A counterclaim may be maintained for rent previously paid to a landlord, and a tenant's recovery is not limited to the rent demanded in the nonpayment proceeding (see Edgemont Corp. v Audet, 170 Misc 2d 1040 [App Term, 2d Dept, 9th and 10th Jud Dists 1996]; see also Alp Realty Corp. v Huttick, 160 Misc 2d 76 [App Term, 1st Dept 1994]). Here, despite tenant's counterclaim regarding landlord's alleged breach of the warranty of habitability since January 2017, when tenant attempted to introduce into evidence emails with landlord regarding repair issues from January and February 2017, the District Court refused to admit tenant's evidence. "Reversal of a judgment based upon the improper exclusion of evidence is warranted when, had such evidence been admitted, it may have had a substantial influence upon the result of the trial" (Platovsky v City of New York, 275 AD2d 699, 700 [2000]).

The District Court also failed to make any findings with respect to tenant's counterclaims, including landlord's alleged breach of the warranty of habitability. "[A] deprivation of light, air and ventilation constitutes a breach of the warranty of habitability" (Edgemont, 170 Misc 2d at 1042; see Sutton Fifty-Six Co. v Garrison, 93 AD2d 720 [1983]). Tenant alleged that five of the seven windows in the premises could not be opened. We note that, despite the District Court's statements to the effect that expert testimony was required to evaluate the repairs that were allegedly necessary, Real Property Law § 235-b provides, in pertinent part, "In determining the amount of damages sustained by a tenant as a result of a breach of the warranty [of habitability], the court . . . need not require expert testimony."