chapter 5 part 2 heat pumps refrigerators air conditioners ground source geothermal systems...

Chapter 5 part 2

Heat PumpsRefrigeratorsAir ConditionersGround Source Geothermal SystemsEfficiency of Heat PumpsEnergy Efficient BuildingsCountering Sick Building Syndrome

Air Conditioner Layout

Home Heat Pump

Heat Pump EfficiencyEfficiency = 100 * Thigh/(Thigh-Tlow)

Where Thigh is the temperature of the high Temperature reservior in degrees Kelvin

Tlow is the temperature of the low temperatureReservoir in degrees Kelvin

As the temperature difference decreases, doesA heat pump become more or less efficient?

Can a heat pump efficiency exceed 100%?

Coefficient of Performance

COP =heat transferred/electricty used=useful work/energy inputwhy does COP change with the outdoor temperature?

Seasonal Performance Factor

SPF= total energy output/total energy used

How does SPF relate to the theoretical efficiency of a heat pump?

Relative Costs of Heating Methods

Ground Source Geothermal Pump

Tradeoffs of Ground Source

More efficient (why?)

Less peak power use (peak shaving) Why?

BUTHigh initial cost for boreholes or trenchesMore than conventional heating/coolingNeeds a superinsulated building to be economicalIn NY winters

Energy Efficient Office Building A-InteriorWindowsFunnel LightB-FluorescentLightsC-Task LightingD-OccupancySensors

Low E FilmLow ToxicityMaterialsAtriumMore Insulation

Energy Efficient Office 21-Solar Panel2-Hot Air Duct3-Air Filter4-Heater5-Air Supply Pump6-Circulation Duct 7-Outflow Duct 8-Exhaust Fan9-Heat Exchanger

Energy Efficient Refrigerator(Vestfrost/Sunfrost)

Features of Vest Frost

Energy Efficiency of Typical Refrigerator

We use about 500 KWH per month. Fridge is 15% of costsOur refrigerator uses 75 kWH per month or 2.25 kWHPer day or almost 3 times the usage of a vestfrost.Why?

Total Energy UsageQ/t = 1/R * A*delta T

Where Q is heat loss per unit time t,R is average R value, A is surface area,And delta T is temperature difference.

Qtotal = sum (A/R)*24*DDWhere DD are the annual degree daysR is the average R value, A is surface areaOf house.Infiltration losses must be added to this.

Prevention of Sick Building Syndrome

House plants can dramatically reduce the levelsOf formaldehyde, benzene and trichloroethyleneWithin a home. Air inside a well insulated homeOften 2 to 5 times more polluted than outdoor air.

Some good onesAloe vera (also good for burns)Bamboo palmSpider plantEnglish ivyJanet CraigWarnecki dracaena

Chrysanthemum

Same as the outdoor plants,Will also grow wellindoors

Devils IvyGrows well inHanging pots

Will tolerate neglect

African DaisyNeeds to be startedIn a professional Greenhouse.

Prefers warmer Climates.

Peace LilyOne of the easiestOf large houseplantsGrows well in low lightSurvives well at averageHouse temperaturesAnd humidity levels.