Type Case Study
Topic Passive House, Mixed-Use, Boston, High-Rise
Date Published October 12, 2017

Architecture and Building Form

The Connector – A New Urban Space for the 21st Century

The distinguishing characteristics of great cities are the civic-scaled spaces that become iconic over time, retaining their essential grandeur and capable of renewing over time with every new generation. They may be plazas, cathedrals or train stations. They may also be grand rooms, of such shape or quality that they remain lodged in our memories: The Galleria in Milan, the Grand Palais in Paris, or closer to home, the Reading Room of the Boston Public Library, Faneuil Hall, or Trinity Church in Copley Square. They become integral to the image of a city. While the public components of the project will foster increased social interaction in the neighborhood, the building as a whole will set new standards for building performance, sustainability, and user wellness. Once realized, the project will become a model for future development in the city.

The most significant public feature of the project is The Connector: a distinctive gathering place active through all seasons and a focal point for activity from morning into the evening. It is a new urban room of shape and size, intended to be inherently civic in scale and function. It is a public connector, a signature space, where an iconic folded ceiling plane visually connects the plaza to the the large, multi-function space at the east end of the connector. The elemental materials of stone, metal, terrazzo and wood are intended to convey simplicity and a robust permanence, adaptable to different activities inside. At either end, as The Connector opens to Winthrop Square and Federal Street, 50 foot tall monumental structural glass walls enhance the continuity of the public realm. A mezzanine with a bar and restaurant wraps the volume and hanging “meeting pods” above provide overlooks across the space. Similar to great streets, the markets, cafes, restaurants, office lobby, and other programs open directly onto and flank the main spine of the space, further energizing the pedestrian realm.

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The High Rise Skyline

The distinguishing features of Boston’s high-rise skyline have remained relatively unchanged over the past 30 years. At the western end, the truncated “High Spine” of the Back Bay has been dominated by the Prudential and Hancock Buildings, recognizable fixtures on the skyline. Downtown, the Financial District has been dominated by relatively blocky and undistinguished office buildings, clustered from Beacon Hill to the waterfront. This has begun to change with several impressive projects under construction, and in particular with the completion of Millennium Tower, whose dramatic form pinpoints Downtown Crossing.

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Winthrop Center, a new shimmering prism situated in the Financial District of Boston, will give new definition and vitality to an important urban space.

Nearly 700 feet tall, this building is a synthesis of form: a complex, angular podium base resolving into a taut, symmetrical tower, emerging from within a neighborhood of bulkier office structures and articulated

at its crown with a distinctive transition of layered facade geometry. The shape and form of this tower will create a new visual pinnacle in the heart of the Financial District and on the city skyline. It will be a new marker in the sky indicating the heart of the new 24-hour, enhanced Financial District.

The architectural DNA of the heart of the Financial District around Winthrop and Post Office Square was firmly established in the early 20th century, with a cluster of distinguished Art Deco-era buildings. It is from this tradition of modernism – with an emphasis on vertical expression coupled with artful detailing – that we draw inspiration for a language of new high-rise expression on this downtown site, harnessed in the service of 21st century high-performance building technology.

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The Hybrid High-Rise

The fundamental characteristic of this project, and what has become a paradigm for successful urban revitalization in historic city centers, we define as a Hybrid High-Rise Residential Building. This is no ordinary mixed-use building. Like a hybrid plant, which is cross-bred with sturdier species to become more robust and often more complex in form, the hybrid building – with its complex and diverse functions – when artfully assembled, has the power to drive significant pedestrian activity on the street through all hours of the day. The more public functions of The Connector (retail, restaurants, events) and the office spaces, when coupled with residents living in the building, will create a critical mass of activity on the streets and squares in this neighborhood.

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Building Form

Elementally, the building is a traditional “tower on a podium.” The tower, composed of residential apartments, is lozenge-shaped and oriented along the north-south axis. The podium, containing retail, restaurants, and office space, is dramatically punctuated by a major public space linking Federal Street to Winthrop Square, forming The Connector. Straddling The Connector is a mid-rise wing of the office. This eastern tower volume stands apart from the primary tower and establishes the building’s presence on Federal Street.

Architecture

The high-performance enclosure of the building is conceived as an articulated glass skin dissolving at its crown into a set of deeply etched planes, creating a lively, ever-changing pleated surface of light, shadow and refractions. At the podium, this language adapts to express a pattern of solidity made necessary by the insulated passive house envelope. In each bay, a fritted, opaque glass panel begins as a sharp density of earth-toned color at the peak which dissolves into a soft transition at the valley. The composition is intended to complement the limestone, light masonry, and warm bronze detailing of the neighboring Art Deco buildings. The glassy, pleated motif is contrasted at the East office wing with a dense pattern of vertically oriented white metal fins. Both the edges of the pleated glass wall system and the vertical fin facade play off the dense angularity and verticality of the neighboring Paul Rudolph masterpiece at 133 Federal Street.

The Pleated Wall

While the fundamental compositional strategy is a tower with podium, the tower, oriented to face east and west, results in a broad surface. Our strategy is then to “break up the box” by fracturing the surfaces. This creates a series of angular planes that wrap the tower and podium and refract the reflections of the sky on the surface, creating an intricate composition of refraction and reflection. This strategy also increases the visual depth of the wall and enhances the presence of the warm colors reflected on the glass.

Not unlike the soft but angular folds of a pleated fabric skirt, the Pleated Wall serves a practical purpose too: bay window spaces inside the office floors orient a large portion of the glazing to the northwest, thereby reducing the solar heat gain while providing ample natural light.

Inspiration

Several distinguished buildings in the immediate vicinity of Winthrop Square provide an inspiration for materiality and detail. These are exemplars of the Art Deco era, dating from the 1920’s to the 1940’s. Located directly across Federal Street from the site is the United Shoe Machinery Corporation Building (now 160 Federal St, 1928).

Other nearby examples include the New England Telephone Building (185 Franklin Street, 1947); The Second National Bank (75 Federal Street, 1929); and the John McCormack Federal Building, by Ralph Adams Cram (Post Office Square, 1932).

Inspiration is not just derived from architectural precedent. The folding language of the facade as well as the connector ceiling recalls the 18th century metal work, decorative and practical, from noted Boston silversmiths. In addition to the noted practicality of the pleated facade, employing folded metal at the ceiling of the connector is a practical building material that can transition from closed to open modules that retain their rigidity and create a rich variety of reflections visually.

Building Uses

Residential Mixed Use Hybrid High-Rise buildings are, as a rule, composed of an intense array of diverse functions. Our project stacks these uses in a vertical arrangement that locates these uses in their optimum location. The ground plane is where all these uses intersect. Flanking either side of The Connector are retail and bar, and restaurant uses on the first two levels. The third level features a set of “floating pod” event rooms that appear to hover within the main volume of The Connector. The office lobby is part of the public realm, accessed through The Connector. The residential lobby is located at the base of the tower at the north corner. Service and parking ramps are discretely situated at the north and south edges of the site.

Each office floor will include an outdoor terrace and the capacity for a double-height common space, promoting a healthier and more uplifting workplace. Both the office tenants and the residents will be provided with extensive amenity areas for exercise, relaxation, and socialization, promoting communities of health and wellness

The mid-level mechanical equipment floor contains the HVAC and plumbing equipment for the podium office and retail spaces. This level also acts as the structural transfer floor for the high-rise sitting atop the podium. The residential amenity spaces (lounge, fitness room, etc.) open onto a planted roof terrace. The tower contains approximately 300 residential apartments ranging from 900 – 5,000 square feet plus penthouses, over 28 floors with several intervening mechanical transfer floors. Contained in a 25- foot high, multi-level stack at the top of the tower are mechanical equipment rooms, and window washing equipment.

Site Design, Pedestrian and Vehicular Circulation and Connectivity

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Downtown “tesserae”

The site is located in the epicenter of three significant districts of downtown Boston: the resurgent creative commercial node of Downtown Crossing to the west; the primary transit gateway of South Station; and the vital Financial District to the east. Our program’s new Connector, coupled with the creative Accelerator office space, will become a pedestrian attractor. In this way it is part of urban “tesserae” – or links – that reinforce and add multiple pathways between these major nodes of Downtown.

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Urban “tesori”

Boston is blessed with iconic outdoor urban spaces: The Common, Copley Square, and The Fenway, among others. Downtown, important intimately-scaled spaces constitute part of the special texture of the Colonial-era city: Post Office Square, Shoppers Park, the plaza dedicated for the Irish Famine Memorial and, between these, Winthrop Square. These are part of the city’s urban “tesori” or “treasures.” These are the memorable outdoor urban rooms of this district. In the summer, these spaces are teeming with pedestrians, vendors, tourists, and workers on lunch break enjoying the sun and verdure.

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The District Street Pattern

Boston’s streets were established by cow paths, or so the story goes. In reality, the Colonial-era pattern was formed by geography: the circumferential pattern east of Beacon Hill traversing the grade around the hill, and the radial pathways connecting the intense commercial activity of the wharves to the upland merchant shops. A distinct pattern of east-west streets are bisected by Washington and Federal Streets, radiating from State Street southwards. Our proposal envisions new streetscape treatments creating a living street and incorporating the 100 Summer Street Plaza into this network of pedestrian links, connecting Summer Street, the open terrace at 133 Federal, and The Connector. In this way, The Connector becomes part of a larger pattern of mid-block pedestrian open space links.

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Reconstituting Federal Street

The east side of the site along Federal Street poses a challenge: how to reconstitute the western street wall that has been missing for more than 40 years? Combined with the “negative space” created by the Bank of America building along half the block on the east side, the shape and character of the Federal Street façade has the potential to create some spatial order in an otherwise unresolved block. Our proposal resolves this problem with a detached vertical building form that mediates the height between 150-foot 133 Federal, the 390-foot 101 Federal Street tower, and the 240-foot 75 Federal building at the north end of the block facing on Franklin Street. All the while, natural light is allowed into the existing office windows at 101 Federal. The resultant stepped massing completes the street wall while respecting the inherent morphology of the disparate buildings on the block.

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Framing Urban Space

The site is bracketed by two 400-foot towers along Devonshire. Our Tower, gracefully inflected on its west face, creates vertical continuity between 100 Summer and 101 Federal. These tower faces roughly trace the contour of Winthrop Square, thus marking on the city scale this special location.

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Completing the Urban Room of Winthrop Square

The Great Fire of 1872 remade much of this district. The straightening of several thoroughfares, the creation of Post Office Square, and the new Boston Herald Traveler newspaper building at Winthrop Square gave new shape and a Victorian-architectural veneer to the neighborhood. But the 20th century transformation of the Financial District has been at best indifferent to cogent urban space-making. At Winthrop Square, while the granite One Winthrop Square building still axially organizes the plaza landscape, shear façades of the 400-foot office towers flank the east side with an uneasy counterpoint of 90-foot masonry loft buildings to the west. The office program in our project introduces an intermediate scale, gently bending to re-establish the Devonshire Street side of the Square, creating a setback for the tower, and giving definition to the stately One Winthrop Square Building. The inflection will draw the eye to the stone portal threshold of The Connector.

Streetscape and Landscaping Elements

New buildings of this scale require a careful balance of respecting and building connections to the existing context while reimagining how the pedestrian realm – notably the landscape and street “furniture” – can create a new and forward-looking environment. Key to enhancing the pedestrian experience in this location will be the repaving of parts of Winthrop Square, Federal Court, and Milton Place. Prioritizing the pedestrian over vehicles can be done successfully in Boston; witness Downtown Crossing at Summer Street or the new Shoppers Park plaza. Our inspiration for this tactic is the plazas and streets in the Netherlands called woonerf, or “shared street.” Vehicles move through the space slowly and purposefully in an environment clearly prioritizing pedestrians. This strategy lets the exterior space and landscape of Winthrop Square extend seamlessly into The Connector and, in similar fashion, the 100 Summer Street Plaza paving reaches northward into Federal Court. This simple paving strategy unifies the block, making the inner portions clearly a pedestrian realm that share in controlled fashion the vehicles moving through it.

Vehicular Access and Parking

With the site’s close proximity to public transportation, shared vehicular and biking options, and its central location, the project will need less parking relative to other projects of its size.

Over the last 20 years, we have seen our retail, residential and office users in this neighborhood reflect the trend in other urban areas of becoming less dependent upon private vehicles for their mobility needs. Further, with the growing diversity of building uses in the Downtown and Downtown Crossing core, many more trips are accomplished on foot. The Roche Bros. grocery store experience in our recently renovated Burnham Building is most indicative of this trend, as patrons are visiting the store more frequently and buying less at a time while exclusively walking, biking, or using public transportation.

This development will require less private vehicular transportation through Transportation Demand Measures, including the promotion of public transportation, shared vehicle use, biking, walking and fostering a culture of reducing each person’s carbon footprint. The project will have as many bicycle parking spaces as the users require, plus showers for bike-to-work commuters. There will be spaces for shared car services. And with valet attendants onsite at all times, the garage will accommodate as many electric-powered vehicles as the users require, even as demand increases over time. There will be accommodations to increase bicycle parking in and around Winthrop Square, and the project will have its own bikes, locks and helmets for shared use among residents.

The overall project’s parking capacity will be approximately 360 vehicles and is closely linked to the building’s structural foundation requirements, also taking into consideration the priorities of off-street loading, resiliency measures and the building’s structural elements. Here, based on the underground conditions, and to optimize the geotechnical and structural design, there will be 4 levels of below-grade parking.

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Access

Primary access for residential parking will be from Devonshire Street with a drop-off at an internal below-grade lobby. After the occupant drop-off, vehicles will be taken by valets into the lower garage levels. Vehicle delivery will be handled in the reverse order and any queuing will be inside the garage. Visitor parking for residents will be accommodated at the same below-grade drop-off. The loading functions for the building will also occur at an internal dock accessed from Devonshire Street, on the narrower portion of the street south of the plaza.

Primary access for commercial parkers in the property will occur off of Federal Street using a separate ramp and the parking spaces located on lower levels. The commercial parking operations will be valet-assisted on each level and the garage will be outfitted with stackers.

Residential and Office Parking Capacity

The garage will have residential and office parking for approximately 360 vehicles for the expected 300 units of housing and 770K sf of office space (approximate). It is expected that, similar to our experience at Millennium Tower, 20% units will be purchased by residents without vehicles and 20% by residents who keep more than one vehicle onsite. Further, we expect the residential vehicles to be used less over time as our experience with our existing residential units indicates. In a study conducted circa 2016, in the three fully occupied residential condominiums that we developed in the area, an average of 230 of the 720 residential vehicles (32%) leave the garage on an average weekday. This is down by 12% since 2004, when 44% left in a smaller sample size. We expect the vast majority of office users to use public transportation, walk, or bike to work, as is the case in our Burnham Building development.

Retail, Restaurant and Connector Parking

During weekday times, we expect users of the shopping, dining and Connector facilities to take public transportation, walk, bike or take a fee vehicle to the site. On evenings and weekends, we expect users may also drive to the site. In this case, we will work with Boston Transportation to designate a valet drop-off and pickup area on Federal Street, with the valets using the Federal Street access ramp to the garage.

Autonomous Vehicles and Reduced Parking Demand

As autonomous driving vehicles become more prevalent, the ramp from the residential drop-off and pickup area to the car parking areas below grade will be able to safely accommodate new technology even as it evolves. Finally, as the demand for parking declines over the coming decades, the subsequent Condominium boards will be permitted to convert portions of the below-grade garage areas to storage for occupants of the building. A comprehensive transportation analysis was done as part of the Article 80 Environmental Review.

Sustainable Development and Green Building

The Hybrid High-Rise is an ideal model to incorporate high-performance, energy efficient, and sustainable design features. The Winthrop Square mixed-use tower accomplishes this using three important sustainability standards: Passive House, WELL Gold, and LEED Platinum. The office program will meet Passive House standards, a rigorous performance-based sustainability standard that results in significant energy reduction and healthier interior environments. The office will also be WELL Gold Certified, a sustainability standard that focuses on increasing the health, happiness, wellness, and productivity of the users by impacting the building from design through construction, and importantly continues through the long term maintenance and operation of the building. The office and public spaces will meet LEED Platinum requirements. The LEED Platinum standard complements Passive House and WELL Gold by prescriptively addressing environmental impacts like water usage, recycling, materials use and sourcing, and building operating procedures. By designing a significant portion of the project to meet these three criteria, we are setting a new bar for market-rate, commercial building sustainable design performance. The Residential component of the building is being designed to LEED Gold standards.

Typically, buildings have a 50-100+ year immediate and long-term impact on the environment. The most important component to the Hybrid High-Rise is a robust exterior envelope. Passive House design has very strict requirements for low-energy consumption; by meeting these PH targets Winthrop Square tower will have the largest positive impact over time. The Passive House office program will reduce energy use by approximately 50-70% compared to the average IECC 2018 code-compliant commercial office building. In addition to the “passive” high-performance exterior envelope, the various “active” systems are highlighted in the accompanying illustrations.

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High Performance Envelope

To meet the high bar we are establishing for energy performance, particularly at the office program, the exterior envelope must meet rigorous design standards quality control during installation. Both solar heat gain and internal heat loss must be minimized, while maximizing the reach of natural light into the deep office floor plates. As the Passive House envelope, the curtainwall design employs a robust, triple glazed insulated glass window unit coupled with glass spandrel panels to obtain an average of R-30. To reduce energy loss, all connections between the exterior wall and the interior structure are thermally broken to minimize heat loss through thermal bridging, and all panel joints are gasketed and sealed to prevent air leakage. The highly insulated spandrel glass panels are designed with a unique fritted pattern that ties aesthetically to the brick and terracotta of neighboring buildings.

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Elements of a high-performance building envelope include:

1. Comprehensive Design

All factors that affect the energy use and physical comfort of the building must be analyzed. High performance design starts with a deep understanding of the building site’s climate and a common sense approach (i.e. thoughtful building orientation). This understanding is weaved together with digital modeling and intensive energy analysis throughout the iterative design process.

2. Minimize Energy Loss

This is achieved through a highly insulated, airtight, thermally-isolated building envelope with high performance windows, specifically double and triple-glazed IGUs with thermally broken frames. Functionally it is vital to ensure window openings (using 3d daylight modeling during design and then confirmed through the construction process) that allow ample natural light to extend into the space to reduce lighting loads. These two strategies will significantly reduce the energy transfer through the façade and in the space.

3. Controlled Envelope Assembly

A building’s envelope is only as good as its weakest link. The unitized panel system is prefabricated off-site allowing for exceptional quality control prior to installation. The increased quality control is especially important with regard to air and moisture barriers, where even a small leak can significantly and negatively impact the overall effectiveness of the envelope.

4. Human Wellbeing

The final test of high performance is conducted daily by those who occupy the building. Natural lighting, well-tempered even temperature, filtered clear air, a great view, and physical comfort result in a healthy indoor environment. Increasing the health of the interior environment are key results of Passive House and WELL Gold design. These goals are achieved in the office program through improved air and water quality, healthier food options, daylit spaces, thermal and acoustical comfort, and the encouragement of increased physical activity through building programs. The result is an office environment with 95% of seating within 35 ft of a window with natural lighting and views.

Building amenity spaces including fitness facilities, social spaces, informal work space, and education/cultural event space available to all employees and residents of the building. The Connector will extend many of the social and educational benefits to the public on a daily basis. Integrated and easily-accessibly Information Technology will help individuals learn about, contribute to, and benefit from the continually monitored sustainability and wellness in the building. At the large scale, LED display walls in The Connector will engage building users and visitors with ongoing performance data for the building: tracking what resources are being used, engaging the public in interactive displays, providing information about upcoming events. At the more individual scale, building users will have access to an app platform developed with the help of the MIT Urban Metabolism Group. This app will connect individuals to social and professional events hosted by the building, while also engaging users with methods to measure their own impact on the environment.

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