“The intent of the Energy Petal is to signal a new age of design, wherein the built environment relies solely on renewable forms of energy and operates year-round in a safe, pollution-free manner. In addition, it aims to prioritize reductions and optimization before technological solutions are applied to eliminate wasteful spending—of energy, resources, and dollars.” International Living Future Institute
The Kendeda Building for Innovative Sustainable Design is expected to become the most environmentally advanced educational and research facility of its kind in the Southeast by achieving Living Building Challenge 3.1 certification. To be certified under the Living Building Challenge, projects must meet a series of ambitious performance requirements – Petals – over a minimum of 12 months of continuous occupancy and operations.
The Energy Petal requires Net Positive Energy, which means one hundred and five percent of the project’s energy needs must be supplied by on-site renewable energy on a net annual basis, without the use of on-site combustion. As with other natural resources, The Kendeda Building must balance the energy it uses with the energy it is able to produce. Consideration is first given to climate-appropriate passive design, then energy conservation measures (ECMs), which reduce the size of energy system needed, and, finally, to onsite renewable energy.
The Kendeda Building will have two, 75-person classrooms, two 24-person class labs, a makerspace, a 170-person auditorium, office space for co-located programs, and a coffee cart. Based upon this programming, it has a pEUI (predicted energy use intensity) of 34, which is 66 percent more efficient than an average building of the same size and occupancy.
Passive design is a technique that designers use at the initial planning stages of a project to leverage the natural climate, solar, and energy characteristics of a building and its surroundings to lower energy demands. For The Kendeda Building, designers prioritized the following variables to enhance the building’s ability to operate passively in Atlanta’s climate, especially to reduce cooling needs and the associated energy needs.
Designing an Efficient Building Envelope
The performance of the building envelope is critical both to the energy efficiency of the building and to the comfort level of the occupants. This includes continuous insulation at walls and under slabs and triple pane window glazing which helps to reduce building loads in winter and summer.
Leveraging Shade to Reduce Solar Heat
The PV array will multitask by producing energy, collecting rainwater, and providing shade for the south and west facades, the elevations that receive the most solar gain. The shaded areas help create a micro-climate which eases the transition between inside and outside of the building.
In addition, exterior operable and non-operable venetian blinds on the building’s west façade will help manage the cooling requirements due to summer sunshine. Shades aid in solar control and daylighting optimization for occupants. Strategically placed trees will also help control unwanted solar gains.
Using Daylight to Reduce Energy Demands
Daylighting design plays a large role in reducing system energy needs, improving occupant health and wellbeing, and connecting occupants to the outdoor environment. In addition, skylights and clerestory windows were designed in the large atrium space for continuous daylighting in the building.
Reducing Air Infiltration
Vestibules, air curtains at entries, and an efficient building envelope help prevent the movement of hot air and humidity into the building. Operable windows – with a system override – throughout the building will be mechanically operated when outdoor temperature, humidity, and pollen count are within an acceptable range to maintain system balance.
The Kendeda Building is designed to operate within a broader range of thermal comfort than a typical building. By carefully considering air and radiant temperature, humidity, and air speed, as well as occupant activity and clothing, the building will operate at higher air temperatures in the summer without sacrificing occupant comfort. This reduces energy use and the size of the mechanical system that needs to be installed.
Energy Conservation Measures
Every variable of the building’s passive design is evaluated using the energy models. The models also predict how much energy savings can be achieved by implementing additional energy conservation measures. Ultimately, the energy model determines how many photovoltaics are required to offset the energy needs of the building. Additional energy-related factors such as operating hours, thermostat set points, and plug loads become enormously important when all power must be generated onsite.
The energy demands for The Kendeda Building are higher than other Living Buildings. The building is set up for occupancy 18 hours a day, 365 days a year, with a flexible program and high energy output demands. Anticipated high pedestrian traffic will increase demand on everything from toilets to lights as well as the heating, ventilating, and air conditioning (HVAC) system – all driving demand on the PV array and the net positive water supply.
Cooling and heating the building with efficient mechanical systems
Equipped with additional condensation sensors and temperature reset strategies to mitigate moist floors, a radiant heating and cooling system in the flooring will be used throughout most of the building. In addition, a dedicated, energy efficient outdoor air system (DOAS) will provide heated or cooled (and dehumidified) ventilation air to a majority of the building’s spaces. To accommodate large audiences, the auditorium will have a dedicated variable air volume (VAV) HVAC. Ceiling fans will be used throughout the atrium space and classrooms for air circulation.
Borrowing Water and Energy from the Campus Central Loop
The building’s mechanical system, including the radiant flooring system and the DOAS (dedicated outdoor air system) uses chilled water from the campus’ central system. When the building needs to provide cooling, the mechanical system draws chilled water directly from the campus loop. When the building needs to provide heating, the mechanical system uses the campus heat recovery chiller to provide heat. Both the water and energy (in the form of heat) borrowed from the central plant is metered and taken into account in the annual net positive calculations.
Harvesting Energy from the Sun
A total of 913 photovoltaic (PV) panels located on the building’s rooftop will generate an estimated 328 kWh that will directly serve the building’s energy demands including lighting, HVAC system, water system, and plug loads. The lithium ion battery will be charged exclusively by the PV array and will serve as the emergency back-up system for the building in the case of power outages. The sizing of the PV array includes the building’s system energy demands, a safety factor of 10 percent, plus a 5 percent net positive factor.
When the PV array is not producing adequate amounts of energy, the building loads will run off of energy from the grid. When the PV array is producing more energy for the building than needed, the building will supply energy back to the grid. The PV array has also been sized to account for energy used from the campus chilled water connection. Water from the campus connection will be metered, energy will be calculated, and an energy offset will be supplied to the grid in order to meet the annual net positive requirements.
The photovoltaic array is designed to generate 40 EUI kBTU/SF/YR which will offset the building’s 34 EUI kBTU/SF/YR. By producing more energy than the building consumes, the systems create a net-positive energy facility on an annual basis.