(a) By January 1, 2021, the commission, in consultation with the Public Utilities Commission, the State Air Resources Board, and the Independent System Operator, shall assess the potential for the state to reduce the emissions of greenhouse gases in the state’s residential and commercial building stock by at least 40 percent below 1990 levels by January 1, 2030. The assessment shall include consideration of all of the following:

1. (1) An evaluation, based on the best available data and existing analyses, of the cost per metric ton of carbon dioxide equivalent of the potential reduction from residential and commercial building stock relative to other statewide greenhouse gas emissions reduction strategies.
2. (2) The cost-effectiveness of strategies to reduce emissions of greenhouse gases from space heating and water heating in both new and existing residential and commercial buildings.
3. (3) The challenges associated with reducing emissions of greenhouse gases from low-income housing, multifamily housing, and high-rise buildings.
4. (4) Load management strategies to optimize building energy use in a manner that reduces the emissions of greenhouse gases.

5. (5) The potential impacts of emission reduction strategies on ratepayers, construction costs, and grid reliability. In assessing the impact on grid reliability, the commission shall account for both of the following:

   1. (A) The commission’s 2019 Building Energy Efficiency Standards, effective January 1, 2020, that propose to require solar energy systems on all new single-family and low-rise residential dwellings.
   2. (B) The increased load and impact on electrical infrastructure due to transportation electrification.

(b)

1. (1) By June 1, 2021, the commission, pursuant to Section 9795 of the Government Code, shall report to the Legislature the findings from the assessment.
2. (2) Pursuant to Section 10231.5 of the Government Code, this subdivision is inoperative on June 1, 2026.