When an architect specifies a building material, that choice casts a long shadow. While most of the environmental effects from materials occur during the extraction and production phases, they continue to influence a structures environmental footprint long afterwards, throughout the operations phase and beyond.

Materials in ActionBuilding Materials:

Construction, Operational and End

of Life Impacts

(Part 2 of a 3-part series)

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This presentation is part two in a three-part series, based on a CEU, Materials in Action, first published in Architectural Record in 2011. Some of the statistics have been updated based on new information.

• Materials Matter (Part 1 of 3) documents the environmental footprint of wood, concrete and steel.• Materials in Action (Part 2 of 3) covers their performance during construction, operation and end-of-life, reaffirming that, in the quest for carbon-neutral buildings, materials do matter. • A Natural Choice (Part 3 of 3) examines how these materials factor into green design and high-performance buildings as well as how green design projects are currently defined.

This presentation covers the differences between wood, steel and concrete in terms of basic material properties, as well as their performance during the building operations phase, and end-of-life impacts.

Materials Matter Series Overview

Materials Matter (Part 1) Materials in Action (Part 2)

A Natural Choice (Part 3)

Copyright Materials

This presentation is protected by U.S. and international copyright laws. Reproduction, distribution, display and use of the presentation without written permission of reThink Wood is prohibited.

© 2013, reThink Wood, www.rethinkwood.com

More specifically, topics covered will include durability and adaptability, the difference between embodied and operational energy and their associated impacts, opportunities for recycling and reuse, and the evolution of building codes as related to wood construction.

Learning Objectives

Evaluate the durability and versatility of wood, concrete and steel. Explain how current building codes permit the extended use of wood. Articulate the importance of embodied and operating energy. Discuss a building material’s end-of-life issues.

Photo Source (in order): naturallywood.com, dreamstime, dreamstime

Table of Contents

Section 1

Design Considerations

Section 2

Materials in the Construction Phase

Section 3

Materials in the Use Phase

Section 4

End of Use – Closer Look at Recycling & Reuse

Section 5

Evolving Building Codes

DESIGN CONSIDERATIONSSECTION 1

To understand a material’s true impacts, it needs to be considered over its life cycle. How durable is it? Is the material thermally efficient? Is it susceptible to moisture damage? Can it withstand seismic activity? What are the code considerations? Can it be recycled or reused and, if yes, at what cost to the environment? These are the kinds of questions that should be considered in the earliest project phases. The answers will determine, in part, a structure’s sustainability quotient.

Consider the Impacts of Materials

Sustainability Quotient

• Life cycle impacts• Durability• Thermal efficiency• Susceptibility to moisture• Seismic performance• Codes and regulations• Recycling/reuse …

at what cost?

While durability is a common goal of green building, adaptability is also important.

For this project in the Pacific Northwest, protecting wood from moisture was a priority. The yellow exterior sheathing is mold-resistant drywall. It was used as an exterior substrate, onto which the weather-resistant barrier and cladding were attached.

University of Washington West Campus Student Housing

WashingtonArchitect: Mahlum

Durability & Adaptability

Photo: W.G. Clark Construction

Good design and quality construction are key to a building’s longevity, as is maintenance. Any building of wood, concrete or steel could last an indefinite period of time, providing it is properly maintained.

This all-wood pagoda—which still exists today—was built in 1056. It’s about as high as an 18-story office building.

Photo: wikipedia

Sakayamuni Pagoda

Built in 1056, China’s oldest all-wood pagoda

About as tall as an 18-story office tower (221 ft or 67.31 m)

Has survived several major earthquakes

So famous it has the nickname "Muta” (木塔 )—literally, "Timber Pagoda”

Wood Buildings CanLast Centuries

Moisture control is critical for all buildings. Without it, concrete will spall, steel will rust and wood will decay.

The most effective and common way to prevent or slow these effects is to eliminate contact with water, either by coatings or protection within the building envelope.

In the case of lumber, grading rules and many building codes require that wood be dried to 19 percent moisture content. This is well below the fiber saturation point of 28 percent, the level at which mold or decay can begin to thrive. Adverse effects are also prevented by avoiding direct contact between untreated wood and the ground or other moisture sources or, where this isn’t possible, using preservative treated wood.

Bulk water, air infiltration and condensation can be a source of moisture in all types of buildings. However, while wood acts as a thermal break due to its inherent insulating properties, steel, concrete and masonry are thermal bridges ... which can provide a cold surface on which warm, moist air can condensate. This increases the possibility for deterioration and mold.

A study by FPInnovations (then Forintek) showed that interior wood paneling can reduce peak moisture loads in a typical Canadian house by 10 to 25 percent—a scenario that leads to both improved user comfort and reduced need for air conditioning.

Study reference: Potential for hydroscopic building materials to improve indoor comfort and air quality in the Canadian climate; C. Simonson, S. Olutimayin, M. Salonvaara, T. Ojanen, and J. O’Connor, Performance of Exterior Envelopes of Whole Buildings IX, December 2004

Moisture is a Challenge for Most Materials

In all cases, proper maintenance and moisture control are CRITICAL.

Steel Concrete Wood

Rust, corrosion Spalling, cracking, rebar exposure Fungi and mold

Causes: constant wetting, high humidity, dilute acids, salts, sea air

Causes: constant wetting, high humidity, dilute acids, salts, sea air

Causes: constant wetting

For wood buildings, there are four key steps to designing for durability ...

1. Protect materials from moisture.2. Prevent insect infestation.3. Use durable materials.4. Maintain quality through good

construction practices.

The building in this photo is the Percy Norman Aquatic Centre in British Columbia, which features a solid wood roof supported on Douglas-fir glulam beams that span up to 130 feet (43 metres) across the main pool area. The facility was built for the 2010 Winter Olympic Games and designed to achieve LEED Gold certification. Because wood tolerates high humidity and is capable of absorbing and releasing water vapour without compromising its structural integrity, it is well suited to the demanding atmosphere found in swimming pools and ice rinks.

1. Protect materials from moisture.

2. Prevent insect infestation with soil/foundation barriers and bait systems.

3. Use durable species or treated wood in areas prone to constant wetting.

4. Maintain quality assurance with good construction practices, frequent inspections and reporting.

Design for Durability

Percy Norman Aquatic CentreBritish ColumbiaArchitect: Hughes Condon MarlerLEED Gold

Photo: naturallywood.com

At the same time, while durability is crucial to the design of any building, designers should be aware that most buildings are demolished long before the end of their useful service lives—for reasons that have nothing to do with the structural material.

Historically, many building industry professionals believed that use of materials perceived as more ‘durable,’ such as steel and concrete, would result in buildings with longer service lives than wood buildings. However, a survey of buildings demolished between 2000 and 2003 in the Minneapolis/St. Paul area demonstrated that there is no significant relationship between the structural system used and the actual life of the building. Reasons for demolition were instead related to changing land values, lack of suitability of the building for current needs, and lack of maintenance of various non-structural components.

Source: Survey on Actual Service Lives for North American Buildings, 2004, FPInnovations

Although it is often believed that ‘durable’ structural materials such as steel and concrete

will provide the longest service lives for their buildings, our results suggest there is no

significant relationship between the structural system and the actual useful life of the building.

-- Survey on Actual Service Lives for North American Buildings

FPInnovations

Durability vs. Service Life

““

Overall, wood buildings in the study had the longest life spans. Sixty-three percent were older than 50 years at demolition and the majority were older than 75 years. By comparison, over half of the demolished concrete buildings fell into the 26-50 year category and only one third of the concrete buildings lasted more than 50 years. Similarly, 80 percent of the steel buildings demolished fell below the 50-year mark, and half of those were no older than 25 years.

This data shows two things ...

1) Wood structural systems are fully capable of meeting a building’s longevity expectations. 2) When you consider the embodied energy and other impacts associated with demolished buildings, the fact that wood is adaptable—either through renovation or deconstruction and reuse—is a significant advantage.

Source of data: Survey on Actual Service Lives for North American Buildings, 2004, FPInnovationsSource of graphic: Tackle Climate Change: Use Wood (book)

Service Life of Actual Buildings

The service lives of most buildings are likely far shorter than their theoretical maximum.

The majority of demolished steel and concrete buildings in the study were less than 50 years old.

Because of the unpredictability of future building needs, many experts advise that, instead of trying to design structures with infinite life spans, designing buildings that lend themselves to renovation or adaptation is a good way to extend their lives and reduce waste. Wood is particularly versatile and flexible, which makes it an easy construction material for renovations. For example, Ardencraig House in Vancouver, British Columbia, comprises four town homes designed within the framework of an existing heritage home and garage. Over 90 percent of the wood in the original structure was retained in adapting the house. Salvaged materials from deconstruction of the garage were also used to construct a coach house behind the main building. Salvaged framing members were used to strengthen roof trusses and increase the space available for insulation.

Longer Life Through Adaptation:90% of the original wood structure retained

CSA-ZT82-06 Guideline for Design for Disassembly and Adaptability on Buildings

Salvaged wood was used extensively in the adaptation of four town homes in Vancouver.

The strength of a building material refers to its ability to withstand an applied load without failure. Several types of load can be applied—tension, compression, torsion, bending and shearing.

Steel is one of the strongest materials for tensile strength, which is the amount of stretching it can take before breaking or failing. It is also one of the few materials that is equally strong in tension and compression.

Concrete is one of the strongest materials for compressive strength; tremendous loads can be put on concrete without crushing it. However, concrete doesn’t have the same advantage when it comes to tensile strength. In building construction, rebar (or reinforcing steel bars) provides the tensile strength lacking in concrete. Concrete also has a very low coefficient of thermal expansion, which means that it shrinks as it matures. All concrete structures will crack to some extent, due to shrinkage and tension.

Terminal 2 at the Raleigh-Durham International Airport features a stunning and innovative timber roof system. Designers envisioned a seamless rolling roof line—which required a combination of large wood and steel members to achieve. A hybrid structural system was created featuring lenticular, long-span king post trusses built from glulam members, steel sections, and locked coil cable tension chords. The major challenge was to develop a connection design to handle significant forces at the steel wood joints, while maintaining a clean, craftsman-like appearance. The result is a system in which the connection mechanisms are nearly invisible, fitting seamlessly into the wood.

Terminal 2, Raleigh-Durham International AirportNorth Carolina

Architect: Fentress Architects

Strength

Photo: Nick Merrick @ Hedrich Blessing, courtesy Equilibrium

Wood’s strength is dependent on loading direction. It is strongest in tension along the fibers and weakest in radial and tangential directions. When loaded longitudinally along the grain, wood can have a strength-to-weight ratio advantage relative to steel of 2:1. However, when wood is loaded in other directions, including radial and tangential to the grain, this advantage disappears.

Wood’s strength also varies significantly by species.

The photo in this slide is the Branson Convention Center, which shares amenities with the Branson Hilton hotel. The salient feature of the building is a sweeping concourse of heavy timber construction that recalls the natural context of the Ozarks.Timber posts provide lateral support for the 25-foot tall curtain wall. Exposed heavy timber decking forms the roof and finished ceiling of the structure. The decking is supported on glulam roof beams, and sloping V-braces—made from 15-inch diameter circular timber columns—support the glulam beams, which span up to 80 feet.

Sources for 2:1 stat: Ho Chi Min University: http://www4.hcmut.edu.vn/~dantn/Matter/Wood.html Roy Mech engineering website: http://www.roymech.co.uk/Useful_Tables/Matter/Wood.html

Wood: The Designer’s Choice

Strength depends on load direction.

Every species has its own strength characteristics and applications.

Branson Convention CenterMissouriArchitect: tvsdesign

Photos: Brian Gassel, tvsdesign

Wood is also an excellent choice for use with other materials—as illustrated by the photos shown here. The 200,000-square-foot Arena Stage at the Mead Center for American Theater has 18 Douglas-fir parallel strand lumber columns that go as high as 56 feet to support the roof’s steel trusses, girders and rafters. The Pocono Environmental Education Center makes use of wood and concrete. Note that wood has been used in both cases to add architectural drama and visual warmth.

Wood complements other materials while expanding design options.

Pocono Environmental Education Center PennsylvaniaArchitect: Bohlin Cywinski Jackson

Leveraging Structural Properties

Steel+

Wood

Concrete+

Wood

Photo: naturallywood.com

Photo: Nic Lehoux

Arena Stage: Mead Center for American TheaterDistrict of ColumbiaArchitect: Bing Thom Architects

For decades, the wood industry has been evolving high-strength products in the form of engineered wood—including plywood, oriented strand board, glulam beams, I-joists and laminated veneer lumber, to name just a few examples. In addition to strength, engineered wood is also highly consistent and can be manufactured to precise specifications. Adding to its sustainability advantages, it is often made from (among other things) chips, particles, fibre's and wood from small-diameter trees not suitable for lumber—which is part of the reason the wood industry now utilizes more than 99 percent of every tree harvested and brought to a mill.

This photo shows the speed skating rink in the Richmond Olympic Oval, which was built for the 2010 Winter Olympic Games. It includes a 6-acre (2.4-hectare) free-spanning wood roof roughly the size of four and a half football fields. For the Games, the Oval housed a speed skating track with temporary capacity for about 8,000 guests. Afterwards, the facility was converted to multi-purpose sports use.

Richmond Olympic OvalBritish ColumbiaArchitect: Cannon Design

Limitless Structural Possibilities

Photo: naturallywood.com

One innovative engineered wood product is cross laminated timber, or CLT, a material widely used in Europe that is significantly increasing the possibilities for North American wood buildings. CLT is comprised of boards stacked together at right angles and glued over their entire surface, creating a product that retains its static strength and shape, and allows the transfer of loads on all sides. Besides being dimensionally stable, it is highly versatile, able to span long distances and appropriate for use in all types of assemblies.

Internationally, CLT has propelled wood construction to new heights, the most recent example of which is the Forté, a 10-story apartment building in Australia. It offers the structural simplicity needed for cost-effective projects, as well as benefits such as rapid installation, reduced waste, energy efficiency and exceptional design versatility.

In North America, CLT is relatively new but quickly gaining momentum. In 2012, the American National Standards Association approved ANSI/APA PRG 320-2012 Standard for Performance-Rated Cross-Laminated Timber, a product standard that details manufacturing and performance requirements for qualification and quality assurance. Due to recently approved code changes, CLT is scheduled to be included in the 2015 International Building Code. In the meantime, a handful of innovative designers have already built CLT structures in the U.S. and Canada, having had them approved under the relevant code through an alternative or innovative solutions path.

Photo: Lend Lease

Cross Laminated Timber

Prefabricated, high-strength wood solution that can substitute for concrete, masonry and steel in many applications

Multiple layers, each oriented crosswise to adjacent layers

Versatile (floors, walls, roofs); able to achieve long spans

Can be prefinished Complements existing light and

heavy-frame options

Photo: Lend Lease

Forté – 10 storiesAustraliaDeveloper: Lend Lease

The Crossroads, a 52,000-square-foot client and staff reception area, is part of the Promega Feynman Center, a 300,000-square-foot Good Manufacturing Practices (GMP) facility in Wisconsin. To contrast the GMP with a warmer aesthetic while meeting sustainability objectives, the design team chose a combination of glued laminated timber beams and a cross laminated timber roof.

The structure has a complex footprint, forming a sinuous S-curve that wraps around one corner of the rectangular GMP facility. The team was challenged to use a material that would perform well for the long-span deck needed to cover the curved roof—and CLT provided the solution. However, with virtually no square angles in the structure, beam-to-column connections were a challenge. To avoid more than 100 different configurations, the engineer designed a steel pin connector that allows as much as 10 degrees rotation in either direction, providing the required swivel to fit nearly all of the connections.

Cross Laminated Timberin the U.S.

Promega Feynman Center “The Crossroads”Wisconsin

Architect and images: Uihlein-Wilson Architects, Inc.

View from Southwest

In Canada, British Columbia has been a leader in the development of CLT projects. One example is the 21,000-ft2 (2,000-m2) University of British Columbia Bioresearch & Demonstration Project in Vancouver, which is designed to achieve LEED Gold certification. The first biomass-fueled heat-and-power generation system of its kind in the world, the building will convert mountain pine beetle-killed wood pellets into synthetic natural gas to offset 12 percent of the campus’ electricity. The facility was the first approved CLT public building in Canada and incorporates 34,000-ft2 (3,100-m2) of CLT panels. Architecture firm McFarland Marceau chose CLT as the structural material for several reasons. Most important, the size of the equipment within the structure dictated installation prior to frame construction and a structural material that could accommodate long spans without supports. Other keys to selection included wood’s inherent environmental properties, particularly carbon sequestration, CLT’s ability to contain noise from the biomass equipment, and speed of construction.

University of British Columbia Bioresearch & Demonstration ProjectBritish ColumbiaArchitect : McFarland Marceau Architects

Cross Laminated Timber in Canada

Photo: naturallywood.comRendering: McFarland Marceau Architects

According to the National Fire Protection Association, property loss from fire was valued at approximately $11.7 billion in 2011. While no building is completely fireproof, construction materials and systems can improve a building’s fire safety.

• Concrete, and especially Insulating Concrete Form (ICF), is a good fire-resistant material. Concrete can’t burn and, unlike steel, it won’t soften or bend. Concrete’s thermal mass properties—slow absorption and release of heat—help to mitigate fire risk, and it is able to achieve fire-resistance ratings without additional fireproofing.

• Structural steel requires fireproofing to prevent the steel from weakening in the event of a fire. When heated, steel expands and softens, eventually losing its structural integrity and, under extreme conditions, melting. According to the National Institute of Standards and Technology, when exposed to fire, steel loses its strength and stiffness much faster than high-strength concrete.

• Although seemingly counter-intuitive, wood can be an excellent performer under fire conditions. According to the Southern Forest Products Association, wood outperforms non-combustible materials in direct comparison fire tests. A 2x4 timber tie maintained more of its original strength under higher temperatures and for a longer period than did aluminum alloy or mild steel. This is because of wood’s unique charring properties. When wood burns, a layer of char is created which helps to maintain the strength and structural integrity of the wood beneath—a scenario that enables an exposed heavy timber system to achieve a fire-resistance rating of up to 90 minutes. Properly designed wood-frame walls, floors and roofs using conventional wood framing, wood trusses and wood I-joists can also provide fire resistance ratings of up to two hours.

Sources:Property loss estimate – http://www.nfpa.org/research/fire-statistics/the-us-fire-problem; concrete facts – Concrete Alliance Inc. http://www.theconcretealliance.com/CastinplaceReinforcedConcrete/tabid/56/Default.aspx; wood performance fact – Southern Pine Use Guide, Southern Forest Products Association, http:southernpine.com/pdf/200_Use_GuideL.pdf

Photo credit: FPInnovations – CLT tire testing

Fire Resistance

Property losses from fire were $11.7 billion in 2011.

No building is completely fire proof.

Wood has outperformednon-combustible materialsin direct comparison fire tests.

Photo: FPInnovations

Advances in building science and fire suppression systems have expanded the scope and role for wood structural and finish materials.

While seismic design is complex, there are certain general principles. To withstand earthquakes, buildings are designed to be flexible and move without breaking. This ability to yield and deform without fracturing is called ductility.

According to Timber Engineering Europe, the type of construction that causes the most fatal injuries in earthquakes is unreinforced brick, stone or concrete buildings that tend not to be flexible and to collapse when shaken. Metal can be formed to flex and bend without breaking, allowing the building to sway and reducing the stress on the building. However, both the elastic limit and ultimate strength of wood are very high under short load durations, which makes it perform well in seismic events.

The many nailed joints in wood-frame structures make them inherently more ductile, which enables them to dissipate energy from the sudden shock of an earthquake. Numerous load paths, such as those found in wood buildings, help avoid collapse in the event that some connections fail. Also, since forces in an earthquake are proportional to the weight of a structure, wood’s relative light weight adds to its performance.

In California’s 1994 Northridge earthquake, where peak ground accelerations nearly broke records and were considerably higher than code requirements, many large structures collapsed. At a hearing before the U.S. House of Representatives, a reason given for relatively limited death and damage toll was ... “The earthquake occurred at 4:31 a.m., when the majority of people were sleeping in their wood-frame, single-family dwellings, generally considered to be the safest type of building in an earthquake.”

Source: The January 17, 1994 Northridge Earthquake, an EQE Summary Report, http://www.lafire.com/famous_fires/1994-0117_NorthridgeEarthquake/quake/00_EQE_contents.htm

Seismic Performance

Low mass and high flexibility make wood-frame buildings more resistant to earthquake damage than concrete or steel-frame buildings.

High strength-to-weight ratio makes wood a good structural material in terms of seismic performance.

Three undamaged wood-frame buildings (background) next to an older building (foreground) whose ground floor has collapsed completely; Nishinomiya, Japan, Hyogo-ken Nanbu Earthquake, 1995.

Photo courtesy European Wood China

This photo is from a ‘shake table’ test conducted in Japan, during which a full-size prototype of a six-story wood-frame building withstood forces greater than those of the 1995 Kobe earthquake. The structure suffered no visible damage.

Click on image to go to video of the shake table test (note – on YouTube).

Shake Table Test – Six Story Wood Building

In 2009, a full size prototype of a six-story wood-frame building successfully passed a seismic ‘shake table’ test conducted in front of 400 international observers in Japan. Subjected to seismic forces greater than those of the 1995 Kobe earthquake, the structure suffered no visible damage.

Photo: John van de Lindt, University of Alabama

MATERIALS IN THE CONSTRUCTION PHASESECTION 2

This section of the presentation will consider materials during the construction phase, including the trend toward prefabrication and panelization, and advantages of wood use such as adaptability and light carbon footprint.

The project in this slide is The Quarter, which includes three separate four-story wood buildings. Two of the structures rest on a 50,000-square-foot post-tensioned concrete podium deck, which separates ground level parking from 150 high-end residential apartment units.

The QuarterMarylandArchitect: Poole & Poole Architecture

Materials in the Construction Phase

Photo: Davis & Church, LLC

Panelizing, the process of assembling roof or wall sections on the ground and then lifting them into place, allows contractors to reduce labor and material costs while offering faster construction.

Panelized wood roofs are a particularly good choice for low-slope roof structures such as big box stores and warehouses. There are two basic types of panelized wood roof systems: • All-wood systems consisting of glulam beam girders with wood purlins, wood sub-purlins and a wood structural panel deck, are commonly seen in buildings with spans of less than 40 feet. They’re particularly well suited for applications where conveyor equipment is hung from the roof structure or in food-processing facilities that need to minimize dust from overhead joists. This is also a good choice for designers who want to take advantage of wood’s aesthetic benefits for an exposed roof structure, for example in retail or school applications. • Hybrid systems consist of steel purlin and girder trusses together with wood sub-purlins and a wood structural panel deck. The long span capability of steel framing makes this system particularly economical when spans are more than 32 feet. Wood decking allows better economy than steel, both in terms of material and installation costs. This is usually the system of choice for large warehouse and industrial structures requiring long spans. CLT is another panelized system that is increasing the opportunities for wood design.

Trends

Prefabrication and penalization: Pre-cast concrete Pre-fabricated

steel Panelized wood

products

Hybrid steel/wood panelized roof

Wood’s advantages on the job site include adaptability—which allows contractors to make modifications during construction, even to a building’s floor plan, the number of rooms, interior design or overall appearance. This same adaptability means wood structures are well suited to renovations if the needs of the occupants change.

Timber’s thermal efficiency also means walls can be slimmer, creating more usable floor space.

For those who want to verify that the products they use come from sustainable sources, wood is also the only material that can be purchased with chain of custody documentation that provides product tracking throughout the entire supply chain from harvesting, processing and transportation to the end consumer.

Adaptability, allows modifications during construction and later renovations

Thermal efficiency, maximizes useable floor area

Product stewardship: Chain of Custody certification

Photo: Arch Wood Protection

Wood’s Advantages On-Site

Another pressing issue during construction concerns the environmental impacts of getting materials to the job site. This slide shows the results of a study examining the carbon footprint implications of transporting four wood products from British Columbia, Canada to the UK—namely softwood lumber, softwood plywood, western red cedar lumber and western red cedar siding.

The study—which was undertaken in accordance with a strict UK protocol known as PAS 2050—took into account the greenhouse gases emitted during the harvest, manufacture and transport of the products. It also considered the fact that wood products continue to store carbon absorbed during the tree’s growing cycle, keeping it out of the atmosphere indefinitely.

The results showed that, despite being transported more than 16,000 km (9,900 mi), all four wood products in the study represent a net carbon sink upon delivery ... that is, each product stores more carbon than is emitted during its respective harvest, manufacture and transport. Unlike wood, steel has no such carbon storage capacity to offset the environmental costs of transportation.

Carbon Footprint Study

UK was first to have a Publicly Available Specification—PAS 2050 —for assessing the carbon footprint of individual products

Study assessed four BC wood products marketed in the UK

Source: A Carbon Footprint of Four Canadian Wood Products Delivered to the UK as per PAS 2050 Methodology, prepared by the Athena Institute and FPInnovations, 2010, www.naturallywood.com

Despite being transported more than 16,000 km (9,000 mi), all four Canadian products represent a net carbon sink upon delivery in the UK.

Results shown are per cubic meter (m3) of product

MATERIALS IN THE USE PHASESECTION 3

This section of the presentation will focus on the environmental impacts associated with materials in the use phase.

The building in the photo is the basketball arena of the 320,000-square-foot El Dorado High School. Glulam bowstring roof trusses span 160 ft over the basketball arena. Designers used exposed wood and natural light to create an environment that would motivate students to stay in school.

Eldorado High SchoolArkansasArchitect: CADM Architecture

Materials in the Use Phase

Photo: Dennis Ivy, courtesy WoodWorks

According to the U.S. Department of Energy, buildings account for 38 percent of total U.S. energy consumption. However, there are certain terms that should be understood as it relates to energy.

There are two forms of embodied energy in buildings: initial embodied energy and recurring embodied energy. For building materials, initial embodied energy is the non-renewable energy consumed in raw material acquisition, processing, manufacturing, transportation to site, and construction.

Recurring embodied energy is the non-renewable energy consumed to maintain, repair, restore, refurbish or replace materials, components or systems during the life of the building. It’s related to the durability of the building materials, the building’s components and systems, how well these are maintained, and the life of the building.

Operating energy refers to the energy buildings consume for heating, cooling, ventilation, lighting, equipment and appliances. Increased insulation in foundations, walls, doors, and windows may improve the operating efficiency of a structure, but the insulation products themselves may increase the structure’s embodied energy. Appreciating—and balancing—the need to reduce operating energy in buildings and its effect on embodied energy is critical to true sustainability.

Terms and Definitions

Initial Embodied Energy Non-renewable energy consumed in raw

material acquisition, processing, manufacturing, transportation and installation

“Cradle to Gate” Recurring Embodied Energy

Non-renewable energy used to maintain, repair, restore, refurbish or replace materials and components during a building’s service life

Related to building durability Operating Energy

Energy consumed by buildings to maintain the internal environment and ensure system functionality

Trade-offs and synergies

Energy performance of buildings depends more on insulation, air sealing and other factors than the choice of structural material. All buildings are typically insulated well, so they tend to have essentially comparable energy performance. The embodied energy of a building, however, is very much affected by structural material. This chart is based on life cycle assessment (LCA) calculations for identical 2,400-square-foot homes designed according to standard local practice. The wood house had less embodied energy than the concrete or steel-framed structures. Concrete structures had the highest embodied energy.

According to the NAHB Research Center, insulated concrete forms (ICF), rigid plastic foam forms that hold concrete during curing and remain afterwards to serve as thermal insulation for concrete walls, are superior insulators to standard concrete. But materials with a heavy carbon footprint like concrete can skew the balance between embodied and operating energy.

About the graphic:• Data comes from an LCA study of different house framing, by the Athena Sustainable Materials Institute for the Canadian Wood Council in 2004. The graphic shown here was generated from the dataset but was not reported in the original study.• The LCA calculation was done by Athena using its software and databases.• The operating energy was calculated by Morrison Hershfield engineers, using Natural Resources Canada’s HOT2000 software, and using a Toronto climate. A 60-year period was used.• The homes are identical 2400-square foot typical homes designed according to standard local practice. The concrete house features insulated concrete forms.

Embodied Plus Operating Energy Over 60 Years

Sources: Athena Sustainable Materials Institute, Canadian Wood Council, Morrison Hershfield Engineers, 2004

As this graphic illustrates, a typical concrete house has nearly as much energy embodied in the materials as it takes to run the house for 20 years. If the embodied energy is increased by adding much more insulation, it is important to make sure that the savings in heating energy will be greater than the embodied energy in the insulation.

This is from the same research as the previous slide.

Reducing Operating and Embodied Energy

Sources: Athena Sustainable Materials Institute, Canadian Wood Council, Morrison Hershfield Engineers, 2004

The thermal conductivity of building materials has direct bearing on their performance as insulators. Low thermal conductivity indicates that a material is a poor conductor of heat and therefore a good insulator. Any material with open pockets of air will insulate better than a material that’s solid. Wood is made up of thousands of tiny open cells that limit its ability to conduct heat. The thermal properties of wood are 400 times better than steel and 10 times better than concrete.1 Their higher conductivity means steel and concrete must overcome lower R-values associated with thermal bridging; as a result, they require more insulation to provide the same level of energy efficiency.

This graph illustrates energy performance in two similar houses near Chicago. The steel house has significantly more insulation than the wood house and still can’t perform as well. In addition, the steel house has a lot more embodied energy, which is not reflected in the graph.

The two identical houses, unoccupied but with heating and cooling systems operating, were built to standard practice for wood-frame and steel-frame. Data was measured for one year and also simulated with software in order to normalize and validate results. Both houses have fiberglass insulation between the studs. The steel house has more insulation volume, because its studs are spaced at 24 inches vs. 16 inches for the wood house. In addition, the steel house has a 3/4-inch layer of rigid polystyrene board mounted to the outside of the framing sheathing—standard practice for steel framing—to reduce conduction of heat at the studs. Yet even with these benefits, the steel house still cannot perform as well as the wood house. Steel framing requires a layer of exterior polystyrene foam, which adds cost and embodied environmental effects. If the wood studs were spaced at 24 inches, like the steel (which is sometimes the case), the wood performance would be even better.

Source: The homes were the subject of a 2002 study prepared for the U.S. Department of Housing and Urban Development, the North American Steel Framing Alliance and the National Association of Home Builders by the NAHB Research Center. http://www.huduser.org/portal/publications/destech/steelval.html

1Thermal Performance of Light-Frame Assemblies, Canadian Wood Council, http://cwc.ca/documents/IBS/IBS5_Thermal_SMC_v2.pdf

Thermal Performance: Wood vs. Steel Homes

Sources: NAHB Research Center for US Department of Housing and Urban Development, the North American Steel Framing Alliance and National Association of Home Builders, 2002.

END OF USE – A CLOSER LOOK AT RECYCLING AND REUSE

SECTION 4

We’ve already talked about the importance of considering a material’s environmental impacts during construction as well as a building’s operational phase, but what about it’s end-of-life impacts?

The U.S. EPA estimates that the U.S. generated more than 160 million tons of building-related construction and demolition (C&D) waste materials in 2003—nearly 53 percent of which was the result of demolition activities, 38 percent from renovations, and nine percent from new construction. Only 40 percent of this waste was estimated to be reused, recycled or sent to waste-to-energy facilities, leaving 60 percent going to landfills.

Source: US Environmental Protection Agency, http://www.epa.gov/wastes/conserve/imr/cdm/index.htm

The U.S. generates more than 160 million tons of construction waste per year.

Only 40% is estimated to be reused, recycled or sent to waste-to-energy facilities, leaving 60% going to landfills.

Source: U.S. EPA, 2003

End of Life: Reduce,Reuse, Recycle

Photo: courtesy Metro Vancouver

In the context of reducing end-of-life impacts, it’s important to highlight the need to minimize waste from the outset by making the most of our resources.

The forest industry is organized to maximize resource efficiency and derived value by making the most out of every tree harvested. For example, high value saw logs are utilized for lumber, while lower value logs are used for pulp, and residual biomass and byproducts from pulping are used for bio-energy, bio-chemicals and bio-materials.

The industry also has a number of interconnected sub-sectors that collectively maximize resource efficiency and derived value. It’s common for companies to have cogeneration facilities, also known as combined heat and power, which convert sawdust, bark and other residual fiber to electrical and thermal energy.

In this way, the North American wood industry now utilizes nearly 99 percent of every tree harvested and brought to a mill.

Source: The Current State of Wood Reuse and Recycling in North America, Dovetail Partners Inc., http://www.dovetailinc.org/reportsview/2013/responsible-materials/pjeff-howep/current-state-wood-reuse-and-recycling-north-amer

Reduce: Minimizing Waste from the Outset

Zero waste –harvested trees are almost entirely converted into usable product.

Plywood is a panel product made from wood fiber unsuitable for lumber.

Photo: naturallywood.com

Reusing wood also has obvious benefits when you consider the impacts of waste disposal, but it also has an impact on their carbon footprint. As discussed earlier, wood products store carbon absorbed by trees during their growing cycle. Reusing wood extends the amount of time the carbon is stored—keeping it out of the atmosphere even longer.

Salvaged wood is valued for its beauty and requires very little energy to process, so the impacts are largely related to transportation. But its use is not without obstacles, since some areas have more established salvaged wood markets than others.

The photos on this slide illustrate two interesting examples of wood’s reuse potential.

Through a novel collaboration between the client and the city, the team developing the Greater Texas Foundation building on the left—led by Dunnam Tita Architecture + Interiors—was able to salvage a large quantity of antique long-leaf pine from the structure of a recently demolished warehouse. This “very local” reclaimed material is prominently featured throughout the new building, in applications that range from structural blocking inside walls to finished wood floors, exposed roof decking, wood ceilings, the front door and several custom furniture pieces.

The Freight & Salvage Coffeehouse, designed by Marcy Wong Donn Logan Architects, exemplifies the use of wood where acoustics, reclaiming history and ideals all come together. Much of the new building’s structural system (in the form of salvaged wood trusses) and all of the paneling in the theater (re-milled roof decking) came from the site’s previous building. The weathered wood used in the theater auditorium—combined with state-of-the-art acoustic backing—created a striking, vintage feel that would have been difficult to recreate with another material. It also helped the design team meet its sustainability objectives.

Photos: (left) Casey Dunn, courtesy of Dunnam Tita Architecture + Interiors; (right) Sharon Risedorph Photography, courtesy of Marcy Wong Donn Logan Architects, Inc.

Wood ‘’Waste’’ is Valuable

Freight & Salvage CoffeehouseCalifornia

Architect: Marcy Wong Donn Logan Architects

Photo: Casey Dunn Photo: Sharon Risedorph

Greater Texas FoundationTexasArchitect: Dunnam Tita Architecture + Interiors

As part of the green building movement, there’s a trend toward designing buildings for deconstruction, which requires less use of resources—in other words, design to facilitate salvaging components during demolition for reuse in their original high value format. Most green building rating systems award points for the use of salvaged materials.

The Lynn Creek branch of the Vancity bank shown in the photo used wood salvaged from a railway trestle in Quesnel, British Columbia. The bridge was disassembled and the wood then graded for structural use.

Design for Reuse

This heavy timber structure was sourced from a railway trestle bridge in Quesnel, B.C.

The bridge was disassembled and the wood then graded for structural use.

Vancity Lynn Creek BranchBritish ColumbiaArchitect: Toby Russell Buckwell Partnership

Photo: Green Building Brain

The concrete and steel industries have made great strides in recycling their materials. Recycled concrete aggregate has found ready markets as road base, asphalt pavement, soil stabilization, pipe bedding and landscape materials; occasionally it is used as aggregate for new concrete. Steel is widely recycled as well. In a year, the American Iron and Steel Institute says the North American steel industry saves the equivalent energy, from recycling alone, to power about 18 million households for a year.

However, while recycling extends the life of our resources, a closer look is warranted. Although reusing concrete aggregate is referred to as recycling, some maintain it’s actually down-cycling, as the greatest economic value is in the cement, which can’t be reused. “Design for Deconstruction,” a report prepared for California’s Chartwell School partially funded by the EPA, says, “Crushed aggregate even tends to require higher cement mix designs, offsetting some of the benefit and reducing virgin aggregate use.” While recycling saves energy, it also expends energy and sometimes in large amounts, particularly in the case of steel. The Chartwell School study says that recycling steel takes 50 percent of the energy required to refine steel from ore.

Sources:Steel fact – American Iron and Steel Institue, http://www.steel.org/~/media/Files/AISI/Fact%20Sheets/50_Fun_Facts_About_Steel.ashxChartwell study – Design for Deconstruction, http://www.lifecyclebuilding.org/files/DFD.pdf

Revisiting Recycling

Difference between recycling and down-cycling Material value should not be depleted in the recycling process. Recycling metals requires large amounts of fossil fuel energy.

Steel mill with two electric arc furnaces. Recycling scrap steel requires about 50% of the energy need to smelt virgin steel from iron ore.

Photo: wikipedia

In some instances, a material with no recycled content can actually be a more sustainable choice than a recycled material. This chart shows the results of a life cycle assessment comparing the environmental profile of two standard structural post-and-beam systems, one with wood and one with steel, and a third option using a theoretical steel with 100 percent recycled content. The wood system is glulam beams on wood columns with no recycled content. The steel system is standard wide flange beam on hollow structural section columns; recycled content is 25 percent, typical for the industry. The wood performance is set as the benchmark at 100 percent, and the other sets of bars are shown by percentage better or worse than the wood.

Figures were calculated by FPInnovations using the ATHENA Impact Estimator for Buildings.

A Closer Look at Recycled Content

Source: FPInnovations, calculated using the Athena Impact Estimator for Buildings, 2008

EVOLVING BUILDING CODESSECTION 5

options for wood use in construction. Earlier in this article, reference was made to the fact that CLT will be included in the 2015 IBC. This particular code change is getting a lot of attention because of the ground breaking nature of CLT; nine- and ten-story CLT buildings exist and exciting concepts have been developed for going higher still. However, the possibilities for wood use have actually been expanding since the IBC was introduced in 2000.

The IBC consolidated three regional model building codes into one uniform code that has since been adopted by most jurisdictions. It created more opportunities for wood use by (among other things) recognizing additional fire protection techniques, and combining the maximum allowable heights and areas from the three legacy codes into one (thus increasing what's allowable in some jurisdictions).

So – how high can a building be under the IBC?

IBC – Expanding Opportunities for Wood

Recognized additional fire protection techniques

Combined three model codes, thus increasing maximum allowable heights and areas in some jurisdictions

Photo: Matt Todd courtesy WoodWorks

Marselle CondominiumWashingtonArchitect: PB Architects

Most midrise wood buildings are Type V Construction and four stories or less. However, Type III offers far greater opportunities for achieving high density at a relatively low cost ... while of course meeting all requirements for safety and performance.

Like all construction types, Type III has base limitations with regard to height, number of stories and square footage. However, the IBC allows increases to these tabular amounts per other code sections.

Source for slides 38-42: Tim Smith, Architect, Togawa Smith Martin, presentation at the 2013 American Institute of Architects Conference

Base Code Height

1989 – UBCBase code height – Table 5B

Type IIIA / 2009 – IBCBase code height – Table 503

For example, when a building has an NFPA 13-compliant automatic sprinkler system, the floor area can be increased by 300% for a one-story building and 200% for a multi-story building. In addition to the area increase, IBC Section 504.2 allows a 20-foot increase to the tabular building height and an additional story above the grade plane. The exception to his is Group I-2 occupancies, which include hospitals and nursing homes and are not allowed the extra story.

Adding an automatic sprinkler system not only means that a five-story wood building is allowed, it means a maximum height of 85 feet instead of 65 feet. So how do we maximize the vertical envelope to take advantage of the extra height when a typical five-story building is only about 55 fee

Sprinkler System

1989 – UBCSprinkler increase – Section 506

Type IIIA / 2009 – IBCSprinkler increase – Section 504

Add 1 floorIncrease height 20 feet

First we add another level. Under the 2009 IBC, you can add a wood-frame mezzanine on top of a multi-story wood building. The area of the mezzanine can’t be more than 1/3 of the floor below and isn’t defined as a ‘floor’ or ‘story.’

Starting with the base height and then adding a sprinkler system and now a mezzanine gets us to six levels of wood-frame construction and about 65 feet in height.

Mezzanine

1989 – UBC1989 – UBC

Mezzanine – Section 507

Type IIIA / 2009 – IBCMezzanine – Section 505

Add level 1/3 of floor below& not defined as a floor

Podium

1989 – UBCPodium – Section 311.2.2.1

2009 – IBCType IIIA / 2009 – IBC

Type I Podium – Section 509.2Separate buildings for area and stories3-hour separation between Type I and III

… We use a sloping site to our advantage.

The IBC recognizes that the world isn’t flat. It allows semi-basements or daylight basements providing they don’t extend from grade more than 12 feet at any one point and don’t extend more than 6 feet from the average grade. As with mezzanines, this ‘basement’ level is not considered a ‘floor’ or ‘story’ … but it gives us an eight-level building that’s in the range of 85 feet high.

Using a combination of Type III and Type I, we’ve now maximized the vertical envelope.

Semi - Basement

1989 – UBCHeight definition – Section 208

Type IIIA / 2009 – IBCGrade plane definition – Section 502

Add another level with daylight basement

In the U.S., it is becoming increasingly common for designers to include five stories of wood over a concrete podium.

Here’s another image of the Marselle, along with two other five-story buildings—Americana at Brand and the University of Washington West Campus Student Housing Project, Phase One.

Podium Buildings

Marselle Condominium5 ½ stories of wood

WashingtonArchitect: PB Architects

Photo: Matt Todd

Photo: Togawa Smith Martin

Photo: Benjamin Benschneider

University of Washington5 stories of woodWashingtonArchitect: Mahlum

Americana at Brand5 stories of woodCaliforniaArchitect: Togawa Smith Martin

The trend toward taller wood buildings is also apparent in Canada. In 2009, for example, British Columbia increased the allowable height of residential wood buildings from four stories to six.

Library Square, shown here, was one of the first buildings built under the new code. It includes five stories of wood over one story of concrete.

Six Stories in British Columbia

Effective starting April 2009

Concrete-wood hybrids also allowed (maximum height 60 ft)

Photo: naturallywood.com

Library Square6 storiesBritish ColumbiaArchitect: JM Architects

As this presentation has shown, wood offers significant advantages during construction, operation and end-of-life, and reaffirms that in the quest for carbon-neutral buildings, materials matter.

The building in this photo is the Kwantlen University College Trades & Technology Centre. Large glulam beams are featured predominantly, and locally produced materials were used throughout the project. The beams were produced within a 500 mile radius of the campus.

From harvest to end-of-life, wood proves its value as a sustainable building material.

Unique features of wood: Strong and durable, performs

effectively in fires and earthquakes Less embodied energy than steel

or concrete, and is a natural insulator

Has a light carbon footprint Lends itself to recycling and reuse

without significant energy input

Photo: naturallywood.com

Kwantlen University CollegeBritish ColumbiaArchitect: Bunting Coady Architects

Materials in Action Matter

For more information on building with wood, visit rethinkwood.com

THANK YOU!