What is a building energy management system (BEMS)?

Through the combined use of sensors, smart meters and automation, a company’s BEMS network generates energy savings and added benefits. The BEMS is a computer-based system that monitors and controls a building’s mechanical and electrical equipment—things like HVAC, lighting, power, fire systems and security.

Specifically, a BEMS performs the following core functions:

• Comprehensively monitors how much energy a building uses in real time
• Tracks a building’s energy performance through the collection of key metrics, finding inefficiencies and reducing waste
• Automates and administers tasks related to heating and cooling, lighting and other systems
• Generates compliance reports for energy auditing and emissions compliance

Upon implementing a building energy management system (BEMS), sensors and meters throughout a building feed data into a central software platform. Facility managers can set rules, schedules and thresholds—the system then operates equipment automatically or alerts staff when something falls outside normal parameters.

Drilling down, a BEMS executes its work through four steps:

1. Data collection: First, a BEMS gathers information from sensors, smart meters (that provide total utility usage data to service providers) and submeters (that measure specific information for departments within that building). This data covers a range of measurements, such as power consumption, temperature, humidity and carbon dioxide levels. 
2. Trend analysis: Energy management software then reviews data collected through real-time monitoring and checks how usage compares with historical data and benchmarks for peak performance. 
3. Decision making: Next, various algorithms go to work, studying the building’s operating needs and using artificial intelligence (AI) to calculate an energy-efficient way to keep the building’s various subsystems (like HVAC and lighting) working as wanted without creating energy waste in the process.
4. Action: Finally, the BEMS takes corrective action based on its analysis of relevant incoming data and the best course of action prescribed by algorithms. 

These steps occur silently and automatically. Suddenly, the office that was getting a touch drafty is now a degree or two warmer, and no employee had to lift a finger to adjust the thermostat. 

But how do these various equipment systems—all made by different manufacturers—communicate with each other? That’s where the BACnet (Building automation and control network) comes into play. BACnet is a global data communications standard for building automation and control networks. It serves as a common-language protocol in BEMS functionality, letting different brands and types of machinery “speak” to each other. 

The benefits a company can realize by using a BEMS can be quite lucrative—in terms of money, government compliance and added company prestige:

• Cost savings: The US Dept. of Energy has estimated that energy costs can be reduced by 30% through careful energy management and the adoption of facility sustainability initiatives.
• Compliant reporting: A BEMS upholds regulatory compliance by generating greenhouse gas (GHG) accounting reports, carbon compliance reports and green certification reports.
• Operational visibility: By using of dashboards, a BEMS offers a helpful, multiperspective view into exactly how the company is using energy.
• Equipment protection: By using a BEMS, a company can prolong the life of its heating and cooling equipment with advanced diagnostics and predictive maintenance.
• Public relations: When a company can demonstrate its support of energy conservation, the company gets to represent itself as a responsible corporate citizen worthy of the public’s trust. 

While there’s much to be gained by companies adapting BEMS, the process also involves some sizable investments and more than a few hurdles to clear: 

• Upfront costs: Companies face some initial capital expenditures when implementing a BEMS and these investments can be steep, such as the cost of sensors and smart meters.
• Complicated integration: Often, a modern BEMS is mated with HVAC or lighting equipment from older legacy systems, and the combination often requires hardware retrofitting and software upgrades.
• Security issues: Many companies are choosing to operate their BEMS in cloud environments, which makes them more susceptible to data breaches and cyberattacks.
• Staff participation: System underutilization can occur when a facility’s staff members lack sufficient experience with a newly installed BEMS.
• Return on investment: A BEMS is a smart investment for a company to make, but it typically doesn’t pay off quickly. Building owners might have to wait years before realizing a significant ROI.

A BEMS begins with the incorporation of a building management system (BMS), which uses a computer-based control system to track the electrical, mechanical and security equipment of commercial buildings. All of these monitored functions—like HVAC, lighting and security gear—feed into a dashboard, where users can follow them all at a single glance. The use of control systems promotes reduced energy consumption, while dashboards help increase operational efficiency.

While the BMS is able to do many things mechanically, it does have limits. For example, the BMS is not really built for higher-level thought. For that you need a BEMS, which takes all the gathered information and applies complex algorithms in order to analyze utility and sensor data and extrapolate ways to reduce energy costs. 

A BEMS also leverages the power of energy management software (EMS), which keeps constant check on energy consumption through real-time energy monitoring of energy-intensive activities. An EMS supports the benchmarking of facility performance and the establishment of baseline performance standards. It also streamlines tracking for environmental, social and governance (ESG) reporting.

In this way, business energy management systems serve in a watchdog capacity. Through automation and constant monitoring of energy sources, they stand ready to alert facility managers when a BEMS begins detecting anomalous behavior within energy consumption patterns. Through the application of diagnostics to energy data, the BEMS can locate inefficiencies and eliminate wasted energy. From an operational standpoint, the use of real-time data helps encourage the making of more informed decisions.

The average US office building consumes around 22.5 kWh of power per square foot each year. Here are the various ways that a typical office building uses energy, which can be broken down into five general building operations:

• Cooling and heating: Cooling and heating usually represent the largest share of an office building’s energy operating costs (30–40%), depending on building size and staff occupancy.
• Ventilation and air handling: Supersized ventilation fans and other HVAC system equipment deliver heating and air conditioning throughout the building, which accounts for 10–20% of the building’s energy costs. 
• Lighting: Another segment of essential equipment involves the facility’s installed lighting, an expense that occupies 10–15% of a building’s energy budget.
• Additional operating expenses: Approximately 5–10% of energy costs is related to miscellaneous energy expenses posed by elevators, restroom fixtures, water heaters and some auxiliary equipment. 
• Appliance outlets: Between 15–30% of a building’s energy needs are for everything that might be plugged into wall outlets within an office. These appliances include personal computing equipment, lamps, office “amenities” (for example, vending machines, coffee makers and microwave ovens), and power for Internet of Things (IoT) devices. 

Forward-thinking companies and stakeholders who want to lessen their carbon footprint and elevate their energy conservation efforts to the next level are currently taking advantage of the opportunities presented by renewable energy.

Many companies optimize those opportunities by designing and constructing smart buildings that take advantage of sustainability principles. Meanwhile, existing offices can be retrofitted with collectors of renewable energy, such as solar panels. The power those panels generate can be efficiently routed into battery storage, which can be summoned forth and used during later periods to supplant expensive grid hours.

Businesses keen on learning how they use energy now and how they can approach energy use more strategically moving forward have tools available to them for just that purpose. One is called the Constellation Business Utility Estimation Guide while another, the Energy Elephant Energy Budgeting Resource, helps companies improve building performance, set achievable sustainability goals and establish systems that will exhibit optimal scalability as their business endures and thrives.