The following shall be exempt from this act:
(1) Any building which has a peak design rate of energy usage for all purposes of less than one watt, or three and four-tenths British Thermal Units per hour, per square foot of floor area.
(2) Any building which is neither heated nor cooled.
(3) Any building or portion thereof which is owned by the United States of America.
(4) Any mobile home as defined by section 71-4603, Reissue Revised Statutes of Nebraska, 1943.
(5) Any manufactured housing unit as defined by subsection (1) of section 71-1557, Reissue Revised Statutes of Nebraska, 1943.
(6) Any building listed on the National Register of Historic Places.
(7) All residential buildings shall be exempt from lighting efficiency standards.