Buildings or developments that are verified and certified as “net zero operational energy and/or carbon.” The building should demonstrate the highest levels of energy efficiency with the use of either renewables generated onsite or renewable energy procured offsite.
Discovery Elementary School is Arlington Public Schools’ first elementary school designed in the 21st century. While built to address rapidly growing student enrollment, the project was designed to meet a larger goal–to prove what can truly be achieved with a new public school facility. Under particular scrutiny, this was the first project in a capital improvement program that is in the process of adding over 500,000 square feet of new school construction to the nation’s smallest county.
Two important design process criteria were paramount: challenge the tendency of low expectations, and focus on children first. The resulting primary design goal was to provide a joyful and engaging environment for learning–a place students couldn’t wait to get to in the morning and didn’t want to leave in the afternoon. The secondary goal was to design a building that would not just use less resources, but make a regenerative contribution to the wellbeing of its occupants, site and the world at large–specifically regarding the crisis of climate change.
A specific site challenge was to integrate the 63,000+ square foot building footprint into a residential neighborhood hostile to the urbanization occurring elsewhere in the county. By breaking down the mass and terracing the building into a south facing hill, the project met local goals for scale, community goals for the preservation of flat, open space for recreation, and global goals for idea orientation for solar generation.
The school is the first net zero energy school in the Mid-Atlantic, the largest in the United States, and the second largest fully-conditioned zero energy building of any type in North America. Discovery offers a positive example of a solution to the global crisis of climate change–and along the way emboldens students with the expectation that they are creative participants in those solutions.
497 kW PV system is self-ballasted 5 degree tilt for maximum density as roof space was at a premium. System is grid tied with no energy storage systems. A net-metering contract existing with dominion power and building frequently provides excess energy generation to the grid. Passive design strategies included high thermal mass through ICF construction, a terraced building section that brought light deep into the building while maximizing rooftop space for PV, and a relentless focus on air-sealing–which produced a building that tested at .12 cfm/sqft: 80 percent better than code. Lighting design is code compliant with IECC 2009. Autonomous daylight harvesting controls were still a bit too expensive and complex in 2012/2013 during design so we opted for strategies that would encourage occupants not to use more light than needed. Most spaces are fully dimmable with daylighting zones controlled separately. The building features 100% occupancy sensor coverage. LPD is 0.43 W/sf so savings from daylight harvesting would have been minimal. Everything that was done at DES was measured against the PV offset cost unless code required. It was more affordable to buy additional PV than autonomous daylight harvesting at the time due to the low LPD. However, subsequent designs incorporate autonomous daylighting harvesting due to the ease and reduced cost of newer stand-alone digital room systems.
You can find out more about this case study from ILFI here.
Discovery offers a positive example of a solution to the global crisis of climate change–and along the way emboldens students with the expectation that they are creative participants in those solutions.
