Which metric is commonly used to assess chiller efficiency in BAS?

• A. COP (Coefficient of Performance)
• B. Total building height
• C. Outdoor humidity index
• D. Number of occupants per floor

Answer: (A)

COP, or Coefficient of Performance, is the measure used to assess chiller efficiency in a BAS. It expresses how effectively the chiller converts electrical energy into cooling, defined as cooling output divided by electrical input. A higher COP means more cooling per unit of energy, so the chiller is more efficient. This direct link between energy input and cooling output makes COP the standard metric for comparing chillers and monitoring performance in real time. The other options don’t quantify how efficiently the equipment converts energy: building height has no bearing on chiller efficiency, outdoor humidity index describes environmental conditions rather than energy use, and occupancy per floor affects cooling load rather than the chiller’s energy conversion efficiency.