§ 801-a. Application to certain garden-type maisonette dwelling projects. For purposes of this article an existing multiple dwelling shall be deemed to include any garden-type maisonette dwelling project consisting of a series of dwelling units which together and in their aggregate were arranged or designed to provide three or more apartments and are provided as a group collectively with all essential services such as, but not limited to, water supply, house sewers and heat, and which are in existence and operated as a unit under single ownership on the date upon which an application for a loan pursuant to this article is received by the municipality, notwithstanding that certificates of occupancy were issued for portions thereof as private dwellings.