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LEO A DALY transforms Capitol Hill office building into mixed-use development

The $200 million adaptive reuse project will add three stories, a new skin and a vibrant mix of uses to a former government building

LEO A DALY celebrated the topping out of 20 Mass, a redevelopment of 20 Massachusetts Avenue NW in the District of Columbia, on April 13. The $200M project will transform the previously seven-story government office building into a 10-story mixed-use development, bringing a vibrant new mix of hotel, retail and office spaces to the Capitol Hill neighborhood. Located directly adjacent to Union Station and four blocks north of the United States Capitol, the project will create a new landmark in the monumental core of the District.

“The 20 Mass project transforms an outdated and imposing office building into a strong and relevant contribution to the urban fabric of the nation’s capital,” said Irena Savakova, RIBA, global design principal with LEO A DALY. “It’s absolutely thrilling to reimagine a signature site in Pierre L’Enfant’s 1791 Master Plan for the District. Our design seeks to restitch the building into its evolving urban context and create a vital new social and cultural hub for the city.”

LEO A DALY is providing full architectural and interior design services for the project, which is being developed by The RMR Group and built by DPR Construction. Construction is now underway and is expected to be completed in 2023.

20 Mass stacking diagram

A complex adaptive reuse project

The existing building will be stripped down to its steel structure, adorned with a new curtain wall, steel and terra-cotta skin and increased in height by three stories. A new program of interior and exterior spaces will create a vibrant mixed-use destination that features a 274-key Royal Sonesta Hotel, 184,000 square feet of Class A office space and 14,000 square feet of retail.

Amenities include a 14,500 SF penthouse with a green roof and 360-degree views, a 50+ seat conference center with state-of-the-art technology, a fully equipped fitness club with private lockers, a 1,260 SF secured bike room and 13,832 SF of in-building retail and chef-driven restaurants. An engaging streetscape redesign and ground-floor retail program will transform the building’s visual and experiential relationship to the Massachusetts Avenue corridor and surrounding streets.

“20 Massachusetts Ave is a great example of how LEO A DALY’s integrated, multi-practice design expertise benefits our REIT clients. 123 design professionals collaborated across five design studios to deliver the breadth of expertise needed for this complex mixed-use development,” said Kristina Crawley, AIA, vice president and global commercial practice leader. “The project kicked off just prior to the pandemic shut down, and thanks to the resilience, dedication and teamwork of our studio leadership and project team members, we successfully completed entitlement approvals, all deadlines and an expedited permitting process while working under extremely challenging circumstances.”

Focus on sustainability and wellness

20 Mass is exemplary in its commitment to sustainability and occupant health. The design, which is targeting LEED Gold and WELL Silver certifications, is aimed at minimizing carbon emissions, maximizing energy efficiency and safeguarding the physical and mental wellbeing of users.

The building’s existing structural skeleton will be preserved, resulting in a significant savings in embodied carbon (that is, the emissions associated with the extraction, manufacturing and transport of building materials). Had the building been razed in favor of a new build, the project would have emitted an additional 6,905 metric tons of CO2e. This is the equivalent of removing 1,500 cars from the road for a year. Prefabrication of guestrooms in the Royal Sonesta will reduce construction waste, accelerate construction and further reduce embodied carbon.

From the earliest stages of the project, the design team focused on reducing operational carbon emissions from the high-performance building. Extensive computer modeling of the envelope, lighting and HVAC systems influenced design decisions which maximize energy efficiency. At the completion of design, the estimated energy use intensity (pEUI) for the project is 28 kBtu/sf/yr, which represents a 66% reduction compared with similar buildings.

Additional design features will reduce energy consumption and water use. Solar studies analyzed the behavior of sunlight inside and outside to reduce hotspots and glare potential. Interior window shading, low-e glazing, textured terracotta panels and matte/opaque finishes are deployed strategically to combat unwanted solar effects and ensure occupant comfort. High-performance glazing will contribute to more than a 20% reduction in estimated energy consumption. To protect local waterways, a green roof passively captures rainwater. Low-flow filters will reduce water consumption by 40%.

To protect the health of occupants, interior materials were selected carefully to minimize embodied carbon emissions and human health impacts, with a special focus on chemical composition and VOC emissions. Enhanced ventilation and filtration are carefully calibrated to maximize the quality of the indoor air. Fresh, clean drinking water is prioritized, and potable water is screened and filtered for contaminants. Designers specified touchless interfaces to fight infectious disease.

Luxury hospitality design

The 274-key Royal Sonesta hotel, designed by LEO A DALY’s hospitality group, blends classical nuance with urban vibrancy, offering a culture-filled stay just a short walk from the U.S. Capitol and Union Station. A finely crafted contemporary palette of exterior materials forms a counterpoint against a modern interior with bold pops of color and angular design expressions, infusing the space with the vibrancy of the city’s thriving arts scene.

The lobby is designed to offer clarity and ease of orientation for guests immediately upon entry. Lobby spaces flow elegantly to support unique program elements. A curated sculpture collection defines the timeless interior space. Lounge seating clusters form a rhythmic sequence along the two-story glazing facing Massachusetts Ave. Each cluster sits on a custom art inspired rug and offers views toward the city.

Guestrooms feature a navy and neutral palette focused on relaxation. Clean lines and sophisticated finishes blend contemporary and modern elements, continuing the theme established in the public areas. The penthouse conference center provides dedicated meeting and conference facilities, including an expansive balcony.