Building Automation Systems and Sustainability

A building automation system’s (BAS) core functionality keeps a building climate within a specified range, provides lighting based on an occupancy schedule and monitors system performance and device failures while notifying designated building staff. Since the BAS is a crucial component of a building, it is also a crucial component of a building’s sustainability.

The Benefits
A building automation system (BAS) performs a lot of functions that save time by operating equipment from a central command.

“It allows the owner or occupant to have centralized control, and it orchestrates building-related systems to work together to save energy,” says Carlos Petty, vice president of Syska Hennessy Group, an engineering company headquartered in New York City.

Angela Lewis, member of the International Facility Management Association’s (IFMA) IT Council and part-time facility maintenance consultant, says that the most common use of a BAS is to control mechanical equipment within a building. This can include, but is not limited to chillers, boilers, pumps and air handling units. The BAS helps control the temperature of a building by varying air, water, and in some cases steam flow through the mechanical equipment within a building. The BAS can also be used to schedule equipment—to tell equipment when it should be on/off, making sure it only operates when the building is occupied.

Because the use of equipment is normally based on occupancy, Petty says the biggest benefit of a BAS is that it achieves energy conservation without sacrificing comfort, such as in the case of air-conditioning, where a BAS can automatically provide air-conditioning to different building areas based on time-of-day schedules or occupancy.

“When the BAS uses a Demand Control Ventilation (DCV) software application program, HVAC equipment will automatically provide the required ventilation based on CO2 occupancy sensors," Petty says. "If only 50 people are in the room versus 200, the BAS provides the appropriate amount of ventilation, thereby saving energy.”

The potential
Although a BAS provides a great deal of benefits to facility managers in terms of energy conservation, it can provide even more than what is initially realized. Lewis says that its ability to “trend” energy is under-utilized but can be tremendously helpful and effective. She says most have the capability to track where energy is used, calculate where it might be overused and then subsequently lower output.

“If you can measure your building’s energy use, you can manage it,” she says.

However, Lewis mentions that the trending function requires the installation of sensors and meters. Then, for example, by measuring chilled water flow and energy consumption from pumps, chillers and cooling tower fans, a facility manager can learn how to air-condition a building efficiently. She points out that many facility managers don’t get the full use out of their BASes because a control engineer is not typically involved in the design and planning process, and it is much cheaper to install sensors during construction than in a building already in operation.

Although the capital cost might be higher at installation, Lewis says lifecycle costs will be lower, and can lead to long-term savings. She mentions that many buildings after LEED certification are installing sensors and meters. However, she says that when deciding to install, there is no need to “go crazy and meter everything.”

“Think about where the major energy consumers are,” she says, “and where the payback has the most potential to be economical. It’s about personal choices.”

For example, she says if you are planning to quantify the building energy consumption for a laboratory, a good starting point is to quantify the energy consumed by the ventilation system. Labs are high-energy consumers because of the 100 percent outdoor air requirements to ventilate them. Measuring energy consumption from plug loads (outlets) would not be a good starting point, as many outlets are not regularly used.

The future
Petty says that BAS technology has come “a long, long, long way” because it adheres to the IT world where there are constant advancements in telecommunications-related technologies, such as Power Over Ethernet (PoE)

“It’s grown with the advent of personal computers,” he says. “They use a lot of Web access techniques to communicate computer-to-computer. There’s a lot of promising things there.”

Petty says web applications for BAS’s are growing in popularity. Building owners will be able to make building-wide temperature control adjustments based on actual weather station’s data. He thinks that “smart devices” with IP network connectivity can benefit facility managers in price and cost.

“Applications include wireless CCTV cameras, security access control, lighting control and control and monitoring of HVAC equipment,” he says. “They reduce the need to install low voltage wiring traditionally needed for many of these systems, reducing overall installation costs by approximately 80 percent.”

Petty says he also sees more active systems interacting with a passive approach. For example, he thinks engineers and installers will start designing lighting systems that correspond with natural light, such as becoming brighter when it becomes darker outside. He also sees an increased use of outside air in HVAC systems rather than mechanically produced air.

Maintaining a BAS
In order to keep a BAS running efficiently while providing sustainability, Petty says it’s important to make sure end devices, such as sensors, are calibrated and commissioned periodically to perform well.

“Commissioning is a systematic process improving the likelihood that all building systems will perform interactively as they were intended,” he says. “It includes specifications in the design phase, inspections during the installation process, tests conducted after installation is complete and operator training.”