An energy-management system (EMS) is used to control energy-consuming equipment, primarily that related to HVAC and lighting control. Ensuring that these systems operate properly can result in lower energy bills. By using basic HVAC fundamentals and mastering EMS design/operation, one can find energy waste stemming from defective control devices and poor EMS programming.

This article will describe how an EMS can support the search for energy waste from the facility-design stage through day-to-day operation.

FACILITY DESIGN

While the ideal time to incorporate energy-saving features into a facility is during design, well before building construction and operation, renovations also provide a great opportunity. Although the incremental cost of installing an energy-saving system most likely would be lowest during scheduled downtime or as a part of new construction, the project budget might not be able to support it. Estimating the potential internal rate of return (IRR) resulting from expected annual cost savings can help justify an increased budget. A business case detailing the scope, showing alternatives, and describing potential risks and rewards of the project can be prepared and a high IRR can help sell a project to management.

Replacement of HVAC equipment is an opportune time to incorporate more-efficient equipment and new EMS controls. Energy-saving strategies can change depending on the climate in which a facility is located. For a hot, humid climate, a few examples of energy-saving products include:

• A heat pipe wrapped around the cooling coil in a 100-percent makeup-air unit, which can control humidity efficiently while minimizing cooling and reheat energy costs.

• A variable-speed drive on a single-zone HVAC system, which can help control humidity and lower cooling and reheat costs.

• Carbon-dioxide sensors on HVAC equipment, which can minimize outside air during low-occupancy periods.

EMS DESIGN

By taking an active role in the EMS-design process, an owner can gain a better understanding of HVAC- and lighting-controls design. This frequently gives the owner the opportunity to make energy-saving recommendations that can be incorporated into the EMS design.

However, there are some inherent problems with the traditional EMS-design process. First, an engineer's controls design seldom is more than a set of “typical” schematics accompanied by a narrative specification describing the desired results with little or no “how-to” instructions. The resulting EMS design is vague and performance-based. In the end, the owner gets a system that meets the original specifications, but might not be the same as — or even compatible with — the existing facility EMS. The owner operates this new system as just one of many disparate systems in his or her EMS portfolio.

An alternative EMS-design approach — one that results in a seamless integration of new facilities into a global EMS — is used by some owners. This process has two fundamental concepts. First, to ensure competitive bidding, EMS hardware is owner-furnished. Second, the EMS is designed as part of facility-design documents, which prescriptively specify all pertinent details. With this alternative approach, the installation of EMS wiring, conduits, sensors, and actuators — generally the most expensive part of an EMS — is competitively bid. A contractor with knowledge of the owner's preferred EMS manufacturers performs the EMS-panel final wire termination, programming, and startup. The owner's energy-management team coordinates the addition of the new panels to the central EMS server and prepares the EMS graphical interface. The owner knows exactly what he or she is getting and that the new equipment will integrate seamlessly into the existing EMS.

Making EMS design part of design documents helps an owner master an EMS, maximizing energy savings. This expertise begins with an intimate understanding of how an EMS works, including hardware and software, and develops with day-to-day operational experience and the adoption of EMS design standards.

BUILDING TUNE-UP

A building tune-up analyzes and optimizes a building's HVAC, lighting, and energy-management systems for improved performance and energy efficiency. Although difficult to predict for a single building, facility energy savings from a building tune-up typically range from 5 to 15 percent. The resulting actions generally are low-cost or no-cost adjustments to an existing EMS that not only minimize current operating costs, but lower future maintenance costs. A building tune-up does not necessarily involve the purchase and installation of new equipment or technology. Instead, it requires an investigative-style approach to ensure that EMS controls are working and managing HVAC and lighting systems optimally.

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