solutions with certain values of NPC, CO2 emission, and RER.
Evidently, no single optimal solution can be made out since there
are three objective functions. In Figs.10-12, the 2D graphs of obtained
solutions spread over PF are depicted. These plots can help
decision makers to select an appropriate solution based on their
priorities. Four solutions are selected over the PF and the component
sizes of these selected solutions are shown in Table 8. These
results show that CO2 emission is reduced moderately (57%) by
increasing RER to 66.9% where the NPC is also increased moderately
(51%). When RER is set at 100%, in order to reduce CO2 emission by
2.4 ton/year, NPC at least must be increased to C$705,180. In this
way, the produced CO2 emission by the building energy system can
be reduced from 277.1 ton/year in the current system to less than 3
ton/year.
By increasing RER from 28.5% (solution 1) to 66.9% (solution 2),
CO2 emission is cut to 73.4 ton/year. Over this trend, NPC is