Figure 1. Three-year estimate for large-tonnage CFC chiller conversion/replacement.

Now over 50%, chiller replacement maintains sluggish pace.

The annual survey of chiller manufacturers by ARI showed that building owners in the United States, as of January 1, 2004, had replaced or converted 43,774 units or 55% of the original 80,000 CFC chillers. New, non-CFC chillers reduce maintenance costs, use less electricity, and can typically pay back the cost of replacing an old CFC chiller in five years or less, according to the U.S. EPA.

ARI said that during 2003 there were 187 conversions and 2,398 chillers replaced with non-CFC equipment utilizing alternative refrigerants accepted for use by the EPA. The pace of the phaseout has been slower than expected due in part to federal tax laws, which require depreciation of the chillers over 39 years.

Four U.S. House members led by Congressman Peter Hoekstra (R-MI), an active member of the Congressional Manufacturing Caucus, have introduced H.R. 3953, the "Cool and Efficient Buildings Act," to set the depreciation period at 15 years for "any property which is part of a heating, ventilation, air conditioning, or refrigeration system and which is installed on or in a building which is non residential real property." (See this month's "Editor's Note," page 8, for more info on this proposal.)

In a bid to alert building owners to the operating cost savings from higher efficiency, new chillers, the EPA published "Building Owners Save Money, Save the Earth," which is available at www.ari.org/consumer/articles. It notes that "Building owners can typically pay back the investment cost of replacing an old CFC chiller in five years or less in virtually all locations that cool for more than three months a year. In fact, replacement chillers integrated with building retrofits can pay for themselves in as little as two or three years, with a typical return on investment of 20% to 35%."

New building construction in the United States and CFC chiller replacements have been affected by employment declines and the slow recovery of the economy during recent years. ARI reported that factory shipments of large tonnage liquid chillers for use in the U.S. and abroad dropped to 5,742 in 2003 from 5,793 units shipped in 2002.

Building owners have replaced 34,890 and converted 8,884 CFC chillers, leaving an estimated 36,226 still in service, most of which use CFC-11 or CFC-12 refrigerants. ARI manufacturers estimated there will be 165 conversions and 2,883 replacements during 2004, bringing the total converted and replaced to 58% of the total by January 1, 2005.

Non-CFC chillers use alternatives accepted for use by the EPA. They include units with hydrofluorocarbons, HFC-134a, HFC-410A and HFC-407C and hydrochlorofluorocarbons, HCFC-123 and HCFC-22. To avoid emissions to the atmosphere and encourage recycling of refrigerants, EPA rules require recovery of CFCs, HCFCs, and HFCs which can then be reclaimed for re-use and sale when they meet purity limits set in ARI Standard 700.

White Paper: ARI Guideline V - Characterizing the Efficiency of Energy Recover Ventilation and Informing the Design of HVAC Systems

ANSI/ASHRAE Standard 84-1991, ANSI/ARI Standard 1060-2001, and ARI Performance Certification provide for characterization of the performance of energy recovery ventilation components. With the publication of ARI Guideline V-2003, the industry has made available a standard methodology for calculating the efficiency of air-to-air energy recovery ventilation equipment. More importantly, for the first time, it is possible to calculate the contribution of this equipment to the efficiency of heating and cooling systems using an industry-approved consensus document. According to recent DOE research, energy recovery ventilation represents one of the single largest sources of energy efficiency improvement available to the HVAC industry. The availability of the guideline means that it is now possible to take credit for these system efficiency gains, effectively removing another barrier to their implementation.

Guideline V presents a rigorous methodology for determining the efficiency of energy recovery ventilation systems. This is based on the standard calculation of useful energy delivered by a process divided by the energy consumed in that process. To distinguish it from similar calculations of energy efficiency ratio (EER) for unitary equipment, a new term, recovery efficiency ratio (RER) is introduced. In the case of energy recovery ventilation, this is a measure of useful space conditioning energy recovered over the extra fan energy required to move the two airstreams through the energy recovery device (an air-to-air heat exchanger). Certified data for effectiveness at a given airflow from ARI Standard 1060 allows the accurate determination of energy recovered. Certified data for pressure loss, combined with available information on the efficiency of the air moving device(s), and any additional power input to the energy recovery device provides the denominator in our equation. Because the recovered energy can be very substantial while the energy used is relatively small, typical RER's for energy recovery range as high as 120.

More easily understood in the context of accepted ratings of efficiency is the new term "combined efficiency" (CEF). Straightforward in concept, the CEF combines that portion of the cooling or heating work done by the unitary equipment at its efficiency (EER or COP) and that portion of work done by the energy recovery system at its efficiency (RER) into a single number.

CEF is expressed in the same terms as the familiar EER or COP for unitary equipment. For the purposes of characterizing the performance of systems with and without energy recovery or systems with various types of energy recovery, the CEF is directly comparable to the traditional EER at any given set of conditions. This makes the CEF descriptor particularly useful for characterizing efficiency at design conditions. The addition of energy recovery ventilation to typical systems results in a 10% to 40% improvement in efficiency at design. Utility rebate structures that provide incentives for reduced demand can use this information directly in an apples-to-apples comparison with other methods of improving efficiency.

Another critical element addressed by Guideline V is the proper sizing of unitary air conditioners when used with energy recovery. As recognized by major manufacturers and discussed in the ASHRAE Handbook - Systems and Equipment, Chapter 44, energy recovery effectively reduces the load of outside air at design, in turn allowing the heating and cooling equipment to be reduced in size. In order to calculate the CEF, the guideline determines that portion of the design load provided by the energy recovery. The capacity required of the unitary air conditioner is effectively reduced. This "downsizing" of the air conditioning system is critical to the economics of energy recovery and to optimum control of indoor humidity (by avoiding oversizing and attendant short cycling).

It is the goal and intent of this effort that Guideline V will assist in market transformation, reducing peak electric energy demand, contributing to federal and industry goals for reduction of building energy use over the next 10 to 30 years, and capturing the 0.55 quads of annual energy savings (as determined by a DOE study) available through the widespread use of energy recovery ventilation. This represents approximately 18% of current building HVACR energy use.

In summary, ARI Guideline V is a first step in describing the efficiency of systems that utilize more than one heating or cooling technology to meet the building load. Specific to combinations of energy recovery ventilation and packaged unitary HVAC equipment, the guideline provides accurate information on equipment sizing and system efficiency that is essential for proper design, product selection, and system optimization. The guideline also highlights the need to consider component application in selecting the appropriate certified or application ratings for use in efficiency calculations. Whether the energy recovery component is integrated in the air conditioner design, added as an accessory in the field, or provided in a separate stand alone package in conjunction with unitary equipment, Guideline V allows the system efficiency to be accurately characterized, providing a level playing field for technology in the context of engineering tradeoffs, utility demand management incentives, and government marketing programs. ES

ARI Guideline V-2003 is available for free download at the standards section of the ARI CoolNet website, www.ari.org. ARI is the national trade association representing manufacturers of more than 90% of North American produced central air conditioning and commercial refrigeration equipment.