Buildings for

the 21st Century

Buildings that are more

energy-efficient, comfortable,

and affordable . . . that’s the

goal of DOE’s Office of Building

Technology, State and

Community Programs (BTS).

To accelerate the development

and wide application of energy

efficiency measures, BTS:

• Conducts R&D on technologies and concepts for energy

efficiency, working closely

with the building industry

and with manufacturers of

materials, equipment, and

appliances

• Promotes energy/money

saving opportunities to both

builders and buyers of homes

and commercial buildings

• Works with State and local

regulatory groups to improve

building codes, appliance

standards, and guidelines for

efficient energy use

• Provides support and grants

to States and communities

for deployment of energyefficient technologies and

practices

T e c h n o l o g y F a c t S h e e t

ENERGY

EFFICIENCY PAYS

Systems approach cuts home energy waste

and saves money

ENERGY EFFICIENCY SAVES MONEY

AND IMPROVES THE COMMUNITY

An Atlanta community found that the annual

energy bills for newly constructed, affordable

homes averaged over $1,200. Increasing the

energy efficiency of the homes saved over

$400 a year and added less than $500 to

construction costs.

Simple energy efficiency improvements can

cut energy costs by over 40 percent in most

affordable housing. Some low-income families

may spend over 15 percent of their income on

energy to operate their homes. The money that

these families save on energy can help them

make mortgage payments and pay for food,

clothing, and other essentials. Studies show

that a dollar saved on energy stays within the

community.

EFFICIENT HOMES PROTECT THE

HEALTH OF FAMILIES AND THE

ENVIRONMENT

Energy-efficient homes provide a healthy

indoor environment, reducing health risks from

mold, pollen, dust mites, radon, combustion

by-products, and other contaminants. In addition, they help to prevent unnecessary pollution. While homes are not often considered a

source of pollution, the electricity, fossil fuels,

and other energy sources they use contribute

to global warming, acid rain, smog, and other

serious environmental problems. Wasted

energy needlessly pollutes the environment.

Energy-efficient homes help to protect the

environment as well as the pocketbooks

of homeowners.

LITTLE IMPROVEMENTS YIELD

BIG SAVINGS

Getting the most efficiency for the least

cost requires careful attention throughout

the design and construction process. Most

energy-efficient homes have dozens of little

improvements that individually add little

to construction costs, yet together yield

big savings.

Many energy features offer additional benefits

such as increased comfort, reduced noise,

greater fire safety, and improved building

durability. Energy-efficient homes also have

less condensation, which protects framing,

windows, and finish materials. Better control

of moisture and temperature means less

movement of materials, which reduces floor

squeaks and drywall cracks.

While some energy features add to construction costs, others can reduce costs. For example, increasing insulation and sealing air leaks

reduce heating and cooling needs, allowing

the use of smaller equipment and ductwork.

The savings on the mechanical systems can

pay for the increased cost of insulation and

air sealing. Energy-efficient framing techniques can reduce lumber costs over 15

percent and prevent mold growth in outside

walls and ceilings.

OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMS

ENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY
WHAT MAKES A HOME ENERGY-EFFICIENT?

Affordable housing programs that have successfully cut energy

waste have champions who understand the importance of a

systems approach to improving energy efficiency and the

need for careful planning, training, and quality control during

construction. The following improvements help to make a

home truly affordable, healthy, durable, and comfortable.

P ROPER DESIGN AND INSTALLATION O F HVAC

Poor design and installation of heating, ventilation, and air

conditioning (HVAC) equipment commonly increases energy

costs 10 to 30 percent in affordable housing. Proper sizing,

design, and installation are usually the top three priorities

for cutting energy bills.

• EQUIPMENT SIZE

Equipment that is too big costs more to buy and operate

and results in less comfort. To size equipment properly

requires exact calculations that consider insulation levels,

window type and orientation, and air-sealing measures.

Do not use rules of thumb that estimate so much heating

or cooling per square foot of living area.

• EQUIPMENT EFFICIENCY AND ENERGY SOURCE

The professional who calculates the size of the HVAC

equipment should be able to determine estimated

operating costs for various equipment efficiencies and

energy sources. It is also important to consider the cost

of energy sources when selecting equipment. Saving a

few dollars on equipment is no bargain if families pay

hundreds more due to a wrong choice. Look for the

Energy Guide label, detailing estimated energy

consumption and annual operating costs.

• VENTILATION

Today’s homes need controlled ventilation systems.

For most affordable home designs, simple systems can be

economical to install and operate. In temperate climates,

spot ventilation provided by higher-quality bath and

kitchen fans vented directly to the outside may be adequate. In more severe climates, heat recovery ventilation

and other techniques may be more appropriate.

• DUCTWORK

Improving the efficiency of ductwork is the single most

important energy measure for most affordable homes.

Poor ductwork can waste hundreds of dollars each year

and cause serious health and safety problems. It is best

to locate ducts inside the living area—not in attics or

crawl spaces. Do not use building cavities, such as closet

returns, as part of the duct system.

Make sure all joints in the ductwork are sealed permanently with mastic; duct tape and insulation do not provide

an effective seal. After ducts are sealed, ensure that they

have adequate insulation. The Model Energy Code sets

minimum requirements, but higher levels are often costeffective. (See page 4 for details on how to obtain a copy

of the Model Energy Code.)

REDUCED AIR LEAKAGE

Excess air leakage in homes can increase heating and

cooling bills by 30 percent. Although windows, doors, and

outside walls contribute to air leakage, the biggest holes are

usually hidden from view and connect the house to the attic,

crawl space, or basement. Reducing air leakage typically

costs less than $200 for the average home and is required

by the Model Energy Code.

A systems approach to

improving energy efficiency

looks at energy usage

throughout the home to

identify key ways to cut

energy waste.

HOME ENERGY USE

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ENERGY EFFICIENCY PAYS

P ROPER INSTALLATION O F INSULATION

Gaps and compressed areas of insulation can cut the energysaving potential of insulation by over 25 percent. Poor installation also leads to condensation and comfort problems. The

Model Energy Code sets minimum requirements for insulation levels, but it is often cost-effective to exceed these levels.

 WATER CONSERVATION

A family of four can spend more for hot water than heating

or cooling. Consider the cost of various fuels for heating

water as well as the efficiency of the water heater, which is

often addressed on the label of the water heater. Simple conservation measures, such as low-flow showerheads, tank

insulation jackets, and convection traps in hot and cold water

lines, pay back quickly. Replacing inefficient plumbing fixtures in older homes can save families hundreds of dollars.

EFFICIENT WINDOWS

While energy-efficient windows cost more than standard

models, they can cut energy bills significantly and reduce

heating or cooling needs enough to permit smaller and

cheaper HVAC equipment and ductwork. They greatly

improve comfort by increasing surface temperatures and

cutting drafts. They also reduce condensation, protecting

building materials and reducing mold growth. Look for the

Energy Star® label when choosing windows.

Window orientation greatly affects energy use—as much as

25 percent for some designs. Major glass areas should face

south for maximum winter heating. Avoid unshaded glass

on east and west sides to reduce summer overheating. Use

solar shade screens, roof overhangs, awnings, and trees and

other landscaping to provide shade.

EFFICIENT LIGHTING

Energy-efficient lighting saves on electric bills, helps keep

the home cooler by reducing waste heat, and lasts longer.

Specify compact or tubular fluorescents for interior fixtures

that will be on for four hours or more each day—usually

kitchens, hallways, and some living areas. Their extra cost is

repaid in energy savings.

Exterior lighting can cost hundreds of dollars a year to

operate if it is not energy efficient. Install only compact

fluorescent or high-pressure sodium fixtures for security

lighting, and consider motion sensors or photo cells that

operate lights automatically.

 EFFICIENT APPLIANCES

Appliance energy use is usually greatest for refrigerators,

clothes washers and dryers, and dishwashers. The true

cost of an appliance is the purchase price plus the cost

for energy and water for operation. A cheap, inefficient

appliance will waste money for years to come. Federal law

requires that most appliances have Energy Guide tags that

compare estimated operating costs between energy-efficient

and standard models. Look for the Energy Star® label when

choosing appliances.

1. Ventilate attic

2. Install adequate insulation with no gaps

or compressed areas

3. Specify efficient windows; consider window

orientation

4. Seal all penetrations

5. Locate ducts inside conditioned space; if not

possible, ensure ducts are sealed with mastic

and insulated

6. Size heating and cooling equipment; choose

efficient models

7. Provide controlled ventilation

8. Install efficient water heating

9. Specify efficient lighting for fixtures

used more than four hours daily

10. Choose efficient appliances

IMPROVE ENERGY EFFICIENCY

THROUGHOUT THE HOUSE

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ENERGY EFFICIENCY PAYS

ENERGY EFFICIENCY IMPROVES

HOME AFFORDABILITY

Energy improvements help make a building

that is more durable and reduce the need for

expensive maintenance. Money saved on

energy bills can be used by homeowners

to better budget for any maintenance and

repairs that must be done. Energy efficiency

is a great investment for homeowners. When

added to a mortgage, energy improvements

usually cost less than the savings they offer

on utility bills. Some areas have mortgages

that encourage energy efficiency, helping to

offset any added construction costs due to

energy improvements.

Energy efficiency makes housing

rehab affordable

In Greene County, Pennsylvania, the

Habitat for Humanity (HFH) affiliate closely

monitored energy usage for remodeled

homes. They discovered annual energy bills

as high as $1,800. The data clearly showed

that the highest energy consumption

occurred where little attention had been

given to energy improvements to the building

envelope and HVAC equipment.

By incorporating proper planning and

quality control during remodeling, HFH successfully reduced air leakage in the building

envelope and duct system and improved

efficiencies of the insulation, water heater,

and space conditioning equipment.

The results were significant: gas bills

for heat and hot water dropped from between

$60 and $110 per month to around $30.

Electricity costs were reduced by improving

lighting and certain “energy hog” appliances,

such as old refrigerators and dryers.

Improvements in water efficiency reduced

water and sewage costs.

HFH has lowered energy use in older

homes to about the same levels as in new,

energy-efficient homes. The key is a systems

approach that considers all energy usage,

including heating, cooling, hot water, lighting,

and appliances.

The average American family spends

$

$1,291 on home energy per year. Energy

use varies according to home characteristics, occupant lifestyle, and climate.

AVERAGE HOUSEHOLD

ENERGY EXPENDITURES

SOUTH

$1,366

WEST

$1,400 $999

MIDWEST

$1,599

NORTHEAST

For more information,

contact:

Energy Efficiency and

Renewable Energy

Clearinghouse (EREC)

1-800-DOE-3732

www.eren.doe.gov

Or visit the BTS Web site at:

www.eren.doe.gov/buildings

Written and prepared for

the U.S. Department of

Energy by:

Southface

Energy Institute

404-872-3549

www.southface.org

Oak Ridge

National Laboratory

Buildings Technology Center

423-574-5178

www.ornl.gov/btc

The Model Energy Code

can be obtained from the

Council of American

Building Officials by

calling 703-931-4533

MECcheck, a companion

compliance software

package, can be ordered

from DOE by calling

1-800-270-CODE

or downloaded directly

from the Web at:

www.energycodes.org/

resid/resid.htm.

NOTICE: Neither the United

States government nor any

agency thereof, nor any of their

employees, makes any warranty,

express or implied, or assumes

any legal liability or responsibility

for the accuracy, completeness,

or usefulness of any information,

apparatus, product, or process

disclosed. The views and opinions

of authors expressed herein do

not necessarily state or reflect

those of the United States government or any agency thereof.

Printed with a renewable-source ink on paper containing at

least 50% wastepaper, including 20% postconsumer waste.

March 1999 DOE/GO-10099-746