To determine the amount of available residential energy efficiency, the Council closely examines the number of homes in the region, by home type, size of the dwelling, current heating and cooling technology, lighting and appliance saturation, and fuel types used.

There are about 6.2 million homes in the region, 70 percent of which are single-family dwellings (one to four units), 22 percent are in multifamily buildings (5 units or more), and the remainder are manufactured homes. Manufactured homes are dwellings regulated by the US Department of Housing and Urban Development (HUD) construction and safety standards (USC Title 42, Chapter 70).[1] Within the multifamily sector, the analysis is divided into low-rise buildings (one to 3 stories) and medium/high-rise buildings (4 stories and above). For medium and high-rise buildings, the residential assessment only includes in-unit potential (i.e. this assessment excludes improvements in building shell, common-area lighting, building-area HVAC or water heating systems, or other common areas potential).

The 2021 Power Plan estimates a total achievable technical potential of 2,441 average megawatts across the residential sector, about 1,467 average megawatts of which is less than $100 per megawatt-hour.[2] The total potential represents about 27 percent of the projected 2041 residential sector load. In addition to providing energy savings, efficiency measures also provide peak savings. The residential potential translates to around 5,100 megawatts of winter peak impact and 5,000 megawatts of summer peak impact. [3]

Nearly half of the residential sector achievable technical potential is from HVAC (shell improvements and efficient equipment); however, about 40 percent of this potential is at a cost of more than $200 per megawatt-hour. Water heating (heat pump water heaters, water-savings devices, wastewater heat recovery, efficient dishwashers, clothes washers, circulator pumps) is the next largest end use and comprises 31 percent of the total potential. Appliances (efficient refrigerators, dryers, air cleaners, ovens, microwaves, well pumps at 16 percent), electronics (efficient computers, monitors, TVs, advanced power strips, at 5 percent), lighting (LED bulbs and integral fixtures at 4 percent), and whole building measures (electric vehicle supply equipment and behavior-based efficiency at 1 percent) round out the remainder. At less than $100 per megawatt-hour, water heating becomes the majority (40 percent of the total), followed by appliances (25 percent) and HVAC (22 percent). The residential supply curve by end use is provided in figure below.

Residential Energy Efficiency Supply Curve

[1] Modular homes, which are regulated by state codes, are considered single family dwellings.

[2] $100/MWh is simply used as an illustrative cut-off and is not intended to imply cost effectiveness.

[3] As estimated by impact during 6pm on a winter or summer weekday.