Thanks to relaxed COVID-19 guidelines from the International Living Future Institute and a digital twin, the 47,000-sq-ft Kendeda Building for Innovative Sustainable Design at the Georgia Institute of Technology in Atlanta lost no time becoming a role model for Living Buildings in hot, humid climates. ILFI’s rigorous Living Building Challenge program anointed the project as a Living Building on Earth Day, April 22.

The Kendeda Building, which won an ENR Best of the Best Projects award, is the first building of its scale to achieve full certification in the Southeast. The building’s photovoltaic solar array satisfies 100% of the energy needs, and overproduces another 125% under the business-as-usual model, according to the Kendeda team.

Though the Living Building is certified net-positive for water and energy use, it’s rainwater-to-potable water system—though permitted and tested—is not operational because state regulators have not given the green light to flip the switch on the system.

Water is Most Challenging

“Water not energy is the most challenging” aspect of creating a Living Building, says Shan Arora, Kendeda’s director. “I knew it was possible to get a building to a high level of [energy] efficiency,” adds Arora, who arrived at the project in July 2018, after construction had begun. “Getting a building to be its own municipal water district” is another matter, he adds.

The permit from the Georgia Environmental Protection Division (EPD), granted for the potable water system during the 12-month Living Building Challenge performance period, validates that the water system produces safe drinking water with continuous chlorination disinfection, he explains. But that is not sufficient.

“We are working with EPD to determine how this first-of-its-kind, public, nontransient, noncommunity water system in Georgia can meet the ongoing testing requirements of U.S. Environmental Protection Agency’s National Primary and Secondary Drinking Water Regulations and Georgia’s Rules for Safe Drinking Water,” says Arora.

This pertains to the number of treated water samples, sampling locations and the frequency of sampling during operation. Once the logistics of ongoing testing are in place and with EPD’s approval, Georgia Tech expects to activate the rainwater-to-drinking water system pursuant to the permit issued in 2020, Arora adds.

The pandemic and subsequent building shut-downs and reduced occupancy threatened to delay certification related to the Living Building Challenge’s required year-long operational period to validate performance objectives, based on occupancy. During the performance period, a project must prove it is net positive for energy and water, which means it generates more energy from onsite renewable sources than it uses and it collects and treats more rainwater onsite than it uses for all purposes, including for drinking.

COVID-19 Disruption Guidelines

In response to the pandemic, ILFI issued COVID-19 disruption guidelines for Living Building teams to justify net-positive energy and water use, without having to postpone the performance period. Under the guidelines, ILFI reviews each project on a case-by-case basis. Projects are evaluated based on energy models or other criteria.

Consequently, the Kendeda Building was reviewed and approved based on its detailed energy model, which is based on its digital twin. For more than two years during the project, researchers from Georgia Tech’s Aerospace Systems Design Laboratory had been embedded with the building’s design team, supporting data analysis and scenario modeling throughout construction and the building’s  commissioning. The lab had access to the building’s data platforms and had gained an understanding of the building hardware and operations.

Digital Twin

Using the data, the lab created and calibrated a Kendeda Building digital twin—defined as a set of models that mimics the structure, context and behavior of a unique physical asset. A digital twin can be updated with real data from its physical twin throughout its lifecycle and can therefore evaluate alternative scenarios that the physical building could encounter—for example a pandemic.

For Kendeda, the 12-month performance period was Dec. 1, 2019 to Nov. 30, 2020. During that time, the building operated on a normal schedule until the end of March 2020, when COVID-19 disrupted operations. Results of the digital twin calculation show that if the building had been occupied based on originally planned class schedules and event programming, it would have supplied and infiltrated back to the ground 15 times more water than it used, and supplied 225% of its energy needs during the performance period, says the Kendeda team.

To create a baseline, the model was calibrated to actual usage schedules, weather and other conditions that the building experienced. The baseline was then modified to show what the building would have used if 2020 had been a typical year.

The energy model was reviewed and vetted by consulting engineer PAE, which provided ILFI a letter endorsing the digital twin’s energy performance data.

“Our peer review looked at the overall process of modeling, the calibration and the results and provided validation that the method used was in line with industry standards and in our opinion, reliable,” says Marc Brune, a principal of PAE, which is no stranger to Living Buildings. PAE is co-developing, designing and leasing its own Living Building, the PAE Living Building, in Portland, Ore. The building is on course for completion in September.

The Kendeda Building’s actual energy use intensity (EUI) over the last year was about 14 kBTU per sq ft per year, or 185% net positive, says Brune. The model predicted that under normal operation, the EUI would have been about 18, or 125% net positive.

The digital twin also calculated results for a “stress test” based on an unrealistic 12 months of maximum occupancy, which was defined as 500 people continuously in the building every Monday through Friday from 7am to 10pm, says the Kendeda team.

The model predicted that under an extreme high-use scenario, the EUI would have been about 32 or 25% net positive, says Brune.       

“The high-use scenario matched most closely with our energy modeling assumptions, which predicted ~30 kBTU per sq ft per year,” he adds.

Seven Performance Categories

The Kendeda Building has met all the conditions for full certification under the Living Building Challenge’s seven performance categories, called petals—place, water, energy, health plus happiness, materials, equity and beauty.  

The team says the energy petal is challenging in a warm humid climate. To meet the challenge, the Kendeda design team segregated ventilation and cooling, which is accomplished through radiant floor heating and cooling that circulates water through piping. For ventilation and dehumidification, there is a dedicated outdoor air system.

“We decoupled ventilation from temperature,” says Joshua R. Gassman, sustainable design director, Lord Aeck Sargent, a Katerra Co., which served as a project lead designer along with Miller Hull Partnership. “Most buildings expend energy to dehumidify not cool,” he adds.

For this, the building envelope is “extremely” airtight to keep humidity out, with weather barriers, air curtains and vestibules at main entrances, says Gassman.

Arora adds, “it is a very big deal that a building can make it to net-positive energy in the hot humid South.”

Back-to-the-Future Design Approach

The Kendeda team also took a back-to-the-future passive-system approach in the siting and layout of the building and its systems. These include natural ventilation, ceiling fans and shading, combined with off-the-shelf technology, such as active blinds. Windows are operable, and some façade openings are as large as 10 ft square.

By opening and closing windows and more, in moderate temperature months, “we can keep occupants more comfortable” without flipping the switch on mechanical heating or cooling, says Gassman.

For certification success, almost every building component or system has more than one simultaneous function. “The only [element] that can only do one thing at a time is the fire extinguisher,” says Gassman.

For example, though the primary function of the rooftop solar panels is to generate energy, the photovoltaic array also serves as a canopy that shades the façade. The canopy also collects rainwater for the potable water system and it defines the porch space on the western façade, Gassman explains.  

There are other Kendeda Building bells and whistles of sustainability. Rainwater water is stored in a 50,000-gallon cistern in the basement, before being treated and used for all purposes, eventually including drinking. For gray water, there is natural treatment outdoors in the form of bioswales.

The building is composed of materials screened for ILFI’s hazardous “Red List” chemicals, such as bisphenol A (BPA), halogenated flame retardants, phthalates and formaldehyde. Chemicals on the Red List have been shown to harm human and environmental health, even though they are common in most buildings, says ILFI.

Wood from sustainably managed forests, salvaged materials and other sourcing strategies significantly reduce the building’s embodied carbon footprint.

By eliminating 99% of its construction waste and incorporating reclaimed locally sourced materials, such as reclaimed wood for the structural decking and salvaged slate tile in the restrooms, the project diverted more waste from the landfill than it sent to the landfill, says Georgia Tech.

Composting toilets nearly eliminate potable water use for sewage conveyance and allow for human waste to be turned into fertilizer for use off site. The building allows for universal access via an accessible ramp connecting the terraced main floor.

Beyond the Equity Petal

The design and construction team went beyond the equity petal by promoting an equitable and inclusive sense of community, says Georgia Tech. For example, general contractor Skanska USA Building Inc. partnered with Georgia Works!, a nonprofit helping chronically homeless men become self-sufficient, to build the ceiling panels and floor systems.

The Kendeda team’s message to others considering a sustainable building in the Southeast or anywhere: Don’t be intimidated by the Kendeda’s full certification.

“As aspirational as we want everyone to be, we also need to be sure that the perfect is not the enemy of the good,” says Gassman. “We don’t need every building to be a Living Building, though it would be nice if it were. But we do need every building to perform a lot better than the status quo.”

Gassman’s advice: “Set ambitious goals and even if you don’t achieve them, you will end up with a building that performs better than if you set less ambitious goals.”

Arora invites all those interested to tour the building. He likens the sustainable systems to a restaurant menu. “For our building, we ordered everything on the menu,” he says. “But simply ordering a few items is better than nothing. If people come in thinking about LEED Gold, we hope they will leave thinking about LEED Platinum.”