Recycled Content of Sheet Steel Building Products

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The construction industry is a vital part of the growth and success of a country. It is responsible for building the physical infrastructure that provides transportation and facilities for citizens, businesses, industries and institutions. Construction has a major influence on the economic wealth, societal well¬being and sustainability of the built environment. The Canadian construction industry employs more than 1.2 million people. In 2010 it accounted for 6% of Canada’s gross domestic product (GDP), with a total value of 73.8 billion dollars. From 2000 to 2010, the GDP from construction increased 42.7% whereas GDP for all industries increased 20.2%.(1)

Construction also has a profound impact on our natural environment. In North America, the built environment accounts for approximately one third of all the greenhouse gas (GHG) emissions, as well as energy, water and materials consumption. Given the increased awareness of “green” construction, there is growing interest in using steel because of the major recycled content and recyclability attributes it provides to architects, engineers and specifiers in the construction industry.

The steel industry, through the Canadian Sheet Steel Building Institute is committed to providing steel solutions that promote the use of sustainable materials in construction applications. This fact sheet provides an overview of the two main methods used to produce steel, and describes the recycled content of the steels used to manufacture building products such as roofing, cladding, decking, structural and non-structural framing and the many other construction products used in the industry.

Once iron ore is extracted and refined into steel, its life never ends. This makes steel an ideal material to deploy in sustainable strategies for the construction industry. Today’s steel is produced using two technologies both of which require “old” (recycled scrap) steel to make “new” steel. The combination of these technologies enables Canadian steel mills the flexibility to produce a variety of steel grades for a wide range of product applications.

Steel – The World’s Most Recycled Material

Steel is the world’s most recycled material. In 2012 alone, 88 million tonnes of steel were recycled in North America.(2) This is done for economic reasons, as scrap is a valuable commodity and the fact that recycling has significant environmental benefits. Even though two out of every three kilograms of new steel are produced from “old” steel, the fact that buildings, appliances, bridges and other infrastructure products have such long service lives, makes it necessary to continue to mine some virgin ore to supplement the production of new steel.

(1) Statistics Canada - http://www.statcan.gc.ca/pub/11-402-x/2011000/chap/construction/construction-eng.htm 
     (accessed January 22, 2014)
(2) Steel Recycling Institute - http://www.recycle-steel.org (accessed January 22, 2014)

Click here to download Fact Sheet 20: Recycled Content of Steel Building Products to learn more.

Care and Maintenance of Pre-finished Sheet Steel Building Products

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Prefinished sheet steel building products, such as wall and roof cladding, liner sheet, flashing, and associated items, have experienced an enviable growth record during the past twenty years or so. Coil coated prefinished sheet steel in a variety of colours and paint systems has greatly enhanced the appearance of thousands of industrial, commercial, institutional, recreational, residential and farm buildings, providing an economical, durable and attractive alternative to traditional materials. As with all materials, a little care and maintenance pays off handsomely in terms of longevity and repair costs. The recommendations which follow have been learned at first hand and represent the collective industry experience with thin-film paint systems applied to metallic coated sheet steel by the coil coating process. In this publication the term "thin-film paint system" refers to a modified silicone polyester or a fluorocarbon type having a coating thickness about 25μm.

When the guidelines listed below have been observed, thin-film paint systems have been used successfully for all types of environments other than severe industrial atmospheres which require special consideration. The guidelines are not intended for barrier coatings, laminates, and new formulations which have different characteristics than the thin-film paint systems on which these guidelines are predicated.

Design, Detail and Colour Considerations 

• Architectural details should permit natural rain-flow cleaning of the cladding. 
• On roofs or other horizontal surfaces, standing water can contribute to the premature failure of the paint system and substrate. Detailing should preclude damming or ponding of rain-flow at stacks, ventilators, air control equipment and other objects. 
• Due to colour tolerances, there may be differences in colour shade between production runs. Where possible, ensure that each building elevation is clad with material from the same production lot. If different production lots must be used on one elevation, as may occur when making an addition to an existing building, try to begin the cladding on an elevation change or break in the building to minimize the effect of possible colour variations. 
• A sufficient roof slope to permit drainage is recommended (e.g. 1 in 48 minimum, and greater where rainfall is heavy, drainage is restricted, etc.). 
• Roof surfaces, defined as those up to 60 degrees from the horizontal, are subject to more severe exposure conditions than vertical surfaces. Conditions such as extended exposure to ultraviolet light may be resisted by using a light colour for the roof. Acid precipitation and drip edge puddling are other conditions that could affect the appearances and durability of the paint finish. Drip edge puddling may be minimized with a steeper roof slope or by modifying the edge details. If severe acid precipitation is experienced, a more resistant prefinish system may be required. 
• The building design should seek to minimize the installation of mechanical equipment on a prefinished roof. Walkways should be provided where regular traffic is necessary for maintenance. 
• In wall applications, horizontal portions of the cladding and base flashing should be sloped to prevent moisture from puddling. 
• Walls shadowed by overhangs and all soffit areas have an increased time of wetness relative to other areas. The increased time of wetness creates a more aggressive environment for the cladding so affected; therefore, architectural details should try to minimize these areas. 
• To decrease the visibility of "oil canning", select an adequate material thickness, a narrower flute and a lighter colour. 
• To prevent unwanted galvanic corrosion, the architectural details should not allow the contact of dissimilar metals (e.g. steel and aluminum or copper) or should provide an adequate means of separation. The path of rainfall runoff should also be directed to prevent water runoff across one type of material to another which can also cause galvanic corrosion.

Click here to download Fact Sheet 3: Care and Maintenance of Pre-finished Sheet Steel Building Products to read the rest of the guidelines.

Reflectivity of Prefinished Sheet Steel

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It’s a fact that buildings consume two thirds of all the electricity produced in North America and one third of all the energy produced in North America. While it is recognized that cooling and heating costs can be reduced by adding insulation under the roof surface, there is a diminishing return on the strategy of increasing insulation to conserve energy costs. This is where “cool roofing” can play a role in further reducing the energy consumed, and in minimizing the Heat Island effect created in the big urban cities. Cool roofing relies on the properties of reflectivity and emissivity of the roofing material. 

Reflectivity

Reflectivity is the ability of the roof to reflect solar radiation back into the atmosphere. Its primary measure is solar reflectance - the proportion of the total solar radiation that is reflected back to the atmosphere. Any solar radiation that is not reflected is absorbed into the building envelope, requiring further energy to cool the building; or partially convected into the atmosphere increasing the ambient air temperature in the surrounding environment (Heat Island effect).

The measure of reflectivity is the Solar Reflectance Index (SRI) which takes into account the properties of the material as well as the cooling effect of wind passing over the roof. The SRI for a low slope roof will be 0 for standard black (reflectance 0.05, emittance 0.90) and 100 for standard white (reflectance 0.80, emittance 0.90).

Emissivity

Emissivity is the ability of the roof to re-radiate absorbed solar infrared radiation back to the atmosphere. This takes place at all times, but mostly at night. Its measure is Infrared Emittance - the proportion of absorbed infrared solar radiation that is re-emitted back to the atmosphere. For prepainted sheet steel colours, the emissivity is generally high and close to 0.90.

Download Environmental Fact Sheet #5: Reflectivity of Prefinished Sheet Steel to learn more.

Lightweight Steel Framing - Looking forward to the benefits

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The CSSBI is committed to the advancement of lightweight steel framing as an environmentally-friendly “green” building product that reduces energy consumption and waste, improves indoor and outdoor air quality and conserves water and natural resources for both new and existing commercial and residential buildings.

Consider the overwhelming benefits of using lightweight steel framing in building construction; it is a product that is produced to consistent properties and dimen- sions, will not rot, shrink, swell, split, warp or provide a food source for mold, bacteria or insects, and is fully recyclable and non-combustible. Steel also has the highest strength to weight ratio of all structural building materials, and is a structural substi- tute for both dimensional lumber and reinforced concrete in building applications. From the perspective of supporting a healthy indoor air environment, steel framing is inert. It won’t release or offgas any volatile organic compounds, since it is free of resin adhesives and other chemicals like those used to treat wood framing products. Read on to find out more about other significant environmental benefits that light- weight steel framing can offer.

The Infinite Life of Steel Framing

All steel building products including steel framing are 100% recyclable. One of the key sustainable attributes of steel is its ability to be recycled without any loss or degradation of its inherent material properties, allowing it to exist for an infinite number of product life cycles.

The steel industry is the single largest recycler in North America. Over 88 million tonnes of steel were recycled in North America in 2012.While some countries report steel recycling rates as high as 85%, Canada’s 2012 recycling rate was in excess of 60%, which translates into over 7 million tonness being recycled that year.

Steel benefits from the most comprehensive and accessible collection infrastructure of any material, and not just in North America, but around the world. Steel is easily and economically extracted from other materials in the solid waste stream through magnetic separation, keeping a valuable commodity out of the country’s landfill sites.

The use of steel scrap is an essential component of the steel manufacturing process. The traditional basic oxygen furnace (BOF) steelmaking practice ensures that there is a minimum of about 30% recycled steel scrap in every ton of steel framing produced. However, over the past 50 years, economic and environmental considerations have driven technological advances in electric arc furnace (EAF) steelmaking technology. The EAF technology utilizes >95% recycled steel scrap in each furnace charge and currently accounts for about 40% of Canada’s steel production.

Using recycled steel for building construction also takes pressure off renewable resources. For ex- ample, framing a typical 2000 ft2 (186 m2) house out of steel only requires the equivalent of about six scrapped automobiles, while the same house framed in wood requires lumber from 40-50 trees, which is about an acre’s worth of forest.

Steel recycling is important for the environment since it affects the sector’s energy performance. The EAF and BOF process together recycle huge amounts of scrap steel in making new steel every year, thus conserving significant energy and other natural resources, while reducing emissions. Using old steel products and other forms of ferrous scrap to produce steel lowers a variety of steelmaking costs and reduces the amount of energy used in the process by 75 percent. It is estimated that for every ton of steel recycled, about 2,500 pounds of virgin iron ore is saved, along with 1,400 pounds of coal, and 120 pounds of limestone. In the U.S., recycled steel saves the nation enough energy to power about 20 million homes for one year.

Download Environmental Fact Sheet 3: Lightweight Steel Framing - Looking forward to the benefits to learn more about how lightweight steel framing is a sustainable construction product.