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Home Heating and Cooling

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					 EGEE 102 – Energy Conservation
 And Environmental Protection


Home Heating Basics
National Average Home
Energy Costs
      14%                         Heating and Cooling

                            44%   Refrigrator

                                  Lighting, Cooking and
33%                               other Appliances
                                  Water Heating
            9%




                 EGEE 102                           2
Why do we need
Heating?




  30 F
            70 'F


                    Furnace




         EGEE 102             3
Typical Heat losses-
Conventional House

                    5% through ceilings




                                              16%
                                              through
 17% through                                  windows
 frame walls

                                    3% through door
                                38% through cracks
                     20%        in walls, windows,
  1% through                    and doors
  basement floor     through
                     basement
                     walls
                   EGEE 102                             4
 Heat Transfer

• Conduction
• Convection
• Radiation




               EGEE 102   5
   Conduction

Energy is conducted down
the rod as the vibrations of
 one molecule are passed
 to the next, but there
is no movement of energetic



                  EGEE 102     6
  Convection


Energy is carried by the
bulk motion of the fluid




                EGEE 102   7
  Radiation


Energy is carried by
electromagnetic waves.
No medium is required



               EGEE 102   8
 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
                  EGEE 102                   9
 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


                     EGEE 102                  10
 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
                EGEE 102            11
 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
                 EGEE 102               12
Degree Days for the
Heating Season
 PLACE             DEGREE DAYS
 Birmingham,       2,780
 ALABAMA
 Anchorage,        10,780
 ALASKA
 Barrow, ALASKA    19,994
 Tucson, ARIZONA   1,776
 Miami, FLORIDA    173
 State College     ???

              EGEE 102           13
EGEE 102   14
Class work




         EGEE 102   15
 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
                           4 780
                                100  44 .3%
Saving in fuel costs are 10 ,780
                     EGEE 102                    16
 Home Energy Saver

• http://homeenergysaver.lbl.gov/




                EGEE 102            17
   Home Heating Costs in
   State College
Average House
   $232 $106                        Heating
                                    Cooling
                       $890         Hot water
$305                                Appliances    Energy Efficient
                                    Misc.         House
                                                 Energy Effcient House




   $227 $133                        Lighting
                              $52
                    $232                                          $327
     Total $1,891



                     $205                                    $89
                                       $114
                       EGEE 102                                  Total 18
                                                                        $1,019
 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-11
  • R-30 better than 102
                  EGEE                 19
 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 EGEE 102   20
R-values for Building
Materials




          EGEE 102      21
Thickness of various
materials for R-22

                                         110"



                                  18"


                  7"
      6"


  Cellulose   Fiberglass    Pine wood   Common
   Fiber                                 brick


                       EGEE 102                  22
R-Value for a Composite
Wall

                           R-Value of material
         1/2" Plasterboard       0.45


         3 1/2" Fiberglass          10.90

         3/4" Plywood                0.94


         1/2" Wood siding       0.81
                      RTOTAL = 13.10

                             ft2 – °F – hr
                                  BTU
         EGEE 102                            23
 Home Heating Energy
• Heat loss depends
  on
  • Surface Area
    (size)                                                 Outside
                                  Inside
  • Temperature                   65¨F
                                                           30¨F
    Difference
  • Property of the
    wall ( R value)

     Q (Btus)          1    A (area) x Temperature Diff (Ti – To)
                   =
     t (time, h)       R
                           EGEE 102                         24
Heat Loss

Thot   Tcold                 Q           AreaxTinside  Toutside 
               Heat Loss =
                                      Areax Re sis  ce ofthe 
                              t      (ThermalTinsidetanToutsideWall , R)
                                  (Thermal Re sis tan ce oftheWall , R)

           Q         Id Q/t is in Btu/h
           t         Area in ft2
                     Tin-Tout in °F
                    Then the thermal resistance is
                    R-value. The units of R-value are
                              ft 2 x oF
                              Btu / hr




                   EGEE 102                                                25
 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 68°F
  and outside temperature 28°F:


 Heatloss Rate  
                            
                Q 320 ft 2 x 68  F  28 0 F 674 Btu / hr
                               2 0
                t            ft x F
                        19
                            BTU / h

                         EGEE 102                         26
 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



                  EGEE 102             27
 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.
                       EGEE 102                     28
 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 MM Btus


  The typical number of degree-days of heating
  or cooling for a given geographical location
  can usually be obtained from the weather service.

                       EGEE 102                       29
Numerical Example




        EGEE 102    30
  Heat loss Calculation

           1    
Qtotal     A    Number of Annual deg ree days 24 h / day 
           R    




                            EGEE 102                          31
 Problem
• A wall is made up of four elements, as
  follows
• ½” wood siding
• ½” plywood sheathing
• 3 ½ in of fibber glass
• ½” of sheet rock
• How many Btus per hour per sq.ft. will be
  lost through the wall when the outside
  temperature is 50F colder than inside?
                   EGEE 102               32
    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).                     EGEE 102                               33
 Pay Back Period
 Calculation
• Suppose that you want to know how many years
  it will take to recover the cost of installing
  additional insulation in your attic. You are
  planning to increase the level of insulation from
  R-19 (6 inch fiberglass batts with moisture
  barrier on the warm side) to R-30 by adding R-11
  (3.5 inch unfaced fiberglass batts). You have a
  gas furnace with an AFUE of 0.88. You also pay
  $0.70/therm for natural gas.
• Given
• C(i) = $0.18/square foot; C(e) = ($0.70/therm)/(100,000
  Btu/therm) = $0.000007/Btu; E = 0.88; R(1) = 19; R(2) = 30;
  R(2) - R(1) = 11; HDD = 7000 102
                           EGEE                              34
Household Heating Fuel
90%
80%
70%
        56%
60%
50%
40%                                             Heating Fuel
                  26.00%
30%
20%                          11.00%    10.00%
10%
 0%
      Natural   Electricity Fuel Oil   Other
       Gas


                           EGEE 102                       35
   Average Heating Value
   of Common Fuels
Fuel Type                              No. of Btu/Unit (Kilocalories/Unit)
Kerosene (No. 1 Fuel Oil)              135,000/gallon (8,988/liter)
No. 2 Fuel Oil                         140,000/gallon (9,320/liter)
Electricity                            3,412/kWh (859/kWh)
Natural Gas                            1,028,000/thousand cubic feet (7,336/cubic meter)
Propane                                91,333/gallon (6,081/liter)
Bituminous Coal                        23,000,000/ton (6,400,000/tonne)
Anthracite Coal                        24,800,000/ton (5,670,000/tonne)
Hardwood (20% moisture)*               24,000,000/cord (1,687,500/cubic meter)
Pine (20% moisture)*                   18,000,000/cord (1,265,625/cubic meter)
Pellets (for pellet stoves; premium)   16,500,000/ton (4,584,200/tonne)




                                           EGEE 102                                36
Typical Heating Furnace
Efficiencies
    Fuel Type - Heating Equipment                      Efficiency (% )
    Coal (bituminous)
    Central heating, hand-fired                              45
    Central heating, stoker-fired                            60
    Water heating, pot stove (50 gal.[227.3 liter])         14.5
    Oil
    High efficiency central heating                          89
    Typical central heating                                  78
    Water heater (50 gal.[2227.3 liter])                    59.5
    Gas
    High efficiency central heating                          92
    Typical central heating                                  82
    Room heater, unvented                                    91
    Room heater, vented                                      78
    Water heater (50 gal.[227.3 liter])                      62
    Electricity
    Central heating, resistance                              97
    Central heating, heat pump                              200+
    Ground source heat pump                                 300+
    Water heaters (50 gal.[227.3 liter])                     97
    Wood & Pellets
    Franklin stoves                                      30.0 - 40.0
    Stoves with circulating fans                         40.0 - 70.0
    Catalytic stoves                                     65.0 - 75.0
    Pellet stoves               EGEE             102     85.0 - 95.0     37
Comparing the Fuel
Costs

 Energy Cost 
             Cost perUnit ofFuel
 HeatingValue( MMBtu / unitoffuel )  Efficiency




                    EGEE 102                       38
 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.
                      EGEE 102                     39
    Heating Systems
•                •




            EGEE 102   40
 Heating Systems
• Some hot water
  systems circulate
  water through
  plastic tubing in
  the floor, called
  radiant floor
  heating.



                  EGEE 102   41
 Electric Heating
 Systems
1. Resistance heating systems
  Converts electric current directly into
    heat
    1. usually the most expensive
    2. Inefficient way to heat a building
2. Heat pumps
  Use electricity to move heat rather than
    to generate it, they can deliver more
    energy to a home than they consume
    1. Most heat pumps have a COP of 1.5 to 3.5.
    2. 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"
                      EGEE 102                     42
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
Additional reading
                                    heating and
http://www.eren.doe.gov/erec/factsheets/geo_heatpumps.html#sidebar
                           EGEE 102 cooling                     43
    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
                   EGEE 102          44
 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



                 EGEE 102            45
 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
                 EGEE 102               46
 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
                 EGEE 102              47
Passive Solar Heating




       EGEE 102         48
EGEE 102   49
Passive Heating
Direct   Gain   Thermal      Storage Suns pace
                W all




Passive Cooling
Shading           Ve nt ilat io n    Earth Contact




                       EGEE 102                      50
 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.       EGEE 102             51
           Active
           Solar
           Heating




EGEE 102        52
Flat Plate Collector
               • Solar Collectors
                 heat fluid and the
                 heated fluid heats
                 the space either
                 directly or
                 indirectly




          EGEE 102                53
 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
                    EGEE 102                54
Efficiencies of Home
Heating
.




                                                                                                                9

                                    110
    space heat (106 Btu/1000 ft2)




                                                                                                                    Btu/ft2 per degree day
                                    100
                                                                       U.S. stock
                                                                                                                7
                                    90
    Annual fuel input for




                                    80

                                    70                                          1975-1976 building practice
                                                                                         (NAHB)                 5
                                    60
                                                                                       LBL standard
                                    50                                              (medium infiltration)


                                    40                                                   LBL standard           3
                                                                                       (low infiltration)
                                    30
                                                                            Brownell      Saskatoon
                                    20
                                                                 Mastin      Ivanhoe Pasqua
                                    10                                                                          1
                                                                        Leger                      Saskatche-
                                                            Phelps
                                                                        Balcomb                    wan house
                                     0
                                          0   2000   4000       6000         8000         10,000

                                                                                        1 Btu/ft2 per degree day

                                                         EGEE 102                                                                            55
                                                 Degree days (base 65°F)
 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.
                      EGEE 102                   56
• 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.

                      EGEE 102                    57
• 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 vents—closing 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
                         EGEE 102                     58

				
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