Enhancing the learning experience in K-12 schools: Electrical and power systems
Tony Cocea, PE, Principal, DLR Group, Los Angeles
Michael Do, CEM, CxA, AX TCP, Director of Engineering Sciences and Commissioning, Setty, Fairfax, Va.
James Dolan, PE, CEM, CPMP, LEED AP, Principal in Charge of Energy Engineering Services, OLA Consulting Engineers, Hawthorne, N.Y.
Mark Fisher, PE, LEED AP, Principal, AlfaTech Consulting Engineers, San Jose, Calif.
Douglas R. Hundley Jr., PE, CGD, LEED AP, CxA, Mechanical Engineer, CMTA Consulting Engineers, Louisville, Ky.
Peter McClive, PE, LEED AP, Senior Vice President, CannonDesign, Grand Island, N.Y.
CSE: Describe a recent electrical/power system challenge you encountered when working on a K-12 project.
Cocea: In a recent K-12 project, we are working with a school district that has a restrictive lighting-selection process. The approved light fixtures do not include LED light fixtures; and to use them, it would take an approval process that will delay the project.
Fisher: One of the challenges we’ve encountered has been meeting the new Title 24 requirements. This has required replacing fixtures rather than refurbishing them.
McClive: An emergency design and construction project for an elementary school to replace the entire electrical service after an excessive rain event caused water to enter the service transformer vault and severely damage equipment. Temporary service was established, and the project was designed and submitted for immediate review and approval (within a week). This was immediately followed by a bid, award, and equipment procurement in time for construction during the school’s two-week spring recess.
Hundley: A recent net zero energy project in Michigan was located several miles from 3-phase electrical service and had to be served at 120/240 1PH. This did not present a problem due to building size, but it was challenging to design all of the high-performance commercial building systems for 240 V/1PH.
CSE: What types of renewable energy systems have you recently specified in a K-12 project?
Fisher: Photovoltaics (PV) were used as a part of the new Willie L. Brown Jr. Middle School in San Francisco. AlfaTech was recently selected to provide MEP, technology, and solar PV engineering design services for "bridging" design and related services. The new approximately 70,000-sq-ft middle school will replace an existing school site complex located at the same address that is being demolished. The new facility is being constructed under a design-build construction delivery method. AlfaTech is providing MEP and technology documents up to design-development level to assist design-build contractors in preparing their engineered design-build construction documents for Division of the State Architect approval. The MEP/technology design-build contractor will be the engineer of record.
Also, ground-source heat pumps were used in the new elementary school for Milpitas Unified School District. This new K-6 elementary school for 800 students is approximately 63,000 sq ft with a construction budget of $22,113,000. The project entails a less-traditional school model and is comprised of grade-level learning communities. (Learning communities are collaborative and activity-based environments.) The new campus also will include administrative spaces, a multipurpose "flexible" space, a resource center, and a warming kitchen. The building will be 1 or 2 stories. Other onsite work includes outdoor play and landscaped areas, staff parking, and a new parking lot for both the school site and the city park. The offsite work involves the widening of McCandless Drive to accommodate a new vehicle drop-off and pick-up lane, a dedicated right-turn lane, and a new traffic signal. The intent is to meet California Building Code green building code requirements.
Hundley: Solar PV and solar thermal energy systems are the only renewable energy systems that work well in most areas of the country. Sufficient wind resources are not available in many locations, and utility-scale wind turbines are generally much more economical than small-scale systems. We have designed a number of large solar PV systems for high-performance and zero energy projects. The falling cost of PV has allowed many K-12 owners to achieve ROI of less than 15 years on a system that will provide clean energy for 30 or more years. We often employ solar thermal demonstration systems, but not large-scale systems unless a significant amount of hot-water demand exists (i.e., large indoor pool facilities, laundry, or central kitchens). K-12 schools are not occupied in the summer when the most solar hot-water production is available.
CSE: How do you work with the architect, owner, and other project team members to make the electrical/power system both flexible and sustainable at the same time?
Hundley: Many school districts are growing faster than they can build facilities right now, so understanding anticipated future growth is critical. The possibility of a new classroom wing or bank of mobile classroom buildings within a year of opening a new school is very real in many areas of the country. One trend in high-performance K-12 buildings has been to use 120/208 V services in lieu of 277/480 V to eliminate added infrastructure and transformer losses. As computers and other plug loads become more efficient, step-down transformers are often loaded far under their designed 35% peak-efficiency load factor. Most transformers are much less efficient when lightly loaded. Although some K-12 buildings do require 480 V services, many are oversized—which is costing the owner money.
Fisher: Early involvement, assessment of the existing electrical system, and working with the district maintenance staff, facilities staff, and the architect to understand the district’s program and sustainable standards.
McClive: Our company is a multidiscipline group of architects and engineers that play a vital hand-in-hand role in the planning effort. All team members are actively involved from project initiation to final construction and commissioning of systems. We know that building performance is intrinsically tied to ROI, operational efficiency, occupant comfort, and safety. Our team of engineers strategically balances cost and quality parameters, operational considerations, code, occupancy, and schedule requirements to achieve resilient, reliable, and efficient building systems that stand the test of time.
CSE: What types of smart grid or microgrid capabilities are owners demanding, and how have you served these needs? Are there any issues unique to K-12 building projects?
Fisher: We have done microturbines for several projects, but we are not typically involved with solar because the school district works with the solar manufacturer directly (it is typically a larger company).
Hundley: We use demand-response schemes in many buildings with demand-related charges, but microgrids are becoming an attractive option for K-12 buildings with very high demand charges. The falling cost of lithium-ion cells along with the opportunity to shift costs from backup generator systems will encourage the use of battery-energy storage systems in K-12 buildings in the next few years. This is something we continue to evaluate for new projects.
CSE: What unique lighting or lighting control systems have you completed?
Hundley: Most owners and operators of K-12 buildings desire simple lighting controls that work without constant attention. Stand-alone digital lighting controls have improved significantly in recent years, allowing most buildings to meet their control and efficiency goals with full-occupancy sensor coverage and a simple BAS-controlled time clock for exterior lighting. Integral motion sensors on outdoor lighting have also become a no-brainer due to energy savings and increased LED lifetime.
Fisher: Multiple daylighting zones, dim lighting to save energy and meet Title 24 requirements.