Appendix B 365
Post-Retrofit Energy Use
After installation and commissioning of the ECM, three separate
weekly test periods were found with an average ambient temperature
between 20°F (– 6.7°C) to 24°F (– 4.4°C) and normal occupancy. The
efficiency results over the three one week periods were 81%, 79% and
80%, averaging 80%.
The post-retrofit annual energy use for Equation 1 is determined
from the baseyear use to be:
Baseyear Condition + Correction to Post-retrofit condition
35,200 × 0.65
= —————— + C
0.80
= (26,410 + C) 10^3 ft^3 ([750 + C] 10^3 m^3 )
C is an unknown quantity needed to convert baseyear projected use of
the new boiler to post-retrofit conditions.
Routine Adjustments
Routine adjustments are needed to bring post-retrofit energy use
to the conditions of the baseyear. This is exactly the correction amount
C million ft^3 (m^3 ).
Savings
From Equation 1, energy savings are determined to be:
————————————————————————————————
Baseyear — Post-Retrofit + Adjustment = Savings
————————————————————————————————
Gas 35,200 — (26,410 + C) + C = 8,790 × 103 ft^3
(248.9 10^3 m^3 )
————————————————————————————————
Note that in this example the savings reported are for operations under
baseyear conditions.
Option C Example: Whole Building Multiple ECM Project
Situation
An energy efficiency project was implemented in a high school,
involving six ECMs spanning lighting, HVAC, pool heating and opera-