 Lv 132 points

# ?

Questions13
• ### How much btu would it take to heat a building of 2700m3 to 20 degree c?

How much btu would it take to a building of 2700m3 to 20 degree c using a oil fired boiler and what is the amount of c02 emitted from the burning of the fuel

• ### how much lpg would the average stove used for cooking on average, cooking three meals per day and the co2 emis?

how much lpg would the average stove used for cooking on average, cooking three meals per day and the co2 emissions from the gas burnt cooking

• ### how much energy would it take to power 10 x 4ft radiators from a oil powered boiler and what would be the co2?

how much energy would it take to power 10 x 4ft radiators from a oil powered boiler and what would be the co2 emissions from the boiler. the heating would be on for 8 hours per day 240 days per year

• ### how much energy would it take to power 11 x 36 watt 4ft flourescent lights?

how much energy would it take to power 11 x 36 watt 4ft flourescent lights and what would the co2 emissions be from the energy used

• ### photovoltaic solar cell maintains a voltage of about 0.5 V.?

Under normal operating conditions, and in adequate light, a particular

type of photovoltaic solar cell maintains a voltage of about 0.5 V. How

many of these would be needed to supply 10 V, and how should they be

connected?

(b) The active area of each of the above cells is 120 mm by 145 mm.

Calculate its output power when it is exposed to a light intensity of

1000 W m−2 and operating with an efficiency of 12%.

(c) Describe how a number of these cells could be connected to provide a

10 V supply delivering about 200 W when exposed to the above light

intensity.

• ### glazed area of 4 square metres, all single-glazing with a U-value of?

The south-facing wall of a house has a window and glass doors with a total

glazed area of 4 square metres, all single-glazing with a U-value of

6.0 W m

–2 K

–1.

(a) During a particular 24-hour period, the average outdoor temperature is

6.6 °C and the indoor temperature is maintained at 20.5 °C. Calculate

the heat loss through the glazed area during this period, in kilowatthours.

If there is a solar gain of 0.60 kWh per square metre of glazing during

the above period, what is the net heat loss, in kilowatt-hours, for the

period?

(b) Suppose that all the glazing is replaced by triple glazing, with a U-value

of 1.5 W m

–2 °C

–1, but a slightly lower solar gain of 0.50 kWh per

square metre. Show that this change should reduce the net heat loss for

the above period to almost zero

(c) Explain why the result in (b) should not be taken to mean that no

heating will be needed during this 24-hour period

• ### The annual lighting requirement of a certain household is 5.6 million?

The annual lighting requirement of a certain household is 5.6 million

lumen-hours per year. Suppose that three-quarters of the existing light

bulbs with efficacy of 14 lumens per watt are replaced by compact

fluorescent lamps (CFLs). As a result, three-quarters of the lighting

requirement is now met by CFLs and only a quarter by GLS lamps. If

the average efficacy of the CFLs is 70 lumens per watt, what is the new

annual electricity consumption for lighting?

• ### reservoir surface area is 1.8 km by 2.0 km its surface how much water need to raise level by 2 meters?

if the reservoir surface area is 1.8 km by 2.0 km its surface

level will rise by nearly 2 metres how many cubic meters of water required to rise level by 2 meters

• ### If a reservoir is 250 metres above the intake, how many cubic metres?

If a reservoir is 250 metres above the intake, how many cubic metres

of water can be raised to it during the night? You may assume that the

density of water is 1000 kg m–3 and the acceleration due to gravity, g, is

10 m s–2.

• ### world population is ~6.9 billion total world energy used 18000 tWh how much per capita?

World total electricity consumption in 2010 was estimated to be 18 000

TWh.

Given that world population is thought to have reached about 6.9 billion (6900 million) people in 2010, calculate the average per capita annual electricity consumption, in kWh per year.