ACSESS Control System


Revolutionary Supervisory Control System

Engineers design their cooling system based on one single extreme condition, whether in the summer or the winter, the ASHRAE Design Condition.

But in reality, we live in spectrum of conditions that vary between hot, mild, cold, dry and wet. Depending on the specific condition, we could use a different cooling strategy, including Traditional Direct Expansion (DX) AC, Direct Evaporative, Indirect Evaporative, Indirect/Direct (IDEC) and/or Economizer (true hybrid operation).

The main problem is how to control all those systems together, the ACSESS™ Control System provides true hybrid operation for a variety of cooling equipment. ACSESS™ control provides the most efficient cooling strategy at any given time and therefore greatest cost reduction on a real-time operating basis.

The system uses a psychometric calculation to determine and then select the best cooling approach at any point in time. Psychometric calculations are based on

» 1993 ASHRAE Handbook: Fundamentals

» The ASAE D271 Standard Psychometric Data


Using state-of-the art electronic controls and sensors to plot the outdoor condition on the virtual psychometric chart

The control system creates a virtual psychometric chart with consideration of specific elevation entered by the user. Thus, the control strategy is location specific anywhere in the world. This allows the system to instantly plot an effective comfort zone for that location based on a series of desired indoor environmental input parameters, including indoor temperature and humidity.

The system then uses state-of-the art electronic controls and sensors to plot the outdoor condition on the virtual psychometric chart.

The ACSESSTM system combines outdoor conditions and the established comfort zone to instantly select the most efficient cooling strategy, thus assuring the highest equipment efficiency. As ambient conditions or comfort zone inputs change, the system will recalculate and choose the best available cooling strategy. Depending on the equipment, these strategies can include fresh air cooling (economizer), direct evaporative, indirect evaporative, IDEC, and/or DX standard air conditioning.

Air2O Newsletter