The time it takes for the money you saved to equal the cost of the insulation.
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What is the equation for pay back time?
Payback time= inital cost/annual saving
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What is draught-proofing?
Strips of foam and plastic around doors and windows- stop draughts of cold air blowing in (reduce heat loss due to convection).
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What is loft insulation?
A thick layer of fibreglass wool laid out across whole floor of loft- reduces conduction and radiation into the roof space from the ceiling.
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What is cavity wall insulation?
Foam squirts into the gap between the bricks- reduces convection, conduction and radiation across the gap.
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How do thick curtains reduce heat loss by conduction and radiation?
The curtains are over/ infront of the window.
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How does a hot water tank jacket reduce heat loss by conduction and radiation?
It has lagging such as fibre glass wool, which reduces conduction and convection.
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What is a U-value?
U-values show how fast heat can transfer through a material.
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The better the insulator the ....... the U-value.
Lower.
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What is specific heat capacity?
Is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree celcius.
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What is the equation for specific heat capacity?
Energy transferred= mass x specific heat capacity x temperature change.
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Why do heaters have high heat capacities?
To store lots of energy.
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Name two reasons why water can be easily pumped around in pipes and what is it ideal for?
1. It has a really high specific heat capacity. 2. It's a liquid. Water is ideal for central heating systems.
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How do electric storage heaters work?
They are designed to store heat energy at night (when electricity is cheaper), and then release it during the day. they store the heat using concrete and bricks because they have a high specific heat capacity.
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Why are oil filled heaters not used as much as water filled heaters?
Because oil has a lower specific heat capacity than water.
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How do you know when an object has electrical energy?
Whenever a current flows.
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How do you know when an object has light energy?
When light is given off e.g. the sun or a light bulb.
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How do you know when an object has sound energy?
When a sound is given off e.g. from loudspeakers
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How do you know when an object has kinetic/movement energy?
Anything that is moving.
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How do you know when an object has nuclear energy?
Released from only nuclear reactions.
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How do you know when an object has thermal/heat energy?
Flows from a hot object to a colder one.
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How do you know when an object has gavitational potential energy?
Possessed by anything which can fall.
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How do you know when an object has elastic potential energy?
It can be stretched e.g. springs, elastic, rubber bands ect.
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How do you know when an object has chemical energy?
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