Keeping warm at home

We need to keep our homes warm in cold weather. We also need to do this as economically as possible. There are several ways to insulate your home and keep the heat in, and in this investigation we tried them out using cardboard model houses. We wanted to see the effect of wall and loft insulation, as well as compare single- and double-glazed windows. For our model central heating systems we used electrical light bulbs. To measure how quickly the houses got warm, we used temperature sensors connected to the computer.

What we did

We set up two (single-glazed) houses: one with loft insulation only and one with loft and wall insulation.
We set up another two houses: one with double glazing and one with single glazing.
We switched on the heaters all at the same time and got the computer to record how fast they warmed.

Our results

This graph of temperature against time shows how quickly the houses warmed up. From top to bottom the lines are: loft and wall insulation, loft insulation, double glazing, single glazing.
You will find some of the questions easier if you put these results into your data-logging software. Click here to get the house SID file, then open it in your data-logging program. If you want know what a SID file is, and how to use one, read the Using SID page.

Looking at the results

• 1. Why are the temperatures of the houses increasing?
• 2. Why do the lines seem to level off instead of continuing to rise forever?
• 3. How do the graphs tell you how wall insulation helps?
• 4. How do the graphs tell you whether single or double glazing is better?
• 5. Tricky this: which of the graphs tell you how loft insulation helps?

Extra

• 1. Try to measure the temperatures at which the lines level off. Do these help you to compare the usefulness of loft insulation?
• 2. Try to measure the steepness (or average gradients) of the graphs. Do these help you to compare the usefulness of loft insulation?
• 3. Which do you think is the best way to use these graphs to compare these methods of insulation - leveling-off temperature or steepness?

What you can do

• Try a similar experiment yourself, but this time warm your houses until they reach a steady temperature. Then measure how fast they cool. Is this a better way of studying insultation?
• There are other ways to heat the houses. You might instead place a hot block of metal in each house and see how well the house keeps it warm. Do you think this is worth trying?
• Find out about the cost of double glazing and how much heat energy you can save by using it. Then calculate how long it would take to pay for its installation.

Where to get help

For other ideas and clues about what you need, see the heat insulation experiment in the logging lab.