It shall be the duty of every person owning or controlling the heating plant which furnishes heat to any factory, workshop, retail business, or other commercial establishment, to maintain a temperature when workers are present within such factory or workshop of not less than sixty five degrees Fahrenheit without such undue restriction of ventilation so as to interfere with proper sanitary conditions therein; provided, however, that this
requirement shall not apply to any factory or workshop where the business conducted therein is of such a nature that a lower temperature than sixty five degrees Fahrenheit is necessary or expedient for work or manufacturing process of such business.