Landscaping to Save Energy (Winter Edition)

Homeowners across the colder portions of the country are about to find themselves yet again being uncomfortably squeezed between cold temperatures and increasingly higher natural gas and energy prices. In fact, depending on the size of the home, residents can expect to spend between two to three times as much on basic heating costs, if not more. Not surprisingly, in many a home chilled fingers are turning down the settings on thermostats and caulk guns and insulation kits are eagerly being snatched off retail shelves.

All of which are virtuous actions for indoor energy conservation. But there are some long-term and attractive landscaping solutions which can provide effective winter climate control by deflecting cold winds and drafts, while providing indoor comfort and increasing property values.

It is important to note that for most homes, almost one-third of all heat loss is due to cold winds, either through conduction, with heat simply “carried off” by marauding winds, or through infiltration, with cold drafts entering through and around cracks and improperly sealed windows and doors.

Of course, it is too late for any plantings this weekend to help your current season’s heating bill, but it is not too late to start budgeting and planning, either for the spring or next fall. Some landscaping choices, like foundation plantings, will make a difference almost immediately, while others, like windbreaks, might take a number of years before their full value is realized. But any and all plantings will certainly boost property values and aesthetic quality.

Moreover, your planting scheme need not be massive. While establishing an effective windbreak may take a substantial number of trees, computer modeling by the U.S. Department of Energy has found that just three well-placed trees, including a deciduous tree for shading the southern side of a house, can save the average household 100-250 dollars in annual heating and cooling costs. Overall, combining trees and shrubs can save from ten to 30 percent on winter fuel consumption, depending on how well insulated the home is already.

Foundation plantings are undoubtedly the easiest and most satisfying landscaping elements in your palette. Typically, you are looking to establish a continuous line of evergreens extending along the length of the foundation and around corners, approximately five feet out from the house. This living wall of vegetation will create a dead air space of slow-moving or still air between the shrubs and the house, effectively establishing an insulating layer which will reduce convective heat loss and infiltration.

Never allow the plants to grow much closer to the house than five feet. The dead air space needs to be of sufficient size to work, and the extra distance will help to prevent potential problems with mildew, insect pests, and humidity, which might lead to fungal diseases.

Visually, you will want to select different types of dense evergreens for your planting scheme, with varied heights, shapes, leaf textures and colors. Planting a simple row of junipers, for example, all growing at the same height, is both boring and impractical. Shrubs with different heights provide a more effective wind barrier, while a mixture of foliar colors and forms is more appealing to the eye. Of equal significance, using the same species repeatedly increases the likelihood that a plant disease could spread from one shrub to another, even to the extent of wiping out the entire planting.

Windbreaks are certainly the most effective components in cutting winter heat loss. A mature windbreak, normally comprised of several rows of tall evergreens, can reduce wind velocity by up to 50 percent, and otherwise deflect or channel wind movement away from the house.

Unfortunately, in many urban areas, there may not be sufficient space for a fully developed windbreak, although new housing developments, especially with larger lots, are prime candidates. Also, while planting a single row of evergreens can provide some appreciable windbreak benefits, the textbook windbreak requires two or three rows of trees, planted in an “L” or “U” shape on the north and northwest corners of the home. That can mean a sizable number of trees. Further, starting with cost-effective container-grown stock, it can take up to ten years or more before the trees will begin to pay for themselves, save for their aesthetic and environmental benefits.

However, few of us strive for textbook perfection, anyway. Even an incomplete or immature windbreak can start to deflect some wind movement. Also, while evergreen trees provide the greatest wind reduction, you can incorporate existing deciduous trees, fences, and walls on your property into a windbreak by adding additional evergreen trees and shrubs.

For the truly ambitious, an efficient windbreak should be about as tall as the house itself, and planted at a distance of one to three times the height of the trees away from the house. Where space permits, it is recommended to start the windbreak planting 50 feet beyond each windward corner of the house. The greatest impact of the windbreak will be on an area within approximately five times the height of the trees, although wind velocities are reduced for a distance up to ten times the height of the windbreak.

Depending on the mature diameter of the selected trees, space each evergreen between six and eight feet apart. If you can plant multiple rows, for maximum impact, stagger each of the trees in alternate rows, spacing each row 12-20 feet apart.

As with the foundation plantings, select a variety of low-branching evergreens for your windbreak, especially with respect to height and species, which will prevent disease outbreaks and ensure some wind penetration. Avoid growing a completely solid wall of evergreens, which can potentially create a vacuum effect on the protected side of the windbreak, thereby reducing its effectiveness.

With large scale windbreaks, it might be advisable to start with some fast growing species, such as White pine and Loblolly pine, and later interplant them with medium growth-rate species, such as Eastern red cedar, American holly, and Common Juniper. Fast-growing specimens will yield results more quickly, although they will also lose some of their lower branches. Your next series of plantings, whether interspersed with the first or established as a second row, will fill in any gaps.

Finally, windbreaks are investments in the future. They will eventually provide valuable screening for privacy, energy savings, and, if native species are selected, abundant benefits for wildlife. However, you should not try this approach on the southern side of your home, especially where the evergreens might block sunlight from providing passive solar heating in the winter.

Copyright 2010, Joseph M. Keyser

Planting Suggestions

Whether developing windbreaks or foundation plantings, the following list of trees and shrubs concentrates on native species, which are far preferable to exotic species which are not necessarily well-adapted to this area, and provide little or no benefit to wildlife. For example, instead of planting Leyland Cyprus, substitute Eastern red cedar, whose berries help feed birds during the winter, and whose aromatic bark is a favorite nest building material for cardinals.

Windbreak Trees (mature height)

American Holly 30-50'
Common Juniper 5-30'
Eastern Hemlock 60-70'
Eastern Red Cedar 50-75'
Eastern Arborvitae 50-75'
Loblolly Pine 90'
Pitch Pine 50-60'
Rosebay Rhododendron 20-35'
Shortleaf Pine 100'
Virginia Pine 50-80'
White Pine 75-100'

Foundation Shrubs

Bearberry (Arctostaphylos) 4-20'
Common Juniper (pruned back) 3-30'
Compact Oregon Grape Holly 2-3'
Cotoneaster 3-15'
Inkberry Holly 4-6'
Mountain Laurel (Kalmia latifolia) 7-15'
Northern Bayberry 4-8'
Southern Bayberry/Wax Myrtle 6-12'
Sweetbay Magnolia (semi-evergreen) 12-20'
Wild Hydrangea (Hydrangea arborescens) 3-9'

GreenMan & the Home Energy Audit

Join the GreenMan as he learns they whys and wherefores of conducting a home energy audit.

Landscaping to Save Energy (Winter Edition)

Homeowners across the colder portions of the country are about to find themselves yet again being uncomfortably squeezed between cold temperatures and increasingly higher natural gas and energy prices. In fact, depending on the size of the home, residents can expect to spend between two to three times as much on basic heating costs, if not more. Not surprisingly, in many a home chilled fingers are turning down the settings on thermostats and caulk guns and insulation kits are eagerly being snatched off retail shelves.

All of which are virtuous actions for indoor energy conservation. But there are some long-term and attractive landscaping solutions which can provide effective winter climate control by deflecting cold winds and drafts, while providing indoor comfort and increasing property values.

It is important to note that for most homes, almost one-third of all heat loss is due to cold winds, either through conduction, with heat simply “carried off” by marauding winds, or through infiltration, with cold drafts entering through and around cracks and improperly sealed windows and doors.

Of course, it is too late for any plantings this weekend to help your current season’s heating bill, but it is not too late to start budgeting and planning, either for the spring or next fall. Some landscaping choices, like foundation plantings, will make a difference almost immediately, while others, like windbreaks, might take a number of years before their full value is realized. But any and all plantings will certainly boost property values and aesthetic quality.

Moreover, your planting scheme need not be massive. While establishing an effective windbreak may take a substantial number of trees, computer modeling by the U.S. Department of Energy has found that just three well-placed trees, including a deciduous tree for shading the southern side of a house, can save the average household 100-250 dollars in annual heating and cooling costs. Overall, combining trees and shrubs can save from ten to 30 percent on winter fuel consumption, depending on how well insulated the home is already.

Foundation plantings are undoubtedly the easiest and most satisfying landscaping elements in your palette. Typically, you are looking to establish a continuous line of evergreens extending along the length of the foundation and around corners, approximately five feet out from the house. This living wall of vegetation will create a dead air space of slow-moving or still air between the shrubs and the house, effectively establishing an insulating layer which will reduce convective heat loss and infiltration.

Never allow the plants to grow much closer to the house than five feet. The dead air space needs to be of sufficient size to work, and the extra distance will help to prevent potential problems with mildew, insect pests, and humidity, which might lead to fungal diseases.

Visually, you will want to select different types of dense evergreens for your planting scheme, with varied heights, shapes, leaf textures and colors. Planting a simple row of junipers, for example, all growing at the same height, is both boring and impractical. Shrubs with different heights provide a more effective wind barrier, while a mixture of foliar colors and forms is more appealing to the eye. Of equal significance, using the same species repeatedly increases the likelihood that a plant disease could spread from one shrub to another, even to the extent of wiping out the entire planting.

Windbreaks are certainly the most effective components in cutting winter heat loss. A mature windbreak, normally comprised of several rows of tall evergreens, can reduce wind velocity by up to 50 percent, and otherwise deflect or channel wind movement away from the house.

Unfortunately, in many urban areas, there may not be sufficient space for a fully developed windbreak, although new housing developments, especially with larger lots, are prime candidates. Also, while planting a single row of evergreens can provide some appreciable windbreak benefits, the textbook windbreak requires two or three rows of trees, planted in an “L” or “U” shape on the north and northwest corners of the home. That can mean a sizable number of trees. Further, starting with cost-effective container-grown stock, it can take up to ten years or more before the trees will begin to pay for themselves, save for their aesthetic and environmental benefits.

However, few of us strive for textbook perfection, anyway. Even an incomplete or immature windbreak can start to deflect some wind movement. Also, while evergreen trees provide the greatest wind reduction, you can incorporate existing deciduous trees, fences, and walls on your property into a windbreak by adding additional evergreen trees and shrubs.

For the truly ambitious, an efficient windbreak should be about as tall as the house itself, and planted at a distance of one to three times the height of the trees away from the house. Where space permits, it is recommended to start the windbreak planting 50 feet beyond each windward corner of the house. The greatest impact of the windbreak will be on an area within approximately five times the height of the trees, although wind velocities are reduced for a distance up to ten times the height of the windbreak.

Depending on the mature diameter of the selected trees, space each evergreen between six and eight feet apart. If you can plant multiple rows, for maximum impact, stagger each of the trees in alternate rows, spacing each row 12-20 feet apart.

As with the foundation plantings, select a variety of low-branching evergreens for your windbreak, especially with respect to height and species, which will prevent disease outbreaks and ensure some wind penetration. Avoid growing a completely solid wall of evergreens, which can potentially create a vacuum effect on the protected side of the windbreak, thereby reducing its effectiveness.

With large scale windbreaks, it might be advisable to start with some fast growing species, such as White pine and Loblolly pine, and later interplant them with medium growth-rate species, such as Eastern red cedar, American holly, and Common Juniper. Fast-growing specimens will yield results more quickly, although they will also lose some of their lower branches. Your next series of plantings, whether interspersed with the first or established as a second row, will fill in any gaps.

Finally, windbreaks are investments in the future. They will eventually provide valuable screening for privacy, energy savings, and, if native species are selected, abundant benefits for wildlife. However, you should not try this approach on the southern side of your home, especially where the evergreens might block sunlight from providing passive solar heating in the winter.

Copyright 2009, Joseph M. Keyser

Planting Suggestions

Whether developing windbreaks or foundation plantings, the following list of trees and shrubs concentrates on native species, which are far preferable to exotic species which are not necessarily well-adapted to this area, and provide little or no benefit to wildlife. For example, instead of planting Leyland Cyprus, substitute Eastern red cedar, whose berries help feed birds during the winter, and whose aromatic bark is a favorite nest building material for cardinals.

Windbreak Trees (mature height)

American Holly 30-50'
Common Juniper 5-30'
Eastern Hemlock 60-70'
Eastern Red Cedar 50-75'
Eastern Arborvitae 50-75'
Loblolly Pine 90'
Pitch Pine 50-60'
Rosebay Rhododendron 20-35'
Shortleaf Pine 100'
Virginia Pine 50-80'
White Pine 75-100'

Foundation Shrubs

Bearberry (Arctostaphylos) 4-20'
Common Juniper (pruned back) 3-30'
Compact Oregon Grape Holly 2-3'
Cotoneaster 3-15'
Inkberry Holly 4-6'
Mountain Laurel (Kalmia latifolia) 7-15'
Northern Bayberry 4-8'
Southern Bayberry/Wax Myrtle 6-12'
Sweetbay Magnolia (semi-evergreen) 12-20'
Wild Hydrangea (Hydrangea arborescens) 3-9'

GreenMan Explores Crystal City Greening Efforts

I was recently asked to tour and explore some of the initiatives of the Crystal City Business Improvement District in Arlington, Virginia, where the community has adopted green practices for its popular Farmer's Market, supports regional agricultural efforts, and a wide range of sustainable practices, from transportation and energy efficiency, to waste reduction and innovative composting programs.

Landscaping to Keep Cool - and Save Money!

Ah summer! The evening air is filled with the seductive smell of cookouts and steamed crab -- and the annoying hum of air conditioners. As the mercury keeps inching up into the nineties, the rising cost of keeping cool becomes more of an issue for many homeowners. Fortunately, there are landscaping solutions that can help save on energy costs without forcing you to break a sweat.

By properly positioning trees around our homes and reducing the amount of sunlight striking rooftops, walls, and windows, we can lower cooling costs by up to 25 percent. In fact, this type of natural cooling is much akin to using hats and sunscreen to protect delicate skin from harmful solar radiation.

Typically, the first step in an energy-efficient landscape is to plant a tree or trees on the south or southwest side of your home, where they can block the majority of sunlight, especially that striking your home in the mid- to late-afternoon. A couple of large trees, such as maples, oaks, and ash, will obviously produce the most shade, although smaller trees, such as dogwoods and serviceberry, can effectively screen the sides of a house.

Larger trees should be planted no closer than 20 feet from the house; smaller trees no closer than 15 feet. Among the fastest growing large shade trees are tulip poplars and sycamores, although both have somewhat weak branches and should never be planted where limbs can actually overhang the roof.

Deciduous trees, those that lose their leaves in winter, are more often planted than evergreens, as it generally desirable to allow the sun to provide passive solar heating in winter, at least for walls and windows. However, native evergreens, such as American holly, eastern red cedar, and eastern white pine, can also be used, depending on your overall landscaping theme.

Of course, if you plan to install photovoltaic cells or solar heat collectors on your roof, taking advantage of all that free solar energy, you will want to avoid shading the future location of your solar array. In this case, plant smaller growing trees that will primarily shade walls and windows.

If your property space cannot accommodate large trees, you can provide shading to walls and windows with small trees and shrubs like redbud, viburnum, deciduous azaleas, and inkberry holly. Be sure to keep shrubs about five feet away from the foundation to prevent problems with mold, mildew, and insect pests.

And while working around the foundation, why not use some evergreen shrubs like Mahonia and inkberry holly to shade your heat pump or air conditioner compressor. You will improve their efficiency, reduce some of the whining-whirring noise, and screen an otherwise unattractive bit of technology from view. Be careful that plants do not block airflow to and from the devices.

Another creative possibility is to use vines to shade wall areas and windows. Vines can either be trained to cover wall spaces, or can be attached to arbors and trellises. For example, Virginia creeper (or woodbine) can climb up the side of a masonry-covered wall without support, providing lush, attractive shade equaled only by its crimson-purple autumn foliage. Climbing hydrangea (Hydrangea anomala ssp. petiolaris) is also able to climb without support – or damage to building surfaces – and is a hardy and brilliant white-flowering specimen introduced from Asia in the 1860's.

Trellis structures can support a wide variety of vines and climbers, from showy roses to native favorites such as coral honeysuckle, crossvine, virgin’s bower, and American bittersweet. You can even take an edible landscaping approach and train pole beans or hyacinth beans to climb up string or wire supports.

It should be noted that shading fully exposed windows is more important than shading walls, most of which are fully insulated. For this reason, arbor structures built along the south side of a house can provide shade like a living awning, but with a great deal more beauty. You can train a host of interesting vines along the arbor, from edible kiwis and grapes, to ornamental hops and American wisteria.

Less involved window shading can be created with ordinary window boxes. Consider using some of the more colorful varieties of sweet potato vine, featuring dark purple, chartreuse, or tricolored leaves. These can be planted in your window box along with other colorful annuals and then trained to grow up and around the window frame. You will block out some of the sun’s heat while providing a dazzling window to the outdoors.

After addressing some of the direct sources of sunlight, think about the energy reflected from patios and walkways. Even the air temperature over grass is about ten degrees cooler than that over asphalt or other artificial surfaces. Simply shading these “hardscaped” areas can help appreciably, or you might want to reduce or replace concrete paths with natural, living materials, such as thyme lawns or mulched paths with herbal borders [see “Fragrant Pathway”]. Moreover, you can improve on the air conditioning benefit of lawns by replacing turf with clumps of native and ornamental grasses, perennial beds, and colorful groundcovers.

Keep in mind that landscaping to reduce energy costs can extend beyond merely shading rooftop and windows. According to national energy conservation expert Karen Anderson at the Alliance to Save Energy, “If it looks cool, it is cool.” Ms. Anderson is referring to the impression we have of a typical forest scene: green, serene, and lush with tall trees, ferns, and the leafy masses of smaller trees and shrubs. It always seems quite a bit cooler in such inviting environments because wooded areas really are cooler.

Trees and vegetation actually provide some chilling benefits through evaporative cooling, the transpiration of water through plant leaves. Research by the Lawrence Berkeley National Laboratory found that midday air temperatures were up to six degrees cooler in tree-shaded areas compared to treeless neighborhoods.

If you want to lower summer temperatures all around your home, try creating your own personal forest by grouping trees together in small groves and expanding green areas with ground covers and shrubs.

The more tree cover you establish, especially if it can help shade hot streets, sidewalks, and driveways, the cooler your immediate landscape will be. Naturally, if you work through a community association to get trees planted along streets and common areas, you can beautify your neighborhood, enhance overall property values, while keeping all of your homes more comfortable and energy efficient. Now that’s a cool idea!

Copyright 2009, Joseph M. Keyser