Split between demand-side and supply-side heating/cooling ECM savings impacts may be too conservative

[jtlangevin]

In the case where demand-side and supply-side ECM markets overlap (e.g., when there are envelope ECMs and heating/cooling equipment ECMs), ECM markets and savings are split evenly between the overlapping ECMs.

This may be a conservative assumption, as presumably the performance impacts of the demand-side and supply-side ECMs would be multiplicative to some degree (e.g., a 40% envelope improvement and 30% equipment improvement could collectively make a 58% improvement (1-(1-0.4)*(1-0.3))*100, rather than a 35% improvement ((1/2)*0.4 + (1/2)*0.3)*100, as would be simulated under the current approach).