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Lighting 101: Wattage VS Lumens

Wednesday, September 9, 2020 By Ariana Thorn

When you’re looking for new lamps to install in a building, wattage and lumens are both important factors to making that decision. When it comes to wattage VS lumens, what exactly is the difference?

It’s all a matter of energy and brightness.

WHAT IS WATTAGE IN A LAMP?

In terms of wattage VS lumens, the wattage of a lamp refers to the output of power while lumens are the brightness. To be more specific, wattage is a measure of the amount of energy needed to power the lamp.

While lumens are a demonstration of the amount of light coming from a lamp and wattage is the energy needed to power a lamp, there is another unit that is measured in correlation to wattage VS lumens. This unit is watthours, which is a measure of the amount of energy from one watt steadily taken from or supplied to an electric circuit for one hour.

As a rule of thumb, always install lamps with wattage no higher than what is recommended for the fixture or appliance. Let’s say you try to use a 100W bulb in a fixture with a maximum wattage of 60W. Using this lamp with wattage that is too high can result in several issues. Some of these issues include over-heating which could lead to wire damage, sockets melting and or need for replacement fixtures.

While keeping in mind proper wattage for a fixture/appliance, also looking at different types of lamps to see what is best for a space is important. Not all lamps use the same amount of energy. Incandescent lamps tend to emit the same amount of light as a compact fluorescent lamp (CFL) or light emitting diode (LED). However the incandescent has higher wattage, meaning more energy usage. Lowe’s gives a great breakdown chart to visualize which lamp types and wattages are equivalent. The chart allows you to see which lamp types can be used interchangeably in correlation with the energy usage. As a consumer with a want to save on energy, using LEDs can fulfill that desire.

Saving on energy usage is not only helpful for the environment but can also be beneficial for your wallet. Installing lamps or retrofitting to LEDs with lower wattage and less power usage can be an excellent solution.

WHAT ARE LUMENS IN A LAMP?

Now that we’ve gone over the first half of wattage VS lumens by showing watts as a measure of power output. What are lumens? To get straight to the point, lumens = light output.

Lumens are a measure of luminous flux, which can be described as a measure of the perceived power of lamp. This measure is useful for how much a specific light source contributes to illuminating a space. To break this down even further – if you’re looking to brighten up your space with more than what is being emitted from your current or previous lamps, think about wattage VS lumens, and focus on higher lumens. Higher lumen rating means higher light output, aka more brightness!

Previously, we talked about incandescent lamps having higher wattage thus more power output than CFLs or LEDs. With lumens, there are higher lumen ratings for LED lamps along with lower wattage – making them a great choice for energy and cost savings. LEDs use less energy, 40-60% in energy savings can be seen, thus energy bill cost savings. Also, their lifespan is much longer than that of an incandescent which is additional cost saving measures as replacement is not needed as frequently.

Perhaps you are interested in knowing the energy efficiency of specific lamps when looking at wattage VS lumens. Knowing how much light is visible with the amount of power output can be helpful when thinking of energy savings. To determine this we calculate lumens per watt. The calculation for this is simple and goes as follows:

lm/w = lumens per watt

To provide an example of this calculation, let’s look at a traditional 60W incandescent lamp that produces 840 lumens:

840 lm/ 60W = 14 lumens per watt

Therefore, we see that for each single watt there are 14 lumens being produced.

There are times when the lumens being produced are not what is considered useful. This can be dependent upon directional or non-directional light. With the different types of lighting and how light is emitted, lumens may not be shedding light from all angles.

For lamps that are non-directional, with a shape like a globe, golf ball or candle the lumen output is calculated for all directions. These can also be dome lights or ambient lighting. Ambient, or general, lighting is what makes up the “base” amount of light in a room. This type of lighting can come from table or floor lamps, ceiling lights mounted to the surface of the ceiling or recessed downlights mounted in the ceiling. These ambient lighting fixtures are popular as they light up a space evenly. 

Directional lights also calculate lumens from all directions of the lamp, however there can be spillage. Examples of directional lights include flood lights, track lights, spotlights, recessed cans and security lights.

The Federal Trade Commission requires that general service lamps have a Lighting Fact label on its packaging. This will allow a consumer to have wattage VS lumens facts when making a product decision.

The Lighting Fact Label looks very similar to a nutritional label you see on food products. Facts required to be present include:

  • Light output of each lamp. Expressed as brightness and measured in lumens.

  • Estimated yearly energy cost of an individual lamp.

  • Lifespan of each lamp expressed in number of years.

  • Light appearance by the correlated color temperature (CCT) which is measured in degrees on the Kelvin (K) scale, from warm to cool.

Pro tip – keeping in mind and comparing wattage VS lumens, along with the lifespan of different lamps can help with the selection of a lamp that will provide an optimal combination of life and light output.

HOW CAN WATTAGE VS LUMENS BE HELPFUL FOR NEXT STEPS?

When thinking of wattage VS lumens, measuring light output in lumens is relevant to the design, visibility, and light output in a building. If looking more at the side of energy usage, and ways to save energy or cut costs then paying attention to wattage is key.

Searching for ways to reduce costs and energy usage is common. Keeping in mind the amount of wattage a lamp uses, and the lumen rating can be helpful when choosing the best lamps for these reduction methods. At Illumetek we can help with lighting installs, LED retrofits and other lighting needs. Please feel free to fill out the form below to get in touch with us at any time.


 

Filed under: LED, Lighting

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Illumetek is a National Program Management company facilitating installs, updates, compliance and rebates for Lighting, Electrical, and associated Controls. If you have additional questions regarding LED lighting technology or design, please feel free to contact us anytime.


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Illumetek is a National Program Management company facilitating installs, updates, compliance and rebates for Lighting, Electrical, and associated Controls. Contact us today!