Over the last few decades, landscape architects have made strong progress in producing more environmentally sustainable landscapes. In some areas, such as water retention, we have made huge innovative leaps by introducing bioretention, bioswales, rain gardens, and even green roofs to urban landscape environments. However, when it comes to the hardscape materials within our landscapes, we have remained stagnant in our material choices, despite new construction techniques introduced every year. In this blog, we’ll explore the issues surrounding hardscape materials and the new approach our profession can take to advocate for sustainability.

Initially, the profession focused heavily on the case of water use in the landscape and moved towards a more sustainable approach when selecting plants and stormwater management techniques. A water-conscious, sustainable landscape is easily achievable, and the options for native and drought tolerant species far exceed cacti and succulents. This allows for the creation of sustainable spaces that save or clean water while improving the aesthetics of a project. Plant suppliers have played a large role in this approach by being transparent regarding the information they provided to the industry, which helped create a new approach to plant selection.

The same must begin to happen with hardscape materials so both designers and consumers can be aware of the manufacturing methods used in the products they are selecting. Without clear and comparable information about the carbon footprint, resource use, manufacturing impacts, and toxicity of materials and products, landscape architects can’t make choices that will have a true impact on sustainability. However, manufacturers claim that, due to their products being proprietary, it would be hurtful for future innovation to reveal such information to their competitors.

Examples of challenging hardscape materials Let’s consider cement as an example. Cement is the second most used natural resource in the world after water, and it’s the main ingredient in concrete. Concrete is the most widely used building material in the world, thanks to its variety and durability. However, its manufacturing process is a highly energy and water intensive process. Over 2 billion tons per year globally is produced, accounting for approximately 7% of CO2 emissions globally. Innovation in new manufacturing techniques for the production of this construction material can have a significant and measurable impact on the environment. As landscape architects, we must push to enable this process to accelerate rapidly.

Concrete also poses problems in construction material disposal as it is very difficult to alter its final form. Again, landscape architects have a role in paving the way for a new approach to the use of concrete, which varies from using crushed disposed concrete as aggregate base to specifying new concrete mixes that have lower carbon footprints. A great example of this is the invention of Solidia cement by Solidia Technologies. Otherwise known as low Portland cement, it is injected with carbon found in the by-product of coal burning called fly ash. This results in a less energy intensive process when compared to the manufacturing process of cement and allows for the reuse of a nasty byproduct of energy production. This product was successfully tested and adopted widely by 1937. It is a success story in moving towards more sustainable practices, however we need major innovative breakthroughs in all materials for a post-21st century construction model.

Not providing a transparent and cooperative framework in the manufacturing process of goods can result in dire consequences for the consumer and the ecosystem. To provide an example, let’s look at the habitat and cultural impacts of raw material extraction. This is often an “out of sight out of mind” issue. We don’t see the immediate impacts of harvesting tropical hardwood lumber from the Amazon, so it doesn’t seem so problematic to use it. The ecosystem decline is not apparent thousands of miles away just because we removed a keystone species from a complex ecosystem. We are also unaware that there is a 78% percent chance that the tropical hardwood we are using was harvested illegally (Greenspace, 2014).

What are low impact construction materials? Low impact materials refer to raw goods used for construction that have a lower carbon footprint for a selected project due to their manufacturing methods and distance of transportation. The Sustainable SITES Initiative™ recommends landscape architects specify materials sources within 35 miles of the project location. This not only reduces transportation cost and carbon footprint, but it also allows for a boost in the projects’ local economy. However, this might not always be possible depending on product availability and technical specification level. For example, highly innovative products that are environmentally conscious tend to originate from the European markets, which consequently will have higher transportation costs. Landscape architects must conduct a cost benefit analysis for all specification materials, taking into account both environmental and monetary costs.

Rethinking the design process to prioritize materials Some projects will never be able to incorporate reclaimed hardscape materials because of their budget and bid structure. Contractors are often brought onto projects after the bid process is complete and budgets are already set. This creates obstacles to using reclaimed materials because it is easier to find the materials first and then design with it, rather than the other way around. For example, if you need to find an exact fit for a 9-foot pergola post that is perfectly detailed, you will never be able to find it. If you do, it will have taken too much valuable time. Instead, the design process should be more focused on inventorying existing materials first to be able to properly incorporate as many reusable products in the site as possible.

We must begin to be more demanding of manufacturers to provide environmental impact information for the manufacturing of their products, and not use them if they refuse. This will be a lengthy process to push a paradigm shift in the relationship between manufacturers and suppliers but is one that could benefit the environment in the most impactful way. We also must be aware of the new alternative products that are on the market today to begin substituting our heavy use and reliance of concrete. We’ve made great strides in regard to many aspects of sustainable landscapes. Now, let’s expand our focus to hardscape.

About Stelios Kalopedis

Email Stelios

Stelios Kalopedis is a Landscape Designer for the Landscape Architecture team at Foresite Group. He graduated from the University of Georgia with his Masters of Landscape Architecture and has a previous background in Risk Management and banking. Stelios was raised on a farm on the Mediterranean island nation of Cyprus and visits his family annually hoping to bring new sustainable practices to their agricultural industry. His passion for Landscape Architecture began young when he found himself exploring, interacting, and shaping the landscape, either by fun activities or agricultural practices.