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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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