a. Service of any order of the department or board shall be deemed sufficient if made:
1. Upon a principal person interested in the business, property, matter or thing, or the nuisance or abuse to which such order relates; or
2. Upon a principal officer charged with a duty in relation thereto; or
3. Upon a person, officer or department, or an officer or employee of such a department, who may be most interested in or affected by its execution.
b. If such order relate to any building or the drainage, sewerage, cleaning, purification or ventilation thereof, or of any lot or ground on or in which such building stands, used for or intended to be rented as the residence or lodging place of several persons or as a multiple dwelling, service of such order on the agent of any person or persons for the renting or for the collecting of rent thereof, or of the parts thereof to which such order may relate, shall be of the same effect and validity as due service made upon the principal of such agent or upon the owners, lessees, tenants or occupants of such buildings, or parts thereof, or of the subject matter to which such order relates.