CHANTILLY, Va. - A report published by the Air-Conditioning and Refrigeration Technology Institute (ARTI) identifies and ranks the residential air conditioning mechanical components, design and installation practices, and load reduction strategies most acceptable to homeowners, builders, and architects. The report, "Optimization of Residential Ventilation, Space Conditioning, and Thermal Distribution," prepared by Proctor Engineering Group Ltd., identifies and evaluates system integration concepts for low-rise residential structures, and ranks them in order of merit.

They are ranked 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. 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.

Ductless mini-split systems and integrated heating, cooling, dehumidification, and ventilation systems were the highest-ranking mechanical systems. Load solar gain windows, roofing with reduced heat gain characteristics, proper sizing to load, and reduced infiltration with controlled ventilation were the concepts that ranked highest. The remaining mechanical systems listed near the top of the list were energy recovery ventilators and heat recovery ventilators 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.