A report from the Air-Conditioning and Refrigeration Technology Institute (ARTI) found 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,” identified and evaluated system integration concepts for low-rise residential structures and ranked them in order of merit. 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
  
  
• Reduced infiltration with controlled ventilation.
  
  Of the various mechanical systems available, ranking at the top were:
  
  
• Ductless mini-split systems
  
  
• Integrated heating, cooling, dehumidification and ventilation systems
  
  
• ERV/HRVs coupled with reduced infiltration
  
  
• Frostless heat pumps
  
  
• Matched components to combined efficiency
  
  
• Evaportively cooled condensers
  
  
• Improved aerodynamics (low watt per draw cfm) of the air handler/furnace and the outdoor a/c unit
  
  
• Higher SEER
  
  
• Combined space and water heating

Time, performance and costs ranked as the top barriers to optimal system design.