Project Example: Space-Heating/Cooling Equipment Replacement

You are planning to replace 30-year old gas furnaces and wall-mounted air-conditioners in your multifamily apartment building in Maryland. One of the requirements of funding is that the equipment must be ENERGY STAR labeled. You are trying to decide between a 95-percent efficient furnace and an ENERGY STAR window-mounted air-conditioner or a dual-fuel heat pump that provides central cooling in the summer and heats via a heat pump in winter until outdoor temperatures fall below about 40 ^oF when it then cycles into gas mode. If you replace the thermostat, the code official will likely require a programmable thermostat.

Because the furnace/air-conditioner combination maintains the same basic type of equipment, you feel comfortable that it will perform well with greater efficiency than what currently exists, that it will be reasonably familiar to your maintenance staff and residents because it does not deviate significantly from the operational elements they are accustomed to, and that it is likely to be at least as reliable and long lived as the existing equipment was.

From what you have read, however, the dual-fuel equipment has some compelling advantages, such as reduced operating costs because of partial winter heating in heat pump mode plus greater comfort in the summer because of central cooling. In addition, the maintenance staff will not have to remove and replace window air-conditioners each spring and fall. Yet, given the senior occupants, you are concerned that they may not “feel” warm enough under winter heat pump operation and they may not use the new programmable thermostats correctly. This scenario could significantly affect the anticipated energy and operating cost savings. How to decide—

• Look for examples of dual-fuel heat pumps in your area and installations where seniors live.
• Talk with your HVAC contractor about his experience with the equipment and whether he has encountered any issues.
• Consult with your maintenance personnel asking them to review literature and specs and provide their input.
• Consult with your code official about his experience with the equipment.
• Can you implement other efficiency measures to ensure comfort, such as—
  
  • Air sealing?
  • Seal ductwork?
  • Replacement windows?
  • Increase insulation levels?
• What type of training can you provide to bring residents up to speed on use of new thermostats and tips on achieving both comfort and energy efficiency?
• What type of routine checks or inspections can you put in place to ensure proper operation?
• Implement a pilot whereby the equipment and programmable thermostats are installed in a subset of apartments to help gauge appropriateness.
• Perform an economic analysis to compare the two alternatives.