Wednesday, January 24, 2018

Sustainable Engineering with Renewable Materials

One of the most innovative buildings built in Canada last year might be one of its most unassuming. Brock Commons Tallwood House on UBC's campus was completed late last year set to be used for student housing. Aesthetically, it comes in about average. The design has stayed with a cost-effective rectilinear form, and the designers have tried where they can to accentuate the exterior facade. What is worth noting, however, is the project's use of innovative materials and building techniques. 

One of the most interesting implications of tall timber structures is that it essentially deepens the number of ways buildings can be solar-powered. Steel and concrete, while contributing to the great heights achieved by modern architecture, also have correspondingly large carbon footprints. Another way of saying it is that steel and concrete are very energy intensive materials to produce. On the other hand, using timber means the growth of the building comes directly from a renewable resource, and that the Sun does most of the work. One can also assume that as time goes on, the carbon footprint of manufacturing and transporting the timber will continue to decrease as manufacturing plants and vehicles become more energy efficient (this point, of course, also applies to steel and concrete production as well). Increasing the use of renewable materials supports the AEC industry's goal of promoting sustainable design. 

To date, there's not a lot of in-depth research about the effects of fire retardants used on mass timber projects. It's definitely a necessary step, as such a building can be viewed as a humongous bonfire, and fire retardants of past decades are now seen to be harmful to human health as they tend not to stay inert in the wood forever. Essentially, the fire retardants need to penetrate the deep into the wood. No doubt this risk was considered at some point in this project, however, I can't yet point readers to any sort of in-depth reporting expanding on the modern use of fire retardants in these types of buildings. I have also heard reports from the UK that sound transmission through mass timber structures can be exaggerated compared to a concrete high-rise. Mechanical energy waves like someone dropping a chair can travel quite far through the timber beams and columns. Decouplers installed between columns and beams can stop mechanical energy noise from transiting through the structural system, but I don't know if any were used in this project. Something to keep in mind as you try to get a good night's sleep in a timber high-rise.  

What I really like about Brock Commons is the modular nature of its building process. Different types of CLT panels, columns and beams were used in combination to complete the structure. It reminds me so much of LEGO but its practical implications for the construction process are immense. It's another good example of how BIM technology brings the construction process earlier into the design phase. Here a lot of the credit goes to Fast+Epp Engineering for structuring a wooden building this tall. The modularity and pre-fabrication of the design had two main benefits of increasing tolerances (for better building performance) and speeding construction. Each of which contributes to the cost-effective and sustainable nature of the design. Timber buildings this tall are not necessarily experiential, but they are a type of specialized engineering as the types of forces put into the timber are quite different from that which normally found in the residential market. In all, I think it can be confidently stated the industry will continue to see an increase in the use of this type of technology, and readers are well advised to familiarize themselves with this type of construction.  

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