Appliances

Install High-efficiency Chillers

What Is It?

Over 24% of the energy in commercial buildings is used for heating, ventilation and cooling (HVAC) (Progress Energy), and cooling components comprise 35-50% of electricity use (FacilitiesNet). Cooling infrastructure is therefore a necessary component of addressing a building’s energy saving goals. Chillers, which are primarily used in commercial and industrial facilities for space cooling and industrial processes, are refrigeration systems that cool fluids or dehumidify air through vapor compression refrigeration or absorption refrigeration cycles. There are two different types of chillers: air-cooled and water-cooled chillers. Air-cooled systems collect and release heat into the surrounding air, often drawing ambient air over a finned coil to condense the refrigerant. In water-cooled chillers, refrigerants remove heat through evaporation and then use water and condensation to release the heat (Carrier Corporation a and b). Both systems almost always include evaporator, condenser, compressor, and expansion valve elements.

Generally, water-cooled chillers are slightly more efficient than air-cooled ones, though the latter have lower installation fees (HVAC Water Chillers and Cooling Towers, by H. Stanford; see Resources for more). A chiller’s efficiency can be expressed in kW/ton (where a kW is a kilowatt of electrical input and a ton is equivalent to 12,000 BTU of cooling per hour), where a lower rating (e.g. 0.5) is better. It can also be expressed as an energy efficiency rating (EER) of Btu/wattage; for EER, the higher is better (the Federal Energy Management Program [FEMP] requires over 10.5). In comparing efficiencies, it is important to consider both the Full-Load (FL) rating and an Integrated Part Load Value (IPLV), the latter of which takes into account the variability of efficiencies at multiple load values (i.e., when is cooling systems is not working at full capacity for parts of the year, etc.).

New chilling technologies increase efficiency in a number of ways, including multiple or multi-part systems to avoid the low efficiency rate that accompanies non-peak cooling; removal of gears to remove oil contamination; high efficiency purge systems; alternative fuels; and newer software that manages cooling systems to avoid waste when the building is unoccupied, for example (FacilitiesNet).

Benefits

Using a high-efficiency chiller will yield a 30-50% average energy savings compared to a normal chiller (FacilitiesNet). FEMP estimates that a high-efficiency model could have a lifetime savings value of $37,690 above a less efficient model with an EER of 10.4 (FEMP). These savings can not only largely reduce a facility’s energy consumption and electricity costs, but also greatly contribute to climate change mitigation through greenhouse gas (GHG) emission reduction. Often upgraded systems use fewer environmentally harmful chemicals as well.

Drawbacks

There are benefits and drawbacks to both types of systems. Of course, new installation costs and premiums should be considered; generally water-cooled chillers have higher installation and maintenance fees than air-cooled options because of the equipment, but generally have a high rate of return because of increased efficiency. They are also impractical or unfeasible if there is no space for a cooling tower, or in areas where water is in short supply. Air-cooled chillers have lower maintenance but higher operational costs because of lowered efficiency (Carrier Corp. B).

Financing Options, Incentives, and Rebates

NEWS

RESOURCES

PROJECT EXAMPLES

  • Gentex Optics, an eyeglass manufacturer, upgraded their cooling systems with two 250-ton high-efficiency chillers, saving $142,274 and about 1,166,181 kWh annually.

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Energy Efficiency