by Russell Boniface
Associate Editor

How do you . . . design a pedestrian-friendly, sustainable, mixed-use development within a historic architectural context?

Summary: The $130 million, mixed-use Portwalk development project in the City of Portsmouth, N.H., is preparing to break ground this summer on its second phase of development. Portwalk is a 600,000-square-foot, pedestrian-friendly, mixed-use project featuring shops, restaurants, condominiums, office space, and an extended-stay hotel. Portwalk, currently pursuing LEED® Silver certification, has sustainable features that include a white roof to reduce the heat island effect and an underground parking garage to minimize current street parking. The first phase was completed in June 2006 by Portsmouth, N.H.-based DeStefano Architects; the second phase was designed by Boston-based Elkus Manfredi Architects and is scheduled for completion in late 2009. The client for both phases is developer Cathartes Private Investments, based in Boston.

Portsmouth, a historic New Hampshire seaport of brick buildings, serves as a popular summer tourist destination. The Portwalk project is designed to be a pedestrian-friendly, sustainable urban center. The completed first phase of Portwalk includes a hotel and a complex of 28 condominiums called Harbor Hill.

Portwalk Phase Two
The second phase of the project will be on an adjacent site to replace an antiquated downtown superblock of stores originally called Parade Mall. It will feature four mixed-use, brick and stone buildings, matching the historic architectural context of Portsmouth. The project also includes the city’s first underground parking garage.

Portwalk’s phase two will offer 400,000 square feet of space above grade and 600,000 square feet overall. The buildings range from three to five stories, adhering to a 60-foot height limit in that portion of the city. Each of the four buildings will have ground-floor retail, totaling 75,000 square feet of 20 shops, cafes, and restaurants, with an extended stay hotel above. Two buildings will have three stories and 170,000 square feet of office space. The four-story extended stay hotel will sit atop shops in one building. Portwalk’s center will be a one-way vehicular and pedestrian “Broadwalk” connecting buildings with brick sidewalks lined with trees and outdoor cafes.

Bringing back pedestrian rhythm
“What the earlier work (phase one) did was bring good urban design principles of using buildings to define public realm and extend the pedestrian connections of the city,” says David Manfredi, AIA, principal at Elkus Manfredi Architects. “Our project gives us the opportunity to create out toward the surrounding city, re-establishing a street grid covered over in the ‘60s to create a suburban super block. The new project gives back the rhythm and scale of the city that was there before, knitting back part of what was lost. We’ve broken it down into smaller parts that have bisecting paths, reversing the scale by creating new streets and extending paths to the surrounding streets. For Portsmouth, it’s really a big project—a big urban block, or four small blocks.”

Tom Kinslow, AIA, architect, Elkus Manfredi Architects, says one of the LEED design credits they are going to pursue is the re-encouragement of the pedestrian path. “By re-introducing these rows and streets it will be even more of a walkable city. There will also be a loop around downtown into the site.”

Broadwalk bisects the site down middle, Manfredi describes. “Broadwalk is actually a new street that extends the mall. It was a pedestrian way, but we are extending it to be a true vehicular street.”

Kinslow explains how Broadwalk was named: “It will be referred to it as Broadwalk because the landscape architects identified one side as being sunnier than the other, so one side will be broader, extending pedestrian circulation. Shops and cafes will be built out but not hamper circulation.”

Portsmouth’s historic context; LEED strategies
Portwalk’s design centers on the historic context of surrounding Portsmouth, Manfredi notes. “Our palette is stone, brick, and a little bit of metal. That comes out of the existing palette. Our goal was to understand the underlying fabric, rhythms, and interesting design precedents of the city, such as how the city has historically treated corners and interior block buildings. Our buildings don’t mimic that historic context—they are clearly new buildings—but they understand those underlying rhythms. They are framed buildings in the historic context, and the scale of fenestration and the rhythm of structural base come out of that existing fabric.”

LEED core-and-shell strategies will be incorporated, Kinslow adds. “We will make the roof more reflective and lighter, introduce pervious areas, and put parking underground so other portions of the site can be utilized for building and city-making, as opposed to the parking desert that it is right now. We will tighten the buildings for energy efficiency and manage the site waste and construction process for LEED prerequisites.” Portwalk will also be close to bus lines and provide bike storage.

Opportunity in a quintessentially small New England town
Manfredi says Cathartes Private Investments saw a mixed-use development opportunity in Portsmouth. “It’s a great small city and stays active in wintertime. It has a very walkable downtown, a waterfront, local retail, a managebable street grid, good tenants, and good coporate citizens. It’s the quintessential small New England city.”