Many different methods are available to detect occupancy they all eliminate wasteful energy usage in unoccupied rooms

Many different methods are available to detect occupancy; they all eliminate wasteful energy usage in unoccupied rooms.

Energy Solutions

Education institutions can take small steps to deliver concrete energy savings, despite the constraints of tighter budgets.

Education facilities managers are faced with a daunting set of challenges: They must find new ways to reduce energy consumption and carry out greener energy policies. HVAC typically accounts for more than 30 percent of a building's electricity costs, so there is a clear incentive to eliminate unnecessary heating and cooling of unoccupied rooms.

With more efficient systems integration aiding the drive for green energy, school facilities managers can benefit from new energy-management strategies.

Unique challenges

The education market is faced with unique challenges in energy management, not least because of the range of facilities involved. Classrooms, offices and student housing have different sets of requirements for energy control and usage. With rooms often unoccupied for considerable periods of time — on a daily basis, as well as through long vacation periods — education institutions need to embrace an intelligent approach that combines the ability to detect occupancy, control temperature settings, maintain ventilation and, equally important, help maintain equipment efficiently.

There also is a need to accommodate outside influences. For example: interaction with utility companies for energy rebates; or monitoring usage to enable rapid responses when utilities approach thresholds and need to shed load swiftly with little notice.

It can be advantageous for an education facility to know when a brownout is going to occur, and respond by lowering and controlling energy at a particular site. Also important is integration — a single facility may be equipped with different systems and equipment, from HVAC to building-management solutions. The energy-management system must integrate with the different systems, whose requirements have evolved over time.

Networked or not?

With a networked energy-management solution, facilities managers can check the status of all the different rooms in a building and provide a degree of control. Seeing the varying conditions — and any alerts — enables the manager to adjust the HVAC and lighting on a daily basis, as opposed to relying on single room-by-room settings that may have to be changed manually. Networked system options range from twisted pair, Ethernet or the latest platforms that employ wireless ZigBee communication methods and can even be self-healing. The ZigBee Alliance is an association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control products based on an open global standard.

The benefits are comprehensive — from centralized control to the ability to communicate data between rooms, floors, classrooms and residence halls. Monitoring and managing HVAC and lighting equipment locally and remotely enables a proactive maintenance strategy, combined with fast access to energy usage and savings reports.

Most of these networked systems also can be integrated into existing building management systems (BMS), which releases a facility manager to focus on more strategic energy-saving goals. It also enables a more analytical and proactive maintenance program; the system flags occurrences of failing equipment, such as a particular fan-coil unit or a compressor, and workers can fix a problem before a breakdown.

Disadvantages, however, need to be taken into account. The costs of establishing networked energy-management systems can vary widely. Interoperability issues with existing equipment may arise because vendors have not adopted a common standard. The key is to identify a solution that is based on a mainstream standard, such as the BACnet data communication protocol for building automation and control networks or the ZigBee wireless standards-based technology that addresses the unique needs of remote monitoring and control, as well as sensory network applications.

Occupancy-based solutions

The core components of networked energy-management systems can be deployed as a standalone solution, even if an overall networked strategy is not appropriate. Occupancy sensors, intelligent thermostats and PTAC controllers can be used to sense occupancy and automatically adjust HVAC, ventilation and lighting, albeit this option is viable only for smaller spaces within an education setting, such as smaller to mid-sized classrooms, portable buildings or residence halls.

Many different methods are available to detect occupancy, such as passive infrared, ultrasonic motion detection, door contacts, light level of room, schedules and network input. In general, they all eliminate wasteful energy usage from unoccupied rooms and provide far greater occupant comfort and overall flexibility.

These in-room devices provide real-time information and analysis. An intelligent HVAC thermostat, for example, also can be used as a central resource for automating other services, such as lighting. Within this style of "smart room" environment, it also can provide the means for the occupant to participate directly in load curtailment.

Occupancy-based solutions can be simple to install and operate, and frequently are available with inexpensive front-end software that provides a degree of centralized control. The benefits of having the flexibility provided by programmable setpoints are clear. A school can limit the temperature for a student room to typically 70ºF in the summer and 78ºF in the winter, and by enabling the students and teacher to see the available range, encourage them to take individual responsibility for controlling their energy usage. When they leave the room, the energy-management system automatically shifts into energy-saving mode. It returns to the occupants' chosen setting when they come back to ensure comfort.

Must-have elements

When selecting an appropriate energy-management solution, education institutions should seek a system that can manage a diverse range of HVAC systems. These can range from fan coil, PTAC units, PTHP, four-pipe systems, two-pipe systems with electric heat, split systems, and multi-stage heating and cooling systems.

Fast, easy and low-cost installation is another factor. Narrow the focus and look at options that avoid costly hard-wiring without compromising reliability. Flexibility is essential; look for a system that defines how the HVAC systems control the heating and air conditioning, rather than being limited to pre-assigned settings. Seek a system that can self-calibrate to each room's environmental and HVAC characteristics and ensure the most energy savings while guaranteeing occupant comfort.

Exercising good control involves having rapid, ideally real-time access to operational data. The system should provide detailed data, at the individual room level, enabling management to monitor and fine-tune the system for the maximum operational efficiency. A state-of-the-art networked energy-management solution typically will capture data across multiple variables, take snapshots of the in-room energy-management thermostats every 15 minutes, and aggregate and store the data for measurement and verification (M&V) analysis and report generation. Reporting also needs to be comprehensive, accessed locally or over the network, to include extensive HVAC runtime usage, savings and efficiency, including occupancy, mode and maintenance statistics.

The energy-management challenges facing education facility managers are wide-ranging, but even small steps can deliver concrete results. Modern systems provide detailed projections of energy savings, and many deliver a rapid return on investment, averaging within two years. As states and the federal government urge education institutions to reduce energy consumption, schools and universities can achieve better performance. In this context, even adopting an in-room approach is a step in the direction of energy conservation, cost savings and green operations.

Sobieski is chief operating officer of Telkonet, Inc., Milwaukee, Wis., a clean technology company that develops and manufactures proprietary energy management and SmartGrid networking technology. [email protected].

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