(a) Every district furnishing light, heat, or power shall expend no funds for advertising when such advertising encourages increased consumption of such services or commodities.
(b) Nothing in this section shall prohibit a district furnishing light, heat, or power from expending funds for advertising which encourages the more efficient operation of the facilities, works, or utilities of the district, or for advertising which encourages the more efficient use of light, heat, or power, the conservation of energy or natural resources, or presents accurate information on the economical purchase, maintenance, or use of any appliance or device using light, heat, or power.