What you need to know
- Add the wattage of every lamp that is on at the same time.
- Compare light output in lumens, not only watts.
- Use hours per day and your electricity price to convert lighting into a monthly cost.
Use your own measurements
BricoDato tools help turn the guide into quantities, kWh, cost or a project plan.
Add the complete lighting load
Multiply the number of bulbs by the wattage of each lamp. If rooms use different lamps or hours, calculate them separately instead of forcing one average.
Compare lumens, not only watts
An LED replacement should provide the brightness you need. A lower-watt lamp is not a saving if the room then needs more fittings or no longer has enough useful light.
Target the longest-running lights first
Replacing or reducing use in lamps that run many hours gives a larger annual saving than focusing on rarely used rooms.
Keep light quality in the decision
Colour temperature, colour rendering and dimmer compatibility can matter as much as raw efficiency.
Final check
Before buying material or doing the work, review the assumptions and technical limits that matter for your specific product, room or installation.
- Count all bulbs in the group.
- Use real operating hours.
- Compare equivalent lumens.
- Check dimmer and fitting compatibility before buying.
Keep a small job sheet
Record the measurements, product reference, technical values you used, date and final result. For maintenance or diagnostics, also note the conditions at the time. A short written record makes future comparisons much more reliable.
Turn the guide into a decision
Use your measurements and the manufacturer’s technical data. If the decision affects fixed electrical work, structure, hidden leaks, refrigerant systems or another safety-critical installation, consult a qualified professional.