Solar Energy Cottage
Below is a list of categorized techniques used to make the Solar Energy Cottage more environmentally sustainable and energy efficient. To jump to a specific category, use the links on the left |
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To view a technical report on the Solar Energy Cottage, click here
To view a case study on the Solar Energy Cottage, click here
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Building Materials
and Techniques
The types of building materials used affect a home's
longevity. The Solar Energy Cottage incorporates the
use of sustainable building materials and techniques
including:
- Engineered wood products stretch wood resources,
are structurally superior, and can be made from new
growth trees
- Fibrous cement siding made from natural materials
is durable and requires little maintenance
- Recycled carpet with low volatile organic compound
(VOC) content improves indoor air quality
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Structural insulated panels (SIPs) used for the exterior
walls and ceiling allow for quick construction and ensure
proper installation of insulation |
| Building materials used to
increase the home's durability by preventing moisture
problems that can lead to mold growth include: |
- French drain around exterior perimeter of footer
- 6-mil polyethylene covering crawlspace floor and
sealed to walls
- Capillary break installed between foundation walls
and framed floor to prevent wicking of water
- Housewrap properly installed on the exterior of
all above grade walls
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- Overhangs above all doors and most
windows
- Quiet bath fan vented to the exterior
and featuring low sone ratings of 0.5 sone at 50 cubic
feet per minute (cfm) to 3.0 sones at 340 cfm
- No combustion appliances
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Recycled content porch decking is easy to use and reduces
landfill waste |
Foundation walls covered along the interior with rigid
foam insulation to prevent condensation |
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Air Sealing
A "leaky" home causes high energy costs,
poor comfort, and promotes entry of moisture and contaminants.
Unfortunately many sites for air leakage are hidden
from view. The best strategy in both new and existing
homes is to reduce air leakage as much as possible and
to provide controlled ventilation with fresh outdoor
air.
- The SIPs (explained above) provided a solid building
envelope to begin with. Additional air sealing was
required:
- Behind shower on exterior wall
- Around door and window rough openings
- In penetrations on the exterior of the SIPs and
in crawlspace walls
- At bottom plates between the concrete foundation
or subfloor and wood framing
- Along edges of plastic floor cover in crawlspace
- Weatherstripping was applied on all exterior windows
and doors
Insulation
The Solar Energy Cottage features a mix of insulation
types to minimize heat transfer through the walls, ceilings
and floors.
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- Insulation for the walls (R-22.6) and ceiling (R-38)
is integrated in the SIPs during production
- R-5 foam board insulation along crawlspace walls
Crawlspace
The standard crawlspace building practice is to insulate
underneath floors over unconditioned and vented crawlspaces.
However, unconditioned and vented crawlspaces typically
cause comfort and moisture problems in the southeast.
Studies have proven that conditioning and insulating
the walls of well-sealed crawlspaces can be an effective
alternative to the standard building practice.
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R-5 spray foam insulation in band area |
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The construction of the Solar Energy Cottage
conditioned crawlspace consists of:
- Poured footer with, CMU blocks stacked
on top, reinforced, and filled with more concrete
- Foundation drain installed around the
perimeter of the footer (as opposed to on top of the
footer) keeps excess water from soaking the footer
- Damproofing on exterior sides of crawlspace
walls
- 6-mil polyethylene covering the floor
with sealant applied to all seems and the edges turned
up and sealed to the walls
- Band area sprayed with expanding polystyrene
(R-5) to further insulate and seal cracks and penetrations.
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Supply vent to condition crawlspace and to maintain
a positive pressure in the crawlspace
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1 inch extruded polystyrene board with an R-value of 7.5,
applied to the interior walls beginning four inches above
grade (to allow for termite inspection) and continuing
to the floor joist bottoms. |
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Heating, Cooling and Ventilation
On average 41% of a home's energy usage can go to
conditioning (heating and cooling) the house. Determining
the correct size of heating and cooling equipment is
key to achieving comfortable interior conditions --
temperature and humidity -- and for saving on the costs
to buy and operate equipment.
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- 14 SEER heat pump with a heating season performance
factor (HSPF) of 8.95 and a variable speed blower
provides high efficiency heating and cooling
- Programmable thermostat allows different temperature
settings during the day, evening, and weekend to save
energy
- All duct work is insulated, located within conditioned
space and
- all connections are sealed with mastic reducing
duct leakage to less than 5%
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Fresh air ventilation controlled by a whole house dehumidifier
keeps the cottage drier and occupants more comfortable
at higher temperatures |
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Lighting
Every $1 spent on electricity for an incandescent
bulb, provides 10¢ worth of light and 90¢
worth of heat. The wasted energy increases lighting
and air conditioning costs and is responsible
for over 500 pounds of atmospheric pollution.
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Compact fluorescent light (CFL) fixtures and CFL
bulbs in traditional light fixtures featured in
the Solar Cottage, replace traditional incandescent
lighting and reduce the amount of energy used for
lighting by 45% |
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Indoor Water Conservation
Atlanta, like many communities, is facing a water crisis.
Water efficient fixtures save money, provide high performance,
and protect the environment.
- All shower and sink fixtures have low flows of 2.25
gal/minute or less
Water Heater
Water heating is the third highest energy cost in a
home representing 16% of total energy cost on average.
Selecting the appropriate fuel and water heater type,
using efficient system deign, and reducing hot water
consumption can manage water-heating energy costs.
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The Solar Energy Cottage displays one 50-gallon super
high efficiency electric water heater with an energy
factor of 0.94
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Windows
The Georgia Energy Code encourages that
windows and glass doors used have a solar heat gain
coefficient (SHGC) less than 0.4 and a U-factor of 0.65
or less. The SHGC is a measure of the amount of solar
heat (heat radiating from the sun) that an object blocks.
U-factor measures the amount of heat conducted through
a material. U-factor is the inverse of the R-value.
The lower the U-factor, or the higher the R-value, the
more efficient the window will be.
- All windows are Low E II with argon
fill gas and have a U-factor of 0.31 and a SHGC of
0.30
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Photovoltaic System
Photovoltaic (PV) systems silently generate electricity
from free sunlight. The Solar Energy Cottage demonstrates
how PV systems can offset the amount of electric power
needed from conventional power plants to improve air
quality and reliability.
The Solar Energy Cottage displays:
- A 4kW grid connected photovoltaic system expecting
to supply approximately 67% of the building's electricity
needs
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