As temperatures continue to rise globally and energy costs increase to keep up, sustainable and cost-effective designs are more important than ever. Passive cooling is a method that landscape designers, green home architects and eco-conscious renovators can use as a functional living infrastructure in houses. Deciduous trees can be used as a “solar panel” to yield a high return on investment (ROI) for energy savings while promoting sustainable practices.
Deciduous Trees as Nature’s Infrastructure
In the summer months, strategically placed deciduous trees absorb sunlight and provide shade to the home — their thin, wide leaves capture energy from the sun and convert it into nutrients. Once the trees lose their leaves, the bare branches allow sunlight to reach a house, warming it when temperatures are colder in winter. The shading and warming properties of the tree absorb and store energy, acting as “natural solar panels” that help maintain comfortable temperatures throughout the year.
Beyond providing shade, deciduous trees serve as seasonal cooling agents. The process of evapotranspiration further cools the surrounding area and can cool green urban forests by an average of 3° Fahrenheit compared to nongreen urban forests. Strategically incorporating greenery into landscaping for urban, suburban and even rural areas can both cool a home and mitigate broader issues surrounding rising temperatures.
Strategic Placement Design for the Landscape
Thoughtful integration of deciduous trees can maximize a home’s ROI and guide passive cooling efforts.
Mapping the Sun
It’s essential to position the trees based on the sun’s location and the areas of the house it hits during each season. Orient trees to block the harsh, summer sun that peaks in the afternoon overhead. Trees should have enough space to root comfortably without damaging your home’s foundation or becoming entangled with each other — about 10 to 15 feet apart. Areas that are more exposed or less insulated, such as garages, may benefit from overhead tree protection, depending on their orientation.
Selecting the Right Species
Several factors can influence which kind of tree may be best in a given climate. Among deciduous trees, the canopy size, growth rate and water needs can impact the effectiveness of the passive cooling. Oaks and maples, for example, offer large canopies and live long, while birches may grow faster and look more appealing to a particular aesthetic.
Supporting the Surrounding Areas
Other landscape design elements can support passive cooling strategies. For example, placing evergreen trees on the north side of a house to block winds can help support temperature regulation. Ground cover of low-growing plants and shrubs can also help keep the soil cool around a house and its infrastructure. Plants at different elevations can create a layered shading effect.
Integrating Trees Within a Whole-Home System
Strategic planting for passive cooling is an effective method for optimizing a house’s cost-effective energy savings, yet it is not a stand-alone solution for a long-term, eco-conscious household. While passive cooling may help reduce an HVAC system’s load and contribute to its longevity, the systems should be regularly cleaned every five years to maintain good air quality.
Additionally, smart devices can optimize the energy efficiency of the passive cooling system.
Smart thermostats can monitor internal and energy-efficient temperature control, and smart watering systems that monitor when to water plants can help homeowners reduce energy and water consumption. Smart devices can also check soil moisture and health, ensuring that homeowners and landscapers don’t over-water or consume more than needed.
Financial and Environmental Payoffs
The benefits of passive cooling through deciduous tree landscaping are more than theory. Studies conducted throughout the U.S. have found significant energy savings from passive cooling and increased greenery. For instance, houses in California saved 30% in cooling energy costs after relocating large trees.
Healthy, mature trees can also increase a home’s property value while promoting mental benefits. The recent trend of biophilic design goes beyond integrating natural elements into a house’s appearance — the “biophilic theory” indicates that people are more inspired and less stressed when surrounded by nature.
The ecological benefits of passive cooling are also significant. With a reduced energy demand, a single home’s carbon footprint is significantly minimized. Contributing to the broader goals of reversing climate change and improving the natural environment, the EPA notes that planting more trees can support biodiversity, create a wildlife habitat and increase air quality.
The Landscape as a Living Asset
Planting deciduous trees strategically around a home can improve its energy efficiency, reducing harmful environmental impacts while improving cost savings. Because deciduous trees offer shade in the summer and let light in during the winter, while cooling temperatures through evapotranspiration, landscaping designs featuring these plants can effectively enhance a house’s ROI and sustainability.
