Caveat Emptor – the infamous Latin phrase meaning “Let the buyer beware”, places the burden of making sound decisions squarely on the purchaser. Knowing what you’re buying is especially important when considering an energy management system (EMS). Buying an EMS is a significant cost for most facilities. Market actors cutting checks (customers or programs) need to be aware of what they are getting for their money so satisfaction with the purchased systems remains high over the long term.
A primary benefit of EMS installations is the potential for energy and demand savings. Significant savings can result from adding scheduling and sequence capabilities. Plenty of opportunities exist for additional functionality as well. A new EMS can add control points for previously unmonitored equipment. Advanced control logic can tie different systems together to improve combined performance.
However, these benefits are entirely dependent on what happened prior to installing the EMS. Using a shiny, new, digital EMS to control equipment in the same manner as a dusty, old, pneumatic control system doesn’t save energy. Period. Control systems save energy by altering the run time, optimally loading equipment, or sequencing to avoid things like simultaneous heating and cooling, which is all too common. Customers who want to save energy need to make sure the new EMS is making schedule changes, implementing different set-points, or adding control functionality such as temperature reset. Utility program managers also need to be aware of this and set requirements or inquire with customers accordingly to avoid “incentivizing” no energy savings.
One of the most impactful non-energy benefits of a new EMS can be the improved visibility into how systems are functioning. The ability of an EMS to centralize readouts, display current operations, and trend data over short periods of time can be useful for building operators. Notifications and alerts can help head off problems before they get noticed by tenants or affect equipment. In many cases, the real time information displayed by an EMS is well worth the cost for the customer, even though this function may generate little energy savings by itself.
While system monitoring provides a substantial non-energy benefit, programs need to be aware that EMS projects save energy only when controls changes are made. Adding program requirements that require schedule adjustments, or adding control functionality, can help push customers to make energy saving decisions.
Building controls programs sometimes include prescriptive incentives based on non-energy parameters such as building square footage. However, as described, there is no correlation between savings and system replacement. The savings may be completely arbitrary, and even negative, if the replaced system did not allow enough ventilation or provided poor temperature and humidity control. The wide range of savings, from negative to hugely positive, make EMS projects prime candidates for custom efficiency programs.