Facility Retrofit: Delivering Daylighting
By Anne Cosgrove
Published in the March 2014 issue of Today’s Facility Manager
Please describe the facilities in the Douglas County School District. What are your responsibilities for the district?
Our schools comprise more than 6.5 million square feet. The district contains 47 elementary schools, nine middle schools, nine high schools, 13 charter schools, two magnet schools, one alternative high school, one night high school, one online school, and 62 preschool locations. Historically, Douglas County has been one of the fastest growing counties in the nation. Since 2008, growth has slowed down, but now residential development is increasing, and that will bring more students to the district.
My department manages facility assessments, long range capital planning for facilities and equipment, and design and construction of our schools as well as renovation projects.
Please describe this most recent daylighting project. What were the motivating factors and goals?
Completed in August 2013, this project involved five of the oldest elementary schools in the district. These are one story buildings, originally constructed between the 1950s and the 1970s. These are sound, solid buildings, but some of the rooms were dark, and we wanted to bring them up to date with the daylighting standards we use for new construction. Since 2006, we have had prototypes for new construction, and these documents include standards on the equipment and systems installed in our schools. Part of the standard for new construction has been to include daylighting.
This latest installation includes a mix of tubular daylighting systems from Solatube, skylights, and clerestory windows. Three of the schools were outfitted with the tubular daylighting. Established as part of our daylighting standard in 2006, these systems disperse light through magnified lenses, and this really brightens up the rooms. We have found the tubular systems are the best way to deliver natural daylight directly into classrooms. We focused on retrofitting all the classrooms first, and then also added the systems to common spaces and the libraries. The Northeast Elementary School has 86 Solatube units (two models); Sedalia Elementary School received 164 units (two models); and Acres Green Elementary School has been outfitted with 185 units. For new schools, we install, on average, two tubular units in each classroom. However, for this project we specified as many as six units in a classroom, since the older schools do not have some other design aspects that bring in light (such as reflective ceilings).
The most important motivator in increasing natural light through daylighting was to enhance student performance and student, staff, and community morale. Daylighting provides a connection to the outdoors, which is proven to improve performance and morale.
But the other reason was to save valuable, and limited, utility dollars. Since our utilities are funded from the district’s General Fund, the savings we get can go directly into the classroom—for technology, textbooks, and equipment, and even for teacher salaries.
How did you research the options for daylighting products? And how did you arrive at the final decision?
Regarding the tubular daylighting, these specific systems have been part of our prototype since 2006. And we have them installed in other schools. Factors that played into the decision back then, and why we continue to use them, include references from the manufacturer’s warranty to the durability, maintainability, and, now, past performance.
In 2006 we had a design competition to establish a new elementary school prototype—you build the same school each time, adapting it to the site. This saves approximately 25% design time and about 15% to 20% in construction costs. This has also standardized our building components so our maintainers are familiar with the items, and we can keep those items in stock.
Key components we focused on in that competition were sustainability and energy performance. There were specific criteria, and this required competing architects to do energy modeling on their concept designs. We established a threshold for energy consumption, in kBtus per square foot per year. We are at about 30 kBtus per square foot annually with the current prototype.
After we established the new prototype, we partnered with the Colorado Energy Office and held a design charrette with the Institute for the Built Environment. The goal was to refine the design further for energy reductions. So, to recap, we used prequalified architects and their subconsultants (such as mechanical and electrical engineers), and we partnered with the state.
We do try to achieve LEED Gold in our designs for new construction, but we do not pursue the certification because of the cost. After construction we test and balance every building; we also have a third-party commissioning agent for every new school to refine the mechanical systems further and provide independent opinion of the energy use, the balancing, controls, and if the systems are being operated as designed.
What have the results been?
To date, since the installation was complete in August 2013, we are seeing an approximately 15% savings in lighting utility costs in those five schools, when compared to the year before. In these, and the other schools where daylighting has been implemented, it is rare to have artificial lights on during a sunny day. Our standards also call for lighting controls, so we do not rely on occupants to turn the lights off, if there is enough natural lights in a school. That is another way we are reducing energy consumption and costs.