(1) The residential buildings, by reason of age, obsolescence, inadequate or outmoded design or physical deterioration have become economic and/or social liabilities.

(2) The residential buildings are substandard or unsanitary for healthful and safe living purposes.

(3) The residential buildings are overcrowded, poorly spaced, or are so lacking in light, space and air as to be conducive to unwholesome living.

(4) The residential buildings are faultily arranged, cover the land to an excessive extent or show a deleterious use of land, or exhibit any combination of the above which is detrimental to health, safety or welfare.

(5) A significant percentage of buildings used for residential purposes is more than 20 years of age.

(6) A substantial amount of unimproved, overgrown and unsightly vacant land exists which has remained so for a period of five years or more indicating a growing or total lack of utilization of land for residential purposes.

(7) A disproportionate number of tax exempt or delinquent properties exists in the area.

“Dwelling unit” means, unless otherwise defined in the ordinance or resolution providing for tax exemption, a house, double house or duplex, townhouse or row house, apartment, or any building intended for occupancy as living quarters by an individual, a family or families or other groups of persons, which living quarters contain a kitchen or cooking equipment for the exclusive use of the occupant or occupants.

“Municipal governing body” means a city, borough, incorporated town or township.

“Residential construction” means the building or erection of dwelling units, as defined above, upon vacant land or land specifically prepared to receive such structures.