A hospital had 415 T12 fluorescent fixtures, which operate 24 hours/day, year round. The lamps and ballasts were replaced with T8 lamps and electronic ballasts, which saved about 30% of the energy, and provided higher quality light. Although the T8 lamps cost a little more (resulting in additional lamp replacement costs), the energy savings quickly recovered the expense. In addition, because the T8 system produces less heat, air conditioning requirements during summer months will be reduced. Conversely, heating requirements during winter months will be increased. The air conditioner COP = 2.6 and the A/C runs at full load 2000 hours/year. The heater efficiency is 80%, and the heater operates at full load 1500 hours per year. Fuel costs $4.00/MCF.

Estimate the simple payback period of relamping.