Chapter 10 Overview

An energy management system (EMS) allows for centralized monitoring and control of energy use across building systems. The upgrades to controls for lighting, office equipment, HVAC and water that have been described in previous chapters all constitute “stand-alone” control systems (e.g., photosensor-based dimming controls for lighting); an EMS is a “central” control system, allowing facilities managers to operate
all stand-alone control systems in a building simultaneously from a single control pad or web application. Sensors throughout the building that measure conditions such as light level, indoor/outdoor temperature and water temperature (called “monitoring points”) serve as data inputs for the EMS, which uses that information to adjust control components (called “control points”) such as dimmers, chillers and boilers. When a new EMS is installed, it can be configured to work with most existing sensors and controls, and to any new monitoring points and control points that are added.

In recent years, EMS technologies have become more affordable and widely used. According to the California Energy Commission, vendors estimate that energy management systems are currently installed in 75% of commercial facilities with over 50,000 square feet of office space.1

Building Management Systems (BMS) and Building Automation Systems (BAS)

Facilities managers and energy engineers may also refer to building management systems (BMS) or building automation systems (BAS). The distinction between these terms and EMS often depends on context or the preferred terminology of a given manufacturer, and can be confusing.

A BMS or BAS typically includes automated controls for a range of building systems: HVAC, security, fire alarms, sprinklers, etc. The term EMS is usually used to refer to an automated system specifically engineered to manage energy use, which usually employs additional and more sophisticated energy monitoring and control technologies than a BMS or BAS. However, some systems referred to as EMS can be configured to control other building functions in addition to energy management. Conversely, some BMS or BAS are designed to include sophisticated energy
management technologies. As a result, the terms BMS, BAS and EMS refer to an overlapping range of system types and are often used interchangeably.

Energy Information Systems (EIS)

Most EMS have the capability to record and track the real-time energy usage of a building or floor, and to store that information for later analysis. Increasingly though, energy information systems (EIS) are being used to supplement the energy monitoring and tracking of EMS with functions including weather information, pricing structures and more sophisticated real-time energy usage data. An EIS can enable a company to further reduce energy costs by integrating factors such as weather and energy prices into energy management decision making. An EIS also enables companies to participate in utility load curtailment programs, where utilities incentivize end users to reduce energy consumption during periods of peak demand.

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