Growing up, you may have been taught not to judge a person based on outward appearance alone.
“It’s what’s on the inside that counts,” many a good parent has said.
The same is true for buildings and parking garages.
At a time when environmental responsibility is top of mind, investors and developers alike are looking closer and deeper at the factors that add up to sustainable development.
How to make parking lots more sustainable
There are a number of factors that make one type of parking garage more sustainable than another. They include:
- The amount of land required for construction.
- The amount of energy required to operate.
- The construction materials themselves.
Relative to points one and two, Robotic Parking Systems structures come out ahead. Our fully automated parking structures require half the land of a traditional concrete parking structure, and, with no public in the parking area itself, our garages require less lighting, less ventilation, and less personnel to operate.
The topic of this piece is point number three, the construction materials themselves. And with parking structures around the country crumbling and collapsing, the topic of sustainable parking could not be more urgent.
Park at your own risk
Reinforced Concrete, Steel and Sustainable Construction
In comparing reinforced concrete and steel, the cost and environmental impact of the following areas must be considered: the production, the maintenance, and the demolition and recycling.
According to a white paper of the American Institute of Steel Construction, 93% of structural steel manufactured in the US today comes from recycled materials. In fact, many of yesterday’s are part of today’s skyscrapers. According to the American Institute of Steel Construction, steel is the most recycled material on the planet. Though prices fluctuate, this fact means that structural steel is generally less expensive than concrete.
In contrast, sometimes only 30% of the materials in new concrete comes from recycled materials. This is because the performance of concrete degrades in the recycling process. In addition, reinforced concrete requires ongoing maintenance and repairs which adds costs throughout its lifetime.
When it comes to the recycling process itself, steel is less expensive than reinforced concrete to recycle. And, the energy savings in recycling steel are substantial, with recycled steel using only about 25-30% of the energy required for virgin steel production. Steel is one of the only materials on Earth that retains 100% of its strength through the recycling process, meaning it can be used for the same construction purposes as new steel.
Recycling reinforced concrete is challenging due to the number of different materials involved, including the presence of reinforcement materials, the steel bars inside the concrete, which significantly alters the recycling process.
While non-reinforced concrete can be directly fed into crushers for processing, reinforced concrete needs an initial expensive and time consuming phase of metal removal. This step often involves manual labor or the use of electromagnets to extract the metal, which is then recycled separately. The additional steps required for recycling reinforced concrete increase time and costs.
Beyond the expense and difficulty of the recycling process, a significant problem is the usability of the recycled concrete itself.
Problems with recycled concrete
Recycled concrete is not the same quality as newly produced concrete. As a result, it is not generally “recycled” but “downcycled.” As a downcycled material it is typically used for site stabilization, a bottom layer road base, and backfill.
There are several reasons for this including:
- Recycled concrete often contains contaminants which affect the quality and strength of the final product.
- Age of the concrete – Old concrete structures have been exposed to the elements for many years. Depending on the type of concrete, its compressive strength has been found to be 10-30% less than new concrete, which means that it might not be suitable or even safe to use in another project.
- Usability – The ease of pouring and placement of recycled concrete is less than new concrete.
- Water absorption – Recycled concrete is known to have an increased capacity for water absorption, from 3% to 9%. Excess moisture in concrete can lead to several problems including: cracking which can weaken the material, and it can make the concrete expand, which can lead to ‘popouts’ – fragments which break out from the surface of the concrete.
Environmental Impact of Concrete vs Steel
The main environmental advantage of steel over reinforced concrete is that the ongoing maintenance of a steel structure is a much easier proposition than the maintenance of reinforced concrete. This is because any surface corrosion can be easily seen and handled by cleaning the surface and repainting. The ease of maintenance means that steel structures can last longer.
On the other hand, corrosion of the metal present in reinforced concrete is hidden, so the extent of the damage is impossible to determine.
The level of emissions produced in iron and steel production and cement production is similar. Still, steel is better for the environment than reinforced concrete. Researchers in both the steel and concrete industries are working to find more environmentally-friendly production methodologies.
Nucor, the producer of the steel in Robotic Parking Systems structures, is a leader in sustainable steel production.
Nucor’s steel making relies on electric arc furnace technology—the cleanest method commercially available today. Nucor produces steel by recycling scrap metal in electric arc furnaces (EAF), also known as circular steelmaking, a process that has a greenhouse gas emissions (GHG) intensity that is less than half the global average and one-third of the average blast furnace steel producer.
Sustainable Parking Solutions Start with Steel
Choosing steel as the primary building material for a parking structure is the best environmentally and economically conscious decision to make. Concrete with its compression strength serves well as base material but cannot compete with steel when it comes to the strength and flexibility required for the garage structure itself.
If you would like to learn more about sustainable parking and how an automated parking system would benefit your commercial development project, reach out at the link below. Our experts will provide initial plans for your project at no cost.