Frequently Asked Questions
DOE Support for Greensburg Residents
Building an Energy Efficient,
Durable, Affordable Home
Advanced Housing Technology
DOE Support for Greensburg Residents
What
support is the Department of Energy
offering to Greensburg residents?
The National Renewable Energy
Laboratory (NREL) and the Department
of Energy (DOE) are providing
assistance on practical and simple
approaches to increase energy
efficiency in new homes. Building
Science Corporation (BSC) and
IBACOS–teams from the DOE’s Building
America Research Program–are working
with homeowners and builders in
Greensburg by providing resources,
builder workshops, onsite technical
assistance, and a demonstration
house incentive program. For more
information, contact Duncan Prahl or
John Holten of IBACOS at
620-210-0281.
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What is
the Building America research
program?
Building America is a private/public
partnership that develops energy
solutions for new and existing
homes. The Building America project
combines the knowledge and resources
of industry leaders with the U.S.
Department of Energy's technical
capabilities. Together, they act as
a catalyst for change in the
home-building industry. More
information about Building America
can be found at
www.buildingamerica.gov.
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Building an Energy Efficient,
Durable, Affordable Home
Will an energy
efficient house cost more?
Not in the long term. And maybe not
in the short term either. Energy
efficiency improvements, if made as
part of a whole house approach,
generally payback quickly in savings
on monthly utility bills. The
additional cost of the improvements
can be reduced or eliminated by a
combination of cost “trade-offs”
during construction and the federal
tax credit for energy efficient
houses. For more information, see
the “Incentive
Specification” on this website.
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Are energy
efficient, durable, affordable
houses "green"?
Houses built to the specifications
described on this website (see
here), and to higher levels of
energy efficiency generally, have a
significantly reduced environmental
impact by nature of the fact that
they use less energy. Construction
techniques recommended by the
Building America program also reduce
the amount of material used, reduce
the amount of construction waste,
create buildings that last longer
with less maintenance and repair,
and have a healthier indoor living
environment.
There are other important areas of
our environmental impact that are
not covered by this specification.
Choice of building site,
landscaping, water efficiency and
selection of interior finishes
should also be carefully considered.
These concerns can be added into the
basic house specification provided
by Building America to create a
fundamentally sound green home. More
information about these areas of
green buildings is available through
Greensburg Greentown (see
here).
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How can I receive financial support
for my new energy efficient home?
Coming Soon
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Can I talk
to someone in person about my
re-building plans?
Yes! Duncan Prahl or John Holten of
IBACOS will be in Greensburg on most
days and available to discuss your
plans. They can be reached at
620-210-0281. Duncan and John can
connect you with local architects,
builders, and other support programs
related to new housing.
The Building America Program is
designed to help both the builder
and the purchaser with reliable
“information”, “knowledge” and
“experience” – and to act as an
“honest broker” for this information
and technology. Building Science
Corporation (BSC) and IBACOS are
working with NREL in Greensburg to
support the rebuilding effort. These
two Building America teams do not
make money by “selling” things. Each
team’s role is to provide proven
information and provide vetted
technical support.
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Advanced Housing Technology
Does
the building code allow for stud
spacing at 24” o.c. and other
Advanced Framing techniques?
Coming Soon
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Does the building code allow the
use of insulating sheathing in lieu
of plywood or OSB sheathing?
For some portion of, or for the
entire exterior wall, the answer can
be yes, depending on the design. The
code provides options for houses
that are in wind zones less than 110
mph (which includes Kansas).
Braced wall panels can be used
instead of completely covering the
entire building with plywood or OSB.
While many types of braced wall
panels are acceptable, the most
common type of braced wall panels
are: 1. A 4 foot wide sheet of
plywood or OSB for outside walls and
2. Gypsum installed on interior
walls. The various types of braced
wall panels are described in Section
R602.10.3 Braced wall panel
construction methods.
For more information, see:
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How do I
attach cladding over insulating
sheathing if plywood or OSB
sheathing is not used?
The Code provides specific
prescriptive guidance on cladding
attachment and allows you to attach
cladding at 24” centers.
In the 2006 International
Residential Code (IRC) cladding
attachment requirements are covered
in Section R703 Exterior covering
with the majority of the
requirements summarized in Table
R703.4 Weather-resistant siding
attachment and minimum thickness.
When sheathings other than wood or
wood structural panels are used
(such as foam plastic insulating
sheathing), the code requires that
the cladding be fastened back to the
studs. The stud spacing is not
specifically stated in Table
5703.4 Weather-resistant siding
attachment and minimum thickness
and therefore other sections of the
code must be referenced for
acceptability of stud spacing. This
information is found in Section
R602.3.1 Stud size, height and
spacing in conjunction with
Table R602.3(5) Size, height and
spacing of wood studs listing
that studs spaced at 24” centers are
acceptable for certain walls.
Depending on the type of cladding,
thickness of cladding, and type and
thickness of sheathing different
fasteners may be required. The
penetration depth of the fastener
into the stud is the basic
requirement. For most claddings the
fastener length is specified since
the cladding and sheathing thickness
is known, a minimum penetration
depth is assumed. Where the
sheathing thickness is variable
(such as with foam plastic
insulating sheathing), the fastener
size needs to take into account the
siding thickness and thickness of
sheathing and still provide a
minimum of 1” to 1.5” penetration
(depending on the cladding type)
into the stud.
In many cases furring strips are
included in the design of the wall
cladding to create a ventilation and
drainage space behind the cladding.
In this configuration it is often
preferable to fasten the cladding to
the furring strips instead of back
to the studs. Unfortunately the code
does not specifically cover this
cladding system configuration so
engineering may be required to
design the cladding attachment to
meet the cladding wind load
requirements for the area.
For more information, see:
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Does
the building code require a vapor
barrier when I use insulating
sheathing?
Yes, in certain cases. The addition
of insulation boards on the exterior
of the assembly helps reduce the
potential for condensation occurring
in the wall assembly. If enough
insulation is added to the outside,
then a vapor retarder on the inside
is not necessary. Also, it is good
practice to allow a wall assembly to
be able to dry to at least one side,
and since many insulation boards can
be classified as vapor retarders,
removing the vapor retarder from the
inside allows increased drying of
the assembly to the inside and
improves the performance of the
wall. The code recognizes this and
addresses it in an exception which
allows for the vapor retarder to be
removed where it can be demonstrated
to the satisfaction of the building
official that the absence of a vapor
retarder will not damage the
materials or adversely affect the
performance of the insulation due to
moisture or it freezing. However
this still requires some
calculations to demonstrate that the
potential for condensation is
managed in the proposed design.
Alternately, most building officials
accept International Code Council
(ICC) prescriptive requirements, and
the current 2007 International
Energy Conservation Code (IECC) has
made some changes to the definition
and use of vapor retarders.
For more information, see:
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How do
I hang drywall with two-stud
corners?
Use drywall clips. A drywall clip is
a small metal bracket that is
attached to wood framing at inside
corners to support the edges of
gypsum board panels. There are a
couple of really good reasons to do
this. First, they replace wood
blocking or extra studs that are
typically used at corners to support
drywall. This allows more insulation
to be placed in the wall and can
help avoid “cold corners.” Second,
clips can be used to create
"floating" drywall corners, which
reduce cracking as the house
settles. There are many different
manufacturers and a couple different
styles of clips. All will work.
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Does the building code allow
insulation to be left exposed on the
inside of basement walls?
The building code requires that
insulation be installed on the
basement walls if the basement is
conditioned—or if the basement is
not conditioned insulation must be
installed on the basement walls or
in the floor separating the basement
from the conditioned space above—to
a minimum value of R-10.
It is often recommended to insulate
the basement walls with foam plastic
insulation as the foam plastic
insulations are not susceptible to
deterioration when in contact with
moisture (as can often be present in
concrete basement walls). When using
foam plastic insulation, the
majority of products require a
thermal barrier, usually ½” gypsum
to be installed over the insulation
as a fire safety requirement.
Certain foam plastic insulations
such as DOW Thermax (ICC-ES Legacy
Report NER 681) are rated to be left
exposed on the interior of basement
walls and do not need to be covered
with a thermal barrier.
For more information, see:
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Why should I use a sealed combustion
furnace and hot water heater?
Sealed combustion appliances protect
your health. In order to ensure good
indoor air quality, all combustion
appliances are recommended to be
sealed combustion units, as opposed
to naturally aspirated units. These
systems are completely decoupled
from the interior environment
through the use of dedicated outdoor
air intake and exhaust ducts
connected directly to the unit. This
change completely disconnects the
combustion process from the interior
environment, and eliminates concerns
of back-drafting of the unit.
For more information, see:
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If my
house is airtight, how do I provide
ventilation air?
With a tight building enclosure,
both mechanical ventilation and
pollutant source control are
required to ensure that there is
reasonable indoor air quality inside
the house.
The recommended ventilation system
is designed as a central fan
integrated system, which is made up
of a 6-inch outdoor air intake duct
connected to the return side of the
air handler. This duct draws outdoor
air in to the air distribution
system and distributes it to the
various rooms in the house. The
intake duct has a motorized damper
controlled by a fan cycling control
to close the damper to prevent over
ventilation of the house during
times of significant space
conditioning demands.
For more information, see:
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Do I
need to place my ductwork inside the
building enclosure?
The location of the duct system can
have a significant impact on the
overall performance of the
system–both the utility use and the
ability to provide comfort. In many
houses, the distribution duct work
is located either in a vented
crawlspace or in a vented attic –
effectively outdoors. With the ducts
located outside of the thermal
envelope of the home, any leakage
and conductive losses from the duct
work is lost directly to the
outside. Even worse, whenever air is
leaking out or the ducts due to the
system running, air is coming into
the house to replace the lost
air—resulting in forced air leakage
whenever your furnace or air
conditioner runs.
Moving the duct work and air
handlers inside the thermal
enclosure can be used to help
prevent this energy loss to the
exterior. Alternately, the thermal
enclosure can be extended to include
areas such as crawlspaces and attic
as part of the conditioned space of
the house.
For more information, see:
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Why is
duct sealing the right thing to do?
Ductwork, furnaces and air handlers
should be sealed against air
leakage. The only place air should
be able to leave the supply duct
system and the furnace or air
handling unit is at the supply
registers. The only place air should
be able to enter the return duct
system and the furnace or air
handling unit is at the return
grilles. A forced air system should
be able to be pressure tested the
way a plumber pressure tests a
plumbing system for leaks. Builders
don’t accept leaky plumbing systems,
so they should not accept leaky duct
systems.
For more information, see:
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What are “transfer grilles” and
“jump ducts” and what are they for?
Transfer grilles and jump ducts are
part of the return air pathway from
closed rooms (such as bedrooms) to
the central return air grille. The
return path needs to allow
sufficient return flow to prevent
room pressurization and prevent
supply flow from being “choked” off.
Note that while undercutting doors
can create part of the return air
path, wall transfer grilles or jump
ducts should be installed to prevent
the return problems stated above.
A transfer grille is installed in an
interior wall or above a door. A
grille plate is installed on either
side of the wall, using the stud
cavity to connect the room with a
space such as a hallway that leads
back to the central return. The
grilles are offset to reduce noise
and light transmission. A jump duct
accomplishes the same goal but
grilles mounted in the ceiling that
are then connected by a short
segment of flexible ductwork. Both
are illustrated in the Information
Sheet listed below.
For more information, see:
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Is special filtration required if
outdoor ventilation air is supplied
through a duct directly to the air
return?
Wind blown dust from fields or a
dusty construction site finds its
way into buildings and is a constant
annoyance for homeowners. Our
experience building in dusty places
like Las Vegas, Tucson and
Albuquerque has shown that
complaints about dust on their
countertops stop once the
airtightness of the building is
increased and mechanical ventilation
systems are installed.
In the recommended system
configuration where an outdoor air
duct is connected to the return, a
“pre-filter” can be installed at the
connection between the outdoor air
intake duct and the return to the
furnace. The “pre-filter” is mounted
in a 12”x12” register box with a
slot cut in for a 12”x12” filter at
the outside air duct connection
point.
Typical forced-air systems have a
filter on the return side of the
furnace that does filter air drawn
into the return. The additional
filter allows for outside air to be
pre-filtered before it is
re-filtered by the main system
filter.
We recommend that the pre-filter be
changed or cleaned more frequently
during dusty seasons to improve the
performance of the primary air
filter on the return side of the
furnace.
This system of a tight building
enclosure with controlled mechanical
ventilation that filters outside air
drawn in from a known fresh air
location is far better than random
uncontrolled infiltration which may
be "filtered" by the building
enclosure to a much lesser extent.
An airtight building enclosure and a
mechanical ventilation system with a
dedicated outdoor air intake greatly
reduces uncontrolled dust entry and
provides an opportunity to
effectively filter outdoor air drawn
into the house.
For more information, see:
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What
is a passive radon mitigation
system?
A passive radon mitigation system is
a vent stack built into a new home
that connects to a gravel bed below
an airtight basement floor slab.
This system depressurizes the gravel
bed and vents to the outdoors. If
severe radon problems are detected
in the future, a ‘passive’ system
can be converted to an ‘active’
system by adding an exhaust fan to
the vent stack.
For more information, see:
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