Transcript Energy Usage and Conservation Within the Household

Energy Usage and Conservation
Within the Household
Darryl Birtwistle
Energy, Society, and Climate
October 7, 2002
Facts
 The energy consumed within the US increased
exponentially from about 1850-1975.
 Projections indicated US would be using energy
at a rate of 160 Qbtu/yr by 2000 (Q= 10^15).
 By 1996, we only used energy at a rate of 93.8
Qbtu/yr.
 Buildings and appliances now use about 38% of
the total energy consumed in the nation.
(industry: 36%, transportation: 26%)
Energy Uses and Sources
Space Heating
Uses largest amount of energy in US
households (20%).
Natural gas is the predominant source
used.
Household heating is a very inefficient
process as hot air leaks out roof, through
cracks in walls and windows, through
doors, and out the basement.
Furnaces, Stoves, and
Fireplaces
 Most use natural gas
 Electric resistance
 Furnaces are 60-90%
heating is 100%
effective. (50% for
efficient, however,
costs more to operate.
older units)
 Electrically powered
 Alternatives are
heat pumps can be
electric resistance
used in places where
heating and the use of
temperatures are not
electrically powered
too low. May also act
heat pumps.
as air-conditioner.
Fireplaces
Are inefficient unless used to heat small
part of house while thermostat is down.
Efficiency of 40-65%.
Open fireplaces have negative efficiency:
they remove more heat from the house than
they provide.
Heat enters fireplace then goes out the flue.
Efficient Fireplaces
 Some fireplaces are
constructed with
connective passages
 Firewood provides
energy at rate of 12 to
30 mil. Btu per cord.
around back of firebox  Cord = 128ft3 stack
so air is air is drawn
 Higher density wood
close to it, heated, then
has more heat per
sent back into the
cord.
room.
 All wood is about
 This type of fireplace
8600Btu/lb.
is more efficient.
Solar Heat
 Heat can be gained through direct light through
south-facing windows.
 Light not reflected back out converts into heat.
 Conversion efficiency from light to heat is
usually around 60–90%
 Transmission of sunlight through glass and
insulation factors need to be taken into account.
Effective Design
Standards for Home Heating
Space Heating and
Conservation
 Most important factor for conservation is
thermostat settings.
 Normal settings have dropped from 72 to 65-68
degrees as comfortable living temp.
 Settings should be turned to around 55 at night,
then brought back up before needed.
 The many critics of this idea are falsely informed.
 Buildings should be properly insulated.
Insulation
 With perfect thermal insulation and no leakage of
air, no energy source would be needed to keep a
constant temperature.
 However, this is not possible.
 Well designed houses have been built that require
no separate heating system.
 They are heated by existing internal sources such
as lights and stoves.
 Insulation is important in controlling heat loss.
Insulation - Building Materials
Air Infiltration
Accounts for a complete change of air in a
house about once per hour.
Also accounts for 1/3 of heat loss.
Air exchange occurs around doors,
windows, leaky siding, and other cracks.
Fireplaces chimneys and furnace vents also
account for loss of warm air.
Heat Loss
Air infiltration
Leakage can be reduced to about 10% by
caulking, weather stripping, the addition of
automatic flue dampers, and closure of
fireplace and openings and chimneys.
Must keep dangerous gases such as carbon
monoxide and radon in mind when
completely sealing a house.
Air to Air Heat Exchanger
 Gets rid of harmful gases without heat loss.
 Heat is transferred from warm to cold air by conduction
through a thin barrier.
 Brings incoming air up to temperature as well as gives
it moisture.
Water Heaters
About 10-20% energy consumed in house.
Usually gas or electricity heats a 30-50 gal.
Tank of water to temp range of 120-140 F
Gas heaters loose heat through flue.
Pipes carrying water take away heat.
Steady expenditure of energy is required to
maintain the water temperature.
Ways to Conserve
 Reduction of the amount of hot water used.
 Lowering heater’s thermostat to 120 deg reduces
energy consumed and still provides hot enough
water.
 Insulation can be added to the tank and pipes.
 Electric igniters eliminate energy wasted by pilot
light.
 Flue damper can be installed.
Air Conditioning
About 60% (57 million) of US households
now have air conditioners.
75% of new homes have central air
conditioners.
Takes output of 7 large power plants to
provide energy for US air conditioning.
Air conditioners should be turned down
when not needed, doors and windows
should also remain shut to prevent loss of
cool air.
Air Conditioning
Central air conditioners are rated by there
seasonal energy efficient ratio (SEER).
Typical SEER ratings have increased from
6 or 8 some years ago to 8.5 or 9.5
recently.
Cost of energy to operate air conditioners
is enough to motivate people attention to
good house design and insulation.
Appliances
Main energy consumers
– Refrigerators
– Clothes dryers
– Air conditioners
Many appliances thought to waist energy
such as electric carving knives and
toothbrushes really use a negligible amount
of energy.
Appliances - Energy Consumption Chart
Water Heater: 6,000
A/C: 4,300
Refrigerator: 1,300
Washer: 1,080
Dryer: 1,060
Lighting: 844
Appliances – Energy Leakage
 Appliances drain energy even when they are off
in order to maintain settings, display clocks, and
keep remote control alert.
 TV’s drain energy to keep tubes warm.
 12-volt power transformers for many appliances
drain energy when off.
 Typical house drains continuously about 50w of
electric power when all switches are turned off.
 This leaked electricity costs about $3 billion per
year nation wide.
Energy Guide
 Must be posted on all new
appliances.
 List energy usage and
cost for appliance for one
year.
 Allows consumer to
compare increased cost of
energy conservative
appliance to savings in
energy usage.
Refrigerators
 Companies began to
minimize insulation to
provide more space.
 Made refrigerators
less energy
conservative.
 1972: 1700kWh/yr
were used ($130)
 1997: 690kWh/yr
($50) is the standard.
 Projected 2001
standard is
535kWh/yr, down
30% from 1997.
Clothes Dryers
 Consume about 15% of household electric
energy.
 Energy can be conserved by hanging clothes
outside.
 Air from electric dryer can be vented back
into the house to conserve heat.
Lighting
 20% of electric energy is used for lighting.
 Standard light levels in public schools have
increased from 20 lumens/sq ft. to 60 (suggested
level for reading).
 Many office buildings have lighting levels of 80
to 100 lumens/sq ft, including corridors and
stairways.
 Many office buildings have single switches that
turn on whole floors at once.
Lighting (light choice)
 Fluorescent light produces about five times more
lumens per watt than incandescent lighting.
– 15 w fluorescent bulb = 75 w incandescent bulb
 Some people complain about quality of light of
fluorescent bulb, this is being fixed
 Fluorescent lamps last about 10,000 hours, ten
times longer than conventional light bulbs.
 Lower energy usage and longer lifespan account
for greater price of fluorescent light bulbs.
Lighting Chart
Lighting - Conservation
Choose efficient light fixtures.
Use effective lighting design.
Use switches allowing lights to be
individual controlled, allow for dimming.
Corridors and stairways should use less
light.
Users should remember to turn off lights or
use automatic controllers to turn them off.
The Energy-Conservative House
 Study done on 1200 sq ft California house to
determine energy conservation in relationship to
cost.
 Largest effect was for space heating which went
from 120 mil Btu/yr to 35 mil Btu/yr, for an
expenditure of $1600. (2/3 reduction)
 Total energy used was also decreased from 235 to
100 mil Btu with an investment of $2700
National Affect
If the conservation steps taken in this
experimental house were used across the
nation, the 36 QBtu used nationally per
year for buildings and appliances could be
reduced to 15 Qbtu/yr, with a cost of about
150 billion dollars.
Demonstrates the potential for energy
conservation in homes and buildings.
Recycling
 Recycling is important in reducing garbage but
also in conserving energy.
 Takes only 1/3 amount of energy to form a
beverage can from recycled aluminum as it does
from virgin aluminum.
 Less energy to just reuse and existing container.
 Takes also 1/3 less energy to form steel products
from scrap than from ore
The End