In a previous blog post, I described the design lifecycle as having three main stages: pre-building, building, and post-building. I spent a lot of time in the pre-building phase, focusing on sourcing and manufacturing sustainable building materials. In this episode, we will move on to the construction phase and explore the depths of sustainable construction techniques.
In his book “Waste”, published in 2011, Mohamed Osmani estimated that the building rubble that accumulates on a typical construction site accounts for up to 30% of the total weight of the construction materials delivered. So for every 100 pounds of building material brought to the site, 30 of it is wasted. This means that by 2025 more than 2.2 billion tons of construction waste will be generated annually.
This creates tremendous pressure to recycle, reuse and reuse wherever possible. While it has been proven to be important to source sustainably harvested and manufactured materials for your construction job, it is equally important to avoid wasting those materials on the construction site. There are several critical paths to consider.
Construction phase: Sustainable construction techniques
We recognized the need for sustainable building techniques, but being aware of the need is not enough to make a difference. That requires action: retrofitting your construction site practices and processes. The conversion of workflows, however, falls under the classic easier said-than-done umbrella. Here are eight questions to help you identify potential areas of sustainable profit in your construction site processes:
- Minimal construction waste: Is there a way to reduce the need for landfill space and save costs?
- Building materials from local production: Can you shorten the transport route from the manufacturer to the place of use, thereby reducing fuel costs and air pollution?
- Energy efficiency: Can you reduce the amount of generated energy that has to be brought to the construction site through lighting systems or electrical / mechanical efficiency?
- Water treatment / conservation: Can you reduce the water consumption at a location, which reduces the amount of water that has to be treated by municipal sewage treatment plants and possibly saves the associated chemical and energy costs for water treatment?
- Non-toxic or less toxic materials: Is there a way to use materials in the construction process that are less dangerous for construction workers and building users (i.e. materials that require less cleaning or treatment after installation)?
- Alternative materials: Can we reduce landfill needs and landfill costs by using alternatives to conventional concrete, which lands over 500 million tons of land each year around the world? Are there ways to use more environmentally friendly materials that don’t require a landfill space, like bamboo, recycled plastic, iron stone, or even hemp concrete?
- Renewable energy systems: Can you add or eliminate heating, cooling or electricity during construction by using alternatives such as:
- Materials with a longer lifespan: Can you build with materials that have a longer lifespan and need to be replaced less often? For example, recycled plastic lasts more than 50 years for a project compared to 20 years for traditional wood or concrete structures, which takes more than twice as long to waste and replace.
This is a checklist of eight things to consider that can help prevent waste from the construction process: Eight Steps to Designing Construction Rubble and Saving Literally Tons of Landfill Space. But we can’t stop there.
A 2020 study titled Life Cycle Thinking for Sustainable Development found that the United States is still one of the countries with the highest production of construction waste. And in the US, 30% of construction and demolition waste ends up being landfilled. So what else can industry do to avoid waste?
Here are two answers to that question: stop making materials that aren’t needed and don’t bring things to the construction site that you won’t be using! It’s that simple. If the industry could follow these two steps, it would greatly reduce the amount of waste that construction projects generate each year.
A new approach to manufacturing
I found it helpful to study manufacturers of perishable materials – things with limited shelf life, like concrete. These manufacturers do not create or store a warehouse full of goods. Your product does not allow that. You adhere to just-in-time (JIT) or LEAN production principles. They do what they need just before they need it and they don’t do more than necessary. They only produce what the customer wants, when they want it and in exactly the quantity they want.
If they do too much too soon, they run the risk of spoiling. If they can’t find someone with an immediate need, they’ll have to dispose of it and take the loss. Sometimes when it takes too long to get it from manufacture to site it is a loss. All of this means waste and costs.
Interested in more sustainable building content? Check out our blog post on sustainable building materials and keep an eye out for our upcoming e-book for additional guidance on sustainable building.
This JIT / LEAN method eliminates waste by eliminating overproduction. Why don’t manufacturers of durable materials do this where possible? Keep excess material storage and associated costs to a minimum. Free up on-site storage space for better overall utilization. And dispose of fewer materials (and inventory costs) at the end of a job. This process is also more efficient overall, since the rejects in the production process are minimized.
Even with this approach, there is still room for improvement in the recycling of construction site waste on site. Several material brands offer discounts or recycling credits that encourage the return of construction waste to the manufacturer as they can recycle / reuse / reuse this material more easily than the construction company.
Reduce waste and costs with prefabricated components
Don’t take it to the construction site when you are not using it! In addition to a percentage saving in transport and storage costs, there is a lot of creative potential for improvement here. My first thought was, “If you want a 2 × 4 91”, don’t order a 2 × 4 eight feet and cut 5 “from one end.” Now, with a 5 “piece of 2, plug into it × 4 that you can’t do anything with.
Even if the customer paid for the 2 × 4 at all, someone had to ship it. Somebody had to measure it. Somebody had to cut it. Somebody had to do something with it. Someone had to pick up that little 5-inch piece from the floor and toss it in a rented dumpster. Someone had to drag the dumpster with the stuff somewhere at the end of the job. All of this indirectly contributes to both total costs and environmental costs. Instead, what if you used pre-built components built to your technical specifications?
Prefabricated materials and processes are very sustainable. Not only do they reduce waste, they also use almost 70% less energy to manufacture prefabricated components than conventionally built components. By designing and building with prefabricated components, the burden of efficiency of the production process and minimization of waste rests with the material manufacturer.
With prefabricated components, process waste can be recycled or reused locally. They never transport waste from the manufacturer to the construction site, so there are no transport costs for the waste portion of the raw material. You can potentially ship more finished materials per truck load, which reduces the overall environmental impact. And you don’t “work” the material on the construction site and generate waste locally. This eliminates the labor cost of cutting five inches from the 2 × 4, no one has to clean up the mess, and no waste of this material is sent to the landfill.
Back in the office
My only selfish addition to this list of construction and demolition waste reduction strategies is to use more software. Using software helps reduce paper plans and files. How big is the influence? A large construction contract can require over 35,000 pages of detailed scope and construction documents!
According to Dartmouth College, a tree makes 16.67 reams of copy paper, which makes 8,333 sheets of paper per tree. Therefore, a large construction contract alone requires 4.2 trees of paperwork before you even start counting the wood used in the actual construction. Now think about how many projects you work on each year and how many trees you only use in paper form. One software subscription could save them all.