In the Village of Hempstead on Long Island, N.Y., architecture is doing much more than providing educational infrastructure. At the Evergreen Charter School, which opened in August 2025, the mass timber building itself has become part of the educational mission. Students learn not only about curriculum subjects but also experience how sustainability, wellness, and community identity come together to support an immersive learning experience.

Located in an economically challenged part of Nassau County, Evergreen Charter School defies the notion that high-performance or mass-timber architecture is reserved for affluent districts. Instead, the school showcases how intentional design and applied building science can serve communities that have historically had limited access to architecturally ambitious learning spaces.

According to Hammad Ahsan, project architect at Martin Hopp Architect PLLC in New York City, an ambition to achieve sustainable performance in a comfortable space was central to the client’s vision from the beginning. These goals drove design decisions affecting almost all aspects of the occupants’ experience, from comfortable, energy-efficient rooms to acoustic management in state-of-the-art music facilities to a roof strong enough to support vegetation and athletic events.

“The client was open to trying things that would give students something they could be proud of,” Ahsan said. “That was a driving force behind the project.”

Importantly, the building was also designed to serve as a community resource beyond school hours. Evening programming means the cafeteria, gymnasium, and gathering spaces are in use long after classes end, reinforcing the school’s role as a civic anchor within the neighborhood.

“After the school day ends, the second half of the building’s life starts,” Ahsan said.

An unconventional location for a high-profile build

According to Ahsan, 90 percent of the community’s population is minorities, with nearly a quarter of residents living below the poverty line. In recent years, the school’s neighborhood has seen significant growth in the number of first-generation immigrant families from Latin America. In fact, Evergreen Charter School emerged from a nonprofit organization serving the Hispanic community, and its educational mission extends well beyond the classroom. The school provides adult programs and services after the school day concludes.

“That’s when the school’s second day begins,” said Ahsan.

A hybrid mass timber approach

The project was designed using a hybrid mass-timber strategy, balancing performance, constructability, and scheduling while accommodating the budget constraints inherent in school projects. Rather than pursuing an all-timber structure, the design team employed cross-laminated timber (CLT) floor decks on a steel frame for the primary school building. A full mass-timber cafeteria was added, becoming, as Ahsan says, the “crown jewel” of the project.

The exposed wood elements in the design create a warm, calming atmosphere that aligns with the ongoing interest in biophilic design in educational settings. Exterior timber shading and a hybrid timber rooftop truss system reinforce the building’s identity while supporting its sustainability goals.

Ahsan believes mass timber’s greatest value may ultimately be experiential rather than aesthetic.

“Once you’re in the space, you feel happier and enjoy the space more,” he says. “The reason to use it is that it creates nicer spaces at a comparable price.”

His viewpoint should resonate with the design-and-build community across the industry who are not familiar with mass timber. While many contractors and subcontractors on the Evergreen Charter School project had little previous experience with mass timber construction, the project generated enthusiasm among trades on the jobsite, Ahsan noted.

“There is a growing energy toward this approach,” he said. “Having built one project, the team came away really excited about the opportunities for mass timber construction.”

The construction schedule reinforced the approach’s viability. Despite some delays associated with masonry and a few kinks in the material supply chain, the project team ultimately recovered time through the prefabricated mass timber installation process. Ahsan estimated the approach helped the team achieve a 12-week schedule advantage.

Sustainability and space as teaching tools

The school was envisioned not only as a high-performance building, but as what the design team calls “a lived lesson in sustainability.”

The facility targets LEED Platinum certification and incorporates several advanced environmental strategies. Rooftop solar arrays provide approximately 40 percent of the building’s energy, while the site retains roughly 99 percent of onsite stormwater runoff. A rooftop urban garden allows students to learn how to grow food, and a teaching kitchen directly below lets them prepare what they harvest.

Space in the neighborhood is limited, and the site area forced the architects to think creatively about programming and open space. Besides its vegetative functions, the roof also provides ground for a soccer pitch, a popular recreational resource for students.

Insulating beyond code

The Evergreen Charter School’s envelope was designed to deliver performance exceeding baseline code requirements. Continuous exterior insulation, rainscreen detailing, and high-performance air and moisture barriers contribute to an enclosure system that improves energy efficiency and long-term durability.

The specification for the rainscreen assembly required 114.3-mm-thick (4.5-in.) continuous insulation (c.i.) installed within an integrated facade system clad with aluminum panels. The insulation was installed in the assembly to support thermal continuity, moisture management, and fire performance. A below-grade retaining wall and below-slab were used; the building achieves NYS Code + 20 percent in envelope performance, verified by whole-building envelope and energy modeling in close collaboration with the envelope consultant and sustainability modeling team.

The roof assembly includes a protected membrane roof system with extruded polystyrene insulation. This assembly delivers compressive strength and moisture management, two important criteria in high-performing roofs. This was achieved using rigid insulation in a typical IRMA green roof application, with insulation protecting the roofing membrane, root barriers, and drainage layers on top, followed by green roofing overburden; all loads were verified and calculated using a structural Engineer of Record (EoR).  

Interior partitions throughout the school include sound attenuation batts to help support acoustic separation between classrooms and shared spaces.

Acoustic performance is particularly important in specialized areas such as gymnasiums and music rooms. In these locations, double-stud wall assemblies combine multiple layers of gypsum board with layered insulation strategies to manage reverberation and sound transmission. Standards and guidelines used for the project included NYCSCA and LEED acoustic guidelines. Acoustic consultant Cerami/Trinity helped develop project guidelines, with typical classroom partitions achieving Sound Transmission Class (STC) 45, corridor walls achieving STC 50, and specialized spaces like gymnasium and music rooms at STC 60. Reverberation was achieved by holistically modeling ceiling % coverage, wall assemblies, and wall coverage with an acoustic consultant.

Looking forward, measuring wellness, and learning outcomes

The project team is especially interested in understanding how building performance influences educational outcomes over time. A comprehensive post-occupancy evaluation (POE) program is being implemented to examine the relationship between indoor environmental quality and student performance indicators, such as attendance, staff retention, and academic achievement. The school includes more than 50 indoor air quality (IAQ) sensors that continuously monitor HVAC performance and classroom air conditions.

“It’s helping us understand how the building is performing and letting occupants understand how the building works,” the architect explains.

The focus on indoor environmental quality aligns with broader industry conversations around healthy buildings and occupant-centered design. High daylighting levels, elevated ventilation strategies, and the natural warmth of exposed timber interiors all contribute to improving occupant comfort and engagement. The building was designed to meet 60 percent+ Spatial Daylight Autonomy in all teaching spaces, based on LEED-defined standards, with passive glare reduction modeled to achieve less than 10 percent under LEED’s Annual Sunlight Exposure standards (ASE), and achieved using exterior mass timber fins sized according to daylight modeling results. A Post-Occupancy Evaluation (POE) based on WELL indoor environmental quality standards found that 100 percent of teaching spaces meet WELL’s task-oriented lighting benchmarks. All occupied spaces have double-filtered MERV (Minimum Efficiency Reporting Value) 9+13 air filtration, with a baseline of six to eight air changes per hour, based on ASHRAE 621, Ventilation and Acceptable Indoor Air Quality, recommended guidelines for optimized interior ventilation. WELL-based POE testing in the building, per ASHRAE 55, Thermal Conditions for Human Occupancy, has demonstrated PMV/thermal comfort levels within ±0.2, well beyond the standard guideline of ±0.5.

The future of mass timber

While the project showcases the potential of mass timber construction for school construction, it also highlights challenges facing the mass timber industry, particularly around codes, detailing, and fire resistance.

Ahsan said that many tested firestop systems and engineering judgments (EJs) commonly available for steel and concrete construction do not yet exist for mass timber conditions. The team worked extensively with fire protection manufacturers, code consultants, and local officials to develop compliant solutions for project-specific penetrations and transitions. Coordination of all firestopping details with code and fire specialists Jensen Hughes + Engineering, judgments for firestopping assemblies were obtained from vendors, and in-depth coordination with the Fire Marshal was undertaken on approving details within the local Authorities Having Jurisdiction (AHJs) for all firestopping and detailing conditions, followed by special inspections to ensure all installed details met design standards. Fire-resistant and non-combustible materials, such as mineral wool insulation, also helped address fire performance objectives.

Despite those challenges, the project team believes the industry is rapidly evolving. Increased familiarity with mass timber in the design-build space, evolving codes, and ongoing interest in biophilic design may drive greater adoption of mass timber in schools and other institutional buildings.

For Evergreen Charter School, however, the most important achievement may not be technical at all. The project demonstrates that high-performance, sustainable educational architecture serves every community, regardless of income level.

“Mass timber architecture can be for all,” Ahsan said. “We’re hoping to design for the future and give kids a place they can take ownership in and be proud of.”

Author

Tiffany Coppock, AIA, NCARB, CSI, CDT, LEED AP, ASTM, RCI, EDAC, is the commercial building systems specialist at Owens Corning.  Tiffany resides in the Dallas-Fort Worth area.

Key takeaways

Evergreen Charter School shows how mass timber, high-performance enclosure design, and occupant-centered planning can create sustainable, welcoming learning environments in underserved communities. Its hybrid approach—CLT floor decks on a steel frame plus a full mass-timber cafeteria—balances biophilic benefits with budget, schedule, and constructability needs. The project also treats the building as a teaching tool, with rooftop solar, stormwater retention, a rooftop garden, enhanced envelope performance, acoustic strategies, and IAQ monitoring supporting wellness and environmental literacy. Its broader message is that high-performance, mass timber educational architecture should be accessible to all communities, not reserved for affluent districts.