The Kentucky Energy Saving Home

Learn how to build an energy efficient home or how to make an existing home energy efficient.

In this fact sheet, you will learn:

• how you can improve the energy efficiency of your home -- saving money and benefiting the environment at the same time;
• how you can build a new house that will have amazingly low energy bills;
• where to get additional information.

Most homes have higher bills for heating and cooling than necessary. Many older homes have little or no insulation in the walls or floors and around the foundations, inadequate insulation in the ceiling, leaking air ducts, poorly fitting single-pane windows, and other air leaks in the building envelope. Some problems of this kind may even be present in newer homes if the builder paid insufficient attention to energy efficiency during design and construction.

There are dozens of ways to save energy and money by tightening up air leaks and adding insulation to an existing home. In many cases, the energy savings can total several hundred dollars a year. Using guidelines distributed by GOEP, you can check your home for the following measures:

• fixing leaks in duct systems and insulating the ducts
• tuning up the furnace
• cleaning the filters of mechanical heating and cooling systems
• adding weatherstripping or caulking around windows and doors
• caulking cracks in the building envelope
• installing storm windows or doors, or replacing single-pane windows with new, energy-efficient
  adding insulation to the attic, walls or foundation walls

In addition to these relatively low-cost measures, guidebooks are available on how to perform a full-scale energy conservation retrofit -- a large project that is best undertaken when the house is being remodeled or renovated for other reasons. Important factors to consider during a full-scale retrofit include: (1) whether additional insulation will be added on the inside or outside of the existing walls; (2) how to achieve an airtight vapor barrier; and (3) how to provide for adequate, controlled ventilation of the home after the retrofit is finished.

GOEP has several practical manuals that can help homeowners make do-it-yourself energy improvements or explain what considerations are important when dealing with contractors. Many electric and gas utility companies provide energy-saving information and low-cost energy audits of existing homes. There are also several Kentucky firms that specialize in home energy improvements.
The principles and methods that will be described in the following discussion of new construction also apply to the renovation of existing homes.

In recent years, building methods and technologies have advanced to the point where it is possible to build a new home that uses about one-third of the energy that a standard home would require -- or less. Moreover, such high-performance homes can be built at an initial cost equal to or only a few hundred dollars more than the standard home. The energy savings more than outweigh any increase in the monthly mortgage, giving the homeowner lower total housing expenses and a positive net cash flow.

For example, consider an energy-saving home costing $126,000 alongside a standard home costing $125,000. The following table shows the comparative expenses of a standard home versus an energy-saving home, assuming that the interest rate is 6% and the term of the mortgage is 30 years:

The two main strategies for achieving superior energy-saving performance are superinsulation and passive solar design.

Superinsulation is more than simply piling up large amounts of insulation in the ceiling. It is an integrated system of building practices and components that achieves very low energy use by careful design, selection and installation of all of the elements that go into a home: walls, ceilings, vapor barriers, floors, windows, ventilation, and heating and cooling systems. All these building elements are carefully designed to make a superinsulated home virtually airtight, so that both heating in the winter and cooling in the summer are more efficient. Close attention to details and careful workmanship are required during construction to ensure that the installed insulation performs up to its full potential.

Walls
Compared to an insulation value of R-11 in standard construction, walls in superinsulated houses generally achieve insulating values of R-25 to R-40. There are several ways to design such high-performance walls, including single walls with insulating sheathing, strapped walls, double walls, and truss walls. Alternatively, foam-core panels, which are manufactured in a factory and assembled on site, can be used, or insulated concrete forms. Construction details may be obtained from the Division of Energy or from several of the reference books listed at the end of this fact sheet.

Ceilings
The insulating value of ceilings in superinsulated homes usually ranges from R-35 to R-50. The amount of insulation tends to be greater in ceilings than in walls because it is usually easier and cheaper to install insulation in ceilings. Insulation gaps that occur in standard construction are addressed by careful design, such as the raised heel truss shown below. Cathedral or truss ceilings present special problems that can be solved through careful design and installation.

Making the Home Air Tight
No matter which framing design is used, it is critical to make the walls, ceilings and foundations as airtight as possible to prevent energy loss and possible future moisture problems. Tight sealing can be achieved through a system called the "Advanced Drywall Approach," which makes use of caulking and low-perm interior paint; the use of rigid insulation panels on the inside surface of the wall studs; or the use of foam-core wall panels, if the joints between the panels are tightly sealed or caulked. All penetrations of the building envelope, such as electrical and plumbing connections, are sealed with caulk or gaskets.

Foundations
Superinsulated foundations generally have rigid insulation boards or insulated stud walls on the inside or outside surfaces of basement and crawl space walls. Above-ground sections of foundation insulation on the outside must be protected from sunlight, termites and weathering. Slab-on-grade floors are insulated around the perimeter and may also have rigid insulation placed underneath. (Many of the techniques of insulating and vapor-proofing foundations also reduce the entry of radioactive radon gas from the soil into a home's living space, an important benefit for people who want to reduce their cancer risk.) Floors over unheated basements are insulated to at least R-19 and have an air/vapor barrier on the side that is warm in winter.  If a crawlspace is used, it is sealed and insulated.

Windows
Windows in a superinsulated house need to have better energy performance than the metal-frame double-glazed windows or single glazing plus a storm window found in standard homes. Double-glazed windows with wood or vinyl frames, or metal frames plus a "thermal break," conduct far less heat through the non-glass areas of the window. In addition, low-emissivity (low-e) surfaces are becoming more common. By reducing the amount of heat that is radiated from the glass surface, a low-e surface can boost the R-value of a double-glazed window from approximately R-2 to R-3, a 50% improvement in performance. Another approach is to install movable insulating shutters or shades on the windows, which can be closed on cold winter nights and opened during the day to let in heat from the sun. During summer, shades can shut out unwanted heat during the daytime.

Air Circulation
Because superinsulated houses are so airtight, it is necessary to provide controlled sources of fresh outdoor air and mechanical ventilation of stale indoor air. Exhaust fans in bathroom and kitchen areas can be used along with adjustable air inlet ports in other rooms (usually located above windows). Another option is to install an air-to-air heat exchanger, also known as a heat recovery ventilator. This device transfers heat between the stale air going out and the fresh air coming in, thus saving some of the energy that was used to heat or cool the indoor air.

Sizing Heating & Cooling Systems
Heating and cooling systems in superinsulated homes should be sized much smaller than in conventional homes. It may be difficult to resist the tendency to buy a big system "just in case." Many superinsulated homes are so energy-efficient that they can be heated without a conventional furnace or heat pump at all. The savings that result from omitting the heating system can free up money to invest in extra insulation, higher-quality windows, or a heat recovery ventilator. Instead of a furnace or heat pump system, some superinsulated homes heat water with a domestic water heater and circulate the hot water through coils in the floor or a fan-coil unit that transfers heat from the water to the air in the living spaces. Other superinsulated homes depend on only 20 to 30 feet of electric baseboard heaters for the few days per year when extra space heat is needed.

A heating system that uses a flame, such as a gas furnace, needs a supply of air to feed the combustion process. Because superinsulated homes are so airtight, it is possible for such a heating system to create a suction in the house as the fuel burns and indoor oxygen is consumed. This situation can be very dangerous, because the suction can draw deadly combustion gases back down the flue into the home. The best option is to use a sealed-combustion unit that has an air intake pipe to bring in outside air for combustion.  Other options include equipping the furnace with a powered exhaust fan to force the combustion gases up the flue,  locating the furnace outdoors, and electricity-based heating systems.
Not only are superinsulated homes much easier to heat in winter, they are also much easier to cool in summer. A single window air conditioning unit, along with fans to circulate the cool air, is often enough to keep the whole house cool during summer weather in Kentucky.
 

The other main characteristic of an energy-saving home is that it makes efficient use of the environmental conditions at the site, including the free solar energy that falls on the home's walls and windows. While active solar heating often requires complex and expensive collectors and other equipment, passive solar design techniques tend to be simple and inexpensive.

The basic principle of passive solar design is to increase the amount of glazing area (windows or glass doors) on the south side of the house and decrease it on the other sides, particularly the north and west sides. North-facing windows tend to lose excessive amounts of heat in winter, while west-facing windows gain too much heat on summer afternoons.

One recommended distribution of window areas is as follows:

• Windows facing south-southwest should comprise 35 to 50 percent of the total window area.
• Windows facing east-northeast should comprise 20 to 30 percent of the total window area.
• Windows facing west-southwest should comprise 10 to 15 percent of the total window area.
• Windows facing north-northwest should comprise 5 to 15 percent of the total window area.

It is not necessary to have extremely large areas of windows if the house is superinsulated. In fact, large expanses of glazing can cause the home to overheat even in winter. An energy-saving home can be quite conventional-looking, unlike some of the futuristic-looking passive solar homes designed during the 1970s and 1980s.

Another important principle in a climate such as Kentucky's is to provide shading of all the glazing areas to prevent overheating of the house in the summer. Trees, overhangs, or awnings can be used to provide valuable shading.

In addition to increasing the window area on south-facing walls, other ways to achieve passive solar heating include sunspaces, greenhouses, or thermal storage walls made of masonry. Massive, dark-colored floors and walls can absorb extra solar heat during the daytime and release it to the room at night when it is needed.

By combining well-known techniques of superinsulation with passive solar design, a homeowner or homebuilder can achieve dramatic energy savings. The extra cost of insulation and higher-quality windows is offset by a much smaller heating and cooling system. The net results are increased comfort levels, lower total housing costs, and less energy-related pollution of the environment.

Home buyers should consider energy efficiency when buying any home, new or existing. When looking for an existing home, get records of past energy bills, or have the home audited for energy efficiency. When planning a new home, seek out an architect or builder who has experience with superinsulated and/or passive solar homes.

Energy costs are as much a part of the total monthly expense for housing as the mortgage is. Four national lending agencies have recognized this fact, and offer "energy-efficient mortgages," or increases in the allowable ratio of debt-to-income for the buyer of an energy-efficient home. The Federal Housing Administration (FHA) and the Federal National Mortgage Association (Fannie Mae) offer a 2% ratio "stretch" for an energy-efficient home, the Federal Home Loan Mortgage Corporation (Freddie Mac) offers a ratio stretch of up to 4%, and the Veterans Administration (VA) calculates the income requirement on the basis of total housing costs, including annual energy costs. This type of debt-to-income ratio stretch can make it possible for a home buyer to qualify for a mortgage on a house that has extra energy efficiency features and a correspondingly higher purchase price than a standard house.

As more people become aware of the importance of energy-efficient housing and begin to insist on energy-saving features, homebuilders will respond to the market and construct more such homes. Eventually, Kentucky's more progressive builders will build all their homes using energy-saving techniques.

The chart above summarizes information from two hypothetical home designs--a “standard” design and an “energy-saving” design.  The energy-related features of these two typical home designs have been developed by working in consultation with a number of energy-conscious architects and home builders. The two home designs have the same floor area and total window area, although the windows in the two designs are oriented in different directions. The standard home is designed to meet the minimum requirements of the energy codes that are now being enforced by building inspection officials in Kentucky. The design for the energy-saving home uses many of the superinsulation and passive solar design techniques described in previous sections of this fact sheet. The energy-saving home is  not intended to represent the maximum energy efficiency that can be achieved. The package of energy-saving features in our design is meant to be cost-effective -- i.e.,  reducing energy bills significantly while adding relatively little to the initial cost of the home. Although the energy performance of the energy-saving home is dramatic, it is certainly possible for an experienced energy-conscious builder to build an affordable home that does even better, exceeding the performance of the energy-saving home.

• A Consumer's Guide to Energy Efficiency and Renewable Energy
• Energy Star New Qualified Homes
• Investing in an Energy Star Home Fact Sheet (pdf 1.2 mb)

Last updated August 2007

Greg Guess
Phone: (502) 564-7192
In KY: (800) 282-0868
Fax: (502) 564-7484
Email: gregory.guess@ky.gov