In discussions about calculating energy consumption and finding ways on to lower our electricity usage, more often than not, our focus will gravitate towards the significant players --- power-hungry appliances, like dishwashers and heaters, electronic gadgets, and more. It’s a rare occurrence if someone mentions the “humble” light bulb.
What we often fail to realize is that this is a ubiquitous source of electricity consumption. Not only do we use this daily, we do it multiple times at once. This is the key here “multiple times at once”. A single light bulb might not substantially impact our power consumption; however, in modern homes, notice how our living spaces are adorned with numerous light fixtures. They are used not only as a source of light but also to set the ambiance and add accent to living spaces. Many houses even have smart lighting control, allowing owners to effortlessly change the color temperature and brightness to set the mood with just a push of a button.
How does this unassuming source of light affect our energy consumption? What sets apart a 60W incandescent light bulb from a 10W LED counterpart? And just how much energy does a bulb consume? – These are only some of the questions that this article could help answer.
Why knowing all of these important?
By understanding how much energy your light bulbs use and adopting ways to make them more efficient, you not only save on your monthly electricity bill but also move closer to having an energy-smart home that pairs perfectly with solar power systems.
To fully grasp this, let's first brush quickly on some light bulb terminologies that you might encounter along the way.
Wattage – In an article by House Grail, “watts are the measurement of the power a light bulb consumes to produce illumination.” For example, a 60W incandescent bulb consumes more electricity than a 9W LED bulb. Understanding how wattage works is important to help evaluate energy usage.
Watt Hours (Wh) – This is the total energy consumption of an appliance. The formula to compute for Wh is the total number of watts x the total number of hours = watt-hours. For instance, if you have a 9W LED bulb running at 4 hours daily, it means that your home consumes 36W of energy each day,
Read more about Watt-Hour and Amp-Hour here.
Lumens - This measures the brightness emitted by a light bulb, essentially quantifying the quantity of light it emits. Larger spaces = more lumens to achieve the same level of brightness as smaller areas. You need to know about lumens to help you find the right bulb for your lighting needs.
Kilowatt-Hours (kWh) – You probably read this term every time you get your electric bill. This is simply a common unit of measuring energy unit using the formula of dividing the total wH by 1,000. For example, that 9W LED bulb running for 3 hours daily consumes 0.027 kWh daily or approximately 0.81 kWh monthly.
So now, the big question, how many watts does a light bulb use?
This will largely depend on what type, size, and purpose of the bulb is. There is a wide range of wattages, from as low as 2W to as high as 100W (or even more for industrial applications)
Here is a general breakdown:
- Incandescent bulbs – This type of bulb has been used for over a century. This was once the standard for home lightning but is now being replaced by energy-efficient options. These traditional bulbs come in various wattages, often ranging from 25W to 100W (there are smaller or larger options available depending on usage).
LED bulbs – LED stands for Light Emitting Diode. According to the Department of Energy, this type of lighting is more durable and offers better light quality than other types of lighting. More importantly, residential LEDs (especially Energy Star-rated ones) use at least 75% less energy and last up to 25x longer. They can range from as low as 2 watts to around 18 watts. Similar to incandescent bulbs, there are also higher-wattage LED bulbs available for specific purposes.
Tip: When buying LED bulbs, make sure to check the lumens and not just the watts to determine the brightness (more lumen means higher brightness. Read here for more tips from the Department of Energy.
- Compact Fluorescent Lamps (CFLs) – This type of bulb is another energy-efficient option that has gained popularity as an alternative to traditional incandescent bulbs. They use about 70% to 80% less electricity to produce the same amount of light as incandescent bulbs. However, this type of lighting choice has also been largely overshadowed by LED-type lights in recent years. The typical watt range for this is from 5W to 30W.
Light Bulb Watts and Usage:
As an example, let's use incandescent light. 60W is a popular choice for general lighting in living spaces and 40W for living spaces that need to have softer lighting, such as bedrooms.
The average use of light in US homes depends on different factors, primarily the number of occupants, size of homes, and even individual habits of homeowners.
Now, here's where your usage really matters. For general lighting, most US homes use light for about 2-4 hours per day for general illumination. So if your home is using a 60-watt incandescent bulb, here’s how the energy consumption adds up:
- Using your 60-watt incandescent bulb for 2 hours each day translates to 0.84 kilowatt-hours (kWh) of electricity per week, 3.65 kWh per month, and 43.8 kWh per year.
- If you run the same bulb for 3 hours daily, the energy consumption increases to 1.26 kWh per week, 5.48 kWh per month, and 65.7 kWh per year.
- Using your 60-watt incandescent bulb for 4 hours per day results in 1.68 kilowatt-hours (kWh) of electricity per week, 7.3 kWh per month, and 87.6 kWh per year.
In comparison to LED bulbs:
- For 2 hours of daily use, you'll consume approximately 0.14 kilowatt-hours (kWh) per week, 0.61 kWh per month, and 7.30 kWh per year.
- For 3 hours, the energy consumption increases to around 0.21 kWh per week, 0.92 kWh per month, and 11.0 kWh per year.
- Using the LED bulb for 4 hours each day results in approximately 0.28 kWh per week, 1.22 kWh per month, and 14.6 kWh per year.
Don’t forget that a household doesn’t typically just have one bulb running in the house. You then multiply any of these numbers by the number of bulbs you have to get a good estimate of your energy usage.
Light Bulb Watts and Alternative Power Sources
If you are thinking of using solar panels, generators, or any other alternative power sources, it is crucial for you to know the wattage of your light bulb (and all of the appliances that you are using) for these reasons:
- Sizing Your Power Source – Knowing your light bulb’s wattage will help you to accurately size your power source. Different light bulbs mean different power requirements, so having accurate information will ensure that you can match the right system that can efficiently handle your needs.
Optimizing Power Generation – You can calculate how many panels or pods you need to meet your power demands. This will also prevent you from either under-utilizing or over-relying on your existing power system.
For example, one of the best whole-house solar generators – Nature’s Generator Powerhouse, will be able to single-handedly provide you will all of your power needs. You have the liberty to customize your eco-system to make it fit your requirements. You can add solar panels, power pods, wind turbines, etc. You can simply upgrade your battery capacity by using power pods and harnessing more free energy. BUT of course, the first step always is to determine what you need, and this will start by knowing the wattage of each device or appliance that you are using, including your light bulb.
- Better Capacity and Preventing Overloading – Having a good understanding of wattage will help homeowners avoid overloading. With each light bulb that you use, energy requirements add up. Overloading your generator or solar system can lead to system damage, inefficiency, or worst-case scenario, a shutdown.
- Cost-efficiency – You can avoid excessive capacity or investing in additional solar panels or pods than you actually require. Knowing the wattage will act as your guide when estimating your energy needs.
Understanding how many watts your light bulb uses is not just about a simple household item; it’s a key player in your overall energy consumption and management strategy. Remember the cumulative effect of this humble item – a single light bulb might not drastically impact your power usage, but we are most likely using multiple light bulbs at once. In addition, knowledge of the wattage of appliances or any fixtures will help you align your home with proper renewable energy solutions.
* We want to give credit where credit is due. Professional writer, Michelle Gamana, contributed research and content to this blog titled: How Many Watts Does a Light Bulb Use Thank you, Michelle, for your contributions!