Written by: Adri Sheppard

Figure 1. Exterior view of the CODE Building during active rainfall. 

Background 

The Center of Developing Entrepreneurs (CODE) building, located on historic Main Street in Charlottesville, Virginia, is a revolutionary commercial and retail development recognized for its sustainable design. As a LEED Platinum-certified facility, the CODE building incorporates an advanced rainwater harvesting system used for non-potable rooftop irrigation of mass vegetation, including many ornamental trees and plants. From the early stages of its construction, before its completion in 2021, water conservation and rooftop plant irrigation were core design priorities. These goals aligned with the criteria outlined in Version 4 of the LEED Building Design and Construction standards, set by the U.S. Green Building Council. 

To meet the stringent requirements for LEED certification, the CODE building implemented several innovative water efficiency strategies. These efforts earned the project 9 out of a possible 11 points in the Water Efficiency category, accounting for approximately 11% of the total LEED Platinum score. Points were achieved for significantly reducing outdoor water use and incorporating water metering to enable ongoing monitoring and management of water consumption throughout the building’s lifespan. 

Figure 2. Estimated monthly rainwater harvest (in gallons) based on the CODE Building’s 30,000-square-foot roof collection area, local daily precipitation data, runoff coefficients, system overflow, and dry-day losses. 

Rainwater System Design  

Rainwater is collected from approximately 30,000 square feet of roof and patio area using a blue roof collection system. With average annual precipitation in Charlottesville, Virginia, this surface area enables the building to capture an estimated 185,727 gallons of rainwater each year (see Figure 2). This water percolates through rooftop surfaces and is directed to a stormwater cistern located on the ground floor. Before entering storage, rainwater passes through a custom-designed High-Volume Separator, which removes debris, leaves, and particulates as small as 350 microns. The filtered water then enters a concrete cistern with an approximate capacity of 12,000 gallons, which has been internally coated for waterproofing.  

An 8-inch smoothing inlet directs the water upward as it enters the cistern, preventing agitation of biofilm or sediment and gently aerating the tank to preserve water quality. Any particulates that pass through the pre-filtration system either float to the surface or sink to the bottom, effectively avoiding interference with the system’s operation since the irrigation intake sits 3 inches above the tank’s floor. 

To monitor water levels and maintain functionality, a submersible pressure transducer is installed at the bottom of the cistern to measure the hydrostatic pressure, providing accurate readings of water depth. A mechanical float switch is also used to manage valve operations and ensure proper water flow throughout the system. If the cistern water level drops below 32 inches, potable water is automatically introduced to supplement supply and ensure continuous operation. In the event of maximum water capacity, an overflow line safely diverts excess rainwater to the stormwater drainage system. 

When irrigation is needed, the stored water is pumped to the rooftop through a custom-fabricated treatment skid designed and provided by Rainwater Management Solutions (see Figure 3). This treatment skid includes a flooded suction pump, a variable frequency drive (VFD), a self-cleaning filter, and an RMS 200 Controller that automates system performance and monitors operational data. The system is designed to handle a flow rate of 25 gallons per minute and operate at a maximum pressure of 150 psi. A custom-built 7.5-horsepower pump—powered by a 460-volt, 3-phase, 60-hertz motor—delivers water to the ninth-floor rooftop irrigation system. Final filtration is provided by a 25-micron automatic self-cleaning filter, which ensures general sediment control suitable for non-potable irrigation applications. This level of filtration is essential to protect the irrigation components from clogging and to ensure long-term system efficiency. The RMS 200 Controller manages all system operations while also collecting and transmitting performance data. 

Figure 3. Custom-built RMS Treatment Skid. 

Challenges 

The implementation of the CODE building’s rainwater harvesting system was not without difficulties. At the height of the COVID-19 pandemic, the project encountered significant shipping and supply chain disruptions, particularly for custom-fabricated components such as the irrigation pump and pre-filtration system. These delays created complications during construction, especially since rooftop landscaping had already been installed before the rainwater system was fully operational. As a result, interim irrigation strategies had to be considered to protect the rooftop flora until the system could be commissioned. 

In addition to logistical delays, the project team had to carefully navigate permitting and regulatory compliance. Both the Virginia Department of Health and the City of Charlottesville have specific codes governing the use of non-potable water for irrigation. Under § 32.1-248.2 of the Virginia Code, the use of rainwater and graywater for reuse purposes must comply with city plumbing and building codes. Meeting these standards required thorough coordination with municipal agencies, design modifications to meet plumbing code specifics, and documentation to demonstrate that the rainwater harvesting system would not pose a risk to public health or infrastructure. This added layer of permitting complexity required foresight and collaboration between designers, contractors, engineers, and regulatory authorities to ensure full code compliance before the system could become operational. 

Outcome 

Despite these challenges, the CODE building stands as a valued example of sustainable urban infrastructure in the city of Charlottesville. Its rainwater harvesting system reduces reliance on municipal water supply for non-potable uses, offering both environmental and social benefits. By prioritizing water conservation and sustainable design, the project has set a new standard for integrating green technologies into commercial development on a local and global scale.