Appendix B 361
The post-retrofit demand is 16.0 kW for each of 10 months and
8.0 kW for each of July and August, bringing the total demand to 176
kW-mo.
Post-Retrofit Fuel Use
Fuel increases resulting from the lighting ECM are derived from
the electrical energy savings. The unadjusted electrical savings are 70,140
- 44,340 = 25,800 kWh per year. Assuming these savings are achieved
uniformly over a 10 month period, the typical winter month electrical
savings are 25,800/10 = 2,580 kWh/month. The associated boiler load
increase is 6% of these electrical savings for November through March,
namely:
= 6% × 2,580 kWh/mo × 5 months =774 kWh equivalent
Extra boiler input energy is:
= 774 kWh * 79% =980 kWh equivalent units of fuel
= 3,344,000 Btu or 3,000 ft^3 (84.95 m^3 ) of natural gas
Therefore total post-retrofit fuel use is estimated to be 2,940 + 3 = 2,943
× 103 ft^3 (83.34 10^3 m^3 ).
Routine Adjustments
Routine adjustments are needed to bring baseyear energy use to
the conditions of the stipulated post-retrofit period.
By applying the 28.8 kW baseyear electrical load to the stipulated
post-retrofit load/duration data, the routine adjustment for the longer
operating hours is derived, as shown at the top of the following page.
No adjustments are needed to electric demand since the increase
in operating hours occurs during the school sessions, therefore not in-
creasing demand.
Though adjustments are appropriate for associated fuel use, they
would be trivial so are ignored.
Savings
From Equation 1, the energy savings for the first year after ECM
installation are determined at shown in the center of the following
page.