More on Energy Conservation

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More on Energy Conservation
Lecture 16 HNRT 228 Spring 2016 Energy and the
Environment
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Overview of Material

• Energy Conservation
• Space Heating
• Thermal Insulation
• Air Infiltration
• Lighting
• Appliances
• Some considerations of agriculture and industry

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iClicker Question

• How many fewer power plants might be needed if
  every household changed to compact fluorescent
  lighting?
• A About one
• B More than one
• C More than 100
• D Depends on power plant output

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iClicker Question

• How many fewer power plants might be needed if
  every household changed to compact fluorescent
  lighting?
• A About one
• B More than one
• C More than 100
• D Depends on power plant output

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iClicker Question

• Which type of washing machine conserves the most
  energy and water?
• A Top loader
• B Front loader

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iClicker Question

• Which type of washing machine conserves the most
  energy and water?
• A Top loader
• B Front loader

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iClicker Question Turning off your computer
will harm it. A True B False
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iClicker Question Turning off your computer
will harm it. A True B False
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iClicker Question Leaving your heat on is more
efficient than turning it down because you need
so much energy to heat the house back
up. A True B False
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iClicker Question Leaving your heat on is more
efficient than turning it down because you need
so much energy to heat the house back
up. A True B False
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iClicker Question

• Which unit is used to measure insulation of
  walls?
• A Q-value
• B R-value
• C S-value
• D T-value
• E U-value

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iClicker Question

• Which unit is used to measure insulation of
  walls?
• A Q-value
• B R-value
• C S-value
• D T-value
• E U-value

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iClicker Question

• Which unit is used to measure insulation of
  windows?
• A Q-value
• B R-value
• C S-value
• D T-value
• E U-value

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iClicker Question

• Which unit is used to measure insulation of
  windows?
• A Q-value
• B R-value
• C S-value
• D T-value
• E U-value

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iClicker Question

• Which of the following will conserve more energy.
• A A wall with R-value 12
• B A wall with R-value 14
• C A wall with R-value 16
• D A wall with R-value 18
• E A wall with R-value 20

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iClicker Question

• Which of the following will conserve more energy.
• A A wall with R-value 12
• B A wall with R-value 14
• C A wall with R-value 16
• D A wall with R-value 18
• E A wall with R-value 20

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iClicker Question

• Which of the following will conserve more energy.
• A A window with U-value 0.12
• B A window with U-value 0.14
• C A window with U-value 0.16
• D A window with U-value 0.18
• E A window with U-value 0.20

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iClicker Question

• Which of the following will conserve more energy.
• A A window with U-value 0.12
• B A window with U-value 0.14
• C A window with U-value 0.16
• D A window with U-value 0.18
• E A window with U-value 0.20

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National Average Home Energy Costs
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Why do we need Heating?
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Typical Heat losses- Conventional House
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iClicker Question

• Energy transfer by electromagnetic waves is
• A Radiation
• B Convection
• C Conduction

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iClicker Question

• Energy transfer by electromagnetic waves is
• A Radiation
• B Convection
• C Conduction

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iClicker Question

• Energy transfer by the bulk motion, or large
  scale motion of molecules in gas or liquid form
  from one location to another is
• A Radiation
• B Convection
• C Conduction

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iClicker Question

• Energy transfer by the bulk motion, or large
  scale motion of molecules in gas or liquid form
  from one location to another is
• A Radiation
• B Convection
• C Conduction

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iClicker Question

• Energy transfer by contact of molecule with
  another molecule is one way to define
• A Radiation
• B Convection
• C Conduction

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iClicker Question

• Energy transfer by contact of molecule with
  another molecule is one way to define
• A Radiation
• B Convection
• C Conduction

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Conduction
Energy is conducted down the rod as the
vibrations of one molecule are passed to the
next, but there is no movement of bulk material
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Convection
Energy is carried by the bulk motion of the fluid
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Radiation
Energy is carried by electromagnetic waves. No
medium is required
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Degree Days

• Index of fuel consumption indicating how many
  degrees the mean temperature fell below 65
  degrees for the day
• Heating degree days (HDD) are used to estimate
  the amount of energy required for residential
  space heating during the cool season.
• Cooling degree days (CDD) are used to estimate
  the amount of air conditioning usage during the
  warm season

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How do we calculate HDD?

• HDD Tbase - Ta
• if Ta is less than Tbase
• HDD 0
• if Ta is greater or equal to Tbase
• Where Tbase temperature base, usually 65 F
  Ta average temperature, Ta (Tmax Tmin) / 2

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Heating Degree Days

• Calculate the number of degree days accumulated
  in one day in which the average outside
  temperature is 17ºF.
• Degree days 1 day ( 65 Tout)
• 1 (65-17)
• 48 degree days

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Heating Degree Days in a Heating Season

• Calculate the degree days accumulated during a
  150-day heating season if the average outside
  temperature is 17ºF
• Solution
• Heating Season Degree days
• 150 days ( 65 Tout)
• 150 (65-17)
• 7,200 degree days

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Degree Days for the Heating Season
For Virginia data see http//cdo.ncdc.noaa.gov/cl
imatenormals/clim81/VAnorm.pdf
Sterling, VA 5237
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Significance of HDD

• Mrs. Young is moving from Anchorage, Alaska (HDD
  10,780) to State college, PA (HDD 6,000).
  Assuming the cost of energy per million Btu is
  the same at both places, by what percentage her
  heating costs will change?
• Solution
• HDD in Anchorage, Alaska 10,780
• HDD in State College PA 6,000
• Difference 10,780 - 6,000 4,780
• Saving in heating fuel costs are

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Home Energy Saver Online

• http//homeenergysaver.lbl.gov/

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Home Heating Costs in State College, PA
Average House
Energy Efficient House
Total 1,891
Total 1,019
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Home Heating Costs

• Related to amount of insulation, material that
  resists the flow of heat
• Insulation is rated in terms of thermal
  resistance, called R-value, which indicates the
  resistance to heat flow. The higher the R-value,
  the greater the insulating effectiveness. The
  R-value of thermal insulation depends on the type
  of material, its thickness, and density.
• R-30 better than R-11

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Places to Insulate

• Attic is usually the easiest ad most cost
  effective place to add insulation
• Floors above unheated basements should be
  insulated
• Heated basements should be insulated around the
  foundaton

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R-values for Building Materials
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Thickness of various materials for R-22
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R-Value for a Composite Wall
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Home Heating Energy

• Heat loss depends on
• Surface Area (size)
• Temperature Difference
• Property of the wall ( R value)

Outside 30F
Inside 65F
Q (Btus)
1
A (area) x Temperature Diff (Ti To)

t (time, h)
R
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Heat Loss
Tcold
Thot
Heat Loss
Id Q/t is in Btu/h Area in ft2 Tin-Tout in F
Then the thermal resistance is R-value. The
units of R-value are
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Wall loss rate in BTUs per hour

• For a 10 ft by 10 ft room with an 8 ft ceiling,
  with all surfaces insulated to R19 as recommended
  by the U.S. Department of Energy, with inside
  temperature 68F and outside temperature 28F

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Calculation per Day

• Heat loss per day (674 BTU/hr)(24 hr) 16,168
  BTU
• Note that this is just through the wall
• The loss through the floor and ceiling is a
  separate calculation, and usually involves
  different R-values

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Calculate loss per "degree day"

• This is the loss per day with a one degree
• difference between inside and
• outside temperature.

• If the conditions of case II prevailed all day,
  you would require 40 degree-days of heating, and
  therefore require 40 degree-days x 404 BTU/degree
  day 16168 BTU to keep the inside temperature
  constant.

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Heat Loss for Entire Heating Season.

• The typical heating requirement for a Pittsburgh
  heating season, September to May, is 5960
  degree-days (a long-term average).

Heat loss Q/t 404 Btu/degree day x 5960
degree days 2.4 Million Btus
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Economics of Adding Insulation

• Years to Payback         C(i) x R(1) x R(2) x
  E-------------------------------------  C(e) x
  R(2) - R(1) x HDD x 24
• C(i)    Cost of insulation in /square feet
• C(e)    Cost of energy, expressed in /Btu
• E    Efficiency of the heating system
• R(1)    Initial R-value of section
• R(2)    Final R-value of section
• R(2) - R(1)   R-value of additional insulation
  being considered
• HDD    Heating degree days/year
• 24    Multiplier used to convert heating degree
  days to heating hours (24 hours/day).

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Household Heating Fuel
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Average Heating Value of Common Fuels
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Typical Heating Furnace Efficiencies
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Comparing the Fuel Costs
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Fuel Costs

• Electric resistance heat cost 0.082 (price per
  kWh) / 0.003413 x 0.97 (efficiency) 24.77
  per million Btu.
• Natural gas (in central heating system) cost
  6.60 (per thousand cubic feet) / 1.0 x 0.80
  (efficiency) 8.25 per million Btu.
• Oil (in central heating system) cost 0.88
  (price per gallon) / 0.14 x 0.80 (efficiency)
  7.86 per million Btu.
• Propane (in central heating system) cost 0.778
  (price per gallon) / 0.0913 x 0.80
  (efficiency) 10.65 per million Btu.

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Heating Systems
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Heating Systems

• Some hot water systems circulate water through
  plastic tubing in the floor, called radiant floor
  heating.

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Electric Heating Systems

• Resistance heating systems
• Converts electric current directly into heat
• usually the most expensive
• Inefficient way to heat a building
• Heat pumps
• Use electricity to move heat rather than to
  generate it, they can deliver more energy to a
  home than they consume
• Most heat pumps have a COP of 1.5 to 3.5.
• All air-source heat pumps (those that exchange
  heat with outdoor air, as opposed to bodies of
  water or the ground) are rated with a "heating
  season performance factor" (HSPF)

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Geothermal Heat Pumps

• They use the Earth as a heat sink in the summer
  and a heat source in the winter, and therefore
  rely on the relative warmth of the earth for
  their heating and cooling production.

Additional reading http//www1.eere.energy.gov/ge
othermal/
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Benefits of a GHP System

• Low Energy Use
• Free or Reduced-Cost Hot Water
• Year-Round Comfort
• Low Environmental Impact
• Durability
• Reduced Vandalism
• Zone Heating and Cooling
• Low Maintenance

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Solar Heating and Cooling

• Most American houses receive enough solar energy
  on their roof to provide all their heating needs
  all year!
• Active Solar
• Passive Solar

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Passive Solar

• A passive solar system uses no external energy,
  its key element is good design
• House faces south
• South facing side has maximum window area (double
  or triple glazed)
• Roof overhangs to reduce cooling costs
• Thermal mass inside the house (brick, stones or
  dark tile)

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Passive Solar

• Deciduous trees on the south side to cool the
  house in summer, let light in in the winter.
• Insulating drapes (closed at night and in the
  summer)
• Greenhouse addition
• Indirect gain systems also such as large concrete
  walls to transfer heat inside

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Passive Solar Heating
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Source Global Science, Energy Resources
Environment
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(No Transcript)
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Active Solar Heating

• Flat plate collectors are usually placed on the
  roof or ground in the sunlight.
• The sunny side has a glass or plastic cover.
• The inside space is a black absorbing material.
• Air or water is pumped (hence active) through the
  space to collect the heat.
• Fans or pumps deliver the heat to the house

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Active Solar Heating
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Flat Plate Collector

• Solar Collectors heat fluid and the heated fluid
  heats the space either directly or indirectly

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Efficiency of Furnace

• The "combustion efficiency" gives you a snapshot
  in time of how efficient the heating system is
  while it is operating continuously
• The "annual fuel utilization efficiency" (AFUE)
  tells you how efficient the system is throughout
  the year, taking into account start-up,
  cool-down, and other operating losses that occur
  in real operating conditions.
• AFUE is a more accurate measure of efficiency and
  should be used if possible to compare heating
  systems.

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Efficiencies of Home Heating
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Tips (Individual) to Save Energy and Environment

• Set your thermostat as low as is comfortable in
  the winter and as high as is comfortable in the
  summer.
• Clean or replace filters on furnaces once a month
  or as needed.
• Clean warm-air registers, baseboard heaters, and
  radiators as needed make sure they're not
  blocked by furniture, carpeting, or drapes.
• Bleed trapped air from hot-water radiators once
  or twice a season if in doubt about how to
  perform this task, call a professional.
• Place heat-resistant radiator reflectors between
  exterior walls and the radiators.

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Tips (Individual) to Save Energy and Environment

• Use kitchen, bath, and other ventilating fans
  wisely in just 1 hour, these fans can pull out a
  houseful of warmed or cooled air. Turn fans off
  as soon as they have done the job.
• During the heating season, keep the draperies and
  shades on your south-facing windows open during
  the day to allow sunlight to enter your home and
  closed at night to reduce the chill you may feel
  from cold windows. During the cooling season,
  keep the window coverings closed during the day
  to prevent solar gain.

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Tips (Individual) to Save Energy and Environment

• Close an unoccupied room that is isolated from
  the rest of the house, such as in a corner, and
  turn down the thermostat or turn off the heating
  for that room or zone. However, do not turn the
  heating off if it adversely affects the rest of
  your system. For example, if you heat your house
  with a heat pump, do not close the ventsclosing
  the vents could harm the heat pump.
• Select energy-efficient equipment when you buy
  new heating and cooling equipment. Your
  contractor should be able to give you energy fact
  sheets for different types, models, and designs
  to help you compare energy usage. Look for high
  Annual Fuel Utilization Efficiency (AFUE) ratings
  and the Seasonal Energy Efficiency Ratio (SEER).
  The national minimums are 78 AFUE and 10 SEER.