Call it sustainable, eco-friendly, environmentally conscious, or green design… it’s really about managing resources. It is the future of all construction trades, and it means a great deal to our clients. So what is green design, how would it apply to engineers, and why is it important?
Green design basically means that you will purposefully choose options that will reduce consumption in the long term. When you consider the full life cycle of the structure, there is a lot of energy that goes into the building during construction, and a small input of energy throughout it’s useful design life. A significant amount of energy can be also be spent during demolition, or the building can be “deconstructed” and recycled. See LEED guidelines published by the US Green Building Council for good tips.
Structural engineers usually have a hard time with the green design metrics. Concrete is cheap, you can throw in recycled content like fly ash, and it lasts basically forever. Structural steel is almost 90% recycled content, and can be optimized so that only a small amount of material is used for a structure. Wood grows on trees – it removes CO2 from the atmosphere and is pretty darn good stuff. As long as you aren’t using dead pandas as building materials, green design is pretty much a slam dunk for us engineers, right?
Well, not quite. Optimizing the structural system won’t amount to much in the end. If you are really concerned about green design, the most important contribution you can make is to help the other design team members meet their goals. Have you done everything possible to help the HVAC designer? Have you eliminated the need for maintenance of the facade? Have you specified low VOC content in your steel paint/primer? Have you maximized your column spacing based on discussions with the architect, and therefore removed 1/3 of your column footings? Have you begun using LRFD and listing all your reactions on the design documents? Have you notated all your design data on the construction documents so that future engineers can renovate and update your building’s structure without having to re-invent the wheel?
If you are working on a project where green design is a priority, I would suggest you go beyond the LEED guidelines and reach out to the other design team members. Communication is the key to this. Make sure everyone knows you are there to support their work, and that whatever they feel will best contribute to the green-ness of the building is what you want. Maybe request an extra coordination meeting with the architect, or ask that the HVAC and interior design/lighting, etc. work be substantially complete before a structural system is chosen. This would upset the normal design flow, but it would put the green design priorities in the right order.
So why is green design important? It comes down to environmental impact and economics. For a long time (the last 100,000 years or so) the human impact on our environment was not really well understood. The true cost of altering our own environment was hidden. Now the cost is being priced into everything we will buy and every bit of energy required to operate a building. Simply put, conventional design is going to get too expensive. That’s the bottom line.
The other reasons for green design may or may not appeal to you, but are certainly important to me. I believe that engineers have an ethical obligation to protect the welfare of the public. If my structure causes excess CO2 to be produced, thus indirectly causing famine elsewhere in the world due to climate change, I can’t say I’ve done my best to protect the public. If you are uncomfortable with the topic of climate change, here is a good primer.
There are simple ways you can reduce the initial “embodied energy” of your structure, but there is so much more you can do to help out the green design of your structure. Not coincidentally, these options will usually reduce the bottom line of the project, thus saving your client money. We are always pressed for time in a design environment, and often the client is enforcing difficult completion deadlines. It’s hard to optimize the structure for cost, safety, and green design and still meet industry minimum profit margins. However, I’m sure that if you set it as a priority, you can accomplish it.