The Commissioner of Energy and Environmental Protection shall establish a program to provide rebates to eligible state residents for repairing or upgrading their existing boilers and furnaces to achieve greater heating efficiency. Eligibility for rebates pursuant to this section shall be determined using eligibility criteria established for rebates pursuant to subsection (a) of section 16a-46e. Persons may apply to the commissioner, on a form prescribed by the commissioner, to receive such rebate for furnace or boiler repairs or upgrades made on or after August 1, 2008. The rebate shall be available only for residential structures containing not more than four dwelling units. No rebate shall exceed five hundred dollars, nor shall a rebate equal more than fifty per cent of the cost of the repair or upgrade.