Keep warm 2


Keeping warm - heating

It was cold April day and the central heating was keeping us cosy indoors. We knew that the central heating system has a thermostat and it cuts off a boiler when the room is warm enough. But there's just a thin piece of glass between us and the outside and we wondered if it really helped much.

What we did

We decided that we needed to measure the temperature both inside and outside the window. We also thought it would be good to use a light sensor to monitor the day light, that way we could record when the day began and ended. We connected the sensors to a data logger because it can make all those measurements automatically and store them till we are ready to look at them.

apparatus results

Our Results

Our graph showing the temperatures inside and outside the window, as well as the light level. 


You will find some of the questions easier if you put these results into your data logging software. Click here to get the results, then Open it in your data logging program.

Looking at the results

  • Look at the graph and decide which line shows the light level, and which shows the temperatures inside and outside the window.
  • Mark your graph, to show when it was roughly midday. Then mark the times of 4:00, 8:00, 16:00 and 20:00.
  • What evidence is there to show that the afternoon was sunny?
  • What happens to the temperature in the small hours of the morning?
  • When does it start to get warmer outside?
  • When does the central heating first switch on? Describe what the central heating does during the day.
  • Is there any connection between the sunshine and the outside temperature?
  • How big a temperature difference is there between the inside and outside temperature? Does this vary much during the day?
  • What would happen if the central heating was not working on this day? Estimate how long it would take before the inside temperature matched the outside.
  • Tricky question: does the glass keep us warmer? Explain your answer.

What you can do

Winter: how does the central heating affect these results? Repeat our experiment and compare a room which is centrally heated with say, a garden shed which is not.
Summer: how important is the greenhouse effect. Repeat our experiment in a room which gets lots of sun, and one which gets hardly any.
Study the inside and outside temperatures with double and single glazed windows.

Where to get help

For other ideas and clues about what you need, see How does heat travel through glass