Chapter 5 part 2 Heat Pumps Refrigerators Air Conditioners Ground Source Geothermal Systems Efficiency of Heat Pumps Energy Efficient Buildings Countering Sick Building Syndrome
Air Conditioner Layout
Home Heat Pump
Heat Pump Efficiency Efficiency = 100 * Thigh/(Thigh-Tlow) Where Thigh is the temperature of the high Temperature reservior in degrees Kelvin Tlow is the temperature of the low temperature Reservoir in degrees Kelvin As the temperature difference decreases, does A 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 input why 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? BUT High initial cost for boreholes or trenches More than conventional heating/cooling Needs a superinsulated building to be economical In NY winters
Energy Efficient Office Building A-Interior Windows Funnel Light B-Fluorescent Lights C-Task Lighting D-Occupancy Sensors Low E Film Low Toxicity Materials Atrium More Insulation
Energy Efficient Office 2 1-Solar Panel 2-Hot Air Duct 3-Air Filter 4-Heater 5-Air Supply Pump 6-Circulation Duct 7-Outflow Duct 8-Exhaust Fan 9-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 costs Our refrigerator uses 75 kWH per month or 2.25 kWH Per day or almost 3 times the usage of a vestfrost. Why?
Total Energy Usage Q/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*DD Where DD are the annual degree days R is the average R value, A is surface area Of house. Infiltration losses must be added to this.
Prevention of Sick Building Syndrome House plants can dramatically reduce the levels Of formaldehyde, benzene and trichloroethylene Within a home. Air inside a well insulated home Often 2 to 5 times more polluted than outdoor air. Some good ones Aloe vera (also good for burns) Bamboo palm Spider plant English ivy Janet Craig Warnecki dracaena
Chrysanthemum Same as the outdoor plants, Will also grow well indoors
Devils Ivy Grows well in Hanging pots Will tolerate neglect
African Daisy Needs to be started In a professional Greenhouse. Prefers warmer Climates.
Peace Lily One of the easiest Of large houseplants Grows well in low light Survives well at average House temperatures And humidity levels.