Sustainable Schools

The Power Of Zero

Schools in the U.S. spend billions each year on energy. With such high energy costs and the growing concern for our environment, there is a need to implement high-performing and net-zero energy strategies into educational design. While net zero has traditionally been seen as cost prohibitive, The Stevens Library at Sacred Heart Schools in Atherton, Calif., the first school building in California to achieve Net Zero Energy Building Certification from the International Living Future Institute, demonstrates that net zero can be achieved within a conventional budget in attractive and inspiring ways, while teaching students about resource conservation and social responsibility.

Commitment to stewardship — The school wanted the library, the learning hub for the K–8 campus, to reflect its environmental stance while instilling in students, faculty and staff a sense of ongoing stewardship. The school’s commitment to teaching students about conservation and creation through a hands-on learning approach motivated the their building committee to take on the ambitious goals for this project and provided the confidence that a net-zero-performing design approach was practical without unusual risk.

Communication is key — Communication and managing expectations was key to the success. The architects and engineers worked closely with the school on the operational strategies and construction program. In doing so, the library was able to meet the budget demands while reaching a ZNE performance level.

Cost-effective solution — The school’s modest, constrained budget necessitated a streamlined design that would be conducive to renewable energy systems. The result is a simple architectural design with a flat roofline that accommodates solar photovoltaic panels and a strong building envelope that reduces energy loads. The design also took advantage of natural ventilation and maximized daylighting.

Energy-saving strategies — The library’s design focuses on energy-saving and water-saving strategies, with a design that visibly highlights the links between energy and water through a glazed exterior showcase space. Below are examples of low energy design strategies that can be modeled for educational ZNE projects.

  • Solar Panels — The high-efficiency photovoltaic system provides all the library’s needed energy. The 250-watt panels were placed horizontally, in a densely packed arrangement.
  • Glazing — The high-performing glazing is color neutral low-e glazing which provides a low U-value equal to 0.28, a solar heat coefficient of 0.28 and a visible light transmittance of 64 percent, ultimately helping reduce energy loads.
  • Insulation — To further reduce energy loads, rigid insulation was added to the building envelope to increase its performance. The resultant performative building envelope is highly insulated with R-15 walls and R-38 white reflective roof.
  • Operable Windows — Carefully placed operable windows were positioned to take advantage of local breezes and maximize cross ventilation.
  • HVAC — A package unit with an efficient air-to-air heat pump that had both indirect and direct evaporative cooling sections was used. For those rare, extreme temperature days, a compressor was added to the unit to provide mechanical cooling.
  • Light Sensors — High-efficiency linear fluorescent direct and indirect light fixtures are continuously dimmed through daylight and occupancy sensors in response to available daylight, although dimming can be overridden by staff.
  • Solar Tubes — A number of mechanized solar tubes at the roof, carefully located between the PV panels, provide top lighting to maximize natural light in order to reduce energy loads.
  • Rainwater — The harvested rainwater is filtered and stored in a 3,000-gallon tank. A system of pumps feeds the irrigation system, and in turn, a grey water system that collects water from all the buildings on the quad, adequately treats the water so that it can be used to flush toilets in all buildings.

Design as an educational resource — In an effort to bring the school’s sustainable story to the forefront, the energy-systems are placed on display as learning tools. The rainwater management and grey water waste treatment systems are made visible by a folding glass door, providing access for use in educational efforts. Environmental graphics are integrated into the glass door, illustrating the water story and potable water availability. Additional dynamic signage highlighting photovoltaic capture, energy usage and daily trends, are on display within the library for the public to observe.

Net zero is an attainable goal. By implementing low-cost design strategies and exposing the building’s sustainable strategies, schools can teach students about conservation and help them build good habits at a young age.

This article originally appeared in the November 2016 issue of School Planning & Management.

About the Author

Pauline Souza, AIA, LEED Fellow, LEED-AP BD+C is a WRNS Studio Partner and director of Sustainability. She also is National Green Schools committee chair — Center for Green Schools and a Green Schools advocate for the USGBC.

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