Figure shows a house whose walls consist of plaster (R = 0.45), R-11 fiberglass insulation, plywood (R = 0.65), and cedar shingles (R = 0.55). The roof has the same construction except it uses R-30 fiberglass insulation. The average outdoor temperature in winter is 25 ?F , and the house is maintained at 75 ?F. The house's oil furnace produces 100,000 Btu for every gallon of oil, and oil costs $2.20 per gallon. Assume that the house has 10 single-glazed windows, each measuring 3.0 ft by 4.9 ft. Four of the windows are on the south and admit solar energy at the average rate of 30 Btu/h?ft2. All the windows lose heat; their R- factoris 0.90. Find the total heating cost for the month. How much is the solar gain worth?

Figure shows a house whose walls consist of plaster (R = 0.45), R-11 fiberglass insulation, plywood (R = 0.65), and cedar shingles (R = 0.55). The roof has the same construction except it uses R-30 fiberglass insulation. The average outdoor temperature in winter is 25 ?F , and the house is maintained at 75 ?F. The house's oil furnace produces 100,000 Btu for every gallon of oil, and oil costs $2.20 per gallon. Assume that the house has 10 single-glazed windows, each measuring 3.0 ft by 4.9 ft. Four of the windows are on the south and admit solar energy at the average rate of 30 Btu/h?ft2. All the windows lose heat; their R- factoris 0.90. Find the total heating cost for the month. How much is the solar gain worth?

Sustainable Energy

2nd Edition

ISBN:9781337551663

Author:DUNLAP, Richard A.

Publisher:DUNLAP, Richard A.

Chapter17: Energy Conservation

Section: Chapter Questions

Problem 11P

See similar textbooks

Similar questions

The air inside a hot-air balloon is heated to 72.00 °C (Tinitial) and then cools to 52.00 °C (Tfinal). By what percentage does the volume of the balloon change?
If a 136.51 g Al rod (c=0.900 J/g°C) is at 100.0°C and placed into 250.0 g of water at 21.8°C, what is the temperature of the system (rod+water) at equilibrium assuming no losses to the surrounding?
A house has a volume of 1200 m3 (a) What is the total massof air inside the house at 15°C? (b) If the temperature dropsto –15°C what mass of air enters or leaves the house?
A pump delivers water from a lower to a higher reservoir. The difference in elevation between thereservoirs is 10 m. The pump provides an energy head of 11 m and the frictional losses amounts to 0.7 m. If the pipe diameter is 250 mm, calculate thedischarge. *can you also provide its figure, Thank you.
Convert the following air pressure readingsfrom cm H2O to Pa.a. 1.5 cm H2Ob. 3.7 cm H2O
Calculate the R-value for the following materials: a. 4 in. thick brick b. 10 cm thick brick c. 12 in. thick concrete slab d. 20 cm thick concrete slab e. 1 cm thick human fat layer
Imagine a parcel of air that has a temperature of 40°C at the surface and a dew-point temperature of 20°C at the lifting condensation level. Assume that the environmental lapse rate is 8°C per 1000 meters, the dry adiabatic lapse rate is 10°C per 1000 meters, and the wet adiabatic lapse rate is 6°C/1000 meters. In Table C , record the environmental temperature, the parcel temperature, and the temperature difference (parcel temperature minus the environmental temperature), and then determine whether the atmosphere is stable or unstable at each height. a. What is the height of the lifting condensation level? b. Does this example describe absolute stability, absolute instability, or conditional instability? c. Would you forecast thunderstorms under these conditions?
Determine the amount of coagulant required per day (kg/day).• Assume that the optimum dosage of alum at 25 mg/L was used and that the density of alum was 600kg/m3, Power = 1736.3 watt, Volume= 10.83 m^3 , water temperature is 20 oC, and velocity Gradient is 400 1/s.• Amount of alum = ? (kg/month)• Volume of alum = ? (m3/month)
Consider one farmer using an aquifer. The volume of water in the aquifer is described by Xt+1 = Xt – Yt + Qt where Xt is the volume of water in period t, Yt is the extraction of water in period t and Qt is precipitation. The marginal net benefits of the farmer in each period are described by MNBt = 20 - Yt There are two periods. The amount of water in the first period is X0 = 7 and Q0 = 1.5. The farmer cannot use more water than available at the beginning of each period such that Yt ≤ Xt. With a discount rate of 10%, what is the efficient water use in the first period?
4. An igloo or Eskimo hut is built in the form of a hemispherical shell with an inside diameter of 12 ft. If the igloo is constructed of snow blocks having a uniform thickness of 2ft and weighing 40 lb per cu. ft, find the weight of the igloo, neglecting entrance. Also, if fresh air contains 0.04 per cent carbon dioxide, find the amount this gas in the igloo when freshly ventilated.
If the viscosity of water at 68 deg F is 0.1008 poise, compute its absolute viscosity (μ)in pound-seconds per square foot. If the specific gravity is 1.02, compute its kinematicviscosity (v) in square feet per second
Determine the rate of flow of water through a pipe of diameter 10 cm and length 60 cm when one end of the pipe is connected to a tank and other end of the pipe is open to the atmosphere. The height of water in the tank from the centre of the pipe is 5 cm. Pipe is given as horizontal and value of f= 0.01. Consider minor losses.