On July 29, 2009, Gov. Jack Markell signed SB 59 which mandated the adoption and enforcement of the most recent versions the model energy codes, the 2009 IECC and ASHRAE Standard 90.1-2007. COMcheck and REScheck software (and ENERGY STAR software as an alternative) may be used to demonstrate compliance. Subsequent versions of the two model energy codes would be reviewed for updates every three years. The bill also directs the Delaware Energy Office to establish a program for zero net energy capable buildings, with the goal of all new residential construction being net zero capable by December 31, 2025 and all new commercial construction being net zero capable by December 31, 2030. The legislation became effective July 1, 2010.