By: Kendall Gillen, Biologist, LEED Green Associate
Associate LEED Process Management for Emerald Skyline Corporation
Many building owners and managers take into account the interior and exterior of a building itself when considering sustainable initiatives, but just as important is the area surrounding the building. Landscaping can make a tremendous difference in the sustainability and qualification for LEED certification of a project. Sustainability is certainly an integration of many different factors, and landscaping is a significant one.
Through employing different strategies, landscaping can be practical, functional, and aesthetically pleasing. There are different factors that affect the level of landscape sustainability. Two of the most important are the types of vegetation chosen and the amount of potable water required to keep the plants healthy, otherwise known as irrigation. Not only can efficient landscape design provide noteworthy credit toward achieving LEED certification, but it can also provide substantial water-energy savings. This should be a great motivator for owners and managers to look to their landscaping for improvements to their bottom line.
As stated in a study conducted by the California Sustainability Alliance, water is a necessary resource for any landscape to survive and function. However, not all landscapes are created equal. Climate, weather conditions, and vegetation grown can all impact the amount of water required to sustain life. Typically, if non-native plants are chosen, irrigation will be needed because they cannot survive on local precipitation levels alone. Thus, researching plants with a low water need specific to the project’s local climate is of the utmost importance.
Many states have online databases for irrigation friendly plants. Since we are located in the tropical climate of South Florida, here are just a few of the many trees, plants, flowers, and grasses that are ideal for reducing irrigation demand as found by the Florida-friendly Plant Database:
- Silver Palm
- Scrub Palmetto
- Jamaica Caper Tree
- Gumbo Limbo
- Crinum Lily
- Blanket Flower
- Beach Sunflower
- Purple Love Grass
All of the above vegetation has a medium to high drought tolerance. There is also a resource listing the Plant Hardiness Zones for the entire nation available through the USDA. Once a project’s Plant Hardiness Zone is found by zip code, one can search for plants that thrive within that particular zone.
Choosing native vegetation is a step in the right direction, however without active management of landscape irrigation with adjustments to precipitation levels, the savings of native vegetation alone could potentially be nominal. To fully benefit from using indigenous and drought-resistant vegetation, the irrigation system must be managed. This is why the integrated process of landscape operation, management, and maintenance is so crucial.
- Low-volume irrigation systems are a broad classification of systems that provide water more directly to the ground instead of spraying in the air where water can be lost to wind or evaporation.
- This is a great starting point when choosing a system that fits a specific sustainable project need. By slowly releasing moisture, these systems greatly reduce runoff1.
- Rainwater collection and re-use for landscape irrigation is another method to decrease water-energy expenditures. This harvested water can also be used for non-potable purposes such as toilet flushing.
The benefits to native vegetation and water efficient landscaping are plentiful. As previously stated, huge savings in water-energy can be achieved as well as the following:
- Reduces the heat island effect which occurs when dark building and paving surfaces absorb the sun’s energy and re-radiates it throughout the day and night raising the ambient air temperature
- Conserves natural resources and provides a habitat for native wildlife
- Improves HVAC efficiency which is achieved through the shade generated by the proper selection and placement of trees and shrubs
- Minimizes landscape maintenance requirements allowing the building owner to save on labor and materials
Undoubtedly, landscaping can play a huge role in the overall sustainability of a project, whether that is a retrofit or new construction. The take-home message should be to plan ahead and strategize when it comes to landscaping and irrigation. Also, having a water efficient landscape does not necessitate elimination of beauty. Use the abundant resources available online or through a professional and be responsible with water use. Water is in fact our most precious natural resource and it is our obligation to conserve.
 California Sustainability Alliance. Water-Energy Savings from Efficient Landscape Design in California. July 2015.