4. How to Save Energy in the Yard

The Yard

The yard is more than a place for a pool or a garden. Trees, grass, and shrubbery can help lower the cooling load through shading and evaporative cooling. For example, a lower floor built into the hillside, removing part of the building envelope from outside exposure, has lower heating and cooling loads.

5.0 HERE ARE SOME FUN IDEAS FROM THE LANDSCAPE GURUS:

The sun is lower in the sky in the winter. A surface perpendicular to the sunlight receives the most direct radiation, the highest intensity. That means a sloping roof (or a house on a hill) facing south is more perpendicular to the sun’s rays than an incline facing any other direction. That’s why solar panels are always on the south or southwest roof, tilted 30° to 40°, equivalent to your latitude.

Growers plant fruit trees in sloping ground to avoid frost. Cold air is heavier and flows downhill, collecting in valleys. (Vice versa with warm air in the summer; warm air rises.) Hillside air is always moving either uphill or downhill, and so it’s well-mixed and closer to ambient temperature than cold valley air.

A mixed forest of evergreen and deciduous trees reduces wind at ground level in the forest, but the most significant reduction is at two to five times the average tree height, for a 60 to 80 percent wind-speed reduction. (Hint: wind turbines don’t work well near forests.)

Use energy-efficient porch lighting.

To landscape against strong winter winds, put a row of mixed evergreens and deciduous trees a distance from your property equal to five times the height of your house to the north and west (e.g., prevailing winter wind direction). For summer winds, use only deciduous trees.

The criteria for selecting a tree for shade and shelter of your home: 

  • Fast-growing (or not)
  • Hardiness zone
  • Mature height and width
  • Spacing
  • Deciduous or evergreen
  • Drought hardiness

Practice outdoor water management via underground drip irrigation and xeriscaping, augmented by rainwater recovery.

Trees well positioned around a house to shade the walls and roof can, when mature, reduce the cooling load by up to 30 percent. Also, evaporative cooling of moisture from the leaves can lower ambient temperatures by 5° or 10° F in the heat of the afternoon.

Select trees, shrubs, and ground cover suitable for your climate and soil type. Shading and the amount of sunlight available are essential, too. It’s always best to plant vegetation that’s native to your area.

Keep the pool filter clean because a dirty filter makes the pump work harder against a higher-pressure head. Get an Energy Star pool pump.

Install windbreaks around the pool to reduce evaporative losses. You save water, and the pool water stays warmer in the spring and fall for a more extended swimming season.

Use hand clippers instead of an electric hedge trimmer. Ditto for all the other garden and shop tools.

Plant small, clumping bamboo (don’t spread like running varieties) at gutter downspouts to use all that extra water runoff. (Tons of mulch, too. Bamboo love mulch!)

Water the lawn early in the morning (watering late in the day promotes disease in the roots) so the grass has all day to soak up the water and grow!

Use a mulching lawnmower, which grinds up the cuttings much finer, to have a healthier lawn.

Set the mower height a little higher. You’ll mow less often, the grass needs less water, and weeds have a harder time getting established.

A greywater modification to your water system collects drain water from certain appliances (everything but the kitchen and toilets) into a separate tank or cistern. With a little chemical treatment (or just time), that water is suitable for watering the lawn.

Put kitchen waste in a compost pile (for garden and yard mulch) instead of running the garbage disposal.

Plant a Victory Garden in your yard, grow tomato plants in pots out on the balcony, or get a plot at your local community gardens—and let’s get dirty!

 5.1 FARMERS PLANT CORN ON ROUNDED MOUNTS (ORIENTED

NORTH-SOUTH) AND HILLS because plants grow earlier and faster thanks to passive solar heating. The ratio of the radiant solar energy incoming to the thermal mass available to absorb it is greater than for a flat field. (Hint: Bolster the thermal momentum for a ground source heat pump field by installing the trenches under conical mounds to increase solar heat gain by 90 percent. Learn more about this idea in the Geothermal chapter.)

 5.2 WATER, PRECIOUS WATER. WATER IS THE NEW OIL. 

Rain barrels can collect water from roof downspouts in arid climates like the American west. Granted, water off your roof may not be suitable for drinking, but it’s certainly good enough to water xeriscape shrubs and ground cover.

 5.3 SEPTIC FIELDS DON’T WASTE ANY WATER AT ALL. 

Wastewater goes into the septic tank, then filters out through perforated PVC pipes into the septic field, delivering water and nourishment to the grass and trees. City folks are charged a sewer fee for all the water they use, even for water used in the yard that never returns to the city sewer. Avoiding a sewer charge like that, by the way, might justify payback on a septic field if your household uses a lot of water and if city regulations allow septic fields.

5.4 GOT A SEPTIC PROBLEM THAT WON’T STOP BACKING UP? 

If the land is limited or you’re on a hillside, even a well-designed septic field can reach its limit—and then some. Ours did that in central Texas. We planted a silver maple tree in the backyard. A large tree (and fast-growing maples, more than most) uses over a hundred gallons of water each day. That breaks down to about ten gallons per day per inch of diameter. Voila! Beautiful shade tree in the backyard. Septic problem solved.

5.5 HYBRID COMMUNITY SEWER SYSTEMS USE WATER WISELY, TOO. 

Communities in lakeside communities sometimes have a two-level sewer treatment system. Part of the sewer water is treated, mixed with lake water, and then returned to the domestic water supply. They send the rest to a “gray water” system: partiallytreated water, with all the “nutrients” still there, used to water a golf course or community landscaping. People who live near golf course runways have a second water spigot, to use that gray water on their lawns.

5.6 PUT KITCHEN SCRAPS IN A COMPOST PILE.

I put fruit, vegetables, peanut shells, stale bread, and old cat food in a small fencedin area out back of the house. Produce decomposes quickly, and if you mix in lawn debris (grass clippings, leaves), you have some excellent mulch each spring for the garden or shrubs. When you’re grubbing in the compost pile, you’ll find lots of earthworms underneath—great for fishing bait. The raccoons like it, too, as well as rabbits!

5.7 A MULCH BARREL ACCELERATES THE DECOMPOSITION PROCESS. 

It’s a plastic drum that sits horizontally on a metal frame. You put the mulch inside a door, shut it tight, and then rotate the barrel every few days to aerate the mixture.

Works great. Very fast.

5.8 BURNING PILES OF LEAVES SENDS THAT CARBON BACK  INTO THE ATMOSPHERE. 

If you have a big yard with lots of leaves in the fall, set aside a whole corner of the yard and pile the leaves there. Turn the leaf pile over once or twice during the winter to aerate the mixture. Add some compost accelerator—a dry mix with all the compost bugs, but in hibernation—to speed up the whole process.

 5.9 BUILD A ROOT CELLAR FOR COLD STORAGE AND SHELTER! 

Back when there was no electricity and much less refrigeration, people would dig a room into the ground, called a root cellar. They stored fresh produce in this dark, cool environment to reduce spoilage. In tornado alley, these underground rooms still serve a purpose as shelters from violent windstorms.

 5.10 EARTH–SHELTERED GREENHOUSES NEED LITTLE SUPPLE MENTAL HEAT. 

Greenhouses usually require heating in the winter to keep temperatures above. With the longest glass wall facing south (for the maximum sunlight in the winter months), the back (northern) wall is dug partially into the ground. Concrete blocks (or anything that absorbs heat, even water barrels) on the north-facing wall, warmed up by direct sunlight during the day, realizes passive heating of the greenhouse at night when temperatures drop. Little, if any, artificial heating is needed to keep the temperatures safely above freezing (actually, 37° F is the critical number).

 

 

5.11 WALK–OUT BASEMENTS REDUCE HEATING AND COOLING LOADS. 

The ground is always cooler than the ambient temperature in the summer and warmer in the winter. One downstairs wall in my last house was below grade, adding all that thermal mass to the structure. The temperature of that wall in the summer was 65°F. On a 30° F day in the winter, the temperature was 50° F. The only heating source downstairs was a gas wall heater, for the coldest days. I didn’t need AC downstairs at all.

5.12 HOUSE APPRAISERS PENALIZE ENERGY–EFFICIENT HOMES. 

When I sold that tri-level house a few years ago, I discovered that real estate appraisers discount the square footage of walk-out basements (it wasn’t a basement at all, but fully as nicely appointed as the rest of the house), so you cannot price out the full square footage of that lower floor. What about apartments that have windows on only one wall of one room? Do their appraised values suffer the consequences?

5.13 EARTH–SHELTERED HOUSES ZERO OUT ALL HEATING AND COOLING COSTS. 

The ground keeps you cool in the summer (you only need the HVAC to dehumidify, which also lowers the ambient temperature a few degrees) and warm in the winter (with a little passive-heating help from sunlight through the south-facing windows in the front of the house). I realize a mostly underground house sounds terrible, but what about all the folks who live in apartments with only one side wall with windows?

5.14 SKYLIGHTS IN EARTH–SHELTERED HOUSES INTRODUCE

EXTRA DAYLIGHT if the roof isn’t covered by too much dirt. Modern pouredin-concrete-wall construction techniques sandwich insulation between two layers of concrete for floor, walls, and roof. The structure has almost zero infiltration (you’ll need exhaust vented to the outside) and no roof load (if there is a layer of earth on the roof). Evaporative cooling from grass on the roof keeps the whole house cool in the summertime.

5.15 GREEN LANDSCAPING CAN SAVE ENERGY, TOO. 

Well, all landscaping is green, of course. You can do better than “pretty green,” however, but functional green. Configure plantings in the open space around your home to save energy—lots of it. Water continually evaporates off grass and leaves, for evaporative cooling. Trees and grass lower ambient temperatures by 5°F or more.

5.16 THE URBAN JUNGLE IS ALWAYS HOTTER THAN THE  COUNTRYSIDE. 

Ambient temperatures in urban areas are 5° to 15° F warmer than in the countryside because sunlight reflects off buildings, roads, and concrete. Everything absorbs sunlight and re-radiates it to the environs. Good in the winter, miserable in the summer. (Just wait until climate change increases temps by another 5°F.) Every bit of green space in an urban setting breaks that thermal pattern: grass, trees, shrubs.

5.17 GREENERY DOESN’T REFLECT HEAT THE WAY HUMAN–MADE  STRUCTURES DO, NOR ABSORB AND RE–RADIATE IT. 

There’s absolutely no downside to regular, abundant green spaces in every urban and suburban environment. Trees have multiple benefits:

  • Trees block harsh winter winds and reduce the “stack effect” on office buildings and two-story houses. A row of evergreen trees is a very effective windbreak.
  • Large deciduous trees on the west exposure shade the whole structure from the heat of the late afternoon sun in the summer. After the leaves fall, warm sunlight gets through in the winter when the sun is low on the southern horizon.
  • Any side of a building shaded from the sun contributes less to the HVAC load. You can paint a building a light color to reflect sunlight if you live in a warm climate. The only way to lower the cooling load for a darker color in a colder climate is via shading from a large deciduous tree.
  • There is a wide variety of fast-growing deciduous trees suitable for any hardiness zone. Mix them with longer-lasting oaks, which grow more slowly but will be mature when the fast-growers start to die off, for many happy years of good shading.

 5.18 WILDFLOWERS ALONG THE ROADSIDE = LESS SPRINGTIME  MOWING. 

Lady Bird Johnson, the former First Lady, started a wonderful tradition in Texas to seed the grassy borders of the state’s roadways with wildflowers. Just think of all the money (and gas) the Texas Highway Department saves not having to mow the grass for a couple of months in the spring so the wildflowers can flourish. You can do the same thing! Your area will be on every bee’s mental map, every hummingbird’s list of favorite summer haunts, and every kid’s afternoon fun list.

5.19 EVERY MAJOR U.S. CITY IS IN THE POLLUTION DANGER ZONE. 

If you live in a big city like Los Angeles, Atlanta, or the Big Apple, just breathing that polluted air is like smoking a pack of cigarettes every day. It’s the same in virtually every urban area in America. Google “U.S. air pollution map.” Every metropolitan area is red, 85 percent of the rest is yellow, and very few areas are green. You can’t do much about air pollution except to plant more trees and open up more green spaces. Get your highway department to plant trees along roads and highways.

5.20 BAN LEAF BLOWERS. 

Raking leaves is very good exercise. The raking action is healthy for the grass, and it aerates the ground. But, no! Instead of getting out in nature for some sunshine and fresh air, people crank up their super-loud gasoline engines and breathe its toxic fumes for an hour.

5.21 BAN ALL SMALL INTERNAL COMBUSTION LAWN–MAINTENANCE  ENGINES. 

My electric mower and weed eater are lovely. (Corded versions are more powerful.) Electric lawn equipment has all the power of gas appliances, but none of the hassles.

None of the pollution, either.

5.22 SMALL–BORE GAS ENGINES GENERATE TEN TIMES MORE  AIR POLLUTION THAN A CAR. 

Jet skis are even worse! A two-hour thrill ride dumps four gallons of gas and oil into the water. A day’s cavorting on a jet ski dumps more pollution into the air than driving one hundred thousand miles in a car. Ski boats and every other vehicle on the lake are the same way. Save the planet and save energy—p get a kayak. Get some exercise!

5.23 GIVE THE GRASS A VACATION. 

Longer grass provides extra shading, which keeps the ground cooler. That means your lawn won’t dry up as quickly, and the grass won’t need water as often. Bottom line: Don’t mow the grass so often in the summer. (Let the clover grow. Bees love clover. Kids do, too.)

5.24 XERISCAPE VERSUS LANDSCAPE. 

Grasses and plants that are native to your area need less water and grow up healthier. You usually hear the term “xeriscaping” applied to regions that get very little rain, but the same principle applies everywhere: go native! Regional plants grow faster, flower more, and require less maintenance for many trouble-free years of nature’s plenty.

 5.25 SHEEP: NATURE’S FAVORITE LAWNMOWER. 

My family rented in a house outside of Madrid, Spain, for a couple of years when I was in junior high. The property had several acres enclosed with a stone wall. Our gardener used to bring a small herd of sheep a couple of times a year to spend a few days in the yard, trimming the grass, the shrubs (OMG—the rose bushes!), and fertilizing. It’s a new fad in suburbia: rental sheep!

5.26 TERMITE HAVEN. 

Trees and shrubs are a great way to shade the house to lower your utility bills in the summer. However, those shrubs close to the house, with the deep mulch around them, retain moisture in the soil. Termites love that dark, moist environment! If you must have the landscaping, space it away from the house and minimize the mulch, leaves, and ground cover near the foundation.

5.27 SPRING–CLEAN THE EXTERIOR OF THE HOUSE. 

Wash clean white exterior walls (dirt splashed up from rainfall, pollen, pollution, mold), so they reflect sunlight better. Clean away wasp nests and spiderwebs blocking soffit vents lining the roof overhang so they don’t block the attic ventilation.

Cut vines off deciduous trees so they grow taller and shade better.

5.28 RX FOR THE SEPTIC FIELD. 

Dissolve a special tablet in the toilet and flush it down right before you go to sleep for the night. Septic pills have bacteria that keep the septic process going. You send the bugs down the drain late in the day, so they stay in the “leach field” piping for a while and aren’t flushed out into the ground right away.

Future Tech! 

5.29

If you want to encourage homeowners to use less energy, adopt new appraisal rules that give extra value to energy-saving features.

5.30

Normally, an attractive yard has no appraisal value other than the “curb appeal” that gets more prospective buyers to visit the property. Yet, large trees and shrubs and lots of grass all contribute to the energy-efficiency of a property. Appraised values should reflect that benefit.

5.31

Wildflowers flourishing along the roadside should be the norm for all of America’s highways and byways every spring, not an army of mowing machines.

5.32

Every square foot of exposed soil in urban areas should be planted with trees to beautify, absorb air pollution, improve aquifers, and cool down the “concrete jungle” in the summertime.

5.33

Every urban area needs “community gardens” where folks can grow their own produce and get back in touch with nature.

5.34

Gas weed-eaters bench more pollution than an old Model T car. Can’t they build a lightweight all-electric version with a battery pack strapped to your back (with a solar panel to charge the battery)?

5.35

Sheep in New York City’s Central Park to trim the grass. Goats? Rabbits! Lots of rabbits!

5.36

A “Central Park” in every major city.