Presentation on theme: "Conservation Doing without and more with less. Outline Energy conservation –Principles –Space heating –Lighting –Recycling –Transportation –Industry."— Presentation transcript:
Why conservation? Electricity Conservation saves 3 X as much fuel as the energy you don’t use. Therefore, a 3-fold reduction in pollution Saves money Deprivation: Dealing with less. Efficiency: Doing more with less
Home heating The goal is to maintain a constant, comfortable temperature. Therefore, Heat in = Heat out. Heat out: –Conduction (50-70%) –Convection (up to 30%) –Radiation (5-10%)
Conduction losses The rate of heat loss (power loss) is proportional to the temperature difference and the surface area. Qloss/t = k A T Area T outside T inside Q loss Material of heat conductivity, k
Reducing heat losses Heat loss is proportional to temperature difference. Q1 / Q2 = T1 / T2 Q1/Q2 = (67-35)/(75-35) = 32/40 = 80% A 20% savings. T out = 35 F T in = 75 F T in = 67 F OR
The law of heat conduction Q loss / t = A T / R –R is the R-value, which is a measure of the resistance to heat loss for a given material of given thickness. – i.e. R fiberglass = 3.7 ft 2 -F-hr/Btu per inch. –The higher R, the lower the heat loss. –Example: A single pane of glass has R = 1 Q loss(glass)/Qloss(fiberglass) = (1/Rglass)/(1/Rfiber) = 3.7 X more loss.
An insulated wall Fiber glass Air layers: In: R =.17 R =.68 Insulating Sheathing: R = 2.06 Fiberglass:R = 11.0 Gypsum siding: R =.45 R total = 14.36 Air layers Insulating Sheathing Gypsum siding
Heating needs HDD = The length of the heating season, in days, times the average temperature difference HDD = 150 days (65 F – 35 F) = 4,500 Macomb has 6000 HDD Heating need per season: Qtotal = HDD (Area)(24 hrs/day) R An 8 x 20 foot wall with R = 14.36 in Macomb. Q total = 6000 (160 ft^2)(24) / 14.36 = 1.6 x 10^6 Btu/season. Natural Gas costs 40c per 1 x10^5 Btu, so $6.4 dollars burned to make up loss from that wall.
Air infiltration Typical house exchanges air with outside every hour. Good insulation can reduce that to every 5 hours. Must have better air-purifying
Lighting and Electrical use Fluorescent bulbs have 10 X longer lifetime, and use 15 W compared to 75W, representing an energy savings of 5 x, and a money savings of 50 x. Leaking electricity – Most appliances don’t turn fully off. Up to 5% of America’s use of electricity for “standby”mode.