Registered LEED projects in the world [infographic]

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Registered LEED projects infographic

Screen reader version:

Number of LEED projects registered and certified in top regions by GSM (gross square metres – reported in millions)

Latin America and Caribbean – 1,704 (39.5 GSM)

Middle East and North Africa – 1,297 (69.2 GSM)

North America – 44,998 (611.6 GSM)

Europe – 1,706 (74.5 GSM)

East Asia – 1,995 (107.3 GSM)

271.6 GSM (registered) + 36.5 certified GSM = 308.1 total

Top 10 countries with registered and certified projects

1. United States – 44,270 projects (595.8 GSM)

2. China – 1,156 projects (66.5 GSM)

3. United Arab Emirates – 808 projects (46.1 GSM)

4. Brazil – 638 projects (18.1 GSM)

5. India – 405 projects (6.9 GSM)

6. Canada – 383 projects (7.9 GSM)

7. Mexico – 322 projects (7.9 GSM)

8. Germany – 299 projects (6.1 GSM)

9. Turkey – 194 projects (8.9 GSM)

10. Republic of Korea – 188 projects (15 GSM)

May 15, 2013 |

Pre and-post retrofit airtightness test results in Winnipeg, Manitoba

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Facade of 363 Broadway in Winnipeg, Manitoba

Facade of 363 Broadway in Winnipeg, Manitoba


This report summarizes the results of pre-and-post retrofit airtightness tests performed on 363 Broadway, Winnipeg, Manitoba. This is a 16-storey office building constructed in 1976 which underwent a major building envelope retrofit during the summer of 2011 to replace the curtain-wall glazing system. The pre-retrofit test was performed on April 14, 2011 while the post-retrofit test was carried out on June 12, 2012. In addition, supplemental tests were conducted on the building’s underground parking facility on June 2, 2012. The tests were carried out for two reasons: to quantify the impact of the retrofit on the airtightness characteristics of the building and to provide data on the airtightness of commercial buildings.

The impact of air leakage on building performance

Air leakage which occurs through a structure’s building envelope is a concern for a number of reasons. First, air exfiltration (defined as the unintentional movement of air from the interior of the building to the outdoors) can transport significant amounts of moisture into the building envelope where it may condense and form interstitial condensation. This can lead to a wide range of damaging and ultimately expensive conditions such as structural distress, corrosion, mould development, etc. Second, air infiltration (the opposite of air exfiltration) can create cold drafts and an uncomfortable indoor environment. Third, air infiltration has the potential to move outdoor pollutants into the building. Fourth, increased air infiltration can lead to unnecessarily high energy costs. Fifth and finally, a leaky structure is usually a noisy structure since the transmission of outdoor noise into the building occurs primarily through the same cracks and openings by which air leakage occurs. Since no structure is perfectly airtight, air leakage, and its undesirable effects, can not be eliminated but can only be controlled within manageable limits.

Test procedure

The test procedure used for 363 Broadway was a modified version of CGSB 149.10-M86 “Determination of the Airtightness of Building Envelopes by the Fan Depressurization Method” (1986). With this procedure, the airtightness is measured by depressurizing the entire structure to a series of indoor-to-outdoor pressure differentials and then measuring the corresponding air leakage rate at each condition. Intentional holes and openings in the envelope, such as ventilation system supply and exhaust grilles, are temporarily sealed so that only leakage through the envelope is measured. Using the air leakage versus pressure differential data, a linear regression curve is then computed to characterize the behaviour of the building. From this data, along with information on the building’s size, the airtightness results can be expressed using various area-or-volume-based metrics.

The major equipment used for the tests consisted of three Retrotec blower door assemblies complete with DM-2 micromanometers/controllers.

With large buildings some judgment is required to define the location of the air barrier and whether specific zones are considered inside, or outside, the test envelope. For 363 Broadway, one such zone had to be addressed: the underground parking garage. This is a three-level, heated garage which has its own HVAC system that supplies treated air to the garage through dedicated air inlets and outlets, although energy for the HVAC system comes from the building. Originally, the parking garage had been included as part of the overall structure being tested and was shown as such in the pre-retrofit test report. However, after consideration, the parking garage (for purposes of airtightness testing) was judged as outside the test envelope since its construction (cast concrete) was completely different from the curtain-wall construction of the rest of the building and because it is intended to be isolated (from an air leakage perspective) from the rest of the structure to prevent carbon monoxide and odour migration from the garage to the building. Therefore, the airtightness results shown in this report for the pre-retrofit condition are slightly different from those shown in the original pre-retrofit report.

There are several methods by which quantitative airtightness results can be expressed. In this report, results are reported using the Normalized Leakage Rate at an indoor-to-outdoor pressure differential of 75 Pa, NLR75. This metric was chosen for consistency with the method used in the National Building Code of Canada. It is also the most common metric used in Canada to express large building airtightness results. The NLR75‘s units are “litres per second per square metre of building envelope (l/s·m2)”, which essentially represents the average air leakage over the building envelope at a standardized indoor-to-outdoor pressure differential. This differential, 75 Pa, is equivalent to that which would be produced by a wind of approximately 40 km/hr blowing simultaneously and uniformly over the entire building envelope area. The building area used for the NLR75 calculation was defined as the total envelope area, including all above-grade components; the parkade was excluded from the tests.

The National Building Code of Canada (NBC) does not (and never has) contained quantitative requirements for airtightness in any type of building.  However, beginning with the 2005 edition of the NBC, it provided non-mandatory “recommendations” for maximum permissible air leakage rates of opaque, insulated portions of the building envelope (2005). This is not the same as the leakage rate for the entire building envelope, such as shown in Table 1, but rather for discrete portions only and does not include glazing or most of the joints and penetrations typically found in a building (and which produce most of the air leakage).  For an occupancy such as 363 Broadway, the recommended maximum leakage rate for assemblies in the NBC is 0.10 l/s·m2.

Blower door testing

Blower door testing


The pre-retrofit airtightness of 363 Broadway, measured in 2011, was 1.23 l/s·m2, as shown in Table 1.  The 2012 post-retrofit measured airtightness was 1.03 l/s·m2.  This gave an absolute reduction in the Normalized Leakage Area at 75 Pascals of 0.20 l/s·m2, which represents 16.3 percent of the pre-retrofit airtightness. All results exclude the underground parking garage.

Comparative data

To provide additional perspective for the results, Table 2 contains some comparative airtightness data for various large buildings constructed in Canada and abroad over the last several decades (Proskiw and Phillips, 2001).  Most of these were existing structures tested some number of years after construction and would not have been designed or built using modern low-leakage construction techniques. Equivalent, comparative data for commercial buildings in Manitoba is extremely sparse.

Comparing the 363 Broadway results with those of other buildings shown in Table 2, the results from the pre-and-post retrofit tests indicate that the building is surprisingly airtight—displaying a measured air leakage rate which is lower than the mean leakage rates reported in the literature.

Table 3 provides some comparative data on the effectiveness of airtightness sealing in large buildings. Although only limited data is available, it shows that the reduction in air leakage achieved on 363 Broadway is comparable to what has been achieved on other major, building envelope retrofits. Also, of note, most of the buildings shown in Table 3 were initially much leakier than 363 Broadway. This is significant because it’s generally easier to achieve major reductions when the building is initially loose.


CAN/CGSB.  149.10, Determination of the Airtightness of Building Envelopes by the Fan Depressurization Method.  Canadian General Standards Board, Ottawa.

National Research Council of Canada.  2005.  National Building Code of Canada.  Canadian Commission on Building and Fire Codes.

Proskiw, G.  and Phillips, B.  2001.  Air Leakage Characteristics, Test Methods and Specifications for Large Buildings.  Report prepared for Canada Mortgage and Housing Corporation.

Table 1

Airtightness Test Results, 363 Broadway Ave., Winnipeg




Building height

57.6 m

Building volume

66,305 m3

Building surface area

10,436 m2

Date of test

April 14, 2011

June 12, 2012

Normalized Leakage Rate

1.23 l/s·m2

1.03 l/s·m2

Absolute reduction in NLR75

0.20 l/s·m2

Reduction in NLR75


Table 2

Comparative Airtightness Test Data For Other Buildings

Type Of Building

Number Of Buildings

Normalized Leakage Rate (l/s·m2)



Office Buildings


1.44 to 4.01


Multi-Unit Residential Buildings


1.18 to 6.37


Commercial Buildings

– Canada

– United States



0.23 to 2.14

0.73 to 24.56



363 Broadway, Pre-Retrofit


363 Broadway, Post-Retrofit


Table 3

Impact Of Air Leakage Sealing On Other Buildings

Type Of Building

Number Of Buildings

Percentage Reduction In NLR75

Multi-Unit Residential Buildings



Office Buildings









363 Broadway


By Gary Proskiw, P. Eng. of Proskiw Engineering Ltd. A report prepared for the Sustainable Infrastructure Technology Research Group (SITRG) at Red River College.

May 3, 2013 |

LEED Canada and taking the LEED exam

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Construction - LEED

Leadership in Energy and Environmental Design, commonly known as LEED, is a third-party certification program used in over 30 countries around the world to rate high performance buildings, homes and neighbourhoods.

Certifying a LEED building requires following a specific rating system and is administered by LEED professionals with specific credentials.  This article examines the basics of taking a LEED exam and gain LEED Professional Credentials.

LEED Canada

As of 2010 the Green Building Certification Institute administers LEED Professional Credentials for the entire world. Prior to that date the CaGBC (Canada Green Building Council) was responsible for administering the credentials within Canada.

LEED Canada now provides education to aspiring LEED professionals wanting to take the exam as well as those who have attained their LEED Professional Credentials by providing ongoing education.

Who administers LEED exams?

The GBCI provides third-party administration and development, giving the assurance that LEED Professional Credentials are objectively and fairly managed, ensuring that the credentials, exams and eligibility requirements are universal and will stand up to international requirements.

The USGBC, the organization which developed LEED, maintains the information on LEED credentials on its website while the GBCI actually administers the process.

LEED exams

If you want to clearly and easily demonstrate your knowledge of LEED and green building and have an easier time finding jobs that specifically call for LEED credentials, it’s worth taking a LEED exam. There are a few LEED Professional Credentials you can attain, depending on your needs:

LEED Green Associate – This entry-level credential is intended for those who do not specialize in technical fields, such as lawyers, real estate agents and educators. Gaining the LEED Green Associate credential signifies that you have basic knowledge of green construction, design and operations. If you have no technical experience working on a LEED project this is a great place to start. And if you don’t get fully involved in LEED projects then this credential could be all you need.

LEED AP – For professionals like engineers and architects who need more advanced and specific knowledge of LEED and have hands-on experience working on a LEED project. The LEED AP credential offers a number of specialties that denote specialization in particular LEED rating systems:

  • LEED AP Building Design+Construction (LEED AP BD+C) – A credential that affirms practical knowledge in design and construction of green buildings for the residential, commercial, education and healthcare sectors.
  • LEED AP Operations + Maintenance (LEED AP O+M) – This credential denotes knowledge of sustainable practices that improve performance of buildings and reduce their environmental impact.
  • LEED AP Interior Design + Construction (LEED AP ID+C) – A credential for those involved in construction, design and improvement of tenant spaces and commercial interiors.
  • LEED AP Homes – A credential specifically for those wanting practical knowledge of the construction and design of green homes.
  • LEED AP Neighbourhood Development (LEED AP ND) – This credential is for those who take part in the development, planning and design of sustainable neighbourhoods.

LEED Fellow – This designation is for exceptional professionals in the green building industry. Becoming a LEED Fellow requires being nominated by peers and selected according to evaluation criteria (based on four of five mastery elements of green building: technical proficiency, education and mentoring, leadership, commitment and service, advocacy—technical proficiency must be one of the four).

Maintaining certification

Once receiving LEED credentials, LEED APs and LEED GAs need to maintain their certification by earning continuing education (CE) hours. GAs need 15 education hours and APs 30 hours every two years. For a list of LEED Credential maintenance courses and resources offered by LEED Canada visit this page.

image: Kyoung Koun Park (Creative Commons BY-NC-ND)

April 10, 2013 |

MONTAGE BUILDING: Interview with Tedd Benson about off-site assembly and building performance

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Unity Homes - Xyla

Based on a philosophy of optimizing for cost and performance rather than compromising, Tedd Benson’s Unity Homes offer both high quality and energy efficiency while being cost competitive. To deliver value to home buyers (including the Passive House standard of air tightness), Benson points to off-site assembly, a method of construction that allows for greater control and a higher quality of craftsmanship than on-site construction. He offers his thoughts about Unity Homes and off-site assembly or montage building.

Why did you choose to adopt the Passive House standard of air tightness with your Unity Homes, but not the other standards that go with Passive House?

The Passive House standard has multiple requirements. Some are more effective than others, and some are more expensive than others. We’re trying to optimize by focusing on controlling  cost and leveraging  for effectiveness. Thicker walls and more insulation is costly and needs to be considered against the value very carefully. We have therefore studied this issue, and our analysis has brought us to the conclusion that after about R30, there are severely diminishing returns with added insulation. At that point, air tightness is a much more significant factor in the building performance. Luckily, air tightness is nearly free. It’s just about good workmanship and good work processes. We can achieve the Passive House air tightness standard on all of our homes consistently, so we focus on that and diminish the PH standard insulation level slightly (R35) to a point where we are getting really good performance, allowing us to use small air-source heat pumps for heating and cooling.

Can you tell me a little about the homes currently in production?

Unity Homes have minimal energy demand, which allows us to eliminate fossil fuels and use an air-source heat pump to supply all the heating and cooling requirements. With this and many other energy features, these homes can achieve net-zero with a modest solar array (5-7 kwh).

We don’t compromise on the structure, as we assume these homes will serve for 300-500 years. In addition, they’re comfortable, light filled, spacious, have great air quality and are filled with great materials, finishes and fixtures.

The Unity standard is the future of homebuilding. You could put it this way: “Nothing compromised. Nothing maximized. Everything optimized.” Or simply “Not too little. Not too much. Just right.”

How far can you transport these houses and how economical is it to transport?

We can ship within a few hundred miles efficiently. This consideration is one of practicality: the distance in which a single driver can make the trip and unload the truck without having to sleep over. We can deliver beyond that, of course, but the costs are higher and need to be more carefully analyzed. Our goal is to extend our production to be closer to our markets. We expect to begin that expansion this year.

A catch-22 facing prefab builders is that volume needs to increase before costs can drop, but for that to happen prices need to be lower for the average consumer. What do you get for the cost of your homes?

That’s right. But it’s not such a bad Catch-22 if we’re strategically accurate as we grow. There are plenty of markets in which Unity is cost competitive now, while providing much higher quality in much faster time. As we grow and bring prices down with scale, we can then bring the Unity proposition to markets where costs are currently lower.

Can you tell me a little about the five key attributes of Unity Homes?

I’ll put this in the form of the Unity Homes goals, and indicate where we are today:

  1. Custom home design will be free (currently is).
  2. The typical build time will be 20 working days (currently 30 to 35).
  3. Living in a home can be free of utility costs and also generate energy for transportation (currently no fossil fuels, net-zero capable).
  4. All systems within the home should be continually alterable and upgradeable, with most of the work able to be accomplished by the homeowners (currently disentangled and reconfigurable within the shell, with easy access to most mechanical systems; all homes designed for unpredicted capacity, not just first space plan).
  5. Cost for this much higher standard design and performance standard is competitive with current on-site, building-code-based standard (currently competitive with lower quality on-site alternative  in many markets where building costs are at the national average or higher).

What advantages do the Open-Built system offer?

Open-Built improves the efficiency of the construction process by disentangling systems for easier installation. That same disentanglement allows for long-term access, which means homeowners and professionals can accomplish changes, upgrades and renovations with less demolition and rework.

Anything else?

Yes. One BIG thing. Words matter, and the words that are used to identify the current off-site construction methods are insufficient for what we’re trying to accomplish. “Modular” and “prefab” are the usual descriptors. Modular refers to the built volumes that are trucked on the highway like carcasses of beached whales, and prefab mostly connotes a modernist style, with an indeterminate percentage actually accomplished in the prefabrication.

The segment of the construction industry referenced by these two words is wholly failing in three significant ways. First, they represent only 2 to 5 percent of new home construction, and therefore aren’t making enough of an impact on the industry. Second, they aren’t bringing the sort of fundamental quality and cost change to the industry that’s needed because they aren’t doing enough to use the off-site advantage to bring real improvements. Third, they are completely failing to create good jobs. This last one is the worst failure. The employee turnover and absentee rates in those sectors of the construction industry is not only worse than the rest of construction (which in itself is quite bad compared to other industries), but is worse than ANY other industry. This is horrible. Nothing good can come of a building system that leans on low pay, low skill and bad working conditions. We do not want to be associated with it.

Therefore, we’re using the Swedish word for off-site building because it precisely translates into English, German and French (and all of those countries where these languages originated have contributed to our work culture and technology). That word is “montage,” which essentially means “assemble.” One of the definitions is perfect: “any combination of disparate elements that forms or is felt to form a unified whole.”

We think it’s a better word because the essence of the process is, in fact, assembly. First we assemble the designs from a collection of digital “Lego” elements, rather than starting from nothing to drive down cost, raise quality and still provide a completely custom home; then we assemble the CNC cut parts and pieces in our production studio into the same elements (panels, cartridges, pods, etc); and finally, we assemble the elements on the site to create the complete house. So montage is perfect in that regard.

Most importantly, we need a different word to help us separate the quality of building and the quality of job that are essential to the Unity vision. These two objectives lean on each other for success. You can’t create good jobs with a bad product. Good jobs only pair with the creation of good products. And the reverse is true as well. Good, industry-disrupting products cannot be created unless the people doing the work have good jobs (with good pay, benefits and working conditions) that require discipline, skills, knowledge and a dedication to constant improvement. That’s Unity. That’s montage building.

February 27, 2013 |

OFF-GRID: How one man saved $4,000 a year by taking his home off the grid

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East Amwell man lives off the grid in solar-powered home (via

EAST AMWELL — When Dante DiPirro was 11, he built a contraption from old mirrors that directed the sun’s heat toward a single point. The makeshift solar collector was his sixth-grade science fair project. Now, decades later, DiPirro is still experimenting with sunlight. Calling himself Mr. Sustainable…

February 7, 2013 |

OPEN BUILDING: An interview with Tedd Benson of Unity and Bensonwood Homes


People are constantly changing, yet the homes that they live in, once constructed, are inflexible to their changing needs. Open Building (OB) represents an alternative approach to building that accounts for the changing needs of homeowners and communities through its application of flexible building principles. Green Building Canada interviewed Tedd Benson, owner of Unity and Bensonwood Homes, about the theory and practice of Open Building.


Tedd Benson of Unity Homes

Tedd Benson, owner of Bensonwood and Unity Homes


Open Building (OB) means different things to different people. How does your Open-Built® implementation of OB fit in with the vision Open Building pioneer John Habraken set forth?

The unfortunate fact is that Open Building doesn’t mean much of anything to most people, and even more unfortunately, that includes most professionals in the home building industry. I wish there were more discussions about the meaning of Open Building, but the conversations are really much more basic at this point, as there is very little awareness about one of the most important industry ideas that could move homebuilding process and product to a better place.

Our adoption of the Open Building principles follows Habraken’s ideas quite closely, but we have then extended the implementation with our own ideas to address current design and building practices and the particular issues of the current American home building industry, including building science, engineering and technology.

Our launch of the Open-Built® system began with Habraken himself. He came to New Hampshire in the early 90’s and gave a thorough seminar to our staff. The seminar grew out of a series of discussions between Habraken and I. He was working at MIT and living in Cambridge, MA at the time, so getting together was pretty convenient. By the time he gave the seminar, he was able to cast the Open Building ideas in a way that made them directly relevant to our company’s design and building systems. What we do today was born from our personal interaction with Habraken, which continues today. I most recently saw Habraken when I gave a talk on Open Building at a conference in Boston last year. It was an honour to have him present.

What benefits does Open Building contribute to the design and building process?

In Habraken’s words, one of the fundamental objectives of Open Building is to restore the “natural relation” between a building’s form and its inhabitants. Design tends to make the inhabitants’ lives generic and buildings are so fixed in their aesthetics and function that people must adapt to buildings because buildings have not been made to adapt to the people who live in them. Here’s an important disconnect to acknowledge: buildings are for people, yet people tend to be dynamic and ever-changing, while buildings tend to be static and thwart change. The central tenet of Open Building addresses this problem by seeking to separate the base building (support) from the interior fit-out (infill).

There are two parts to the OB proposition. First, in the process, the supports side of the building is seen as public, long term, and involves regulation and professional skills to create a durable and sustainable structure that will be an asset to the community as well as its owners. The infill, on the other hand, is seen as private and should be in the full control of its occupants. It is designed for occupant control, and is designed and organized to reinvigorate the natural relation that people should have with their living environment. Second, in regards to the product of the home, the result is a “disentanglement” between the long term and short term (base building and infill), and inevitably between numerous building “layers” that live in time differently.

From this essential philosophical idea flows a whole host of solutions, from organizational rationale that can revolutionize design methodology, to unique building systems that will radically alter assumptions about the process of building.


Tedd Benson of Bensonwood Homes

Tedd Benson at work

Can you give an example of how OB benefits homeowners?

Open Building is intended to ease and even facilitate renovation, upgrade and change as the occupants desire and require. The central idea is to allow the building to adapt to changing needs, changing technology and changing fashion. There are two important added advantages: it makes the construction process more efficient since there is less entanglement and more open access, while also allowing the owners to finish the building as they can afford it rather than being forced to finish the entire home during construction because of the inherent entanglement.

Does it benefit the community or environment in any way?

By separating the base building from the infill, the focus for the underlying structure is on long-term durability, which is the essence of sustainability. We believe there should be a 250-year standard, which Open Building encourages because it allows constant renewal for the occupants but seeks to keep the structure inviolate.

In addition, since the infill is designed for renewal and access, there is more opportunity for parts, components and equipment that are all demountable, reusable and recyclable. So the community gets a long-term asset, the occupants get a building that adapts to them, and the environment benefits from less demolition and the usual landfill impact.

What impact does Open Building have on the communication process between the various people involved in the building of a home and the homeowner?

Since an OB building is more organized, and there’s therefore much more access to the service and finish layers, there’s less anxiety about making all decisions and predicting the near- and long-term future because the short-term and long-term aspects of the building are not entangled. The homeowner simply has more control even if the initial considerations turn out to not be accurate. The result is that the homeowner isn’t so pressured because design and process decisions are not weighty with finality.

The Open Prototype Initiative that you are taking part in seeks to prototype the future of home building. How are you working towards this goal?

The recession has slowed down the Open Prototype progress, but we have decided to accelerate it despite conditions by launching a new company called Unity Homes. Unity Homes is a direct outgrowth of the Open Prototype project and is named for the second one at Unity College. We intend to pursue the future of home building in actual homes that people can buy. The first two Unity homes are under construction now. More will be built this spring. We think this effort will be extremely successful as it will be off-site built to higher standards than any typical home and will also display the Open-Built advantages.


Tedd Benson and crew working on the Favat house (This Old House)

Tedd Benson and crew working on the Favat house (featured on the show This Old House)

The popularity of open-source software propagates the notion that “open” means free and accessible by all to use. Your Open-Built® system is registered as a trademark, so is the Open Prototype Initiative aimed at opening up this process of building to the whole building industry to freely use?

Open Building and Open-Built® have the occupant/homeowner in mind for the use of the word “open,” but in fact there’s much about Open Building that must be widely accessible if it’s going to be widely adopted. The basis for Open-Built® is what I call an Operating System, which includes a 3D grid and interface/connection standards. This is where the industry needs to come together to create an environment in which suppliers, manufacturers, designers, and builders can all make, create, and deploy with a host of agreed upon standards. This will make good design more available and good building parts, components and equipment more affordable. In the coming year, we intend to make a formal proposal in this regard and we’ll invite everyone to participate.

You state in your 2003 White Paper, “What is Open Building?” that the theories, practices and projects in residential Open Building are largely unknown, even within the building industry. What would you most like builders to know about Open Building?

Open Building is a disruptive idea. It inherently unseats the status quo assumptions about how design and construction should proceed. The main thing I want builders to know is that the change is coming—just as it has in every other industrial activity—and they can either be victims or beneficiaries of the inevitable.

Why do you feel builders have been so slow to adopt the principles of open building?

Yes. Not just slow. Complete denial.


by UB Hawthorn

January 28, 2013 |

AIR SEALING: 5 ways air leakage impacts building performance

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Air leakage is the movement of air into and out of a building that is not controlled through an exhaust system but rather through factors such as wind blowing through gaps in the building envelope. Air leakage is a concern for the following reasons:

1. Air exfiltration (defined as the unintentional movement of air from the interior of the building to the outdoors) can transport significant amounts of moisture into the building envelope where it may condense and form interstitial condensation.  This can lead to a wide range of damaging and ultimately expensive conditions such as structural distress, corrosion, mould development, etc.

2. Air infiltration (the opposite of air exfiltration) can create cold drafts and an uncomfortable indoor environment.

3. Air infiltration has the potential to move outdoor pollutants into the building.

4. Increased air infiltration can lead to unnecessarily high energy costs.

5. A leaky structure is usually a noisy structure since the transmission of outdoor noise into the building occurs primarily through the same cracks and openings by which air leakage occurs.  Since no structure is perfectly airtight, air leakage, and its undesirable effects, cannot be eliminated but can only be controlled within manageable limits.

by Gary Proskiw, P. Eng. of Proskiw Engineering Ltd.

Excerpted from Pre-and-post Retrofit Airtightness Test Results: 363 Broadway, Winnipeg, a report prepared for the Sustainable Infrastructure Technology Research Group (SITRG) at Red River College.

January 22, 2013 |

CONSTRUCTION RECYCLING: Why construction sites should recycle [infographic]

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Construction recycling infographic

Screen reader version:

Recycling by the numbers

13,000 feet of framing lumber the average newly constructed home requires – that’s enough lumber to line 2.5 miles of road if laid end-to-end.

85 million tons of material recycled in the U.S. in 2010.

9,000 tons of waste the largest landfills in the U.S. receive on a daily basis.

25-30% tons of waste the largest landfills in the U.S. receive on a daily basis.

The benefits of construction site recycling

50% – recycling rate builders must achieve to receive awards from the LEED program.

1/2 – amount of U.S. steel produced in the last 50 years that has been recycled

1 ton of recycled stell conserves 2,500 pounds of iron ore, 1,400 pounds of coal and 120 pounds of limestone.

70% – amount that a steel mill can reduce water pollution, air pollution and mining waste by using recycled scraps

8,000 – pounds of waste created from the construction of an average 2,000 square foot home

Recyclable construction site materials

  • asphalt
  • concrete
  • clean wood
  • plastics
  • glass
  • carpeting
  • plubming fixtures
  • cardboard
  • drywall
  • metals
  • and more!


January 19, 2013 |

PREVENTION THROUGH DESIGN: A new approach to reduce construction risks

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Deborah Young-Corbettt - construction risks

Deborah Young-Corbett is an assistant professor of civil and environmental engineering at Virginia Tech and a member of the university’s Myers-Lawson School of Construction, is working to reduce health risks.

“Some of the most pressing occupational health hazard risks in construction” are associated with masonry operations, asphalt roofing, and welding, wrote Deborah Young-Corbett in an article recently accepted by the Journal of Civil Engineering and Management.

To reduce these health risks to construction workers, Young-Corbett, an assistant professor of civil and environmental engineering at Virginia Tech and a member of the university’s Myers-Lawson School of Construction since 2007, has studied much of the existing literature, identifying numerous gaps or problems in current construction practices.

As a result, Young-Corbett is working in a new field of engineering known as Prevention through Design or PtD. The optimal method of preventing occupational illnesses, injuries, and fatalities is to “design out” the hazards and risks; thereby, eliminating the need to control them during work operations, Young-Corbett said. This approach involves the design of tools, equipment, systems, work processes, and facilities in order to reduce, or eliminate, occupational hazards and environmental risks.

She is teaching these new state-of-the-art design tactics in her classes, providing her undergraduate and graduate students with a better understanding of how to improve the long-term success of the construction industry. Young-Corbett is a certified industrial hygienist, safety professional, and hazardous materials manager with a background in environmental sciences, human factors engineering, and industrial engineering.

In 2008, the National Institute for Occupational Safety and Health (NIOSH) launched the PtD initiative in an attempt to mitigate hazards in the construction sector in the design stage. Yet, four years later, Young-Corbett’s review of the industry’s safety procedures shows some of the “barriers” to PtD adoption and she identifies strategies for the construction industry to use to improve its health records.

Young-Corbett provides evidence in her assessment of the industry of a “gap” in the PtD initiative that does not address the approaches to “occupational health hazard control,” with the key word being “health.” These “health risks arise when workers are exposed to chemical, biological, or energetic hazards that might lead to various illnesses or fatalities,” Young-Corbett said.

For example, additional changes in tool selection in masonry could alleviate much of the health risks, according to Young-Corbett. With a masonry operation, a key issue is to reduce the silica dust produced when sawing. Now that wet methods are available for hand-operated grinders used for surface finishing and cutting slots, these devices can keep operators’ exposures to silica below Occupational Safety and Health Administration (OSHA) limits, she noted.

Construction supervisors should also be advocating hand operated surface grinders that are made with better vacuum dust collection systems, also reducing an operator’s exposure to silica.

In roofing, the workers’ exposure to asphalt fumes and vapours lead to both acute and chronic effects. Lung cancer is at an elevated risk for asphalt roofers. But, as Young-Corbett argued in her paper, delivery of hot asphalt to a job site via a tanker, eliminates the on-site kettle operation for handling and heating the asphalt, and makes a difference to the health of the worker.

Similar relatively simple changes in the practice of welding can also make an impact in the decline of health-related problems. The use of local exhaust ventilation systems can prevent worker exposure to metal fumes during welding, Young-Corbett wrote in her article in the Journal of Civil Engineering and Management.

In general, Young-Corbett said there are still needs for designs for better tools or materials, but in other cases, “effective tools exist but are not widely adopted within the industry… there is a need to elucidate the barriers to PtD adoption and to identify strategies for improved diffusion within the construction industry.”

“The further refinement and marketing of PtD solutions such as the smokeless welding gun, the low-smoke welding wire, and the local-exhaust ventilation systems for welding are needed,” she asserted.


Several of the research endeavors of Young-Corbett’s laboratory have been in the realm of PtD. A NIOSH-sponsored research project entitled “Dust-control Usage: Strategic Technology Intervention (DUSTI),” developed new equipment design solutions for dust control in construction and an intervention for improving adoption rates within the industry. In a project sponsored by the National Science Foundation, a pervasive computing system was developed for sensing construction worker exposure to carbon monoxide and wirelessly summoning assistance in the event of over-exposure. Young-Corbett recently received a grant from NIOSH to develop PtD design and intervention strategies for health hazard control in masonry, asphalt roofing, and welding trades.

January 10, 2013 |

FURNACE EFFICIENCY: Is your oversized furnace wasting your money?


Is Your Oversized Furnace Wasting Your Money? (via Green Building Elements)

An oversized furnace is a very wasteful shortcut taken by many homebuilders and HVAC service providers. The result is that many unsuspecting homeowners are straddled with an appliance that overly dries their indoor air, wastes copious energy, and sends a lot of money right up the chimney. When it comes…

December 30, 2012 |
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