As fall ends and winter approaches, the days are getting shorter and the temperatures are dropping. But that doesn’t mean that we need to give up outdoor living. By using simple landscape design solutions to create warmer ‘microclimates’, we can extend the time we can enjoy outdoor spaces.
A microclimate is a local set of atmospheric conditions that differ from those in the surrounding areas. There are many different strategies that landscape designers can use to impact the microclimate of outdoor landscapes. Here are a few examples:
- As the earth’s tilt takes the northern hemisphere farther away from the sun during the winter, the sun drops lower on the horizon. As a result, southern-facing slopes will receive much more sun in the winter than north-facing slopes. Landscapes intended for use during the fall, winter, and spring seasons should be oriented on south-facing slopes to maximize the amount of sunlight they receive, which will make them feel warmer.
- The slope of the landscapes also impacts the prevailing wind, which in the northern hemisphere primarily blows from the northwest during the winter and southwest in the summer. Landscapes on southeast-facing slopes will not only be protected from the harsh winter winds but will also be open to cooling breezes in the summer, making southeast slopes the ideal place for multi-season landscapes.
- Wind can be blocked with simple convex landforms like mounds, berms, and ridges. Constructing a mound or berm and locating an outdoor space on the southeast side will actually increase wind in the summer, exposing users to cooling breezes on hot summer days, and more importantly, the mound will block harsh winter winds, making the area feel warmer during cooler months.
- Landforms such as berms, mounds, and ridges can also be used to channel cooler summer winds and focus them on outdoor spaces for maximum cooling during hot months.
- Rolling undulations in the landscape will also collect snow blown by the wind in the winter months. By locating path systems on slightly raised topography, snow accumulation is minimized and users can avoid having wet feet.
- If your property doesn’t have any slopes and there is no space to build mounds or berms, the location of usable landscape around a building can make all the difference. Buildings effectively block harsh winter wind, so locating multi-season landscapes on the southeastern side of a building can dramatically increase the length of time they can be used.
- Planting deciduous trees on the south and west boundaries of landscapes will create cooling shade in the summer and in the winter when the trees lose their leaves sunlight will bathe the landscape. Larger trees should be planted on the south side of landscapes, and the trees should get shorter as they are planted along the west side.
- Evergreen trees planted on the north, west, and east sides of landscapes will block harsh winter winds and create a pleasant line of greenery during winter, which will add much-needed color to bleak, gray winter days.
- Dense hedges of tall ornamental shrubs can also provide effective windbreaks in winter, especially when planted along walls. The dead space between the wall and the plants traps air, creating an extra layer of insulation against cold winter wind.
Walls and Fences:
- It would seem obvious that a solid wall would be the most effective way to regulate wind and temperature in space. However, this is not true. A solid wall creates an eddy of downward and reverse-flowing circulating wind on the leeward side as air blows up and over the wall - which actually will make the space on the leeward side of the wall feel windier and colder.
- Constructing walls made with openings will allow some wind to go through, but this wind will carry air upwards and away from the landscape on the leeward side of the wall instead of allowing the eddy to form and air to circulate.
- The most effective windscreens have been found to be louvered fences with the louvers tilted upwards.
- As with berms, mounds, and vegetative screens, walls and fences meant to block harsh winter winds should be located on the west and northwest side of the area to be screened.
- Water evaporates in the sun, cooling the surface of the water and the air temperature in its vicinity. Also, when the wind blows across ice it cools the air, increasing wind chill. Therefore, fountains and pools should be drained in the winter to prevent them from cooling the surrounding landscapes.
- Lighter colored materials reflect more sunlight and darker materials absorb sunlight.
- Thick dark materials such as brick will absorb sunlight during the day, and slowly release heat once the sun sets. By adding dark brick pavers to patio landscapes, the ambient temperature above the bricks will be warmer than air over natural materials like grass, even after the sun is gone. Dark-colored pavers will also be more effective in melting snow and ice. While dark pavers also absorb heat in the summer, and they won’t feel as hot as bright-colored pavers. Look for dense pavers made with natural materials like stone, clay, and organic matter.
- Thick hardwood mulch also traps and stores sunlight energy, so adding fresh mulch to your planting beds right before fall may increase the ambient temperature around them.
- Metals tend to heat up and cool down quickly because they have more free electrons than materials like wood and plastic, and shiny metal seating can be dangerously hot in the summer and freezing in the winter. Seating should be made out of dense materials like wood, recycled plastic, stone, or painted metal so that their temperature will not fluctuate as dramatically with the weather. No one wants to sit on a scalding hot bench in the summer or a freezing cold chair in the winter!
- Repositionable chairs are preferred to stationary seating so that people can move the chairs into the sun or more comfortable places in the landscape.
- Installing temporary or permanent outdoor heating equipment such as propane stoves or fire pits can not only warm up space but also create a fun and unique ambiance for users.