A Second Life for Tall Buildings

Every North American, European and Asian city with a significant skyline will face a complex challenge over the next two decades, as they grapple with the need to curtail greenhouse gas (GHG) emissions and the materials and components of their tall buildings will reach the end of their natural life span. The number of buildings involved is staggering — Singapore, Hong Kong, New York City and Toronto alone have close to 20,000 buildings that are over 12 storeys.

While Singapore and New York boast iconic buildings that date to the 1930s, the vast majority of towers in Europe and North America were built in the 1960s and 1970s, while the tall buildings in Asia date from the 1980s and 1990s. This means a significant number of tall buildings around the world are now between 30 and 40 years old, an age at which major systems and components need replacement.

These buildings not only show the effects of everyday wear and tear, but were designed in a time when energy costs were low and the awareness of GHG emissions did not exist. Today, buildings account for the lion’s share of GHG emissions — 48 per cent of all GHG emissions and fossil fuel energy consumption — and as awareness about how emissions affect global climate change and the cost of power increase, governments are developing legislation and policy incentives to help building owners undertake sustainable retrofit projects. A recent McGraw Hill Construction report projects a rise in green retrofit and renovations from a $2 to $4 billion market to a $10 to $15 billion market by 2016. Currently, green building comprises five to nine per cent of the retrofit and renovation market activity by value and is projected to grow to 20 to 30 per cent in just five years.

Unless a building has serious structural issues, tearing it down is rarely an option; it is financially prohibitive, difficult and time-consuming. The cost of rebuilding is also high in dollars and time — it can cost upwards of C$250 per square foot for new construction, with a timeline of at least four years. Many tall towers are also landmarks that can’t be demolished.

Since building structures are generally designed for a 100 year durability timeline, retrofits are perfect for bringing a building back to life for less than half the cost of new construction. An envelope re-skinning is 15 to 20 per cent of the cost of new construction, or less than C$100 per square foot.

Drivers of Renewal

Significant energy savings are realized by replacing or retrofitting the building envelope and performing mechanical and electrical retrofits. The energy cost saving can range dramatically, depending on the building’s location and whether it was originally constructed with insulation. Typical American commercial buildings achieve a 10 to 50 per cent energy savings.

The condition of a building is a key factor for attracting and retaining tenants. A building must be maintained to the highest standards to keep its status in the leasing hierarchy, procure premium rents and attract the world’s leading companies. Companies who value innovation and social responsibility are increasingly looking for green building renovations, which can garner significant rental premiums for buildings that meet these criteria. Revitalization is also motivated by the desire to improve tenants’ physical comfort.

Mitigating the safety risk of failing panels (and the associated public relations and economic costs) is another factor that drives the revitalization of tall buildings. Failures can range from the catastrophic to the quotidian, including: falling building parts such as pediments and cladding panels; failing systems including elevators and escalators; and aging faulty wiring and plumbing. Many building owners have no way of monitoring building failure as part of due diligence because the building’s height poses additional challenges.

Because of commercial buildings’ rampant energy use and GHG emissions, more governments and organizations are also introducing incentives to help building owners undertake sustainable re-cladding and retrofit projects. Financial incentives are increasingly common, for example the Singapore Building and Construction Authority introduced a $100 million Green Mark Incentive Scheme for Existing Buildings to encourage building owners to retrofit their buildings, and the U.S. offers a similar program through Energy Service Agreements and Property Assessed Clean Energy bonds.

In 2007, the City of Toronto developed a framework to reduce GHG emissions in the city. The “Change is in the Air: Toronto’s Commitment to an Environmentally Sustainable Future” sets several reduction targets, including: reduce GHG emissions by 30 per cent below 1990 levels in the Toronto urban area by 2020; reduce GHG emissions by 80 per cent by 2050; and reduce smog-causing pollutants by 20 per cent by 2012. Recognizing that buildings cause a large percentage of GHG emissions, the City proposes to develop financing for high-rise rental and condominium energy efficiency retrofits. The Better Buildings Partnership New Construction Program [BBP-NC] was established to encourage building owners to design buildings to be more energy efficient than those designed to only meet the minimum requirements of the Ontario Building Code. Eligible buildings include commercial, industrial and multiunit residential buildings that are being constructed under Part 3 of the Ontario Building Code.

Retrofit Challenges

One of the greatest challenges of revitalizing tall buildings is that the retrofit must often be conducted while the building is operational. Changing the windows on a 50-storey tower while companies conduct business is no easy task. As illustrated by Toronto-Dominion Centre and First Canadian Place, it often involves developing state-of-the-art processes for managing retrofits with minimum disruption to tenants, combined with inventive solutions for dealing with the particularities of construction, as every tall building is uniquely structured and clad.

Building owners and managers also face several financial and technical challenges with a revitalization project. The process often starts with a branding challenge which relates to the tower’s ability to maintain its status and qualitative rating in its local real estate market. In addition, the capital costs and life cycle costs of a building are not easily tied together, and while interest rates are low, it is not easy to get a bank to fund a building retrofit. A recent McGraw Hill study indicates that green retrofits are financed almost entirely from operations revenue. Many building owners use alternative financing measures in addition to company profits: for example 41 per cent also use energy-efficiency savings that result from retrofits/renovations and 14 per cent use performance contracting.

Financing varies widely between building types. Research such as the McGraw Hill study shows that financing for a retrofit is often derived from operating cash flows. In the case of prestigious Class A towers (usually privately owned by large developers or governments), financing is not an issue: competitive pressures, market presence and the occupants’ safety and comfort are paramount and drive the retrofit.

Financing retrofits of aging Class C buildings and housing towers pose huge social, financial and environmental challenges, whether they are privately or publicly owned. For example, 30 and 40 year old social housing projects and condominium towers with poor maintenance records are now in dire need of repair and pose a huge challenge to owners, occupants and cities, which may need to step in and remediate. 

First Canadian Place

Originally completed in 1975 and still unrivalled as Canada’s tallest office tower, First Canadian Place established a new standard in the design and construction of tall buildings. Innovative from its inception, First Canadian Place (FCP) incorporated many design, construction and engineering firsts, such as b
eing one of the earliest examples of structural tube steel construction. Its design also included double-decker elevator cabs and a state-of-the-art mechanical infrastructure with enormous fresh air capacity. B+H was the architect of record and worked with design architect Edward Durell Stone (1902-1978).

At almost 35 years of age, FCP reached a critical point in its lifespan, suffering from many common ailments a building of its generation can face. So in September 2009, owner Brookfield Properties and its partners embarked upon an extensive rejuvenation of the 72-storey tower involving re-cladding the exterior; renovating the office lobbies and retail areas; and extensive mechanical and electrical systems upgrades.

The exterior treatment is complex and technically challenging. The 45,000 marble panels that make up the building’s skin will be removed and replaced by over 5,600 white fritted glass and bronze glass panels that will once again give FCP’s façade a commanding silhouette on Toronto’s skyline.

Many other aspects of the renewal are invisible and systemic, including mechanical and electrical system upgrades. Interior renewals include updated lobbies, staircases, water features, an underground market and retail areas. According to Tom Farley, president and CEO of Canadian Commercial Operations for Brookfield Properties, “This rejuvenation program will reinforce the iconic status of one of Canada’s most prominent and recognizable buildings.”

Project Challenges  

How do you undertake a massive internal and external renovation with minimal disruption to tenants? Re-skinning a building of the size and scale of FCP was unprecedented. Each marble panel weighs 90 kilograms, so safely and systematically removing each panel was critical to this challenge. In order to do so, a highly sophisticated scaffolding system was designed specifically for this project. Beginning at the top and working its way down, this unique system is mechanically connected to the building giving it the ability to scale up and down the building.

The scaffolding unit is a three-storey movable platform with 14 separate sections that can hold up to 160 workers at a time. On average, it takes three days for 80 workers to replace all of the marble on an entire floor. In order to minimize tenant disruptions, work on the building is done in three shifts, the loudest and most disruptive work done at night so as not to disturb the tenants in their offices.

The marble panels are removed on the bottom level of the platform. After this, workers remove the sealant, stone and panel support brackets, which is then wheeled to the elevator hoist. The installation of the glass panels then begins on the top level of the platform. The 450-kilogram glass panels are transported to the platform by an elevator hoist and carried across by monorail.

The new glass panels are being sourced and manufactured locally, less than 50 kilometres from the site, significantly reducing the carbon footprint. Additionally, the 45,000 marble panels being removed will not end up in a landfill. Instead, each panel is being recycled and repurposed for multiple uses including concrete, base product under roadways, landscaping, and community art projects.

The project is presently undergoing LEED EB&OM certification, a process that includes significant building retro-commissioning and energy benchmarking. This process will naturally lead the owners and designers to become intimately aware of the building performance and how it can be improved. The process is also inherently ongoing, requiring a commitment to establish and achieve goals and maintain performance levels. Additionally, the re-skinning is taking place within a spectrum of retrofit strategies, many of which focus on energy optimization such as: new heat recovery chillers; new high efficiency condensing boiler installation; retrofitted and re-calibrated induction system; scavenger exhaust heat recovery; and new lighting and lighting controls.

 

Aesthetics

It was imperative for both the owners and the designers that the building maintains its iconic image and commanding presence on the skyline while also enhancing it. The design solution was therefore to renew the image while paying homage to the original Edward Durrell Stone design. The beautiful white colour of the original Carrara marble had lost its lustre, succumbing to years of weather damage and pollution. The designers chose to use modern glass technology that could restore the whiteness of the building while adding sharpness and flair. The slim build of the tower was accentuated by tinted glass in the re-entrant corners, giving the tower a sleeker but highly-recognizable look.

Toronto-Dominion Centre

Commissioned by the Chairman of TD Bank, Allen Lambert, in partnership with Fairview Corporation, the Toronto-Dominion (TD) Centre is arguably the heart of Toronto’s financial district. The complex is arranged around a granite-paved pedestrian plaza and originally consisted of three buildings: the 56-storey TD Bank Tower (1967); the one-storey Banking Pavilion (1968); and the 46-storey Royal Trust Tower (1969). All three original buildings were designed by Ludwig Mies van der Rohe, one of the seminal modernist architects of the 20th century, working in association with B+H and John B. Parkin Associates.

After completion of the TD Bank Tower in 1968, construction methods were evaluated and refined for the second tower, the Royal Trust Tower. Its steel cladding was pre-assembled into large panels to speed and simplify construction. The panels were two-storeys (24 feet) high and 30 to 40 feet wide. The pre-assembly technique was developed after a study of steel construction methods used for the TD Bank Tower, in which sections of cladding were erected piece by piece.

Revitalizing a Living Heritage Monument

An icon in Toronto and one of the world’s most important examples of Mies van der Rohe’s large projects, the TD Centre one of the only modernist buildings to receive Ontario Heritage Act designation (2003). Because of its historical significance in the city, the decision to undertake a complete revitalization was not taken lightly. In May 2010, Cadillac Fairview Corporation announced that it would begin revitalization of the TD Centre, starting with the Royal Trust Tower. After a major tenant moved out of the Royal Trust Tower, suddenly vacating 17 floors, Cadillac Fairview seized the opportunity to revitalize the property as part of a strategy to attract tenants in an increasingly competitive commercial real estate market.

The primary challenge of this project was to ensure that all interventions remain true to the original design by Mies van der Rohe. Under the Ontario Heritage Act, no owner of historically-designated property is permitted to alter the property in a way that is likely to affect its attributes. In addition, the client wanted to replace the windows with minimal disruption to the tenants. The revitalization includes replacing the existing windows, painting the exterior, performing mechanical and electrical system upgrades, replacing elevators and a complete renovation of the lobby and exterior plaza.

The renovation of the plaza, now called Oscar Peterson Square, is a critical component of the revitalization. Over the course of the plaza’s life, cracks in the thick, honed granite pavers were simply patched, resulting in a quilt-like appearance in the stone. Intact original pavers are being repurposed to replace broken pavers, and the waterproofing under the plaza is being replaced.

Renewal is in the Details

“…I am hopeful that The Toronto Dominion Center will become one of the finest of building groups; but this can be so only if we set certain standards below which we never fall. In my opinion, a building is fine precisely because of an accumulation of such standards-from the top to the bottom and every det
ail.”
   – Mies van der Rohe, in a letter to Sidney Bregman, July 5, 1966

To guarantee the meticulous historic preservation of this architectural gem, B+H is working with noted heritage architect Michael McClelland of E.R.A. Architects. The team has gone to great lengths to ensure that all of the interventions remain true to Mies van der Rohe’s original design vision.

When it came time to choose paint for the exterior of the building, the team travelled to Chicago to meet with consultants at the firm Wiss Janney Elstner and Associates. It took two months and several mock-ups to select the most appropriate paint to match the original, unique graphite paint. Some 5,676 single pane windows are being replaced with double-glazed thermal pane windows that are tinted bronze to match the originals and reduce heat loss by 50 per cent.

During replacement, considerable care was taken to minimize disruption to tenants. Instead of starting the retrofit from the top down or the bottom up, the windows are systematically replaced based on tenant occupancy, with vacant floors and offices retrofitted first. The windows are replaced using a swing stage that can support six workers who work overnight. The furniture is moved to the interior of the building to give workers unobstructed access to the windows. Workers cut out the existing windows and install the new ones. Once work is complete, the furniture is returned to its original location. At a rate of 16 windows per night, it takes just over a week to replace the 132 windows on each office floor.

The exterior of the building was not the only challenging aspect of this project. The interior, also designated as a heritage space, required significant care and detail. For example, to restore and repair the existing glass mosaic tile ceiling, the design team spent over two months searching for matching tiles. With no success, they decided to remove the mosaic ceiling so the tiles could be cleaned, polished and repaired. The existing ceiling was cut down into 3-ft. by 3-ft. pieces with the drywall still attached. The pieces were then soaked overnight and tumbled so crews could pan for tiles to clean and polish them. This process resulted in a 20 per cent loss, so new glass tiles were blended back in with the original tiles, re-assembled onto 1-ft. by 1-ft. sheets and re-installed.

In the lobby, the office directory and information desk were redesigned to keep much of their original material. The information desk maintained its original granite surround and internal structure. Only the interior of the desk was changed to allow space for computers and storage. The directories were also updated with touch-screen monitors.

“It is so easy to spoil a fine space by introducing arbitrary elements; I ask you to imagine the lobby of The Seagram Building with a cigar stand! I feel that our lobby in Toronto should be seen at its best right from the moment that the public has access to the building.”– Mies van der Rohe, in a letter to Sidney Bregman concerning an idea to place a temporary pavilion in the tower lobby until the banking pavilion was in operation.

Douglas Birkenshaw and Kevin Stelzer, both Principals at B+H, are currently the Principal-in-Charge and Director for the First Canadian Place renewal, respectively.

SIDEBAR

Renewal by the Numbers

 

First Canadian Place

  • 5,625 fritted glass panels replace 45,000 marble panels
  • 80 glass panels cover one floor (vs. 320 marble panels)
  • Each glass slab weighs 450 kg
  • Each marble slab weighs 90 kg
  • On average, it takes three days for 80 workers to replace the panels on one floor
  • The custom-designed construction rig weighs 113,000 kg, is 15 meters high, supports 160 workers and can withstand winds up to 265 kph
  • The fritted glass panels are locally sourced
  • Lifespan of the glass: 100 years

Original Construction

  • 1.3 million man hours saved thanks to the advanced building technologies
  • 48,7741 sq.m. or 120,000 sheets of drywall – if stacked, the sheets are nearly eight times the height of the finished building
  • In a traditional building, it would take 6.3 minutes to bring a sheet of drywall into the building, versus 1.0 minute per sheet for First Canadian Place
  • 4,400 tonnes of marble – enough to build a 26 km sidewalk from Toronto City Hall to Port Credit
  • 46,450 sq.m. of insulation- enough to cover 8 football fields
  • 56,600 linear feet or about 17 kilometres of window

Project Team

Original Building Architect of Record: B+H

Original Building Design Consultant: Edward Durell Stone

Retrofit Architect of Record: B+H

Retrofit Design Architect: Moed de Armas & Shannon

Retrofit Consultant Team         

Construction Managers: EllisDon

Structural Engineer: Halcrow Yolles

Engineering Consultant: Brook Van Dalen        

Preconstruction Engineers: Halsall Associates Ltd.

Toronto-Dominion Centre

  • 132 windows per floor X 43 floors = 5,676 windows total
  • A crew of 16 workers can replace 16 windows in one night
  • Royal Trust Tower: 600 feet (46 floors)
  • Structural steel weighs 23,500 tons

Project Team

Original Design Architect: Ludwig Mies van der Rohe (1886-1967)

Original Architects of Record: John B. Parkin Associates and Bregman + Hamann

Architects (B+H) -in joint venture

Retrofit Architects: B+H

Structural: EXP

Mechanical & Electrical: H.H. Angus

Lighting Design: Gabriel McKinnon

Vertical Transportation: KJA

Landscape: Janet Rosenberg + Associates

Heritage: E.R.A.

Painting Consultant: Wiss, Janney, Elstner Associates Inc.

Envelope Consultant: ZEC

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