Aqa heating and insulating buildings

Heating and Insulating Buildings

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!

The lower the U-value, the better the material is as an insulator

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.

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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.

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Draught excluders

8

Brushes and seals on doors.

Prevents warm air escapingfrom the home.

Cost - £30

Saves - £20 every year.

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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.

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Floor insulation

10

An insulation layer under the floor

Prevents heat loss because it is a poor conductor.

Cost - £300

Saves - £20 every year.

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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

Make an advert advertising a energy saving installation

• Video on IPAD.

• Floor Insulation

Specific Heat Capacity

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

Practical set up

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?

Equation to calculate specific heat capacity

The SHC of Water is 4200 J/Kg/oC