Evaluating Independent versus Interdependent ECMs

The ECMs to be bundled might be independent. For example, the bundling of an HVAC replacement in one building with a chiller replacement in another building of a facility combines two independent measures into one project. Only one measure, let's say the HVAC system, meets the LCC criterion for implementation. When combined, the project as a whole is still life-cycle cost effective compared with the base case of doing nothing, but Net Savings will not be maximized.

When ECMs are interdependent, as for example an HVAC system and a lighting system in the same building, their energy usage is analyzed simultaneously to properly account for the interaction among the systems. If bundled with a third system, for example, an improvement in the thermal integrity of the overall building envelope, a whole-building energy analysis is required to estimate the energy usage of this new combination. The LCCA result of this new combination, if cost-effective, will maximize Net Savings.