Reducing The Carbon Footprint: Updating and re-skinning building façades

April 1, 2012

Photo © Tom Arban [1]
Photo © Tom Arban

By Ron Dembo, PhD
Greenhouse gases (GHGs) are being released into the atmosphere with potentially devastating consequences. A large amount of GHGs from this country can be attributed to operating buildings, but not enough is being done to reduce this.

Scientists calculate the concentration of carbon dioxide (CO2) needs to be stabilized in the atmosphere at no more than 350 parts per million (ppm) to prevent runaway global warming. However, the atmosphere is already at 390 ppm, and it is being added to at roughly 2 ppm annually. (See the U.S. Department of Commerce National Oceanic and Atmospheric Administration (NOAA) Research Earth Systems Research Laboratory’s “Trends in Atmospheric Carbon Dioxide.” For more, visit www.esrl.noaa.gov/gmd/ccgg/trends[2]). In other words, not only does the increase of global carbon emissions have to be slowed, but the process also has to be turned around, and fast. Much can be done, but when looking at the major sources of carbon emissions and where the efforts are currently directed, there is one area where the surface has barely been scratched—the world’s buildings.

Forty-one per cent of total GHG emissions in Canada can be attributed to operating buildings––heating, cooling, and lighting them, and providing hot water. (See “Tackling Global Climate Change: Meeting Local Priorities,” by the World Green Building Council (WGBC) from September 2010. Visit www.worldgbc.org/site2/index.php?cID=98[3]). Globally, buildings contribute to 40 per cent of worldwide energy use and 30 per cent of GHG emissions. For example, the carbon footprint of Toronto’s buildings make up 60 per cent of the city’s total GHG emissions. (For more information, visit the City of Toronto website at www.toronto.ca/environment/buildings.htm[4]).

For the issue of global warming to be successfully tackled, it is clear something has to be done about the carbon footprint of buildings. More than 90 per cent of buildings in most cities are old, and most of them will still exist in 2050. However, building efficiency is about more than just the quality and age of physical infrastructure––it is also about how the building is used.

This aging and energy-inefficient residential and office stock has to be tackled, but tearing it all down and replacing it with new, high-performance buildings is not practical. This destruction would generate overwhelming amounts of waste, consume unimaginable levels of resources (e.g. carbon-intensive cement), and cost a fortune. Further, it would take decades, if not centuries, to accomplish––far longer than the planet has for things to improve. The only choices left are to retrofit entire cities and change behaviour on a massive scale so occupants maximize the energy efficiency potential of buildings.

There are now well-established techniques that improve old buildings, such as upgrading heating and ventilation systems, fitting low-energy lights, and draft-proofing. Retrofitting programs for old buildings are underway around the globe in cities like Johannesburg, South Africa, Mexico City, and Mumbai, India. However, interior retrofits alone will not bring the reduction needed in the carbon footprint. A huge cause of energy inefficiency in older buildings is also their lack of insulation. Without an adequate thermal break between the interior and the outside world, older buildings just soak up heat in the summer and leak it away in the winter. Retrofitting older buildings will not be successful without new ways to design and insulate their external envelopes. In effect, what these buildings need is a new ‘skin.’

Each perforated metal panel of the exoskeleton of The Palms, a residence in Venice, Calif., is made of recycled steel shaped to form an undulating pattern. They change the density of the site and provide additional living areas by making the building envelope inhabitable, without increasing the home’s environmental impact or compromising the residents’ privacy. Photo © Jason Schmidt[5]
Each perforated metal panel of the exoskeleton of The Palms, a residence in Venice, Calif., is made of recycled steel shaped to form an undulating pattern. They change the density of the site and provide additional living areas by making the building envelope inhabitable, without increasing the home’s environmental impact or compromising the residents’ privacy.
Photo © Jason Schmidt

Many old buildings have had their exteriors refurbished. Re-skinning, however, goes much further than just adding a layer of cladding to the outside of a tower block to freshen up its look or protect its deteriorating exterior. In addition to adding an essential layer of insulation, a new skin can hide added piping, cabling, and other systems, which can make retrofitting internal energy-efficient systems quicker and cheaper. A well-designed re-skinning project can also upgrade a building’s façade, rejuvenating its esthetics while making it a more comfortable, energy-efficient place to live or work.

Re-skinning is about looking at the building as a whole and rethinking the very process of retrofitting. It is about tackling the major cause of building energy inefficiency head-on, and creating a proper thermal barrier so all the internal improvements made in terms of lighting, heating, and so on can have their full impact. Even the very word ‘re-skinning’ is part of rethinking how one looks at buildings; it is part of a shift toward seeing buildings as living, breathing participants in cities.

Advances in re-skinning
The first thing that must be done is identifying and communicating current innovations and best practices. To stimulate advances in re-skinning design and technology, a software company introduced an annual re-skinning awards program in 2010. Now in its third year, the initiative has received the support of partners such as the United Nations Human Settlements Programme (Un-Habitat) and the John H. Daniels Faculty of Architecture, Landscape, and Design at the University of Toronto (U of T). Winners of the awards demonstrate exemplary and reproducible efforts to transform old buildings through holistic retrofitting.

First Canadian Place
A finalist in the commercial/industrial category in the 2011 re-skinning awards, Toronto’s First Canadian Place was considered innovative at the time of its initial construction in 1975 because it featured many design, architecture, and construction firsts, such as a very high fresh air capacity and structural steel tube construction. However, 35 years later, Canada’s tallest office tower was showing its age. Its marble façade was beginning to crumble and outdated internal components consumed too much energy.

An ambitious retrofit saw 45,000 exterior marble panels replaced with 5600 larger ones made from locally-sourced fritted glass. Workers used an innovative moveable scaffolding system that allowed work to be done around the clock without disturbing employees inside. The three-storey apparatus included a monorail to carry glass panels along the platform, and could transport up to 160 workers at a time. The marble panels were later recycled into material for construction, roadways, landscaping, and community art projects.

The water, electrical, and mechanical systems were also updated with more modern components. New high-efficiency boilers and heat-recovery chillers further reduced energy consumption. Assessment for certification under the Canada Green Building Council’s (CaGBC’s) Leadership in Energy and Environmental Design (LEED) Existing Building: Operations and Maintenance (EBOM) program is underway. An integral part in obtaining this LEED certification was incorporating smart energy management systems into the design. This meant the retrofit had to include:

The building also implements an innovative ‘demand response charge reduction’ strategy to reset office floor temperatures from approximately 24 to 26 C (75 to 79 F) and dim office lighting by agreement with Ontario Power Generation (OPG) during peak times. Due to significant building size and large air volume, there is a substantial thermal lag. It would take three hours before noticeable temperature variation occurred; in the meantime, the power authority reserves the power.

Toronto’s Artscape Wychwood Barns uses lighting controls and occupancy sensors in all public areas to limit the use of electric lighting when adequate daylighting is available. Photo courtesy du Toit Architects[6]
Toronto’s Artscape Wychwood Barns uses lighting controls and occupancy sensors in all public areas to limit the use of electric lighting when adequate daylighting is available.
Photo courtesy du Toit Architects

355 Eleventh Street
The 2010 overall winner for the re-skinning awards was 355 Eleventh Street in San Francisco. Originally constructed in 1912 as a warehouse for a local brewery, the building had become derelict and an eyesore by 2008. Nevertheless, it was protected from demolition because of its historical significance. When a green building contractor bought the building to develop as its new headquarters, it aimed to make it a showcase of its commitment to sustainability and its proficiency in modern building techniques. Given the original warehouse’s generic utilitarian design and construction––corrugated sheet metal nailed to a timber frame––a successful refurbishment would be applicable to tens of thousands of similar old buildings in cities around the world.

The designers, Aidlin Darling Architects, faced a challenge in reconciling the new owner’s requirements of ample light and air with the city’s planning constraints that stipulated no new windows, and insisted any replacement of the outer corrugated sheeting had to be ‘in kind’ to maintain the building’s industrial character.

The solution was to fit the building with a new façade perforated with fields of small holes that allow light and air to pass through while screening out direct sunlight. Behind this new skin, they set opening windows to allow controlled cross-ventilation of the interior. The gap between the outer façade and the inner construction acts as an insulating buffer. A green roof was planted with drought-resistant native or adapted plant species for filtering stormwater, insulating the building, and decreasing the urban heat island (UHI) effect.

The building’s new skin not only prevents solar gain and provides passive cooling of the interior while meeting listed building planning constraints, but it also gives the building a facelift––transforming it from a mundane run-down structure to an esthetically attractive modern building. Due to its natural ventilation and lighting and thermal buffer, among other improvements, the building is extremely energy-efficient and has received LEED Gold certification. The re-skinning methods used on 355 Eleventh are low-tech, cost-effective, and could be replicated on a global scale.

The Palms
The 2011 overall winner was The Palms in Venice, California––a private house whose owners wanted to add livable space for their relatives without increasing their home’s footprint. They also wanted to implement sustainable technologies to minimize its carbon footprint.

In Aachen, Germany, HKW building’s skin provides weather protection, an anti-dazzle shield, and striking esthetic value to a formerly derelict building. At night, the curtain wall is backlit in a bright orange, mimicking glowing embers of coal as a reminder of the building’s historic use as RWTH Aachen University’s heating plant. Photos © Hendrik Daniel[7]
In Aachen, Germany, HKW building’s skin provides weather protection, an anti-dazzle shield, and striking esthetic value to a formerly derelict building. At night, the curtain wall is backlit in a bright orange, mimicking glowing embers of coal as a reminder of the building’s historic use as RWTH Aachen University’s heating plant.
Photos © Hendrik Daniel

The design team––architects Daly Genik, structural engineers Energy Code Works, consultants Title 24, and landscape architects Polly Furr Venice Studio––came up with a solution where the addition of an exoskeleton armature of corrugated recycled steel panels supports new balconies, giving the small property 214 m2 (2300 sf) of total living space. All indoor space opens to outdoor space, maximizing airflow and minimizing the need for cooling in summer. The exoskeleton also dampens sound and provides shading for the house’s inhabitants. The steel exoskeleton is an easily reproducibly design, a variation of which Daly Genik has already used to upgrade the façade of a charter high school in Los Angeles.

Green performance
First Canadian Place, 355 Eleventh Street, and The Palms are examples of excellence in re-skinning and are helping to drive innovation in green building, along with energy efficiency construction programs such as LEED, Energy Star, and Germany’s Passivhaus standard. However, as mentioned earlier, building energy efficiency is not just about the infrastructure, but about occupant behaviour as well.

LEED, Energy Star, and Passivhaus have set benchmarks for what can be achieved in building construction or refurbishment, but the standards alone are not enough. As currently specified, they do not account for occupant behaviour once the projects are completed. This can undermine the whole purpose of such standards if energy-efficient light bulbs are fitted and left on all night, if windows are fitted for passive cooling but are shut and an energy-intensive air-conditioner is turned on instead, or if taps are left running. Unfortunately, there are numerous examples where LEED-certified or other low-energy specification buildings have been found to perform no better than comparable buildings with no rating.

The problem is rating systems such as LEED only predict how a building might perform, and do not measure how it actually performs. If carbon emissions can be cut by any significant amount, the way people behave inside these buildings also has to be changed. Conforming to a rating system like LEED will ensure the occupants have all the tools they need to operate the building efficiently and sustainably, but there has to be a way of making them aware of how they are using energy. To do this, energy use must be made more tangible.

To safely execute the recladding, a custom scaffolding system was designed and built. This unique three-storey platform was mechanically connected to the building, allowing it to easily scale the tower. The 450-kg (992-lb) glass panels were brought to the platform by an elevator hoist and moved across the platform by monorail. On average, it took three days and 80 workers to replace all of the marble panels on an entire floor. Images courtesy B+H Architects[8]
To safely execute the recladding, a custom scaffolding system was designed and built. This unique three-storey platform was mechanically connected to the building, allowing it to easily scale the tower. The 450-kg (992-lb) glass panels were brought to the platform by an elevator hoist and moved across the platform by monorail. On average, it took three days and 80 workers to replace all of the marble panels on an entire floor.
Images courtesy B+H Architects

The problem with carbon emissions is they cannot be seen. It is not just that CO2 is a colourless gas; most emissions are elsewhere and out of sight––certainly when it comes to electricity. Unless one lives in view of a power station and can see the smoke rising out of the stacks, one will not see the emissions produced by the electricity generated when enjoying the breeze of the air-conditioning system while working at the computer or relaxing watching TV.

To make energy consumption visible, people must first measure it. This is already being done in a crude way via meter readings for energy bills. However, this provides a number without any context. A person cannot tell by looking at the bill whether he or she is an efficient energy user. One way to find out would be to compare energy efficiency with his or her neighbours. One would also need to create a metric to allow him or her to make a comparison adjusted for the relative size of the buildings. The easiest way to do this is to divide the total amount of energy consumed by the area of the building to give a rating of energy per square metre. Now, like can be compared with like, and the performance measured against others.

If people collected these measurements on a wide scale––energy consumption divided by area––the performance of all the buildings in a neighbourhood, district, or across an entire city could be compared. People would see which buildings performed best and which performed worst, compared on a like-for-like basis. This would enable people to create a new definition of a green building: one that performs in a green manner.

Instead of just a building’s age or energy efficiency designations to make assumptions about its performance, actual performance is measured, which is determined by the infrastructure in addition to occupant behaviour. Only by aligning infrastructure and behaviour can people maximize the energy efficiency potential of buildings and reduce their emissions.

Recladding First Canadian Place was particularly complex and technically challenging since all 45,000 marble panels that made up its exterior had to be removed. The old panels were replaced by 5600 brilliant white and fritted glass panels, sourced and manufactured less than 50 km (31 mi) from the building site.[9]
Recladding First Canadian Place was particularly complex and technically challenging since all 45,000 marble panels that made up its exterior had to be removed. The old panels were replaced by 5600 brilliant white and fritted glass panels, sourced and manufactured less than 50 km (31 mi) from the building site.

By measuring and comparing building performance as described above, benchmarks can be developed. These can be invaluable in bringing about change. There are already numerous organizations to capture and compare their energy use data, and reveal opportunities to change. For example, a company is working with Ontario school boards where it is able to show how the energy use of individual schools––standardized as a per student or per square foot measure––compare with each other. Using this benchmark, school boards can quickly see which schools in their localities are using higher amounts of power and thus incurring higher costs.

Some of these differences might be traced back to building age and inherent energy efficiency or inefficiency of their infrastructure, but the other key component is behaviour. By providing objective benchmarks, the company enables key stakeholders––including students, teachers, parents, and administrators––to identify where savings can be made and work to reduce energy consumption.

Much could be accomplished if entire cities could be re-skinned and building occupant behaviour could be changed, the same way schools in Ontario are. Saving energy is far more cost-efficient than making energy. With the Ontario schools example, the company estimates the cost of building a megawatt (MW) of generating capacity in the province is $300,000. By contrast, the cost of saving one MW of electrical capacity is $10,000 per year. This is a ratio of 150:1 for the return on investment (ROI). Re-skinning buildings and giving occupants the tools to maximize their energy efficiency is time and money well spent.

Ron Dembo, PhD, is the founder and CEO of Zerofootprint, a cleantech software and services company that makes environmental impact measurable, visible, and manageable for corporations, governments, institutions, and individuals. He is the founder and former CEO and president of Algorithmics, and a former professor of operations research at Yale University. Dembo can be reached via e-mail at ron.dembo@zerofootprint.net.

Endnotes:
  1. [Image]: http://www.constructioncanada.net/wp-content/uploads/2015/12/First-Cdn-Place-Half-Finished-Credit-Tom-Arban.jpg
  2. www.esrl.noaa.gov/gmd/ccgg/trends: http://www.esrl.noaa.gov/gmd/ccgg/trends
  3. www.worldgbc.org/site2/index.php?cID=98: http://www.worldgbc.org/site2/index.php?cID=98
  4. www.toronto.ca/environment/buildings.htm: http://www.toronto.ca/environment/buildings.htm
  5. [Image]: http://www.constructioncanada.net/wp-content/uploads/2015/12/The-Palms-Backyard-Credit-Jason-Schmidt.jpg
  6. [Image]: http://www.constructioncanada.net/wp-content/uploads/2015/12/Wychwood-Interior-Credit-du-Toit-Architects-Ltd.jpg
  7. [Image]: http://www.constructioncanada.net/wp-content/uploads/2015/12/wychwood.jpg
  8. [Image]: http://www.constructioncanada.net/wp-content/uploads/2015/12/Galss-Removal-Diagram.jpg
  9. [Image]: http://www.constructioncanada.net/wp-content/uploads/2015/12/Suspended-Elevated-Platform.jpg

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