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ACADEMIC LESSON
Passive solar design
7 An important technology applied in many
green homes is passive solar design. Through this
technology, windows, walls, and floors collect
warmth from the sun, and this warmth is distributed
to heat the home. This is accomplished without
the use of mechanical heating systems. In one
type of passive solar system, cement or brick walls
absorb heat from sunlight, store it, and then use
this heat to warm the building at night. An effective
passive solar design includes strategically placed
windows and vents that can direct airflow inside the
home and allow for cross ventilation that aids air
movement.
Windows
8 The placement, number, and size of windows
are important elements of the building design.
Windows should be placed on the sides of the
house that receive morning and early afternoon
sun. To avoid overheating in hot summer months,
the roof should be designed with overhangs that
block direct sunlight from entering the windows.
Some parts of the structure may require fewer
windows. For example, west-facing windows may
get too much direct sunlight in the summer. The
windows should be double- or triple-glazed and
well-sealed to achieve maximum insulation and
minimize temperature transfer.
Insulation and sealing
9 Placing the proper amount of insulation inside
walls and ceilings is essential for keeping heat in
during the cold season and cool air in during the
hot season. The effectiveness of the insulation is
indicated by its R-value—a measure of thermal
M02C_MOLI3098_SE_U02B.indd 37
resistance. Insulation is made from a variety of
substances, including environmentally friendly
materials such as recycled newspaper, sheep’s
wool, and shredded denim. Openings around
windows, doors, and vents need to be well-sealed.
Eliminating air leakage reduces energy needs.
wood stove solar panel roof and walls
water treatment
insulated
organic
garden
wildlife
pond
water
butt
double glazing
conservatory local materials
Other Features of Green Homes
Materials
10 The choice of building materials and construction
methods is important to consider in terms of their
effect on the environment—for example, the use
of nonsynthetic and nontoxic paints, finishes,
and glues; the use of wood products for kitchen
cabinets that do not contain air contaminants; and
the use of renewable resources such as bamboo
and wood for flooring. It is also worth noting that
an efficient home design and proper building
techniques can reduce the quantity of materials
used in construction.
Equipment
11 Energy-efficient appliances such as refrigerators,
freezers, and water heaters will keep energy
consumption low, as will the use of LED light bulbs.
The heating, ventilation, and air conditioning
(HVAC) system in a house usually accounts for at
least 50% of the home’s total energy consumption.
A highly energy-efficient system can greatly reduce
the amount of gas and electricity a home would
otherwise use.
12 Some builders prefer a geothermal or ground
source heat pump, an alternative heating and
cooling system that makes use of the natural
temperature of the earth. A heat pump moves heat
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