Energy efficient landscape design

1. Energy efficient Landscape
design

2. • A well-designed landscape will:
– Cut your summer and winter energy costs dramatically.
– Protect your home from winter wind and summer sun
– Reduce consumption of water, pesticides and fuel for landscaping and lawn
maintenance
– Help control noise and air pollution.
• Weather
– ‘A state or condition of the atmosphere (temperature, pressure, wind, rainfall, etc) at a
given place and at a given instant of time’.
• Climate
– ‘The generalized weather or summation of weather conditions over a given region
during comparatively longer period (usually, a season or a year or even a decade)’
– Factors affecting climate
• Latitude
• Altitude (elevation)
• Precipitation
• Soil type
• Nearness to large water bodies
• Topography
• Vegetation
– Scales of climate
• Microclimate
• Meso climate (10 & 100 km across )
• Macro climate

3. • Microclimate
– The climate immediately surrounding your home
• If your home is located on a sunny southern slope, it may have a warm microclimate, even if you live in a cool region
• Even though you live in a hot-humid region, your home may be situated in a comfortable microclimate because of
abundant shade and dry breeze.
• Nearby bodies of water may increase your site’s humidity or decrease its air temperature.
• Various methods
– Shading
– Windbreaks
– Water conservation
– Arbors
– Absorbent and Reflective Materials

4. Solar Insolation
• Amount of solar radiation
received on a surface is
dependent
– the altitude of the sun due to
the season
– the position of the sun due
to the time of day
– the inclination of the
receiving surface.
• Assumptions for purposes of
simplifying the calculation of
the sun ’ s position in
relationship to a building
– the sun rotates around the
Earth
– the Earth is flat.

5. • Azimuth angle
– the angular distance
between the zero
azimuth (either due
South or due North)
and the projection of
the line of sight to the
sun on the ground.
– Northern Hemisphere -
if the zero azimuth is
set to South, the
azimuth angle value will
be negative before solar
noon, and positive after
solar noon.

6. Radiation spectrum and seasons

7. Equinox and solstice

8. Path of the sun on solstices and equinox

9. Stereographic sun path diagrams• Used to read the solar azimuth and
altitude throughout the day and year
for a given position on the earth.
• Azimuth Lines -
– run around the edge of the diagram.
• Altitude Lines -
– represented as concentric circular
dotted lines that run from the center
of the diagram out.
• Date Lines
– start on the eastern side of the graph
and run to the western side -
represent the path of the sun on one
particular day of the year.
– first day of January to June are shown
as solid lines
– July to December are shown as dotted
lines.
• Hour Lines/ Analemma
– shown as figure-eight-type lines that
intersect the date lines - represent the
position of the sun at a specific hour
of the day, throughout the year
– The intersection points between date
and hour lines give the position of the
sun.

13. Basic Orientation
– East:
• Receive direct morning sun but will be shaded in the
afternoon by the shadow of the building itself.
– West:
• Shaded in the morning but fully exposed to the hot
afternoon sun.
– South:
• Most critical to passive solar design because it receives the
most sunlight throughout the day but never as intensely as
the east or west sides.
– North:
• Almost always in shade.

14. Shading
– trees can reduce surrounding air temperatures as much as 9° F (5°C).
– Using shade effectively requires you to know the size, shape, and location of the moving
shadow that your shading device casts
– Trees are available in the appropriate sizes, densities, and shapes for almost any shade
application.
– To block solar heat in the summer but let much of it in during the winter, use deciduous
trees.
– To provide continuous shade or to block heavy winds, use dense evergreen trees or
shrubs
– Deciduous trees with high, spreading crowns (i.e., leaves and branches) can be planted
to the south of your home to provide maximum summertime roof shading.
– Trees with crowns lower to the ground are more appropriate to the west, where shade
is needed from lower afternoon sun angles.
– Trees should not be planted on the southern sides of solar-heated homes in cold
climates, because the branches of these deciduous trees will block some winter sun.
– Plant trees far enough away from the home so that when they mature, their root
systems do not damage the foundation and branches do not damage the roof.
– A 6-foot to 8-foot (1.8-meter to 2.4-meter) deciduous tree planted near your home will
begin shading windows the first year. Depending on the species and the home, the tree
will shade the roof in 5 to 10 years.

15. Windbreaks
• To use a windbreak effectively, you need to know what landscape strategies will work best in your regional
climate and your microclimate.
• A windbreak reduces heating costs by lowering the wind chill near your home.
• Wind chill is the temperature it "feels like" outside and is based on the rate of heat loss from exposed skin
caused by wind and cold.
• As the wind increases, the body is cooled at a faster rate and the skin temperature drops.
• A windbreak will reduce wind speed for a distance of as much as 30 times the windbreak's height. But for
maximum protection, plant your windbreak at a distance from your home of two to five times the mature
height of the trees.
• The best windbreaks block wind close to the ground by using trees and shrubs that have low crowns.
• Dense evergreen trees and shrubs planted to the north and northwest of the home are the most common
type of windbreak.
• Trees, bushes, and shrubs are often planted together to block or impede wind from ground level to the
treetops.
• If snow tends to drift in your area, plant low shrubs on the windward side of your windbreak. The shrubs will
trap snow before it blows next to your home. Snow fences can also help trap snow.
• Evergreen trees combined with a wall, fence, or earth berm (natural or man-made walls or raised areas of
soil) can deflect or lift the wind over the home.
– Be careful not to plant evergreens too close to your home's south side if you want to collect passive solar heat from
the winter sun.

17. Water conservation
WATERING
– determine how much water your plants actually need and evapo-transpiration.
– Evapotranspiration (Et) is the amount of water that is evaporated from the soil and transpired through the
plant's leaves.
– This amount of water needs to be replaced through watering.
– If you know your area's Et rate, you can plan the amount of water to be replaced through irrigation. Your
particular microclimate will also affect evapotranspiration in different areas of your yard.
– It's best to water or irrigate your plants in the early morning when evaporation rates are low. This also
provides plants with water before mid-day when the evaporation rate is the highest.
XERISCAPING
– Xeriscaping is a systematic method of promoting water conservation in landscaped areas.
– landscaping designed specifically for areas that are susceptible to drought, or for properties where water
conservation is practiced.
– xeros meaning "dry," the term means literally "dry landscape."
– Seven basic xeriscaping principles:
• Planning and design
– Provides direction and guidance, mapping your water and energy conservation strategies, both of which will be dependent upon
your regional climate and microclimate.
• Selecting and zoning plants appropriately
– plant selections - those that will flourish in your regional climate and microclimate; Always group plants with similar water-needs
together.
• Limiting turf areas
– Reduces the use of bluegrass turf, which usually requires a lot of supplemental watering. Consider substituting a turf grass that
uses less water than bluegrass.
• Improving the soil
– Enables soil to better absorb water and to encourage deeper roots.
• Irrigating efficiently
– Encourages using the irrigation method that waters plants in each area most efficiently.
• Using mulches
– Keeps plant roots cool, minimizes evaporation, prevents soil from crusting, and reduces weed growth.
• Maintaining the landscape
– Keeps plants healthy through weeding, pruning, fertilizing, and controlling pests.

18. Arbors
• Arbors along the sides of the house, attached or detached, will similarly reduce temperatures as the air
movement can pass through the arbor and be cooled by evaporation at the plant’s leaves.
• The shade created by the arbor is also beneficial.
• The arbor is a traditional cooling method used worldwide.
Absorbent and Reflective Materials
• Groundcover and/or turf also has a cooling effect from evapotranspiration (the loss of water from the soil by
evaporation and by the transpiration of the plants growing therein).
• The temperature above a groundcover will be 10 to 15 degrees cooler than above a heat absorbent material
such as asphalt or a reflective material such as light colored gravel or rock.
• A heat absorbent material like asphalt will also continue to radiate heat after the sun has set.
• It is best to either minimize the use of heat absorbent and reflective materials near a house and/or shade them
from any direct sun.