Chapter 16 A Race For The SunSlide 2In this chapter you learn how a college team form the University of Massachusetts, Dartmouth, builds a home during a 21-day National Solar Decathlon.Advantages of cooling/warming up a house through designAdvantages Con’tSlide 6Slide 7Measuring EnergyPowering UpACTIVITY Is solar power enough?Chapter 16Chapter 16A Race For The SunA Race For The SunBy Whitley JohnsonBy Whitley JohnsonNovember 23, 2009November 23, 2009Passive Solar Heating-Passive Solar Heating- refers to designing refers to designing a home to take advantage of sunlight.a home to take advantage of sunlight.Active Solar Heating-Active Solar Heating- systems use pumps systems use pumps to circulate a fluid that has been heated by to circulate a fluid that has been heated by the sun.the sun.EfficiencyEfficiency- is the comparison of energy - is the comparison of energy input with respect to useful energy output input with respect to useful energy output of a system.of a system.In an ideal system that is 100% efficient, the useful In an ideal system that is 100% efficient, the useful outputs are equal to the input.outputs are equal to the input.No system is 100% efficient!No system is 100% efficient!In this chapter you learn how a college team form In this chapter you learn how a college team form the University of Massachusetts, Dartmouth, builds the University of Massachusetts, Dartmouth, builds a home during a 21-day National Solar Decathlon.a home during a 21-day National Solar Decathlon.All systems of a house are important.All systems of a house are important.A reliable climate-control system is A reliable climate-control system is most critical for getting through the most critical for getting through the ever changing seasons.ever changing seasons.Primary function of a house is to Primary function of a house is to shelter inhabitants.shelter inhabitants.Advantages of cooling/warming up Advantages of cooling/warming up a house through designa house through designLarge windows facing the south= sun can Large windows facing the south= sun can warm up the air inside house. (If house is warm up the air inside house. (If house is located in southern hemisphere, windows located in southern hemisphere, windows must face north for the most sunlight.)must face north for the most sunlight.)The sun can warm the thermal mass of a The sun can warm the thermal mass of a home through concrete or flagstone floors home through concrete or flagstone floors and/or walls. (at night when the temp and/or walls. (at night when the temp drops, the floors and/or walls release drops, the floors and/or walls release stored energy to warm up the house.stored energy to warm up the house.Advantages Con’tAdvantages Con’tTo block the hot midday sun during the To block the hot midday sun during the summer, windows use overhangs. This summer, windows use overhangs. This helps to keep the inside air cool.helps to keep the inside air cool.Good insulation helps keep the hot air out.Good insulation helps keep the hot air out.University of Massachusetts, Dartmouth University of Massachusetts, Dartmouth use a thick slab of polystyrene between use a thick slab of polystyrene between two pieces of ply board for their insulation. two pieces of ply board for their insulation. (Polystyrene is the same material used in (Polystyrene is the same material used in disposable coffee cups.) disposable coffee cups.) The team also use another heating system The team also use another heating system that uses pumps to circulate a “working that uses pumps to circulate a “working fluid” (water or antifreeze) through fluid” (water or antifreeze) through collectors and into storage tanks. These collectors and into storage tanks. These collectors are positioned on the roof and collectors are positioned on the roof and use the sun to heat up the fluid and the use the sun to heat up the fluid and the storage tanks to hold the fluid until used to storage tanks to hold the fluid until used to heat up the house.heat up the house.To transmit the heat throughout the house, To transmit the heat throughout the house, the team embedded radiator pipes in the the team embedded radiator pipes in the floor. floor. The pipes will move back and forth to heat The pipes will move back and forth to heat the entire floor.the entire floor.When the hot water is pumped through When the hot water is pumped through these pipes, energy is transferred to the these pipes, energy is transferred to the floor thus transferring the energy to the air floor thus transferring the energy to the air above it.above it.Measuring EnergyMeasuring EnergyJoule is the unit for energy in the metric Joule is the unit for energy in the metric system.system.It takes 4.186 Joules to raise the temp of It takes 4.186 Joules to raise the temp of one gram of water by one degree Celsius.one gram of water by one degree Celsius.The British use BTU (British Thermal Unit).The British use BTU (British Thermal Unit).BTU is the amount of energy required to BTU is the amount of energy required to raise the temperature of one pound of raise the temperature of one pound of water by one degree Fahrenheit.water by one degree Fahrenheit.1 BTU = 1,055 Joules1 BTU = 1,055 JoulesCoal, oil, and natural gas store energy and Coal, oil, and natural gas store energy and then release energy when burned.then release energy when burned.Powering UpPowering UpThe team equipped the home with The team equipped the home with photovoltaic (PV) panels.photovoltaic (PV) panels.PV panels use the energy of the sun to PV panels use the energy of the sun to generate electricity. These panels will be generate electricity. These panels will be located on the roof next to the solar located on the roof next to the solar collectors. The extra electricity will be collectors. The extra electricity will be stored in a battery, which will be used to stored in a battery, which will be used to power the home at night.power the home at night.ACTIVITYACTIVITYIs solar power enough?Is solar power enough?If it is 30 degrees outside and you want If it is 30 degrees outside and you want your house to be 40 degrees warmer, your house to be 40 degrees warmer, between how much BTUs will it take to do between how much BTUs will it take to do this?this?How does this process work?How does this process