Sean O’Connor Lighting’s design for the LEED Platinum Certified Sidwell Friends School, in collaboration with Benya Lighting, creates a lighting solution which, despite significant challenges, realizes exceptional efficiency and enables the use of daylighting as the primary light source for the first LEED Platinum K-12 school in the world. The project has been designed to reduce overall energy expended for lighting to 8%25 of that of a comparable building, in turn reducing the required cooling for the building; this integrated system of shading, lighting controls, and daylighting is the single most energy conserving measure deployed in the LEED Platinum project.
The existing 37,000 square foot middle school, built in 1950, was in dire need of renovation and expansion. The school was founded on Quaker philosophy, which includes a dedication to environmental stewardship. This brief was complicated by the existing classroom wing’s solar orientation, which is poor, and by the need to design the 39,000 square foot addition as a three-story building to fit within the site.
In addition to renovating an existing classroom wing, the project also created new classrooms and a large commons area for the school. This central circulation space is protected from solar gain along the south-facing windows by a series of exterior light shelves.
Daylighting studies under clear and cloudy conditions were carried out for the addition and existing classrooms. These studies resulted in a strategy which would provide the minimum necessary lighting under all conditions without excessive light under sunny conditions.
These studies were carried out using point calculation methods and renderings to illustrate these methods, and were the basis of a collaborative effort between the lighting design and architectural design teams to create an integrated series of exterior shading devices and interior daylighting strategies.
The resulting design was certified with daylighting for over 90%25 of normally occupied spaces and views for over 75%25.
In addition to providing shading, indirect solar light is reflected from the fins, made from recycled lumber taken from the original structure on the site. Achieving successful shading of west-facing windows gained a LEED innovation point; the daylighting solution for the new classroom wing also was awarded an additional innovation point.
ssadhsadh
sadhsadh
sahsdahsdah
On each floor, classrooms are lit from a series of windows along their north side as well as from light reflected over the corridor and into the classroom through transom windows to the south. Solar gain is controlled by the careful selection of glazing and motorized shades.
In each classroom, this dual system of light-filtering roller shades are installed that can be adjusted to accommodate natural light changes over the course of the day as well as darkening rooms for AV projection through shades with five percent transmission.
Between classrooms, the second- and third- floor corridors have sloping ceilings that collect light for work zones, with integrated electric lighting that includes narrow pendants and compact fluorescent downlights.
For the east- and west- facing classrooms, vertical fins were designed to prevent direct solar radiation of harsh low-angle light and heat gains for the duration of the school day. Electric shades with five percent transmission are also provided in these classrooms for AV projection.
In addition to the daylighting provided to each classroom, each learning space is equipped with two-scene pendant lighting systems, producing 45 footcandles in the semi-indirect mode and 15-20 footcandles of carefully controlled light for presentations in the direct mode, allowing a range of flexible use.
Luminaires are equipped with digital dimming ballasts and each room is equipped with a photosensor, manual override control station, and a motion sensor to ensure minimum energy use.
The school’s library uses a combination of pendant lighting and recessed narrow troffers with motion sensors in addition to daylighting. Low transmission glazing of the clerestory above and mechanically controlled shades are also provided, augmented with custom designed prismatic skylights, creating an intimate space for study.
In addition to the flexible deployment of each classroom space within the building, there is a dedicated media classroom which has limited daylighting and is located on the project’s first floor. This classroom is lit using the same dimmable ballasts with two-scene capability as other learning spaces to simplify maintenance and provide design consistency to the entire project.
The project attained over 52 points in the USGBC LEED rating system, becoming the first LEED Platinum project in Washington, D.C. The integrated lighting and daylighting system was directly responsible for over thirty percent of the point total.
Using the advanced measurement and verification provided for the building to attain LEED Platinum Certification, the building use has been carefully monitored. Over the first year of operation, lighting energy consumption has been reduced a remarkable 92%25—significantly more than the 85 to 90%25 expected—due to the careful design of both the building’s daylighting strategies and advanced digital controls, and are the principal reason the building’s energy use is 55%25 less than the Ashrae 90.1 2004 baseline.
