September 1, 2011
By Bob Marshall, P.Eng., BDS, LEED AP
In October, Canada will host the U.S. Green Building Council’s (USGBC’s) Greenbuild show for the first time when the event comes to Toronto. Given the country’s burgeoning community of sustainability advocates, it seems fitting there will be a dedicated stream of educational sessions highlighting Canadian projects and strategies.
Greenbuild 2011’s theme is “next”—as in, what are the next big leaps for sustainable design? To help ascertain the answer, the Canada Green Building Council (CaGBC) appointed this author to chair a team to work through a three-stage selection process established by USGBC to evaluate the abstracts.
From over 1200 submitted abstracts, seven sessions were selected for Canadian content. They cover diverse topics, including:
Clearly, multiple sustainable practices are being integrated across all key sectors—this green transformation will only increase over the next decade. Fortunately, many of the solutions to be presented in the Greenbuild sessions are already being implemented.
For example, reducing energy intensity is critical for lowering emissions and energy cost savings during the operational stage of buildings. In the 2012 update to USGBC’s Leadership in Energy and Environmental Design (LEED) rating program, there will be a new category for measuring energy performance, which addresses one of the more controversial issues surrounding USGBC’s LEED rating system.
In the current version of LEED, many points can be achieved from energy modelling based on design, rather than actual operational energy performance. Canada has been more rigorous with energy performance requirements and measured performance. Therefore, the educational solutions already put into practice in this country will be of great interest to the expected 25,000 attendees at Greenbuild. This article touches on some of the related topics, specifically building envelope commissioning and wood use. (For more information on this author’s approach to sustainable design, see the May 2010 Construction Canada article, “Time for Holistic Thinking-Integrated building energy performance solutions.” Visit www.constructioncanada.net and select “Archives.”)
Institutional green buildings
Innovative measures being implemented in institutional buildings will be featured in the session, “Canadian Building Commissioning: How does it impact your Igloo?,” presented by this author, along with Andrew Cunningham (EllisDon) and Michael Tiffe (TAB Mechanical). While there are not many igloos in Ontario, the province does boast the most LEED buildings in Canada.
Infrastructure Ontario is managing $14 billion in green construction projects, most of which are institutional. Landmark LEED candidate buildings include 20 new 400-series highway travel centres (pictured at left), which are part of a $300-million government/industry renewal project. For this work, building envelope commissioning practices have been implemented.
The act of commissioning covers the envelope, vertical/horizontal transportation, and electrical, mechanical, and control systems. For the travel centres, commissioning work has been implemented on both the steel and wood-frame buildings; it has included review of details, construction quality field reviews, and air and water tests.
The building commissioning process is recognized by LEED 2009 as a possible exemplary credit where the practices contribute to tighter buildings that improve energy efficiency, comfort from drafts, and reduce the risk of condensation buildup. There is also the new Canadian Standards Association (CSA) Z320-11, Building Commissioning, which covers the systematic process to verify and document various systems during the facility’s design, construction, testing, and operation stages. This standard is not yet mandatory for new construction under the codes, but benefits of a tighter, more thermally efficient building envelope can be realized by reducing or eliminating some heating equipment.
For the highway projects, one challenge involved creating constructible details at changes in cladding and roof/wall interfaces. This task was exacerbated by the multiple consultants involved—some reviewed the roof, others reviewed the wall, but seemingly constructability at the roof/wall interface was a challenge that needed to be overcome.
Fortunately, at the onsite pre-construction meeting with the architect, general contractor, building science consultant, and trades, details were marked up on a projected image before construction, thereby minimizing the need for rework. Subsequent phases of the project allowed for the roof/wall details to be made more easily constructible and improved in terms of thermal performance.
Construction quality reviews
Even with constructible details, construction quality reviews are required to verify the general contractor and trades understand the intended performance and can install the various components of an assembly in the proper sequence. This attention to detail is important especially for through-wall flashings and membranes that cannot be easily changed without costly rework.
Medium-density sprayed polyurethane foam (SPF) is increasingly being used to improve the energy efficiency of green buildings. This material provides both thermal protection and an air barrier between the many building penetrations (i.e. windows, doors, and ducts). It is extremely important interfaces between penetrations and different substrates be provided with membranes to bridge gaps and provide continuity of the air barrier system.
Underwriters Laboratories of Canada (CAN/ULC) S705.1 and S705.2, Standard for Thermal Insulation: Spray Applied Rigid Polyurethane Foam–Medium Density, are referenced in the National Building Code of Canada (NBC) as the material and installers’ responsibility. However, mandatory quality checks by third parties are not spelled out in the code, so it is important quality control reviews be specified during construction. On several LEED buildings, this author has found faulty sprayfoam installations that have had to be removed and replaced. The material can be a suitable choice, but only when correctly specified, installed, and reviewed during construction.
Commissioning and documentation
Commissioning documentation is required at completion. In addition to the commissioning manual, it consists of maintenance and data manuals, system operator manuals, contract documents, and record drawings. As this work is intended to be re-applied throughout the facility’s life, these documents can be used in the creation of a re-commissioning manual.
Part of the onsite commissioning should also include testing of window/wall interfaces. Envelope commissioning tests for windows and doors are important to be spelled out in the contract documents. The pass criteria should be reflective of the assemblies’ expected exposure. For example, in the case of sloped outward windows not protected by large canopies, the air and water pass criteria should be higher than with vertical recessed windows.
In some projects, this author has found localized sprayfoam, specified to fill the gaps, was not uniformly installed, serving as a source of air leakage and water infiltration. When this is the case, a recess on the interior side of the foam between the frame and opening can be made so a compatible interior sealant can be applied. (Ideally, this sealant would be free of volatile organic compounds [VOCs] so indoor air quality [IAQ] is not impacted.)
Residential green buildings
Canadian seminars at Greenbuild will also deal with aspects of residential design and construction. Wood-frame multi-family mid-rises are now being built. In British Columbia, there are about 60 of these buildings, five or six storeys tall, under construction. These sorts of projects will likely be increasing throughout the country as urban populations grow. At Greenbuild, this topic will be explored in “Canada Leads the Way with Codes for More Affordable, Renewable Wood Mid-rise Green Buildings” (YL 14) session—conducted by Russ Thomas (National Research Council Institute for Research in Construction [NRC-IRC]), Michael Green-McFarlane (Biggar Architecture+Design), and Sukh Hohal-Wood (WoodWorks BC).
Wood allows for sustainable expansion in the use of local materials. Specifying wood from certified Canadian sources can also mean support services provided by regional professional firms, thereby increasing local employment and economic activities. Further, RHC Design/Build estimated wood’s affordability improvement (i.e. in terms of labour and material costs) to be 12 to 15 per cent for two recent Ontario projects when compared to steel, assuming all considerations for increased structural enhancements as well as sprinkler systems and fire separations.
It is important thermal and moisture performance principles be understood and applied in the design and construction of mid-rise buildings to prevent health and safety problems. For this project, a condominium construction guide, similar to the high-rise one published by Ontario’s Ministry of Municipal Affairs and Housing (MAH)—a resource that is referenced in NBC—would help with knowledge transfer.
Thermal performance is better with wood construction as there is reduced thermal bridging when compared to steel or concrete buildings. In terms of energy performance, wood buildings have both lower embodied energy and lower operating energy over a 60-year lifecycle, according to the Canadian Wood Council (CWC).
Modelling of wall and roof assemblies in residential buildings that have elevated indoor relative humidity (RH) conditions is critical. In taller buildings, the stack effect is more significant which raises the risks of moisture building up within the roof assembly. Based on recent American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) research conducted in Chicago (a cold climate similar to much of Canada), it was determined moisture would build up on a cathedral roof’s oriented strandboard (OSB) sheathing with a tight air barrier and white roof. A dark roof covering provides additional drying capacity due to heat conduction, thereby reducing moisture levels in the roof assembly and mitigating risk of mould growth.
Constructing taller wood buildings onsite (i.e. without use of pre-fabricated components) will extend exposure time of the structural wood components to moisture and particularly its effects during construction. Therefore, a temporary roof canopy is required to minimize moisture risks from rain. Moisture-mitigation design is also necessary due to the risk of mould growth and rainwater penetration at the numerous windows, doors, balconies, and penetrations typical in current multi-family buildings. Rainscreen wall assemblies must be specified and detailed as a minimum. Building science professionals experienced with multi-family projects are recommended for the design of components and building envelope assemblies.
As mentioned, construction reviews are necessary to check details are being followed; this is especially the case for through-wall flashings and weather protection membranes, as they cannot easily be rectified after the building envelope is finished. Envelope commissioning is also extremely important for wood buildings to achieve proper moisture control at the design, construction, and operational stages. Based on 15 recently completed LEED wood-frame building envelopes commissioned by this author, it was found the installation of through-wall flashings and membranes was a challenge despite proper details being provided. Since mid-rise buildings need the envelope to be compartmentalized at floor levels and window/door openings, experienced trades and third-party review are recommended. A better practice would be to construct the compartments in the factory where they would be protected from the elements, and to use durable pressure-treated woods at the sills.
There are other items, including structural design and fire safety, are being addressed by the industry for mid-rise wood buildings. The use of cross-laminated timber (CLT)—which is similar in some respects to heavy timber—for fire performance is one emerging material. (For more on CLT technology, see the March 2011 Construction Canada article, “The Advent of Cross-laminated Timber,” by David Moses, PhD, P.Eng., PE, LEED AP, and Sylvain Gagnon, Ing. Visit www.constructioncanada.net).
Businesses, neighbourhoods, and communities
Greenbuild’s Canadian contingent is also going to examine the built environment from a larger perspective than simply just individual buildings. In the session titled, “The Green Revolution of the Central Business District (CBD) of Toronto,” Douglas Birkenshaw (B+H Architects), John Lowden (Mitchell Partnership), and Lisa Bate (CaGBC) will discuss how the coming of LEED Gold office buildings has put pressure on the existing building stock to retrofit and upgrade to improve performance.
Similarly, the impact of wider development is covered in two other sessions. “CivicAction Transforms Organizations” is presented by Cara Clairman (Ontario Power Generation [OPG]), John Tory (CivicAction Alliance and radio personality), Linda Mania (Royal Bank of Canada), and Cameron Fowler (BMO Financial Group). “Know Before You Build: Predicting Carbon Profiles of Large-scale, Mixed-use Developments,” will be led by Seth Schultz (Clinton Climate Initiative), Dan Stone (Waterfront Toronto), Eric Miller (University of Toronto), and Albert Wei (Arup).
The CivicAction Alliance of thousands of volunteers has launched a “Green Procurement Initiative,” a “Commercial Building Energy Initiative,” and a “Greening Canada Fund.” The development of its non-proprietary carbon modelling tool will allow decision-makers to better understand integrated large-scale infrastructure systems.
A session dealing with community revitalization is “Evergreen Brick Works: Heritage Industrial Brownfield and LEED Platinum (candidate) Converted into Environmental Community Centre,” presented by Robert Plitt (Evergreen), Joe Lobko (Du Toit Allsopp Hillier), Michael Leckman (Diamond and Schmitt Architects), and Douglas Webber (Halsall Associates). This project serves as a platform to explore and address global issues such as the green economy, urban ecology, transportation, water, energy, waste, agriculture, building design, and land-use planning.
The seventh session is “A Roadmap for Climate Action: Strategies, Tools, and Results,” and is co-presented by representatives of three schools—the University of British Columbia (Nancy Knight), the University of Calgary (Joanne Perdue), and American University (Chris O’Brien). Each institution has already adopted a comprehensive climate action plan and has already realized significant emission reductions.
This article touches on topics that are some of the next steps in innovative green construction that are already being implemented across Canada. These steps are among the strategies and technologies to be discussed at Greenbuild, which should be considered to achieve these leaps in all projects, regardless of size and scope. (For more information on various seminars and the show itself, visit www.greenbuildexpo.org).
Bob Marshall, P. Eng., BDS, LEED AP, is the Canada Green Building Council’s (CaGBC’s) appointed chair for the Best of Canada Bucket Team subcommittee for Greenbuild 2011. He is the country’s appointed expert for the International Organization for Standardization (ISO) Joint Working Group JWG 4 of TC 163-205 on Energy Performance of Buildings using Holistic Approach. Marshall is a member of the CaGBC’s Education Committee. He is a senior building envelope and sustainability consultant at Halcrow Yolles. Marshall can be contacted via e-mail at firstname.lastname@example.org.
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