4 Essentials of Sustainable Site Design

The $1 trillion bipartisan infrastructure bill passed by the U.S. Senate in August 2021 proposed a variety of improvements, such as $7.5 billion for the installation of thousands of charging stations for electric vehicles. Green initiatives like this highlight the ever-growing importance of sustainable infrastructure.

For a fraction of what the U.S. government is spending, designers have the power to influence sustainable site design. Let's look at a few examples of how:

As designers already know, before you begin any grading, planting, or hardscaping, you must first consider a project site’s existing conditions with an intent to make the least amount of adverse impacts possible. This should be done as part of the site assessment, even before the client commits to moving forward with the prospective site.

Ahead of walking around and taking inventory of your client’s project site, the best way to understand this space contextually is with GIS. If you are already familiar with the support GIS data can provide, such as parcel data, zoning overlays, building footprints and topography, there's an even broader range of information available from online services like Esri’s ArcGIS. This data can be brought into Vectorworks Landmark to provide real-world context to your site, which leads to better decision-making.

GIS data will allow you to document and inventory existing trees and vegetation into your design. As well, GIS data can also account for protected areas, natural watersheds and flood zones within the site and surrounding area, which is vital for an understanding of how you’re impacting nearby waterways.

Water conservation strategies, like slowing down the flow of water is the name of the game for a lot of projects involving sustainable site design.

According to Ann English, PLA, LEED AP, CBLP D+I, and RainScapes manager,“ Plants need water. And fast flowing water erodes soil. Plants support the ecosystem pollinators, knit together soil, and transfer carbon from the atmosphere to the soil.”

English continued,“Imagine your soil is a dry sponge. If the water goes too fast, it doesn’t have a chance to soak in and the soil stays dry, meaning that plants don’t have a chance to use the water to grow. The goal is to have soils that are able to absorb the water and reduce the amount that runs off to be more similar to that from a healthy forested condition; in a forested condition, somewhere between four and ten percent of water runs off from the surface. The rest is either infiltrated or evapotranspired.”

It’s also important to manage the flow of water to ensure the quality of water. If rainfall reaches the nearest waterway too quickly, not enough toxins and possible pollutants will be removed from it. Slowing down the flow of water aids in its purity.

One solution is to control the flow of water with a bioswale. A bioswale is like a swale in that it's a graded area designed to redirect water. However, unlike a concrete swale that may simply push rainfall elsewhere, a bioswale is constructed with soil, plants, and other elements that make the surface penetrable. This way, the water is encouraged to seep into the earth.

There’s a natural tension between sustainability and hardscapes like concrete, since the latter are installed to the detriment of the former.

Moreover, most concrete doesn’t properly manage the flow of water. After a heavy rainfall, water may pool in certain areas; or, if a grade is present, race towards the lowest points. In both situations, flooding becomes a great risk. `

A permeable pavement system allows water to be absorbed by the soil beneath the concrete or other paved surface. Because the water can soak into the layers of soil and porous rock underneath the system, it can benefit the moisture content of the soil in nearby plantings, enter an underground drainage system, or perhaps recharge the water table in that area.

An underground drainage system is going to cost your project time and money. As is the case with most green infrastructure and sustainable site design projects, the more you can do above ground, the more money your client will save.

A long-standing, yet still growing trend in sustainable design are green roofs. Rooftop gardens and urban agriculture are becoming more and more popular in urban areas. Not only does rooftop farming provide building tenants with fresh vegetables or beautiful greenery, but ir also helps control water runoff and carbon levels in urban areas.

Not all rooftops are conducive to harboring rows of plants, however. So, there must be more intentionality and consideration in the design process. When designing intensive rooftop gardens and extensive green roofs in Vectorworks Landmark, it’s important to consider structural loads, water management systems, climate, and the ability to access the spaces. All these details can be considered and recorded using Vectorworks’ powerful worksheets.

If you're working with other engineers or architects on your rooftop garden, you also have the option of seamless file sharing (DWG, IFC, image files, etc.) in Vectorworks.

But don’t stop with rooftop gardens — a green roof can be taken to a whole new level bi integratings solar energy-capturing panels. This is a practice of combining greenery and photovoltaic panels. The greenery will keep your panels cool — and therefore, more efficient. In turn, the panels will promote more variety in the plants that can be used on the roof. This is due to areas of greater sunlight and of greater shade.

Explore Vectorworks Landmark for more information on how you too can design sustainable sites with software built for landscape architect and site design professionals.