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Science project idea

Classroom lighting audit: lux readings and how much LEDs would save

Measuring light levels and counting lamp hours shows where electricity is wasted. Comparing old tube lights with LED tubes on paper gives the units and rupees saved per year.

Make it yourself8 numbered steps, the materials and the science, all free.Go to the stepsGet a ready-made kitReady-made models, kits and spare parts in the store under Science.Browse ScienceAsk on WhatsAppAsk the head office whether a model or kit for this idea is available.Send a message

What it shows

Measuring light levels and counting lamp hours shows where electricity is wasted. Comparing old tube lights with LED tubes on paper gives the units and rupees saved per year.

The science

Energy used is power multiplied by time, measured in kilowatt-hours, and a bill is units multiplied by the rate. Lux readings show whether a room has enough light for reading, which should be around 300 lux. Switching to higher-efficiency lamps gives the same light for fewer watts.

Materials

Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.

  • A phone lux-meter app or a light meter
  • A notebook and a floor plan sketch
  • Wattage labels read from the lamps
  • A calculator or spreadsheet
  • The school’s electricity bill (ask the office)
  • A ruler and a tape measure

Safety

For this project: Do not touch lamps or fittings; an adult must climb any ladder and switch off at the board before reading labels. Never open a lamp or fitting.

Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.

All the safety rules

Step by step

8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.

  1. Draw a plan of the room and mark each light and fan.

  2. Read the wattage from each lamp label, with an adult’s help.

  3. Measure lux at six desk positions at the same height and on a cloudy and a sunny day.

  4. Ask the teacher for the hours the lights are on each day.

  5. Work out energy used per day in kWh by watts times hours divided by 1000.

  6. Multiply by school days and the unit rate to get the yearly cost.

  7. Repeat the calculation for LED lamps with lower wattage and compare the saving.

  8. Present a table and a bar chart of cost for current and LED lighting.

What you should see

You find the room’s daily and yearly energy use, the spots below 300 lux and the money that LED lamps and switching off in daylight would save.

Viva questions

A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.

1What is one unit of electricity?

One kilowatt-hour.

2What is lux?

A measure of light falling on a surface.

3Why switch off lights near windows?

Daylight already gives enough light.

4How is a bill calculated?

Units used multiplied by the rate per unit.

Free ebook: Viva Questions for Science Projects

Take it further

Repeat for the whole school and suggest three changes with their payback time.

Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.

Free ebooks for this project

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