Because the building was designed and built after the 1973 energy crunch, it has many basic energy savings features built in. Among them are sun shades, enthalpy, free cooling and heat reclaim. The basic control system is pneumatic. Transducers interface with the computer for digital and analog sensing and control. Parameters and strategies weremodified to meet the requirements of the emergency building temperature restriction regulations and to maintain economies developed through operating analyses. Approximately 1000 points are monitored and recorded at scan rates varying from 100 ms to 1 min. These can be displayed every minute for the past 2 hrs (for current observation), or printed every minute for the past 24 hrs. They are useful for determining data trends and recreating events after the fact.

There are many other features to this system but for purposes of this paper, discussion will be limited to those related to dynamic response.

Citation: ASHRAE Transactions, Volume 87, Part 2, Cincinnati, Ohio



Product Code(s): D-CI-81-01-3