Solatube vs Light bulb

This is a frequently asked question and the answer is both far more obvious than you might think, whilst also being a little more confusing! So let me try to explain about how bright a Solatube can be.

The first thing to do is to think of a Solatube as a little like a window, and this is the most important point to remember – if its dark outside then it will be dark inside. And if it’s light outside then it will be light inside too. So, however, bright it is during the day, the Solatube will deliver all that light inside.

There are 2 significant differences, however, between a window and a Solatube:

  1. If you compare the amount of light you get through a Solatube against the amount of light you get through a window of the same size, then a Solatube will easily and significantly deliver a lot more light, i.e. size for size, a Solatube is much brighter than an equivalent window.
  2. Secondly, a Solatube allows you to pipe that daylight to wherever you want it within a building, whereas a window can only let the light in near the outside walls of a building.

OK, but that doesn’t compare how bright a Solatube is compared to a light bulb, does it? No, but it does make you think about a similar question – have you ever asked how bright a light bulb is compared to a window…? Probably never, because a light bulb emits a single, constant level of light whereas a window (and a Solatube) can only ever be ‘as bright’ as the daylight outside, which is constantly changing. Hence, the question “How bright is a Solatube sun tunnel compared to a light bulb?” is an almost infinitely difficult one to answer because it depends on how bright it is outside.

It also depends on how you measure a light bulb. Typically in the UK we’ve been used to talking about old-style, incandescent light bulbs with a wattage rating of 40w or 60w, yet now we have LED light bulbs with equivalent wattage ratings approximately 10 times lower, delivering the same amount of light. So LED bulbs we use today will range in wattage from around 2w upto 10w and even 15w.

However, light is actually measured in ‘lumens’ whereas watts is a measurement of energy usage – completely different things. So if we talk about light output from a bulb (or a Solatube), which is measured in lumens, we start to get closer to answering our initial question. A standard 100 watt incandescent lamp produces 1200 lumen. A 60W bulb produces 800 lumen, a 40W bulb is 4-500 lumen.

But to cut to the chase, if you really want to have some sort of comparison between a light bulb and a Solatube, here are some approximate figures:

A Solatube® 160 DS will provide an average equivalent light as follows:

Spring – 75 Watt
Summer – 150 Watt
Autumn – 75 Watt
Winter – 60 Watt

A Solatube® 290 DS will provide an average equivalent light as follows:
Spring – 100 Watt
Summer – 200 Watt
Autumn – 100 Watt
Winter – 75 Watt

Now, even at the lowest 60 Watt rating, that’s a lot of bright daylight. However, I always suggest that it’s best not to try to compare a Solatube with a light bulb. Rather, think of it as a ‘window on steroids’! delivering daylight from outside but far more of it than you would from a window, through a far smaller aperture.

So, have you seen the light yet? 

I hope all the above helps and If you are interested in bringing natural light into your home, why not contact us at info@solatubescotland.co.uk; 07778 283 427 to find out whether a Solatube sun pipe can help you. Typically, a fully installed system might cost anywhere between £900 – £1,200; that’s supplied, professionally installed and includes the VAT.


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