N.Y. Real Prop. Tax Law § 487-a

§ 487-a. Exemption from taxation of conservation improvements to\ncertain residential premises. Insulation and other energy conservation\nmeasures hereafter added to one, two, three or four family homes, which\nqualify for (a) financing under a home conservation plan pursuant to\narticle VII-A of the public service law, or (b) any conservation related\nstate or federal tax credit or deduction heretofore or hereafter\nenacted, shall be exempt from real property taxation and special ad\nvalorem levies to the extent of any increase in value of such homes by\nreason of such addition.\n