Transcript The Energy Star Home

The Energy Star Home
Drew Tepper
Overview
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What is an energy star home?
New Homes
Existing Homes
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Windows
HVAC
Insulation
Plumbing
Conclusion
What is an energy star home?
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“More home for less money than standard homes.”
Energy Star labeled homes are at least 30% more
energy-efficient than standard homes.
Use reliable and established technologies and building
practices to operate significantly more efficiently than
homes built to the Model Energy Code.
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These technologies and practices save the owners of Energy Star
homes money on their utility bills.
They provide a home that’s more comfortable, more durable,
environmentally friendly, and cheaper to own.
To receive an Energy Star label, homes must undergo a
third party evaluation of their energy efficiency.
Standard Home
$200,000
$1,654
$155
$1,809
Energy Star
Labeled Homes
List Price
Monthly Mortgage
Monthly Utilities
Total Monthly Costs
Monthly Savings
$203,000
$1,679
$100
$1,779
$30
Model Energy Code
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The Energy Star standard for new homes is measured by
the Home Energy Rating System (HERS) scoring.
The HERS rating is a calculation of the energy efficiency
of a home compared to an identical ‘house’ that meets
the minimum requirements of the Model Energy Code
(MEC).
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The HERS score will be between 0 and 100.
The reference ‘house’ will have a score of 80.
Each 5% reduction in energy usage will result in an
additional point on the HERS scale.
An Energy Star home must receive a score of at least 86
on the HERS score.
Builder Option Packages (BOP Ratings)
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BOPs are a set of construction specifications for a
specific climate zone.
These specifications include performance levels for the
thermal envelope, insulation, windows, orientation,
HVAC systems, and water heating efficiency.
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The United States has been divided into 19 climate zones for
purposes of BOP.
A home built to BOP specs is not rated by the HERS
system but still is subject to third party verification.
BOP homes either pass or fail as Energy Star homes.
New Construction
Tight Construction.
 There are hundreds of holes that penetrate the
outside of a house.
 These occur due to gaps and holes from framing
and penetrations for wiring, plumbing, and ducts.
 Air sealing combined with proper ventilation can
reduce energy bills and eliminate unwanted drafts
and pollutants.
New Construction Cont.
Tight Ducts.
 Duct Sealing – typically ducts leak
more than 35% of the air traveling
through them before reaching a
destination. Duct tape does not
seal ducts adequately.
 Duct location – should only be
placed where the air will be heated
and cooled. Attics can reach
above 150 F.
 Duct insulation – if used outside
the living area.
 Duct Sizing.
New Construction Cont.
Insulation.
 A continuous boundary of insulation is necessary
between the inside and outside for a home to
maintain temperature efficiently.
 Insulation must be installed carefully with no
gaps, crimping, or compression, as these can
allow unwanted air and heat exchange between
the outside and inside.
Old Construction
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Existing houses can be modified to meet
Energy Star standards.
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Not necessary.
Improvements can be made to increase
efficiency.
Windows.
High-efficiency heating and cooling
systems.
Replacement Windows
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Windows typically
make up 10 – 25% of
a home's exterior wall
area.
Energy Star labeled
windows are twice as
efficient as the
average window
produced just ten
years ago.
U-factor, R-value and Solar Heat
Gain Coefficient
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U-factor is the measurement of heat transfer
through a given building material (such as
glass).
R-value depicts the resistance a material has to
heat transfer.
U-factor = 1/R-value
The solar heat gain coefficient (SHGC) is a
measure of the amount of solar energy that a
glazing material allows to pass.
Window Facts
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In heating-dominated climates, windows account
for up to 25% of a typical house’s heating load.
In cooling-dominated climates, windows account
for up to 50% of the same house’s cooling load.
In recent years, many technological advances
have improved the thermal performance of
windows.
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These advances include low-emissivity and solar
control coatings, low-conductance gas fills, improved
thermal breaks and edge spacers, and better edge
sealing techniques.
What’s a good window?
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Windows can improves the thermal performance
of homes by minimizing heat loss in heatingdominated climates and by minimizing solar heat
gain in cooling-dominated climates.
Windows with lower U-factors (higher R-values)
perform better in heating-dominated climates
while windows with lower solar heat gain
coefficients (SHGC) perform better in coolingdominated climates.
“Vacuum” can be filled with other gases
Thermal Window
Windows Cont.
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Air tightness (unconditioned air leakage into a house).
 A rating of 0.2 cfm/ft (cubic foot per minute of air
leakage per linear foot of window edge) or lower is
considered good.
 The best windows have a rating of 0.1 cfm/ft or lower.
High-Performance™ Low Emissivity, Argon Blend Filled
Window:
Air Leakage: 0.15 cfm/ft
U-Factor: 0.28.
Solar Heat Gain Coefficient (SHGC): 0.43
Insulation (R-values put to use)
Insulation Specs
Insulation Material
R-value per inch of
Thickness
Batt-type
3.1 to 3.5
Loose fill
2.9 to 3.7
Board stock
3.5 to 6.2
Spray-type
3.5 to 6.0
Rigid Foam Insulation
HVAC
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The average air conditioned home uses 2000 kWh per
year.
The efficiency of Central A/C units is governed by U.S.
law and regulated by the U.S. Department of Energy.
The Seasonal Energy Efficiency Ratio (SEER) is defined
as the total cooling output (in Btu-British thermal units)
provided by the unit during its normal annual usage
period divided by its total energy input (in Watt-hours)
during the same period.
The minimum SEER allowed by law for a central A/C is
10.
The best available SEER is about 18.
Water (not addressed in the energy star program)
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When buying shower heads, look for low GPM
(gallons per minute).
Toilets
Light Bulbs – Compact Florescent
Bulbs (CFLs)
25 watts used is the
equivalent of a 100 W bulb
Conclusion
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New construction Energy Star Homes make sense
because during construction upgrade costs are nominal.
Upgrades to existing homes have a cost benefit if the life
of the product is taken into account.
Keep in mind that Energy Star Homes take advantage of
current technologies used in efficient ways; no solar or
wind power (but maybe back at the power plant!)
Energy Star improvements will increase resale value of
homes.
With a hybrid in the driveway and an energy star home,
who wouldn’t want to be your friend?!