What are specific Cost-Effective Energy Savings Measures for Multifamily

The approach to selecting energy savings measures is different for multifamily than other building types. Although there are opportunities (depending on the climate zone) to save space-conditioning energy, the shared wall geometry of dwelling units and reduced external surface area in multifamily buildings means that less heating and cooling energy is lost to the exterior. Therefore in multifamily buildings, less of the savings will come from building envelope and heating, ventilation and air conditioning (HVAC) measures, and more will come from water heating efficiency gains and appliances. The predominance of water heating as the primary energy use is exaggerated in coastal areas where there is little need for heating and cooling.

The single largest and most consistent opportunity in multifamily housing is reducing the energy consumed to heat domestic water, particularly when central systems are present. It is common for multifamily buildings to have central water heaters, typically gas appliances with a large distribution system and recirculation loop. Increasing the AFUE (Annual fuel utilization efficiency (AFUE) is a measure of the thermal efficiency of combustion appliances such as gas-fired boilers, water heaters and furnaces.) of the water heater, combining the water heater with solar pre-heat systems, and implementing distribution system strategies such as extra insulation, recirculation controls and high-efficiency recirculation pumps, represent significant opportunities for cost-effective savings. These savings are weighed against the limitations in hot water sub-metering of central systems.

There are many other ways in which multifamily savings opportunities diverge from single-family opportunities. For example:

  • Common area and garage lighting in multifamily properties can use significant amounts of energy.

 

  • There are operational efficiencies associated with ongoing equipment commissioning and professional energy management in multifamily properties.

 

  • Multifamily properties may have fairly extensive irrigation and lighting of the exterior landscape and site.

 

  • Multifamily buildings often have limited room for installation of photovoltaic arrays.

 

  • Compared to single-family homes, taller residential buildings have a smaller roof area relative to the overall building envelope area. As a result, measures such as attic insulation and radiant barriers will have less impact.

 

  • Air infiltration to the exterior is less of an issue with multifamily buildings than is heat and air transfer between dwelling units, and between dwelling units and common areas.

 

  • Multifamily properties often have common ventilation systems utilized to exhaust kitchens, bathrooms and laundry rooms. These can contribute substantially to energy use.

 

  • Cooking and refrigeration comprise a larger portion of the energy budget in multifamily homes.

 

  • Appliances in single-family homes are almost always owned by the occupant, whereas in multifamily, appliance ownership is less common.

 

  • Almost all single-family homes have a washer and dryer, while apartment buildings often have central laundry facilities or no on-premises laundry at all.

 

Each of these differences will impact energy efficiency decisions and need to be taken into account when designing retrofit programs and incentives and discussing ROI with multifamily property owners.

Share →

Leave a Reply