Published on September 28th, 2017 | by Carolyn Fortuna0
Landscape Architects Argue That Sustainable Design Results In Net-Zero Homes
September 28th, 2017 by Carolyn Fortuna
Landscape architects and clean tech? Sounds like the old nature-versus-society conundrum, doesn’t it? Well, the American Society of Landscape Architects (ASLA) says that homeowners can implement cutting-edge methods so that residential landscapes support the environment — no matter the location or property size. And the ASLA is backing up its argument with a series of free online sustainable design guides to help spread understanding about sustainable and resilient residential practices.
Developed for homeowners as well as landscape architects and designers, the guides outline ways that, through a comprehensive approach of integrated site design and sustainable building, sustainable residential landscape architecture practices cannot only improve the environment but also result in net-zero or even climate-positive homes.
The four ASLA guides fit into a larger trend about the growing preparedness of homeowners to make changes to their landscapes in response to climate change and technological innovations. The ASLA 2017 Residential Landscape Architecture Trends Survey showed that, yes, consumers prefer sustainable design elements for their outdoor living spaces. But they also want tech-friendly elements to merge indoor and outdoor spaces. For the first time, wireless/internet connectivity entered the top 10 project types, suggesting that people want a backyard that allows them to enjoy both nature and digital communications/ entertainment.
The survey was fielded February 2 through February 16, 2017, with 817 responding. Here are the top 10 exterior project design types with the expected highest consumer demand:
- Native/adapted drought tolerant plants – 82.31%
- Native plants – 81.60%
- Low-maintenance landscapes – 79.25%
- Food/vegetable gardens (including orchards, vineyards, etc.) – 76.52%
- Permeable paving – 76.31%
- Reduced lawn area – 72.66%
- Fire pits/fireplaces – 71.51%
- Drip/water-efficient irrigation – 71.05%
- Wireless/internet connectivity – 70.77%
- Rainwater/graywater harvesting – 70.32%
“Well-designed residential landscapes provide social interaction, enjoyment of nature, and physical activity, while also reducing water use and stormwater runoff,” said Nancy C. Somerville, executive vice president and CEO of ASLA. So sustainable landscapes and technology make valuable partners in the quest to mitigate greenhouse gas(GHG) emissions.
In response to consumer demand outlined in the trends survey, ASLA has designed the free online guides to offer a wide selection of tips, research, and best practices, including The Sustainable SITES Initiative™ (SITES®), a system for developing sustainable landscapes. The guides center around increasing energy efficiency, improving water management, applying ecological design, and using low-impact materials.
Increasing Energy Efficiency with the Help of Landscape Architects: Guide #1
Back in 2014, CleanTechnica featured an article about California’s net-zero energy mandates. It described how all California residential buildings by 2020 and all California commercial buildings by 2030 must produce as much energy onsite as they consume on an annual basis. It seemed visionary then, but now we know that inefficient home energy use is not only costly but also contributes to the growth of GHG emissions, the primary cause of climate change.
The U.S. Energy Information Administration reports that the residential sector accounted for 21% of total primary energy consumption and about 20% of carbon emissions in the U.S. in 2012. Architecture 2030 adds that building construction and operations-related energy use add up to almost 50% of total GHG emissions. So ASLA’s guide #1 supports research in the field around planning and designing collaborative efforts, which have the potential to usher in a sustainable and carbon neutral future.
Homeowners can leverage clean energy technologies, like solar-powered LED outdoor lighting. If part of a broader integrated site design, sustainable residential landscape architecture can help eliminate the need for fossil fuel-based energy. Landscape architects can help homeowners by undertaking a comprehensive energy audit and then identifying landscape-based solutions for generating renewable power or reducing energy waste.
Other examples of integrated site design are residential green roof and wall systems, which can cut energy use and home heating and cooling costs. Green roofs are energy-efficient vegetated roof systems. Green walls, also known as vertical gardens, can increase energy efficiency, lessen indoor and outdoor temperatures, and improve air quality. Additionally, when homeowners use trees and dense shrubs to shade their home and external HVAC systems, green walls help to block wind, thereby further limiting energy use.
Improving Water Management: A Landscape Architect Approach: Guide #2
In 2014, the U.S. National Climate Assessment determined that “the risks from future floods are significant, given expanded development in coastal areas and floodplains, unabated urbanization, land-use changes, and human-induced climate change.” Just three short years later, with the series of continual hurricanes in autumn 2017, extreme weather and climate events that have direct relation to human activity are — unfortunately — becoming the norm.
The Federal Emergency Management Agency (FEMA) estimates that flooding caused some $260 billion in damages from 1980 to 2013. And, in the past decade alone, flood insurance claims have totalled $1.6 billion annually, putting further pressure on the already deeply indebted flood insurance system. However, in the second guide, the American Association of Landscape Architects says that sustainable landscape architecture practices, including green infrastructure, can impact the effects of climate action on residences. With green infrastructure design, residential landscapes reduce flooding during storms, conserve water in times of water scarcity, and limit the massive energy costs associated with running complex water management systems. Here are some sample green infrastructure approaches that landscape architects can offer to residential homeowners to help protect against flooding:
- bioretention ponds;
- rain gardens;
- rain water harvesting;
- water recycling; and,
- drip irrigation.
Minimizing water usage is another way that homeowners can create a healthy residential environment by promoting infiltration, storing, and recycling of water. Limiting the use of valuable potable water for landscapes also helps. The ASLA calls for recycling and reusing greywater (and even blackwater) for landscape maintenance, car washing, and toilet flushing. They also point to maximizing the benefits of natural stormwater systems by improving the quality of soil on residential properties. Remediation techniques decrease water and air infiltration when soil is degraded and compacted.
Applying Healthy Ecological Design with a Landscape Architect: Guide #3
Among the many effects of urbanization is the transformation of intact, ecologically productive land into a monoculture of lawns that no longer support functioning ecosystems. According to the Audubon Society, the continental U.S. lost a “staggering” 150 million acres of habitat and farmland to urban sprawl. The remaining isolated natural areas are not large enough to support wildlife.
Why are plants so central to a functioning global ecosystem? Plants oxygenate the atmosphere and reduce atmospheric pollutants. They are the ecological basis upon which life depends, and without them and the insects that co-evolved with them, local birds cannot survive. Landscaping choices have meaningful effects on the populations of birds and the insects they need to survive. When homeowners, landscapers, and local policy makers select native plants for landscaping, such as are suggested in ASLA guide #3, they are engaging in ecological restoration, which is a valuable strategy for mitigating the impacts of climate change.
When applying a healthy ecological design to residential landscapes, homeowners who use native plants reduce the use of excess water, energy, chemical fertilizers, and pesticides that damage natural ecosystems. A healthy ecological design also supports pollinators. Native plants can be used to regenerate sustainable plant communities and reconnect fragmented ecosystems in residential areas. They are not only key to the global ecosystem: they are crucial to environmental and human health at the residential and neighborhood scale. Sustainable residential landscapes can build into a community and regional network of productive landscapes. Landscape architects can help residential homeowners to create a network of productive ecosystems, expand wildlife habitat areas, and boost human health and well-being.
Landscape architects partner with communities, non-profit organizations, and local governments to increase public awareness about using sustainable residential design practices that yield productive plant systems and reduce the negative ecological impacts of typical residential development.
When Landscape Architects Use Low-Impact Materials: Guide #4
Homeowners who don’t reuse or recycle existing materials contribute to the waste materials that fill our landfills and create additional waste when they are demolished. Sure, many materials designated for residential landscaping projects aren’t designed to be recycled. But there are alternatives, such as are listed in guide #4.
- Homeowners can identify local materials that reduce the energy consumption associated with transportation.
- Many innovative low-impact materials are permeable, which allow water to infiltrate and recharge aquifers rather than being routed to stormwater and sewer systems.
- Some of these materials are also reflective, which helps to limit air temperatures and minimize air conditioning to cool buildings.
- Certified, sustainably-harvested woods, recycled woods, and recycled plastic or composite lumber preserve forests, which are critical to sequestering GHG emissions.
- Sustainable concrete from materials like fly ash (a byproduct of coal-fired power plants) or repurposing concrete from structures on the existing site can avoid sending useful materials to the landfill, conserve natural resources, and reduce a project’s carbon footprint.
Used in both landscapes and buildings, low-impact materials can reduce GHG emissions and create a healthier environment. Human industry does not necessarily need to harm the natural world. We do need to do research into sustainable materials, consider multiple options for material reuse and recycling prior to embarking on exterior home projects, and discuss with others alternative approaches so that materials within well-intentioned landscape projects don’t contribute to the problem of GHG emissions.
We’ve known for a long time that an essential link exists between nature and human society. But never before has the need to draw upon local sustainable practices been so important. We need to partner with nature wherever possible to secure our neighborhoods against flooding or excessive heat, to help improve air and water quality, and to protect human and environmental health. When nature is harnessed by people and used as an infrastructural system, it’s called “green infrastructure.” Green infrastructure can begin with the smallest of projects, beginning with residential landscapes and moving into park systems and urban forests. It’s efficient, cost-effective, and smart. If you’d like to learn more, here are 40 case studies from the ASLA that illustrate the transformational effects of sustainable design on residences. If you’d like to teach your child more, here are a series of educational resources from the ASLA that are written in a fun but developmentally appropriate way to help the next generation of homeowners to learn more about sustainable practices.
Increasing energy efficiency: ASLA 2011 Professional Residential Design Honor Award. Carnegie Hill House, Charlottesville, Virginia by Nelson Byrd Woltz Landscape Architects. Image credit: Eric Piasecki. Image link A green wall with lush plantings and edibles sits above a children’s sandbox.
Improving water management: ASLA 2010 Professional Residential Design Honor Award. Catalina Foothills, Tucson, Arizona by Design Workshop, Inc. Image credit: D. A. Horchner / Design Workshop, Inc. Image 142-08 link (via Dropbox) This project implements the first graywater reuse system for residential application in the region. It is intended to reduce water consumption by approximately 40 percent.
Applying ecological design: ASLA 2016 Professional Honor Award, Residential Design Category. Kronish House by Marmol Radziner. Photo credit: Roger Davies. Image link Over the four-year construction period, the addition of hundreds of mature trees and countless flowering shrubs, perennials, and groundcovers, brought in a flood of nesting birds and insect pollinators. The transformation was evident to workers who had been at the site from start to finish. They went from seeing virtually no wildlife at the beginning to experiencing a cacophony of bird song at dusk and swarms of bees, butterflies, and moths bouncing from plant to plant as they came into bloom. The diverse plantings ensure staggered bloom times to keep pollinators busy year-round, and create niche habitats for many bird and small mammal species. The property is now a lush oasis for urban wildlife in an otherwise biologically monotonous neighborhood.
Using low-impact materials: ASLA 2010 Professional Honor Award, Residential Design Category. Pacific Cannery Lofts by Miller Company Landscape Architects. Photo credit: Dennis Letbetter. Image link The landscape architect mined elements from the cannery structure, including abandoned machinery, for repurposing in the new gardens. The recycled tumbled glass riverbed in the Dining Room Court, and stone columns in the Lew Hing Garden add to the historic character. Hand crafted site furnishings made from FSC-certified wood, concrete, steel, and glass were designed by the landscape architect and crafted by Miller Company Landscape Architects’ in-house installation team.
Overall image: ASLA 2010 Professional Residential Design Honor Award. Lily Lake Residence, Dalton, Pennsylvania by Michael Vergason Landscape Architects, Ltd. Image credit: Nic Lehoux. Image link The project reduces electricity costs for the house by leveraging shade from the site’s mature trees.