Energy and Efficiency

Question 0

What does it mean when something is more efficient?

Answer 0

Less of the energy supplied is wasted.

Question 1

What happens to wasted energy?

Answer 1

It is eventually transferred to the surroundings, which become warmer. So it becomes increasingly spread out and becomes less useful.

Question 2

In a TV what energy would be useful and what would be wasted?

Answer 2

Useful: sound and light energy
Wasted: heat

Question 3

What is a Sankey diagram?

Answer 3

It shows energy transfer by providing a visual representation of how much energy there is of each type and therefore how much energy is wasted.
The widths of the arrows are proportional to the amount of energy they represent.
The useful energy is shown going straight through and the wasted energy branches off.
They are sometimes shown on a grid.

Question 4

In a lightbulb what energy is useful and what is wasted?

Answer 4

Useful: light energy
Wasted: heat energy

Question 5

In a kettle what energy is useful and what is wasted?

Answer 5

Useful: heat energy (in water)
Wasted: heat and sound energy

Question 6

In an electric motor, what energy is useful and what is wasted?

Answer 6

Useful: kinetic energy
Wasted: heat and sound energy

Question 7

How can you reduce energy consumption?

Answer 7

Switching lights off when leaving a room.
Energy-efficient light bulbs.
Using electrical equipment during the night, e.g. Washing machine.
More efficient tumble driers, or letting clothes dry naturally.
Tankless water heater.

Question 8

What are the pros and cons of switching lights off when leaving a room?

Answer 8

Pros:
Easy and simple way to reduce energy consumption.
Cons:
People forget to switch lights off or do not like being in a dark house.

Question 9

What are the pros and cons of energy efficient light bulbs?

Answer 9

Pros:
Use less power so cost less to run.
Less wasted energy.
Last longer than standard bulbs.
Cons:
More expensive to buy.

Question 10

What are the pros and cons of using electrical equipment during the night?

Answer 10

Pros:
Cheaper time of the day for using electricity.
Cons:
Can be noisy and keep people awake.

Question 11

What are the pros and cons of using more efficient tumble driers or letting clothes dry naturally?

Answer 11

Pros:
Driers with a sensor stop automatically when the clothes are dry, which saves energy.
Cons:
New driers are expensive to buy.
Cannot hang clothes out to dry if it is raining.

Question 12

What are the pros and cons of using a tankless water heater?

Answer 12

Pros:
Water is heated when needed so less energy is used to heat unnecessary water and keep it heated.
Cons:
Some units do not have enough power to supply to more than one tap at a time.