OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMSENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

Buildings forthe 21st CenturyBuildings that are moreenergy efficient, comfortable,and affordable...that’s thegoal of DOE’s Office of BuildingTechnology, State andCommunity Programs (BTS).To accelerate the developmentand wide application of energyefficiency measures, BTS:• Conducts R&D on technologies

and concepts for energy efficiency, working closely withthe building industry and withmanufacturers of materials,equipment, and appliances

• Promotes energy/money

saving opportunities to bothbuilders and buyers of homesand commercial buildings

• Works with state and local

regulatory groups to improvebuilding codes, appliance standards, and guidelines for efficient energy use

• Provides support and grants

to states and communitiesfor deployment of energyefficient technologies andpractices

A typical family may spend 60 percent or moreof its annual utility budget on heating andcooling. Careful selection and sizing of heatingand cooling (conditioning) equipment canreduce initial costs, increase homeownercomfort, increase operating efficiency, andgreatly reduce utility costs.

stop cycles), poor furnace heat exchanger life(due to flue gas water vapor condensation), andhigh operating costs. Oversized equipment mayalso be noisy because of large fans or undersized ductwork and may use more electricityto operate the blower fan.SYSTEM SELECTIONProper heating and cooling system selectiontakes into consideration fuel sources (e.g.,natural gas and electricity), distributionmechanisms (e.g., air and hydronic), equipmentoptions (e.g., furnace and heat pump), andequipment efficiency.Perform a life-cycle analysis of various properlysized HVAC options to select a cost-effectivesystem. Cost considerations include equipmentand installation prices, annual heating andcooling expenses, and maintenance costs.Although more difficult to evaluate, equipmentreliability, longevity, warranty coverage, andsafety are also important.For example, the heating fuel source directlyimpacts operating costs. Also, high-efficiencyheating equipment often costs more thanstandard-efficiency models, but it costs less torun. So the life-cycle cost—rather than initialpurchase price—may make high-efficiencyequipment or one fuel rather than another theeconomical choice.Some HVAC contractors and local utilitiesprovide life-cycle analysis of various equipmentoptions. A summary of many easy-to-usesoftware products for estimating annualheating and cooling costs is compiled byDOE’s BTS (www.eren.doe.gov/buildings).

Lighting, cooking and other appliances

Refrigerator

Heating and cooling

Hot water heating

HOME ENERGY COSTS

WHY SIZING IS IMPORTANTA common mistake in the heating, ventilation,and air conditioning (HVAC) industry is tooversize heating and cooling equipment,especially air conditioners and heat pumps.Bigger does not always mean better. Overcapacity equipment has a higher initial cost,costs more to operate, and may be lesseffective than optimally sized equipment.Because conditioning equipment reaches itshighest operating efficiency only after about 5to 15 minutes of continuous run-time, oversizedunits, which often run for shorter periods oftime, are less efficient than properly sized units.This short cycling can result in cold, clammyindoor conditions during cooling seasons, largeconditioned-space temperature swings,
t control can save energy by

needed. A heat pump should have

at that locks out the supplemental

heat) when the outdoor

he heat pump balance point

g on the climate) except during

.

nd efficient heating systems that

th hydronic heating, boiler-heated

pipes to radiators, baseboards, or

 dry climates, hydronic systems

 In more humid climates, they are

g because condensation can occur

mestic hot water and space

e. Water is heated within the unit

dler to supply space heating.

 are high-efficiency, sealed

ems pair an efficient air handler

high-efficiency, hot water heater.

an be buried

enches or

foot boreholes, as
nd efficient heating systems that

th hydronic heating, boiler-heated

pipes to radiators, baseboards, or

 dry climates, hydronic systems

 In more humid climates, they are

g because condensation can occur

mestic hot water and space

e. Water is heated within the unit

dler to supply space heating.

 are high-efficiency, sealed

ems pair an efficient air handler

high-efficiency, hot water heater.

Where central air conditioning is desired, a heat pump can bemuch more economical to operate than an electric furnace.EFFICIENCY LEVELSEquipment efficiency is a measure of how much energy iseffectively converted into heating and cooling the home. Moreefficient systems use less energy to achieve the same degree ofconditioning. Efficiency varies with operating conditions, soannual or seasonal efficiency ratings based on standard testsare included on product labels to aid purchasers. The yellowEnergyGuide label helps consumers compare the energyefficiency of similar products. It shows the estimated annualfuel consumption on a scale that compares similar products.A medium-efficiency unit with an ENERGY STAR

® label is the most

cost-effective choice in many applications. High-efficiency unitsbecome cost effective in homes with higher heating and coolingcosts. Higher cost can be due to an inefficient building envelope,a severe hot or cold climate, high fuel costs, or larger house size.

GA S FURNACES

Annual Fuel Utilization Efficiency (AFUE)—The seasonal orannual energy efficiency of fossil-fueled furnaces:

• 78% AFUE—minimum-AFUE natural gas furnaces.• 80 - 82% AFUE—medium-efficiency furnaces employing

efficient heat exchangers, better intake air control, and/orblowers to exhaust combustion products.

• >90% AFUE—high-efficiency (condensing) furnaces.HEAT P UMPS

Heating Seasonal Performance Factor (HSPF)—The energyefficiency of a heat pump during a full heating season:

• 6.6 and 6.8 HSPF—minimum-efficiency single-package

and split systems, respectively.

• 7.2 - 7.8 HSPF—medium-efficiency units.• >8.0 HSPF—high-efficiency units. Variable speed heat

pumps have HSPF ratings as high as 10.

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)EUFA%87(muminiM-ecanruFsaG 091$ 003$ $ 854

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OPERATING COSTSUsing U.S. average fuel costs in the year 2000, annualheating and cooling costs for various fuel sources andequipment efficiencies are estimated in Table 1 for threeclimates. System selection includes consideration ofoperating costs together with equipment price, longevity,and other factors. A 1,500 square-foot house with abuilding envelope that meets the International EnergyConservation Code 2000 was assumed in performing thecalculations for Table 1.

> 14 SEER

high

efficiency units. Some super high

efficiency units are as high as 18 SEER.
OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMSENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

Buildings forthe 21st CenturyBuildings that are moreenergy efficient, comfortable,and affordable...that’s thegoal of DOE’s Office of BuildingTechnology, State andCommunity Programs (BTS).To accelerate the developmentand wide application of energyefficiency measures, BTS:• Conducts R&D on technologies

and concepts for energy efficiency, working closely withthe building industry and withmanufacturers of materials,equipment, and appliances

• Promotes energy/money

saving opportunities to bothbuilders and buyers of homesand commercial buildings

• Works with state and local

regulatory groups to improvebuilding codes, appliance standards, and guidelines for efficient energy use

• Provides support and grants

to states and communitiesfor deployment of energyefficient technologies andpractices

A typical family may spend 60 percent or moreof its annual utility budget on heating andcooling. Careful selection and sizing of heatingand cooling (conditioning) equipment canreduce initial costs, increase homeownercomfort, increase operating efficiency, andgreatly reduce utility costs.

stop cycles), poor furnace heat exchanger life(due to flue gas water vapor condensation), andhigh operating costs. Oversized equipment mayalso be noisy because of large fans or undersized ductwork and may use more electricityto operate the blower fan.SYSTEM SELECTIONProper heating and cooling system selectiontakes into consideration fuel sources (e.g.,natural gas and electricity), distributionmechanisms (e.g., air and hydronic), equipmentoptions (e.g., furnace and heat pump), andequipment efficiency.Perform a life-cycle analysis of various properlysized HVAC options to select a cost-effectivesystem. Cost considerations include equipmentand installation prices, annual heating andcooling expenses, and maintenance costs.Although more difficult to evaluate, equipmentreliability, longevity, warranty coverage, andsafety are also important.For example, the heating fuel source directlyimpacts operating costs. Also, high-efficiencyheating equipment often costs more thanstandard-efficiency models, but it costs less torun. So the life-cycle cost—rather than initialpurchase price—may make high-efficiencyequipment or one fuel rather than another theeconomical choice.Some HVAC contractors and local utilitiesprovide life-cycle analysis of various equipmentoptions. A summary of many easy-to-usesoftware products for estimating annualheating and cooling costs is compiled byDOE’s BTS (www.eren.doe.gov/buildings).

Lighting, cooking and other appliances

Refrigerator

Heating and cooling

Hot water heating

HOME ENERGY COSTS

WHY SIZING IS IMPORTANTA common mistake in the heating, ventilation,and air conditioning (HVAC) industry is tooversize heating and cooling equipment,especially air conditioners and heat pumps.Bigger does not always mean better. Overcapacity equipment has a higher initial cost,costs more to operate, and may be lesseffective than optimally sized equipment.Because conditioning equipment reaches itshighest operating efficiency only after about 5to 15 minutes of continuous run-time, oversizedunits, which often run for shorter periods oftime, are less efficient than properly sized units.This short cycling can result in cold, clammyindoor conditions during cooling seasons, largeconditioned-space temperature swings,

vely higher or lower latent capacity.

UMP

 selected that meets the air

ner requirements provided in the

s item. Resistance heaters are added to

ment the unit heating capacity to meet

gn heating load, but they should not

120 percent of the design heating

ment. In cold climates, total cooling

y can be up to 125 percent of the total

design load. This builds in more

capacity and greater seasonal heating

cy but limits summer dehumidification.

STATS

able thermostats automatically allow

mperature settings during the day

o save energy, although not all users

table with their complexity. Setback

ormed manually using standard

 models, but a consistent pattern is

 achieved in practice. If a

able thermostat is desired, choose a

 an ENERGY STAR® label to ensure

rogramming features and accuracy.

mps, a thermostat compatible with

ms must be chosen. Changeover

ating and cooling should be performed

ther than automatically. The thermostat

quipped with an emergency heat

permits all supplemental heaters to be

hen the refrigerant system is

and activates an indoor indicator light.

ble models for heat pumps that meet

requirements ensure that costly back

ot engaged under routine conditions or

back practices.