Recently the Ontario Provincial Government announced they are making cuts to the Environmental Commissioner of Ontario’s office and has also produced a less than enthusiastic environmental policy. Silencing the environmental critic isn’t going to change the fact that we have to do something about Climate Change.
Since the Ontario government isn’t going to take responsibility for our environment it falls on our businesses to take up the challenge.
That got us thinking, what can engineers do to reduce green house gases, especially in the construction industry?
Our office at IN Engineering has adopted a substantive environmental policy. We offer engineering services that are completely paperless including drafting and plans, invoicing and reporting. We also use Google servers for all of our file hosting that means our data is stored in the most efficient way possible (compared to local office servers that require a lot of energy). However, as an engineer we have the ability to specify products and materials that lean towards reduced green houses gases.
For demonstrative purposes we designed a beam for a residential property. The beam is supporting a roof and is subject to snow, weight and a maintenance person load. The length of the beam is 10 feet and it supports a tributary width of 10 feet.
The first beam designed was a concrete beam. In order to support the loads the beam has to be 8″ deep x 6″ wide with 2 – 20M bars at the bottom for tension reinforcing. It also requires 10M stirrups at 12″ for shear reinforcing. This design is at 98% capacity in bending resistance. The CO2 emissions for cement was researched to be 410 kg per cubic metre . The reinforcing steel in the concrete 0.762 kg of CO2 per kg of steel, 50% of the steel was assumed to be recycled.
The carbon footprint of the concrete beam was estimated to be about 343kg.
Concrete is responsible for about 5% of CO2 emissions worldwide, this is predominately due to the fact that it takes a lot of energy and burning to produce cement. Concrete also requires quarries to produce aggregates and sand which destroy the natural environment. Even worldwide availability of construction sand is becoming an issue – only beach sand is appropriate for concrete as river sand is too smooth.
The second beam designed is a steel beam. To support the loads, a W5x16 beam was selected with a maximum capacity of 61% in deflection. The CO2 emissions for steel were estimated at 0.762 kg of CO2 per kg of steel and 50% recycled.
The carbon footprint of the steel beam was estimated to be about 28kg.
The last beam designed was a built up wood beam made of 3-2×12’s and Spruce-Pine-Fir No.1/2. The beam is at 99% capacity in bending. Wood actually sequesters carbon dioxide at about 1.7 kg of CO2 per kg of wood . This means the wood beam actually has a negative carbon footprint.
The carbon footprint of the wood beam was estimated to be about -3400kg (stored).
There are actually more environmental benefits for using sustainable wood products. Forests will sequester carbon as they grow and mature to harvesting. At the end of the life of a wood product it can go to a landfill where it will decompose and produce methane. If the methane is collected then the environmental efficiency of wood increases. Wood is also a light building material, meaning it takes less effort to ship to site and construct.
This is a simple demonstration of how engineers can influence green house gas emissions in the construction industry. A more detailed study on the benefits of wood products was completed by Sathre, R. And J. O’Connor. 2010. A Synthesis of Research on Wood Products and Greenhouse Gas Impacts, 2nd Edition. Vancouver, B.C. FPInnovations. 117 p. (Technical Report TR-19-R)
At IN Engineering we believe that we are responsible for Climate Change and a sustainable future. In our designs we will always prefer to use wood products when the situation allows. We believe that engineered wood products are the future of construction as we enter into a post-industrial era to an environmental renaissance.
 Environmental Impact of Concrete, https://en.wikipedia.org/wiki/Environmental_impact_of_concrete  Carbon Footpring os Steel, http://www.newsteelconstruction.com/wp/the-carbon-footprint-of-steel/  Canadian Wood Council - Carbon Calculator, http://cwc.ca/carboncalculator/