Offical Nebraska Government Webpage
A Series of Factsheets on New Construction Issues

Summary
Waste prevention is even more beneficial than recycling. Activities that prevent waste production, such as reusing building materials, not only cut garbage and recycling collection costs but also reduces materials' expenses. Small changes to building practices and extra attention to detail can add up to significant savings to the builder, the homebuyer and the environment.

  Efficient Design and Construction
Efficient Site Selection and Development Options

Often times site development decisions are made and completed long before home design or construction of an individual home begins. Many of these decisions are outside of the scope of things that can be influenced by the homeowner or builder.

However, there are some items that you can consider when selecting your home’s site. When selecting a housing development consider locating your home where efficient design has been considered in the development of the lots. Some efficiently designed developments include the following features:

  • Minimal land disturbance so that the existing topography and trees are preserved. The typical practice of clear-cutting a site or entire development allows builders and developers easier access, which is beneficial and cost effective for them, but it also has detrimental effects such as:
    • Increased stormwater runoff during development and construction often carries away valuable topsoil.
    • Requiring the purchase of replacement topsoil, trees and grass which increases the owner’s final construction costs.
    • Increasing the owner’s initial costs to establish the replaced grasses and trees. New plantings typically require additional watering and fertilizing.

  • Minimize paved areas in the development such as sidewalks on only one side of the street, use of porous paving materials and limited use of curb cuts. All of these options help to reduce the amount of stormwater runoff which reduces the amount of topsoil lost during construction, the amount of road salt required for winter driving, and can help reduce the demand on a city’s storm drainage system.

Additional siting options that should be considered by the individual homeowner prior to purchasing a lot:

Solar Access:

  • How will the sun’s access and latitude affect the heating and cooling requirements of the home?
  • Are there planned outdoor areas that will be affected by the sun’s access or shading?

Winds:

  • What is the direction of the prevailing wind?
  • Will the home experience cold winds in the winter or are there wind blocks?
  • Will there be breezes in the summer months that will help to reduce cooling costs?
  • Are there planned outdoor areas that will be affected by the wind?

Winter Conditions:

  • What are the directions of prevailing snowfalls and drifting?
  • Will the home’s location increase or decrease the amount of snow removal required?

Current Water and Drainage:

  • Evaluate the site’s current drainage patterns and design your home to incorporate as much of the natural drainage system as possible. This will minimize the possibility of future water damage, while retaining as much of the current site topography as possible.
Efficient Building Design Options

A well-designed and constructed building will reduce the amount of natural resources needed for future operating costs as well as the amount of construction material resources. 

Achieving the goal of an efficient design may include simple or dramatic design statements, standard or highly efficient mechanical systems or changes in standard construction practices, but quite often it is best achieved through a combination of these options completed by all participants in the construction process. These participants include, but are not limited to the architect/designer, the contractor, sub-contractors and owners.

Some options for the participants to consider include:

Architect/Designer:

  • Locate rooms/spaces with little or no HVAC requirements such as garages, breezeways and storage rooms toward the colder areas of the site, if the home is being built in cold climates.
  • Evaluate appropriate window locations and views.
    • Limit the number and size of windows on the north and south sides of the house in cold climates.
    • Limit the size and number of window areas in the home’s service rooms.
    • Locate operable windows in each room to provide cross-ventilation or “free cooling” during spring and fall seasons.

  • Specify insulation types and R-values and verify that the insulation is installed appropriately. Unless specified, you can assume only “typical” insulation levels will be installed, which is generally less than that found in efficiently constructed buildings.
  • Require that the mechanical systems be accurately sized. Well-built, efficient homes have lower heating/cooling requirements and their heating and cooling equipment should not be sized based on standard industry approaches. Oversized systems cost more to install, more to operate and require more maintenance. In areas where the cooling system also provides de-humidification, larger than needed equipment can result in an uncomfortable home.
  • Consider how daylighting will affect each room of the home. Proper use of daylighting strategies can greatly reduce the amount of artificial lighting required in the future.
  • Locate mechanical rooms centrally to reduce the amount of ductwork required to condition the house. This not only reduces the mechanical installation cost , but it reduces the future energy costs of the home because conditioned air is not lost or tempered through long expanses of ductwork. This type of design can also increase the comfort level of the home because rooms located at the end of long mechanical ducts often have different heating/cooling requirements than what is being experienced where the thermostat is located.
  • Provide areas for mechanical ductwork within the interior of the insulated building envelope. Ductwork located outside of the insulated building envelope requires additional insulation to transport conditioned air through unconditioned space and back into conditioned space. The air temperature differences that occur around the conditioned air cause the temperature of the air to moderate. The likelihood of conditioned air losses from the building envelope also dramatically increases each time additional penetrations are made in the thermal envelope.

Contractors:

The successful construction of an efficiently designed home depends largely on the commitment and contributions of the general contractor and all of the sub-contractors and suppliers. Attention to detail and scheduling are essential to the construction of a truly efficient home. The following options should be evaluated and incorporated into the bidding and construction of the home:

  • Use resource efficient construction — also called “optimum value engineering” — techniques that reduce the amount of wood required for construction, the initial construction costs and future energy costs. Some of the framing techniques to consider are:
    • Locate studs at 24” on center rather than the often used 16” spacing.
    • Use two vertical studs per exterior corner, with clips or blocking to attach drywall, rather than building up four studs.
    • Eliminate the double top plate and use a single top plate in single story homes.
    • Where required structurally, use single and double headers for doors and windows and fill the remainder of the cavity with insulation.
    • Use single studs or ladder blocking to secure the connection of interior partition walls to exterior walls.

  • Install air and vapor barriers appropriately for the climate and protect the barriers until they are properly covered. A vapor retarder is a material or structural element that can be used to inhibit the movement of water vapor, while an air retarder can inhibit airflow into and out of the building envelope of a house.
    • Most damage to interior vapor barriers occurs when numerous sub-contractors are working simultaneously in the building. Impress on all workers in the home that one unsealed cut or tear in the vapor barrier of the home eliminates the benefits of the entire system, but not the cost!
    • Exterior air barriers can be damaged following installation in numerous ways such as by other construction work, weather and vandalism. Securely taping and sealing the barrier following installation and promptly installing the siding material will reduce or eliminate damage.

  • Properly sealing air leaks in the home’s thermal envelope can help reduce future energy costs by up to 50 percent when compared to other houses of similar type and age. Properly sealing a home during initial construction is the most cost effective and efficient approach. Sealing as indicated below will ensure an effective airtight barrier:
    • Under the bottom plate during installation and the inside edge of the bottom plate after the frame walls are erected.
    • Behind bathtubs before they are installed and around the bathtub and drain penetration after installation and before any floor insulation is installed.
    • Windows and exterior doors to rough openings.
    • Wiring, plumbing and HVAC penetrations at top and bottom plates, ceilings and floors.
    • Plumbing pipes, bathroom ventilation fans and electrical boxes to drywall.
    • Attic bypasses and chases before attic insulation is installed.
    • Drywall and penetrations in return duct plenums.
    • Duct boots to floors and drywall.
    • All exterior wall penetrations such as porch light fixtures, outside outlets and phone and electrical services.
    • Gaps around whole house frame.
    • All exterior sheathing cuts and openings.

  • Make certain that the specified insulation is installed according to the manufacturer’s recommendations. Inappropriately installed insulation can dramatically reduce the R-value of the product and, in extreme cases, be detrimental to the life of the home. Some specific insulation installation issues to consider:
    • When installing faced batt insulation, the facing material should be attached to the interior side of the stud ends, not the inside cavity face of the stud. Compaction or gaps in the batt insulation to accommodate gypsum board, piping and wiring can reduce the insulation’s overall R-value by nearly 1/3.
    • When installing blown-in insulation make sure the proper density is installed to achieve the specified R-value. Different manufacturers require varying depths and densities of products to meet specified R-values. Require insulation sub-contractors to provide the manufacturer’s density requirement data and written documentation of the total amount installed. Blown-in attic insulation should also be identified and documented to allow verification of the installed R-value following natural settlement.
    • Make sure all exterior building envelope wall cavities are insulated. Although this seems like a simple concept, quite often as different sub-contractors work in a home, exterior wall areas get covered up prior to the insulation being installed. Pay particular attention to areas such as shower surrounds, behind tubs and medicine cabinets.

  • Require the mechanical contractor to seal and mastic all supply and return air duct connections including the attachments to the air handling equipment. Experts indicate that nearly 30 percent of conditioned air, in residential buildings, is lost through poorly sealed and connected ductwork.
  • If the home design requires ductwork to be located outside of the insulated building envelope make sure that the mechanical contractor has insulated the ductwork to a minimum of an R-8 and properly secured the insulation.
  • If flexible duct is to be installed in the home, verify that the duct has no sharp bends or crimps in the system. Blocked or crimped ductwork reduces the amount of conditioned air delivered into specific areas of the home causing occupant discomfort, often requiring that mechanical systems operate longer.
Selection of Mechanical Systems, Appliances, Fixtures and Colors

Mechanical Systems

  • There are numerous manufacturers of residential mechanical systems — heating, cooling and water heating – as well as numerous types of systems provided by each manufacturer. And each system type has its own variances in efficiency, excluding electric resistance heating. We recommend owners research the types of systems available and appropriate for their needs as well as the efficiencies of the systems. More specific information regarding many types of mechanical systems is available on the Nebraska Energy Office web site.
  • Heat recovery ventilators — also called energy recovery ventilators — are increasingly being used for controlled ventilation in airtight homes. These ventilators can salvage about 70 percent of the energy from the stale exhaust air and transfer that energy to the fresh air entering by way of a heat exchanger. They can be attached to the central forced air system or may have their own duct system.

Appliances

  • Home buyers should purchase high-efficiency appliances such as clothes washers, dishwashers, freezers and refrigerators, especially if these appliances will be used frequently. Because all major appliances must have an EnergyGuide label, read the label carefully to make sure you have selected the most efficient appliance.

Light/Electrical Fixtures

  • Energy efficient lighting not only reduces the owner’s cost for operating the fixture, it also helps keep energy bills down by producing less heat, thereby reducing cooling requirements. Fluorescent lighting, both conventional and compact, is generally the most efficient lighting available for home applications.
  • Lighting controls, such as timers and dimmers, can also contribute greatly to energy savings. Timers should be installed to control restroom area lighting as well as the lighting used in rooms that are minimally used. Timers ensure that lights and fans are not left on accidentally. Dimmer switches can provide savings where minimal lighting levels are maintained. There are restrictions on using dimmers in combination with fluorescent lamps, so make sure your lighting supplier and electrician know if you intend to incorporate fluorescent lamp replacements on dimmer controls.
  • Fans used for kitchen and bathroom exhaust often have vents that penetrate the roof or walls. All exhaust fans should include a backdraft damper. The damper closes when the fan is not in use and helps to stop conditioned air from leaving the home. It is also recommended that no exhaust fans terminate or exhaust into the attic space. Exhaust air from kitchens, dryers and restrooms has a high moisture content. When the air is exhausted into a cold or cooler attic area condensation will occur and damage attic insulation as well as the roof and ceiling structure.

Plumbing Fixtures

  • Low water use fixtures such as showerheads, faucets and toilets can reduce water use by nearly half. Although water costs in many areas of the country are low, many municipal systems use large amounts of electricity to provide water to their customers. Installation of these types of fixtures can help to keep a community’s future electrical supply costs lower.

Colors

  • Installing light colors on exterior building surfaces such as roofing, siding, stucco and face brick helps to reflect the sun’s rays which reduces the amount of heat transferred into the home. This will help reduce cooling costs as well as the damage that can occur when extreme temperatures build-up in attics and wall cavities.
  • Light interior color selections for wall, ceiling and floor surfaces helps reflect natural light that enters through windows and skylights and helps to reduce the need for artificial lighting.
Nebraska Green Building Program

Participants in the Nebraska Green Building Program are encouraged to incorporate efficient design in all aspects of the construction of their homes. Efficient design options that provide participants with “Green Building” credit include:

  • Orienting the home so east and south areas are for outdoor use
  • Orienting the home on the lot so the longest axial dimension faces within 20 degrees of south
  • Shading 100 percent of south glass in June, July and August at 12 noon
  • Limiting the south glass area to between 5-10 percent of total finished floor area, including skylights
  • Limiting the total glazing area less than 20 percent of the livable floor area, including skylights
  • Properly designing interior thermal mass to assist heating and cooling the house
  • Daylighting that allows natural light to enter house from two sides of rooms in at least 50 percent of the total livable floor area, excluding skylights
  • Locating the air-handling unit centrally, creating no duct runs greater than 25 ft. in length
  • Installing active or passive solar heating systems that provide 40 percent or greater of the home’s heating needs. (Verification required by load calculations.)
  • Installing an active solar system for cooling, contributing at least a 30 percent reduction in mechanical cooling. (Verification required by load calculations.)
  • Locating all air-supply and distribution ducts within conditioned building envelope.
  • Return air ducts or transfer grills are located in every enclosed livable room
  • Completing an earth-sheltered design that reduces heating and cooling needs by at least 30 percent. (Verification required by load calculations.)
  • Installing a thermal chimney to increase natural ventilation
  • Designing for stack and/or cross ventilation for seasonal cooling with ventilation paths no greater than 20 ft.
  • Using light interior colors.
  • Installing light colored floor coverings.
  • Implementing daylighting strategies that reduce the need for artificial lighting
  • Installing operable windows that allow cross-ventilation in all living areas
  • Using light colored walls.

 

  Resources
 
 

Efficient Design and Construction is one in a series of factsheets on issues related to energy and resource efficient construction of new homes and buildings.

Other factsheets and additional information 
can also be found at: http://www.neo.ne.gov/home_const/design_build.htm

This fact sheet was partially financed through the Nebraska Department of Environmental Quality Litter Reduction and Recycling Program.

Produced by the
Nebraska Energy Office
521 S 14th Street, Suite 300
P.O. Box 95085, Lincoln, NE 68508
Phone 402-471-2867, Fax 402-471-3064

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