Use clear bulbs in fully shielded fixtures or when the fixture lens is diffuse or translucent. We use 4100 hours as typical of the annual operating time of a street light or any other fixture controlled by a photosensor that comes on at dusk and goes off at dawn. A sampling of several cities indicates that 4100 hours is typical of the hours that their street lighting system is operating each year. The U.S.A. national average for electrical utility rates is close to 8 cents per kilowatt-hour. One can and should use a rate that is representative of local utility rates.
Any spreadsheet program makes such comparisons easy.
One should allow for future rate changes, which are most generally upwards. Kilowatts measure power. A kilowatt is 1000 watts. A KWH is one kilowatt of power used for a duration of one hour. Initial lumens is a measure of how much light the lamp is emitting near the beginning of its life.