With the goal of optimizing three functional aspects of residential air conditioning systems, a recent Air-Conditioning and Refrigeration Technology Institute (ARTI) report identifies the mechanical components, design and installation practices, and load reduction strategies most acceptable among homeowners, builders, and architects, as well as the market barriers facing optimized systems.

The report, System Optimization of Residential Ventilation, Space Conditioning, and Thermal Distribution, was prepared by Proctor Engineering Group, Ltd. of San Rafael, Calif. with funding from ARTI. It identifies and evaluates system integration concepts for low-rise residential structures, and ranks them in order of merit, according to the following criteria: perceived costs, first cost, expected reliability, energy and other operating costs, peak-load reduction, thermal comfort, health and safety impacts, the likelihood of acceptance by industry and consumers, and major changes required for market acceptance by homeowners, architects, builders, HVAC contractors, distributors, and manufacturers.

Of the more than 30 concepts ranked, topping the list were load solar gain windows, roofing with reduced heat gain characteristics, proper sizing to load, and reduced infiltration with controlled ventilation.

Of the various mechanical systems available, ductless mini-split systems, as well as integrated heating, cooling, dehumidification and ventilation systems, ranked highest on the list. The remaining mechanical systems listed near the top of the list were ERV/HRVs coupled with reduced infiltration, frostless heat pumps, matched components to combined efficiency, evaporative-cooled condensers, improved aerodynamics (low watt per draw cfm) of the air handler/furnace and the outdoor air conditioning unit, higher SEER, as well as combined space and water heating.

The top-ranked design and installation practices included properly sizing the equipment to loads, sealing ductwork, and using shorter duct runs with improved register placement.

In addition to identifying favored concepts for optimizing residential air conditioning systems, another goal of the study was to uncover barriers to bringing optimized design combinations to the marketplace. Time, performance, and costs ranked as the top barriers identified among all surveyed. Homeowners said they were concerned about the amount of time it would take for them to determine which equipment would best meet their needs. Architects were concerned about the time required to learn more effective design practices to optimize air conditioning systems, while builders were concerned about the amount of time they would spend installing an optimized HVAC system.

With regard to performance, homeowners said they were concerned that optimizing their system design was worth the cost, while architects and builders were more concerned about durability and liability of the optimized system's performance.

ARTI was established in 1989 by the Air-Conditioning and Refrigeration Institute (ARI) to undertake pre-competitive scientific research related to HVACR. Funding for this project was provided in part by the U.S. Department of Energy.

Publication date: 07/24/2006