P4 – The bills are what?!
(Heating and Insulating a House)
There are many ways of insulating a house Some of these ways of insulating a house cost more than others in the first place.
But some save you more money than others. The time it takes for you to save the money that you paid in the first place is called the „payback‟ time. So, if the double glazing cost £3000 to install and it saves you £150 a year on your heating costs. It will take you 20 years to save what you first paid. It has a payback time of 20 years.
Payback time = Cost of insulation / Saving per year
U values U values are used to measure how good an insulator a material is. The LOWER the U value, the BETTER a material is at being an insulator. The HIGHER the U value, the WORSE a material is at being an insulator.
Using solar panels to heat water Some solar panels have copper tubes inside them so that the water is heated as it runs through the tubes. Using solar panels like this relies on the using the specific heat capacity of water (the amount of energy needed to change the temperature of 1 kg of a substance by 1oC.)