(a) To achieve energy conservation in single-family residential construction, the energy efficiency chapter of the International Residential Code, as it existed on May 1, 2001, is adopted as the energy code in this state for single-family residential construction. On September 1, 2016, the energy efficiency chapter of the International Residential Code, as it existed on May 1, 2015, is adopted as the energy code in this state for single-family residential construction. On or after September 1, 2021, the State Energy Conservation Office may adopt and substitute for that energy code the latest published edition of the energy efficiency chapter of the International Residential Code, based on written findings on the stringency of the chapter submitted by the laboratory under Subsection (b-3). The office:
(1) may not adopt an edition under this subsection more often than once every six years; and
(2) by rule shall establish an effective date for an adopted edition that is not earlier than nine months after the date of adoption.
(b) To achieve energy conservation in all other residential, commercial, and industrial construction, the International Energy Conservation Code as it existed on May 1, 2001, is adopted as the energy code for use in this state for all other residential, commercial, and industrial construction. The State Energy Conservation Office may adopt and substitute for that energy code the latest published edition of the International Energy Conservation Code, based on written findings on the stringency of the edition submitted by the laboratory under Subsection (b-3). The office by rule shall establish an effective date for an adopted edition that is not earlier than nine months after the date of adoption.

(b-2) The State Energy Conservation Office by rule shall establish a procedure for persons who have an interest in the adoption of energy codes under Subsection (a) or (b) to have an opportunity to comment on the codes under consideration. The office shall consider persons who have an interest in adoption of those codes to include:
(1) commercial and residential builders, architects, and engineers;
(2) municipal, county, and other local government authorities;
(3) environmental groups; and
(4) manufacturers of building materials and products.
(b-3) The laboratory shall:
(1) submit to the State Energy Conservation Office written findings on the stringency of the latest published edition of the International Residential Code energy efficiency provisions only if the date of the edition allows the office to adopt the edition under Subsection (a)(1);
(2) submit to the State Energy Conservation Office written findings on the stringency of the latest published edition of the International Energy Conservation Code not later than six months after publication of a new edition; and
(3) in developing the findings, consider the comments submitted under Subsection (b-2).
(c) A municipality shall establish procedures:
(1) for the administration and enforcement of the codes;
(2) to ensure that code-certified inspectors shall perform inspections and enforce the code in the inspectors’ jurisdictions; and
(3) to track and report to the state energy conservation office on implementation of the codes.
(d) A municipality may establish procedures to adopt local amendments to the International Energy Conservation Code and the energy efficiency chapter of the International Residential Code. Notwithstanding the requirements of Subsection (e), a municipality located in an area defined by § 388.002(11) or in an affected county may establish procedures to adopt local amendments to the Energy Rating Index Compliance Alternative or subsequent alternative compliance path as described by Subsection (j).
(e) Local amendments may not result in less stringent energy efficiency requirements in nonattainment areas and in affected counties than the energy efficiency chapter of the International Residential Code or International Energy Conservation Code. Local amendments must comply with the National Appliance Energy Conservation Act of 1987 (42 U.S.C. Sections 6291-6309), as amended. The laboratory, at the request of a municipality or county, shall determine the relative impact of proposed local amendments to an energy code, including whether proposed amendments are substantially equal to or less stringent than the unamended code. For the purpose of establishing uniform requirements throughout a region, and on request of a council of governments, a county, or a municipality, the laboratory may recommend a climatically appropriate modification or a climate zone designation for a county or group of counties that is different from the climate zone designation in the unamended code. The laboratory shall:
(1) report its findings to the council, county, or municipality, including an estimate of any energy savings potential above the unamended code from local amendments; and
(2) annually submit a report to the commission:
(A) identifying the municipalities and counties whose codes are more stringent than the unamended code, and whose codes are equally stringent or less stringent than the unamended code; and
(B) quantifying energy savings and emissions reductions from this program for consideration in the state implementation plan for emissions reduction credit.
(f) Each municipality, and each county that has established procedures under Subsection (d), shall periodically review and consider revisions made by the International Code Council to the International Energy Conservation Code and the energy efficiency chapter of the International Residential Code adopted after May 1, 2001.
(g) The laboratory shall have the authority to set and collect fees to perform certain tasks in support of the requirements in Sections 388.004, 388.007, and 388.008.
(h) Within the boundaries of an airport operated by a joint board created under Subchapter D, Chapter 22, Transportation Code, the constituent agencies of which are populous home-rule municipalities, the powers of a municipality under this section are exclusively the powers of the joint board.
(i) A building certified by a national, state, or local accredited energy efficiency program and determined by the laboratory to be in compliance with the energy efficiency requirements of this section may, at the option of the municipality, be considered in compliance. The United States Environmental Protection Agency’s Energy Star Program certification of energy code equivalency shall be considered in compliance. A home energy rating system index utilizing Standard 301 of the American National Standard for the Calculation and Labeling of the Energy Performance of Dwelling and Sleeping Units using an Energy Rating Index, commonly cited as ANSI/RESNET/ICC 301, as it existed on January 1, 2021, as described by Subsection (j) shall be considered in compliance provided that:
(1) the building meets the mandatory requirements of Section R406.2 of the 2018 International Energy Conservation Code; and
(2) the building thermal envelope is equal to or greater than the levels of efficiency and solar heat gain coefficient in Table R402.1.2 or Table R402.1.4 of the 2018 International Energy Conservation Code.
(j) For the purposes of this chapter, Standard 301 of the American National Standard for the Calculation and Labeling of the Energy Performance of Dwelling and Sleeping Units using an Energy Rating Index, commonly cited as ANSI/RESNET/ICC 301, as it existed on January 1, 2021, used to measure compliance for single-family residential construction that uses an energy rating index is as follows:
(1) for climate zone 2, an energy rating index of:
(A) 63 or lower from September 1, 2019, to August 31, 2022;
(B) 59 or lower on or after September 1, 2022;
(C) 57 or lower on or after September 1, 2025; and
(D) 55 or lower on or after September 1, 2028;
(2) for climate zone 3, an energy rating index of:
(A) 63 or lower from September 1, 2019, to August 31, 2022;
(B) 59 or lower on or after September 1, 2022;
(C) 57 or lower on or after September 1, 2025; and
(D) 55 or lower on or after September 1, 2028; and
(3) for climate zone 4, an energy rating index of:
(A) 67 or lower from September 1, 2019, to August 31, 2022;
(B) 63 or lower on or after September 1, 2022;
(C) 61 or lower on or after September 1, 2025; and
(D) 59 or lower on or after September 1, 2028.
(k) This subsection and Subsection (j) expire September 1, 2031.

For expiration of Subsections (j) and (k), see Subsection (k).
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