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UrbanToronto is celebrating Earth Month throughout April with features that examine the issues and challenges of sustainability in the development industry.
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When it comes to talking about sustainable development, much of the conversation revolves around new construction and how we can create buildings that are more energy-efficient with lower carbon footprints. But there is a popular saying in the heritage community: the greenest building is the one that already exists. In recent years, the conversation around sustainability has broadened to include heritage preservation and the retrofit of existing buildings as one of the most effective ways to achieve sustainability goals. Heritage and sustainability go hand-in-hand, and there are many different aspects to heritage preservation that are integral to achieving a truly green urban environment.
To better understand the relationship between heritage and sustainability, UrbanToronto spoke with Dima Cook, Principal at EVOQ Architecture and Chair of the Canadian Association of Heritage Professionals (CAHP) Advocacy Committee, which focuses on how retrofitting and adaptively reusing heritage buildings can contribute to sustainable development goals.
The most obvious relationship between heritage and sustainability is through embodied carbon. Simply put, renovating and maintaining an existing building consumes vastly less energy than demolishing and building new. As Cook explained, the savings mainly come by avoiding carbon emissions: the construction of a new building emits massive amounts of carbon, through the manufacturing process of its materials and the process of assembling them on the construction site, which is completely avoided when retrofitting the existing building. It also prevents large amounts of existing materials being thrown away; it is estimated that roughly 20% of all landfill deposits in Canada come from construction waste. A study completed in 2011 by the National Trust for Historic Preservation in the US found that, “it takes between 10 and 80 years for a new building that is 30% more efficient than an average-performing existing building to overcome, through efficient operations, the negative climate change impacts related to the construction process”.
There is a common myth that older buildings are by nature inefficient, and replacing them with new, energy-efficient structures is the best way to build a more sustainable city. Cook stresses that this, however, has repeatedly been proven false. A recent study by the US Department of Defense examined all of their pre-World War II masonry building stock and concluded that it would be significantly less expensive to modernize their existing buildings with new energy-efficient systems rather than demolish and build new, and their sustainability targets would still be achieved. A similar study in Chicago found that their historic pre-war skyscrapers were inherently more efficient than the post-war glass towers, due to their thick masonry walls; smaller floor plates; higher ceilings; punched windows in lieu of floor-to-ceiling glass; and natural ventilation.
A high-profile example of a heritage building retrofit is the iconic Empire State Building in New York City, which recently underwent a comprehensive $550-million overhaul to modernize the 94-year-old tower. A big part of the renovation focused on making the building more energy efficient. All of the building’s systems were improved or replaced, from the elevators recapturing energy that would be lost to heat, to the radiators minimizing heat loss with reflective barriers, to the lighting system adapting to daylight using new energy-efficient fixtures. Every one of the 6,514 windows in the tower were retrofitted, quadrupling their performance, with roughly 96% of the existing materials being reused. When it comes to sustainability, the Empire State Building is now in the top 20% or higher of all Class A commercial buildings across the entire USA.
Closer to home, the Evergreen Brickworks is a good example of sustainable adaptive reuse in Toronto. In 2010, the former Don Valley Brickworks complex was transformed by Evergreen into a centre for social and environmental sustainability. Much of the existing building stock was retained and reused, with new structures slotted in between. More recently, Evergreen transformed the Kiln Building into a carbon-neutral event space in 2017. The designers took a minimal-touch approach, leaving most of the building in its original state, while making targeted interventions - implementing geothermal heating and cooling; installing a raised floor level to protect from flooding complete with radiant heating; installing skylights for natural ventilation; and adding a triple-glazed curtain wall to infill large openings in the structure for weather protection. The remainder of the building was left as is, including all of its graffiti and imperfections.
The link between heritage and sustainability goes beyond buildings as well. The conservation of natural heritage is an integral part of sustainability, with a focus on landscapes and ecosystems that are specific to the local area. Take, for example, Toronto’s ravine networks, which not only provide popular green spaces that are essential for a healthy urban environment, but also preserve native flora and fauna species that have been largely wiped out by the sprawl of the city. Their conservation is not only imperative for maintaining a green and sustainable city, but also for preserving our natural and cultural heritage, as ravines have been an important resource for Indigenous peoples, colonial settlers, and modern-day residents throughout the history of Toronto.
The construction of Villiers Island and reshaping of the mouth of the Don River is also a form of heritage reconstruction. The project is creating a new naturalized mouth for the river, whose outlet to the lake had been completely reconfigured over the last century due to industrial development at the waterfront which has routinely caused flooding. The project is now recreating a natural outlet into the lake, thereby reducing the flood risk and restoring natural wetlands to the area, using native plant species and fostering habitats that will attract local birds and wildlife back to the industrialized area.
Natural heritage is not a static thing either, it also extends to living practices in how we care for our natural spaces. Prescribed burns have been conducted in High Park over the past two decades to help preserve the park’s rare black oak ecosystem. This practice, however, is nothing new, as Indigenous Peoples regularly engaged in controlled burns in pre-colonial times as a way to encourage new growth and keep the land clean. Indigenous knowledge has come to the forefront for the preservation of our natural heritage, and is essential to maintaining our fragile ecosystems in sustainable ways.
Heritage preservation also has benefits when it comes to social sustainability. The preservation of buildings and landscapes that are culturally significant contribute to a more vibrant urban environment, where residents can relate more to their surroundings and are more engaged with their cities which actively represent and display their culture and history. Older buildings often have lower rents and unique spaces that fill a crucial role in the real estate market, and are also often located in denser neighbourhoods that encourage walkability and transit use. As well, when it comes to restoring old buildings, the majority of the construction costs are spent on labour rather than materials, so the money is reinvested back into the local community.
Despite the benefits of preserving existing buildings, the focus on sustainability is still on new construction. Cook lists several reasons as to why there is still a lag in our understanding of these issues. A major one is the lack of expertise and knowledge in the assessment, treatment, and design approaches to existing and heritage buildings across the construction industry. Architects, engineers, contractors, and owners are typically educated in new construction, and each discipline exists within a silo where each prioritizes their own data and fails to understand the bigger picture. When making decisions about whether to renovate, restore, or build new, the experience and collaboration required to make informed decisions is simply lacking.
As well, Cook points toward overly prescriptive requirements that are not adapted to existing buildings. The Building Code, for example, is heavily weighted toward new construction in its requirements, and does not always take into account the unique circumstances of building retrofits. Environmental standards such as LEED only focus on new construction, and do not offer any targets geared to maintaining existing buildings. Life cycle assessments are often missing entirely from design processes, and energy audits frequently focus only on mechanical and electrical systems rather than regarding the building as a whole.
There is also little financial incentive from governments to maintain existing building stock. While grants and tax rebates do exist, these are often delegated to municipalities to dole out, with no consistency across provinces or at the federal level. As well, they are often only for buildings that have been designated as heritage, which ignores the majority of existing structures. The incentives that do exist are sometimes misguided; for example, the federal government offers grants for homeowners to make their houses greener, which includes money for replacing the existing windows - but it offers nothing for restoring or retrofitting the existing windows of your home. With so much of the political discussion these days revolving around housing supply and affordability, the incentives being offered overwhelmingly favour new construction; what can be done with our existing buildings that may contribute to the housing supply is notably absent from the conversation.
All this to say, the bias against preserving existing buildings is a systemic issue. As a society, we tend to value the new and shiny over the worn and used, but this attitude is counterintuitive to any sustainability goals we may strive to achieve. Heritage preservation is inherently green, and in order to take meaningful strides to reducing our greenhouse gas emissions, the construction industry and our governing bodies must work together to reshape the conversations around sustainability so that existing buildings and landscapes become an integral component of the way forward.
The vast majority of our built environment already exists, and will continue to exist far into the future. The key to creating more sustainable cities lies in how we deal with what we already have; without this, we are only fighting half the battle.
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UrbanToronto has a research service, UrbanToronto Pro, that provides comprehensive data on construction projects in the Greater Toronto Area—from proposal through to completion. We also offer Instant Reports, downloadable snapshots based on location, and a daily subscription newsletter, New Development Insider, that tracks projects from initial application.
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Thank you to the companies joining UrbanToronto to celebrate Earth Month.
