Green Buildings & Sites

The North Carolina Arboretum’s Operations Center provides workspace for grounds, gardens, landscape, maintenance, and IT staff members and volunteers. Work areas include: an automotive, electrical and carpentry shop; research library; laboratory; loading dock; and shipping and receiving area. Outside the building, there is a vehicle washing station, a bulk storage and soil mixing area, and a pesticide mixing building. A 5,160 square-foot steel structure adjacent to the facility provides additional storage space for vehicles and equipment.

The Arboretum’s Operations Center follows guidelines adapted from the U.S. Green Building Council which require the facility to meet criteria for innovative design, energy efficiency, and environmentally responsible practices. Rather than relying on high-tech materials, the Operations Center uses standard building components innovatively. Over time, the facility will save the Arboretum energy, water and money, which which is translating into savings for North Carolina taxpayers. Furthermore, the staff finds the building a healthy and productive place to work because of the space design and day-lighting features.


Operation Center environmental high performance features:

  • A cistern for collection of rainwater runoff reduces the demand on new water usage.
  • Solar panels on the roof preheat water before it enters the water heater, reducing heating costs.
  • North facing, operable, clerestory windows in both office and workshop areas provide natural airflow, called the chimney effect, reducing the need for cooling. They also provide natural daylight for workers inside, reducing the use of artificial lighting.
  • The workshop area utilizes natural air circulation rather than air-conditioning. “Air curtains” at interior doorways of all the workshop areas produce a blast of air, providing extra insulation and protecting interior air quality.
  • A geothermal heat pump cycles water through a series of nine, 380-foot deep underground wells keeping the water for the building’s heating and cooling system close to a constant temperature of 55 degrees. This will save money throughout the year by eliminating the need to cool or raise water temperature greatly.
  • An oil-water separator filters pollutants from water used to wash vehicles and equipment before the water is recycled for irrigation.
  • Lights controlled by photo sensors and timers lessen the usage time.
  • Water conservation methods such as two waterless urinals each save 40,000 gallons of water a year.
  • Low maintenance and low water consumptive landscape surrounds the facility and includes a combination of native and non- native grasses, perennials, shrubs and trees.


A living “Green Roof” was also installed on the Operations Center to cool the building in the summer and mitigate the harmful effects of storm water runoff. Ways in which a green roof helps reduce impacts to the environment include:

  • Cools air temperatures through a process known as transpiration, in which plants release moisture into the air
  • Enables the structural roof to last longer by reducing the degree in which the surface temperatures fluctuate
  • Insulates the roof thereby reducing heating and cooling needs
  • Treats and reduces water runoff by slowing it down and allowing it to evaporate into the air or be absorbed by the plants growing on the roof.


Green roofs are composed of a series of material layers including waterproof and root barrier membranes, filter fabric, lightweight well-drained growing medium and plants. This 3,000 sq ft roof is bordered with limestone gravel to allow access for roof maintenance and to buffer rainwater as it passes through. Plants, such as sedums, grasses and chives, are appropriate for Zone 6 and are low maintenance and able to tolerate vast fluctuations in temperature and water are critical to a successful green roof. This mix of more than 8,000 plants, in a random meadow type planting, provides year-round interest with extended flowering, fall color and some evergreen presence during winter months.

A Permeable Paved Parking Area is located adjacent to the Operations Center using interlocking concrete pavers. This type of paving system allows rain and snowmelt to pass through, thus reducing storm water runoff to local surface waters. Most porous pavements also reduce the pollutant load as the water filters through the system. Permeable pavements are generally placed over a bed of open-graded gravel that acts as a temporary storage reservoir. Geotextile fabric underlies the gravel and keeps it from migrating to the soil below. The amount of gravel storage and possibility of adding perforated drainage pipes are modifications that vary with the specific site design and goals.

Advantages of installing permeable pavement include:

  • Treatment of pollutant load
  • Less need for curb and gutter
  • Better skid resistance and improved safety
  • Recharge to local aquifers
  • Requires no additional land (good for a densely developed area)