This is the least expensive and most energy-conserving type of lighting to use in the long run (considering both purchase price and cost of energy.)
(This; is; the least expensive and most energy-conserving type of lighting to use in the long run () (the least expensive and most energy-conserving type of lighting; to use; T:in the long run)
This the least expensive and most energy-conserving type of lighting
is to use
the least expensive and most energy-conserving type of lighting to use in the long run (
T:in the long run