Except as provided in this section, new construction or substantial renovation of any commercial building undertaken after January 1, 2004 must conform to ASHRAE Standard 62-2001 and either ASHRAE Standard 90.1-2001 or the 2003 edition of the International Energy Conservation Code published by the International Code Council under any of the compliance methods specified in the standards. For the purpose of this section, "substantial renovation" means any renovation for which the cost exceeds 50% of the building's current value prior to renovation. [2005, c. 350, §9 (AMD).]