(b)to any payment made under an agreement by any person to a landlord for the purpose of financing the construction of the whole or part of any premises on the land belonging to, or taken on lease by, the landlord if one of the conditions of the agreement is that the landlord should let to that person the whole or part of the premises when completed for the use of that person or any member of his family but not exceeding the amount of agreed rent for a period of five years, for the whole or part of the premises to be let to such person.