HVAC – Strategies for Energy Efficiency

Chillers Even minor improvements to chillers, the largest electricity users in most buildings, can result  in significant savings. Over-sizing is the single largest cause of energy waste in chiller systems. Building chillers are typically designed to carry the largest cooling load that occurs in the facility during the course of a year – the rest of the time the chillers operate at a greatly reduced load. Unfortunately, chillers operate at their peak efficiency when operating at or near full load conditions. As the load on the chiller decreases so does the unit’s operating efficiency. When the cooling load in the facility is low only one chiller should come online at a time. As the load increases, additional units can come online to meet the increased demand for cooling. If the facility has more than one central chiller, managers can improve operating efficiency by staging the the operation of the chillers. When the cooling load within the facility is relatively low, only one chiller should come online. As the load increases, additional units can come online to meet the increased need for cooling. Another option is to install a variable-frequency drive (VFD) on the chiller’s motor. A VFD automatically reduces the operating speed of the chiller to match cooling load requirements. By reducing the speed of the chiller, the VFD enables the chiller to continue operating at near full load  capacity, even as the cooling load drops to as little as thirty percent of the unit’s full load rating. Managers can expect VFD’s to reduce the chiller energy use by up to thirty percent annually. Stay Cool and save cost at the same time! ]]>