Saving Energy At Home: Do Dimming Lights Save Energy?

In case you haven’t noticed by now, the UK (and the rest of the world) is in a bit of an energy crisis. The prices are going up and we’re faced with the impossible choice between not using energy, or making up the surplus with either fossil fuels (coal, etc) or nuclear energy.

I’m not a huge fan of nuclear energy. After visiting Pripyat in Chornobyl a few years ago, it doesn’t seem safe to me. What are the options then?

Well, that’s where saving energy at home could make a huge difference.

In order to fully invest in renewable energy like solar and wind power, we need to change our habits at home and focus on saving energy, which is why we’ve switched to low-energy LED lighting as a first priority, and some of these bulbs can be used with a dimmer too.

That leads to the question: do dimming lights save energy? If so, how much? If not, what are the options?

Let’s dive in and have a look.

The simple answer to this question is yes, dimming lights does save energy. However, the actual mechanism by which this occurs is a bit more complicated. When you dim a light, you are essentially decreasing the amount of power that is being sent to the light bulb. This decrease in power results in a decrease in the amount of heat that is produced by the light bulb, thus saving energy in the long term.

Dimming Your Lights: How Does It Work?

The process of dimming your lights is actually quite simple.

When you dim your lights, you are essentially reducing the amount of light that is emitted from the lightbulb. This is done by reducing the amount of electricity that is sent to the lightbulb. By doing this, you can be saving energy and lowering your electricity bill in one step.

Dimming your lights works by reducing the amount of electricity that flows to the light bulb. This can be done with a dimmer switch, which is a special type of switch that is designed to control the flow of electricity.

Dimmer switches are usually used with incandescent bulbs, but they can also be used with LED bulbs.

When you dim an incandescent bulb, the filament inside the bulb becomes less hot, and this makes the light appear dimmer. With an LED bulb, the dimming effect is achieved by reducing the amount of current that flows through the LED.

lightbulb 4

How Much Electricity Do Dimmers Save?

In order to really understand the savings, and whether they are worth it, this table below looks at some real-world examples of saving energy and calculates how much energy you would be saving.

Energy prices are changing constantly, but this chart should help you calculate whether switching to dimmer switches and bulbs is a good idea or not.

The results below were gained by using an LM465 lamp module connected to a table lamp. The lamp was tested with a 200W bulb, a 100W bulb, both of which were LED bulbs, a GE 60W and GE 40W incandescent bulb and a Philips Marathon 23W dimmable CF which is a fluorescent energy-saving bulb.

Saving energy at home is great when it comes to ambient light, but perhaps not as good when a work light is needed.

200W100W60W40W23W(CF)
100%18292563622
90%17989553521
80%16985523320
70%14373442819
60%12462382416
50%10152322013
40%804025169
30%552817117
20%2512866
10%10632<1
This table shows the results of dimming various wattage bulbs to a % of their water and the resulting watt usage.
Original source

As you can see from the table, turning your bulb down does indeed save energy, and that will equate to a cost saving when you’re looking at saving energy at home too.

The next question is, how much money can a dimmer save? That isn’t quite as easy to answer.

How Much Energy Does a Dimmer Save?

lightbulb 3

Let’s take the scenario of a 100W bulb. If you turn the 100W bulb down using a dimmer so that it is only emitting the equivalent light of a 40W bulb then, theoretically, you have a 60% energy saving.

This only works, however, if you are actually able to do what you want to do with a bulb emitting 60% less light. If you are watching TV, a dim room may be perfect, but if you’re trying to read a book, it may be that you need to turn the light back up again so as not to strain your eyes.

The maths on electricity usage for a 100W bulb is quite simple:

100w bulb, used at full power for 4 hours per day, 360 days per year = 144,000 watt hours per year (144 kWh) using a simple equation of (100 x 4) x 360.

If that same 100W bulb was dimmed to 40W the equation would look like this: (40 x 4) x 360 = 57,600 watt hours per year (57.6 kWh).

That works out to 40% less electricity being used over the year from that one bulb.

In the UK, as of September 2022, we are paying on average 55p per kWh (£0.55 per kWh).

If you run a 100w bulb run for 4 hours per day, 360 days per year will cost you around £79.20 per year (at September 2022 prices). If you were to dim that bulb to 40W and run it for the same amount of time, it would cost £31.68, on average.

lightbulb 1

Are Light Dimmers Worth It?

Dimmers are a popular way of saving energy and saving money, but are they really worth it? Here’s a look at the pros and cons of using dimmers in your home.

Benefits of Using Dimmer Lights

  • Dimmers can help you save energy and money on your electric bill.
  • By lowering the light level, you can reduce the amount of electricity needed to power your lights.
  • Dimmers can also extend the life of your lightbulbs.
  • Dimmers can create a more relaxing atmosphere in your home.

Drawbacks of Using Dimmer Lights

  • They can be more expensive than traditional light switches.
  • Dimmers may not work with certain types of lightbulbs, such as LED bulbs.
  • Dimmers can be difficult for some people to operate.
  • Dimmers may need to be installed by an electrician, adding to their initial set-up costs.

Another (Smart) Option For Saving Energy on Lighting

As a final wrap-up, there is another option for people looking to save energy at home, and that is to install motion detection lighting.

This is definitely not an option that will save money outright, but in the long run, it will help to reduce costs and lead to saving energy at home.

At home, we use the Xiaomi Mi Home smart system with smart LED wifi bulbs, a set of motion detectors, a light sensor, and a gateway hub to run the whole thing.

How this works is quite simple:

  • The light detector detects how much light is in a room, deciding whether or not additional lighting is needed.
  • The motion detector knows if there is motion in the room or not.
  • If additional lighting is needed and there is motion, the lightbulb comes on.
  • If no motion is detected, or the ambient light is bright enough, the lightbulb stays off.
  • Each bulb can be adjusted in brightness and light temperature from very dim and warm right up to daylight brightness (1700K to 6500K)
  • The motion detectors turn the lights off when motion isn’t detected after a set period (we have ours set to 2 minutes).
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Using a system like this allows us to only have the lights on when we need them, and we have control over the brightness allowing for a nice soft ambient atmosphere for TV watching, or a bright atmosphere for sewing and other activities in the evening, and this helps in our quest of saving energy.

The LED bulbs use less electricity to begin with, being around 8 watts, and the motion detectors allow us to only have lights on when they are needed, saving that wasted energy of lighting up a room when no one is in it!

Having the light sensor in the room gives us another level of control, allowing us to only have the lights turn on when they are actually needed so that our motion detectors aren’t turning the lights on at 1 pm!