aqa heating and insulating buildings
TRANSCRIPT
U values measure how effective a material is as an insulator
It is defined as the rate of heat flow in watts (W) throughan area of 1 square metre (m) for a temperature difference across the structure
of 1 C degree centigrade
You don’t need this
definition!
Solar panels may contain water that Is heated by radiation from the Sun. This water may then be used to heat buildings or provide domestic hot water
The payback time of an energy-saving solution is a measure of how cost-effective it is. It is the
time it takes to pay back the outlay
The double-glazing for a house costs £3,000 but saves £150 per year in fuel costs. What is its payback time?
Loft insulation
6
A thick layer of insulation of the loft floor.
It works because it’s a poor conductor and traps air,stopping convection.
Cost - £450
Saves - £150 every year.
Return to home
Cavity wall insulation
7
Insulation placed in the cavity of the walls
It works because it’s a poor conductor and traps air,stopping convection.
Cost - £500
Saves - £100 every year.
Return to home
Draught excluders
8
Brushes and seals on doors.
Prevents warm air escapingfrom the home.
Cost - £30
Saves - £20 every year.
Return to home
Double glazing
9
Windows and doors with 2 planes of glass with air trapped inbetween.
Air is a poor conductor and there is no convection because the air is trapped.
Cost - £3000
Saves - £100 every year.
Return to home
Floor insulation
10
An insulation layer under the floor
Prevents heat loss because it is a poor conductor.
Cost - £300
Saves - £20 every year.
Return to home
Other methodsHot water Jacket Radiator control valves
11
An insulating jacket around the hot water tank.
Costs - £20Saves - £40 a year
Not very common now because few homes have a hot water tank.
Valves to control the temperature in each room.
Costs - £200Saves - £40 a year
The specific heat capacity of a substance is the amount of energy required to change the temperature of one
kilogram of the substance by one degree Celsius
Experiment to find out the SHC of a substance
• The metal I’m testing is ___________. • Mass of metal _____________• Initial temperature =• Final temperature after 8 minutes =• Change in temperature = • Time in seconds = • Current = • Voltage =• Power = current voltage • Energy transferred to the metal in 8 minutes =
power time (seconds) Challenge: What is the SHC of the metal?