This new chiller simulation module being developed by Building Performance Assurance Project members will help building managers compare optimal and actual chiller efficiency.

Chillers are the single largest energy consumers in commercial buildings. These machines create peaks in electric power consumption, typically during summer afternoons. In fact, 23% of electricity generation is associated with powering chillers that use CFCs and HCFCs, ozone-depleting refrigerants. Satisfying the peak demand caused by chillers forces utilities to build new power plants. However, because chiller plants run the most when the weather is hot and very little at other times, their load factors - and hence the utilities' load factors (the percentage of time the power plant is generating electricity) - are low. Thus, to utilities, chillers are more costly to serve than other loads.

The phase-out of CFC refrigerants, intended to protect the ozone layer under an international agreement, has triggered an unprecedented wave of chiller replacements that will accelerate during the next 10 years. Energy-efficiency measures implemented in conjunction with chiller retrofits can reduce the load and therefore the required chiller size, making the change more economical overall. But once the chiller is replaced, the opportunity for an integrated approach is lost. Most chiller plants are oversized, and even those that are correctly sized operate most of the time at low part-load efficiencies. New technologies such as direct digital controls and variable frequency drives, combined with improved design, commissioning, and operation, can decrease chiller plant energy consumption by more than 50% while improving their reliability and helping the environment.

Chiller projects in which the Center participates include: