Project Subtitle:
Project Description:
The new Annie E. Fales Elementary School, a K-3 grade school in Westborough, Massachusetts is projected to achieve net-positive energy use when it opens in Fall of 2021. Westborough’s commitment to renewable energy significantly shaped the design of the new school, which is the first facility to support the Town’s goal to be carbon-emissions free by 2035. The innovative facility achieves this ambitious target by reducing energy use and producing renewable energy on-site through a rooftop solar array capable of generating 10% more energy than required for the school itself. The light-filled interiors, warm natural materials, and thoughtful integration into the school’s surrounding establishes Fales as a vibrant learning environment year-round.
The building runs entirely on electricity. The saw tooth roof houses a 25,000 square foot photovoltaic array that produces all the building’s annual energy needs. Westborough is also working with National Grid to establish a net-metering contract. This will allow the school to off-load excess energy generated in the summer and draw electricity in the winter. Excess energy will be credited to offset electricity used at other schools in the district.
Experts in sustainability joined HMFH early on to establish the big moves that minimize energy use. The final design features triple-glazed windows; roof and wall insulation 40% above code requirements; forty, 600-foot deep geothermal wells for heating and cooling; high efficiency mechanical systems designed to improve air quality; LED lighting with daylight and occupancy sensors to lower electricity demand; a 508 kW solar photovoltaic array; and a building management system that monitors and controls mechanical systems and lighting for maximum efficiency. These elements combined, reduce energy use to one-third of what is used by typical school buildings.
The projected EUI for the school is 24.9 and the project is tracking towards earning LEED Gold and LEED Zero Certifications. Fales Elementary School is one of the first net-positive energy schools completed within the Commonwealth of Massachusetts’ community partnership program under the MSBA.
"The building educates students about the natural environment and sustainable practices, and we hope it inspires a life-long care for the world they live in."
Amber Bock, superintendent
Building Type Summary:
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Occupancy Type and Details:
100% occupancy from 8am to 3pm weekdays during the school year.
Summer school has the same schedule as above, except that only one classroom wing is occupied.
The Gym has additional hours of 3 pm to 10 pm on weekdays, 8 am to 10 pm on weekends and during school vacation weeks.
The Cafeteria, Art, Music, Maker Space, and Media Center are occupied after school from 3 pm to 5 pm, and periodically on the weekend.
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Multiple buildings?:
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Historic?:
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Site description:
The site is 14-acres previously developed for school use. The long and narrow hillside site drops 130 feet from the western, wooded end of the site, to a pond within a wooded wetland on the eastern end of the site. The south edge is a suburban street, with residential neighbors across the road, and the north side is adjacent to residential properties. The existing school and parking needed to remain operational during construction, limiting the available locations for a new building. The new school is nestled into the upper hill, a strategy that minimizes the facade exposure of the larger public spaces while maximizing the roof area available for solar PVs and daylight to internal spaces. The second floor classroom wings are on a north-south orientation to optimize energy use in these spaces, while the lower level public spaces are face east and outdoor play areas. A upper level entry courtyard is sunny, yet out of the prevailing winds, creating a micro-climate amenable for outdoor learning.
Energy Highlights:
The building’s well-insulated envelope, highly efficiency mechanical and electrical systems, and use of geothermal heating and cooling reduce the Energy Use Intensity (EUI) to 24.9, one-third of what is used by typical school buildings. The 25,000 square foot roof-top solar array produces 110% of the building’s annual energy need, making Fales a fossil fuel free, net energy exporter. Westborough is establishing a net-metering contract with National Grid to apply unused credits towards electricity costs at other district schools.
Annual renewable energy generated:
Electric Utility Company:
Gas Utility Company:
Datasets and Utility Bills sources and reliability:
Current energy use data is estimated. Once operational, a Data Acquisition System (DAS) will collect PV production data from each array. Additionally, an exterior mounted utility owned meter will measure the total system production.
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Energy Storage type:
No on-site energy storage is used.
Subslab assembly:
Slab on grade with
Above grade wall assembly:
Wall Type 1: 4" masonry, air gap, 5" mineral wool continuous insulation, gypsum sheathing, 6" metal stud, 2 1/2" mineral wool cavity insulation, gypsum wall board
Wall Type 2: 1/2" phenolic panel rainscreen, air gap, 5" mineral wool continuous insulation, gypsum sheathing, 6" metal stud, 2 1/2" mineral wool cavity insulation, gypsum wall board
Flat attic assembly:
N/A
Cathedral ceiling assembly:
Exposed roofs at sloped monitors: 5" acoustic metal roof deck, 10 mil polyethylene vapor retarder, 8" polyisocyanurate board insulation, 60 mil PVC membrane
Door Area:
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Other Software tools:
Revit - design and construction documents
Sketchup - early design studies
Enscape - 3D visualization, rendering
Diva - daylight analysis
Honey Bee - radiance analysis
Rhino - 3D rendering, diagrams
Total Cost of Project:
Construction hard cost:
Published References:
“Overcoming Obstacles on the Path to Zero Net Energy Schools” High-Profile Monthly, 11/16/2020
https://www.high-profile.com/overcoming-obstacles-on-the-path-to-zero-ne...
Energy Strategies:
Photovoltaic System: The PV system consists of 11 arrays mounted on the south side of the saw tooth roofs for a total DC power of 508 kWdc and an estimated annual production of 648,300 kWhr/yr, 10% more than the estimated annual electricity need of 584,600 kWhr/yr. Sloped roofs are 3, 4, or 5 panels high with tilts varying from vary from 21° and 30°, and are spaced roughly 30 feet apart, a strategy that maximizes the square footage of roof available for PV without compromising solar exposure.
Geothermal System: A network of forty, 600-foot deep, High Performance Geo Exchange (HPGX) wells connect to a centrally located geothermal vault, which in turn connects supply and return lines to water-to-water ground source heat pumps located in the building mechanical room. A reversible heat recovery chiller delivers heating and cooling, and a separate heat recovery chiller heats the domestic hot water.
Energy Use and Production Documentation:
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Scope Description:
elementary school
Site conditions:
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Other Purchased Fuels Description:
No other fuels are used to regularly power the building. Propane will be used for emergency generators, a requirement from the local building official that the emergency generators operate on an alternate fuel source.
Summary of enclosure strategy/description:
The building’s enclosure is 38% more energy efficient than required by code and includes masonry and phenolic panel rainscreen walls with R-27 of effective wall insulation, R-40 membrane roofs, and triple glazed windows and skylights. A low window to wall ratio of 20% required careful positioning of each window and skylight to maximize daylight and minimize solar heat gain. Portions of the exterior wall are below grade, buffering the interior space from temperature swings.
Roof Assembly:
Flat roofs: 5" metal roof deck, 10 mil polyethylene vapor retarder, 5/8" glass-fiber, water resistant gypsum protection board, 8" polyisocyanurate board insulation, 60 mil PVC membrane
Roof R-value:
Window Description:
uPVC triple glazed awning and fixed windows, Intus
aluminum triple glazed curtainwall, Kawneer
aluminum triple glazed skylights, Velux VMS
tubular skylights, Velux Solartube
U-factors noted are for window units, center of glass u-value is 0.13
SHGC varies by orientation from 0.19 to 0.40
VT varies by orientation from 43 to 60
Door Description:
aluminum triple glazed doors, Kawneer
fiberglass reinforced doors
Project Team:
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Team Members:
Caitlin Osepchuk, HMFH, Architect
Vassilios Valaes, HMFH, Architect
Andrea Yoder, HMFH, Architect
Julie Darling, HMFH, Architect
Sam Landay, HMFH, Designer
Rosemary Park, HMFH, Architect
Hazel Ryerson, HMFH, Architect
Jaime McGavin, HMFH, Designer
Chin Lin, HMFH, Architect
Quy Ve, RWS, Mechanical Engineer
Tom Secondo, RWS, Mechanical Engineer
George Chan, RWS, Electrical Engineer
Jonathan Patch, McPhail, Geothermal Engineer
Tracey Ogden, TOC, Geothermal Consultant