Located in the central business district of Charlotte, North Carolina, Duke Energy Center is the headquarters facility for Duke Energy Corp, as well as a number of Charlotte’s most reputable businesses. As well as being the second tallest building in Charlotte, the Center is also a LEED Core and Shell 2.0 Platinum certified office tower with 48 stories and 1.5 million square feet.
In the Duke Energy Center, 16 separate building systems, including three Building Automation Systems (BAS), are integrated on one network. With the Center’s integrated BAS, the facility has improved its operational efficiencies, reducing energy consumption by 22 per cent. The Center’s integrated systems include HVAC, power reliability, security, metering, lighting and daylighting, water management and emergency preparedness.
The Duke Energy Center utilises an advanced energy management system, which uses digital sensors, rather than conventional thermostats. This allows the building temperatures to be adjusted within a predetermined range, which is prescribed by building operating specifications and regional energy codes. Temperatures throughout the Center actually vary depending on weather conditions, time of day, building occupancy, and tenant preferences. Some tenants, for example, have energy management policies that prescribe a specific set point range in winter and a different set point range in summer.
Duke Energy Center utilises a lighting control system designed to reduce energy consumption by dimming perimeter lights in response to available natural light, turning tenant lights off during Non-Occupied hours and turning lights off in all enclosed rooms when unoccupied regardless of the time of day.
Offices are designed to operate in a Vacancy Mode, meaning that the lights will always be off unless the office is occupied. Upon entering the office, the occupant must physically push a button on the wall switch to turn on the lights. Perimeter offices are programmed this way as an energy saving measure to guard against the sensitive occupancy sensors in each office turning the lights on unintentionally when someone walks by an empty office.
The lighting control system for perimeter offices is set up in a Self-Learning Mode where the system learns occupant behaviour over time and automatically adjusts how long the office must be vacant before the lights turn off, anywhere from 8 to 45 minutes.
Open spaces are larger spaces that would typically include areas with multiple workstations. Lights in open spaces are designed to turn on and stay on during Occupied Hours and turn off during Non-Occupied Hours. During Non-Occupied Hours, lights in open spaces are operated in an Occupancy Mode and are controlled by zone occupancy sensors that turn lights on and off as needed by zone. If a person is occupying a portion of an open space during Non-Occupied hours, the lights in that zone will be on and stay on during the duration of the occupancy.
Speciality areas are spaces with custom lighting needs that could include audio-visual requirements or lighting scenes. These areas could include board rooms, conference centres, reception areas, galleries, work/copy rooms and other areas based on the tenant lighting design requirements. Although Specialty Areas are allowed some flexibility, generally they are designed to operate in Occupancy Mode like the Open Spaces. Speciality areas are also set up in a Self-Learning Mode that will adjust the period of time the room is vacant before the lights are shut-off.
The Duke Energy Center features Destination Dispatch™, a new concept in elevator controls designed to help occupants reach their destination faster. Instead of pressing traditional up/down buttons to call an elevator, passengers tell the system where they want to go before they board the cab. Knowing this information in advance, the system is able to assign elevators to passengers with common destinations. The assigned elevator will then transport them to their desired floor in the most efficient manner by making the fewest possible stops.
One of the most significant accomplishments of this project includes the water efficiency measures implemented to reduce overall usage and consumption.
Water use by tenants and visitors to the building has been reduced by more than 46% through the use of highly efficient fixtures in bathrooms. Use of these fixtures saves more than 4.3 million gallons of potable water from being flushed!
Approximately 25 million gallons of water per year are required for the HVAC system in a building of this size. Approximately 95% of the contaminated groundwater is being captured and treated to supply 100% of the water required for HVAC systems to cool the building and 100% of needed water from on-site sources, avoiding the purchase of this water from the city, thereby reducing the demand on city infrastructure.
Duke Energy Center is not only a trophy tower, but it is also a statement of conscience, a progressive and sustainable offering that sets a new standard for environmental accountability.
Certified as the first and tallest office tower to receive the highest level of certification under the USGBC’s LEED for Core and Shell rating system Version 2.0, the Duke Energy Center incorporates industry-shaping measures such as rainwater harvesting to provide irrigation for the campus and adjoining park. 26 million gallons per year of groundwater and HVAC condensation are also reclaimed and treated to provide all make up water for the tower’s cooling system. Individually metered electric supply gives tenants the ability to govern and reduce energy usage, enabling lower operating expenses. The green roof reduces stormwater run-off and alleviates the heat island effect by replacing heat-absorbing surfaces with plants, shrubs, and small trees, which cool the air.
Daylight harvesting blinds move with the angle of the sun to reflect light deeper into the interior and when coupled with day-lighting glass, provide increased natural light over traditional buildings. Additional key health measures include low-emitting paints and adhesives and continual monitoring that draws in fresh air to maintain proper oxygen/CO2 levels.
The roof of a commercial building is often used to house the mechanical equipment. The DEC roof is landscaped with native and adaptive plants. The green roof is a strategy used to mitigate stormwater, while simultaneously providing tenants with a connection between the indoors and outdoors.
The building harvests approximately 1.6 million gallons of stormwater annually, this results in greatly reduced impact on city infrastructure as this water is not sent through city pipes to be treated, rather it is used where and when needed. The utilization of onsite captured stormwater will provide 100% of the irrigation needs for the plaza and green roof vegetation, eliminating typical potable water usage for landscaping.
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