ᐅ How much natural light does a window provide?

Created on: 4 Jun 2016 21:56
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garfunkel
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garfunkel
4 Jun 2016 21:56
Let's assume we have a room with an area of 20m² (215 sq ft). Now, planning a window with 2m² (22 sq ft) of glass surface for this room.
How bright would that be?

What about if the room had 10m² (108 sq ft) of glass surface?

At what glass surface area in m² would the room no longer get significantly brighter?

And so on.

Is there a rule of thumb to figure this out, or maybe even a calculator or a simple formula to determine it?

Perhaps one that also takes external factors into account, such as a nearby tree, a carport, a neighboring house, an overhead balcony, or the window’s orientation to the north/east/south/west?
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Traumfaenger
4 Jun 2016 22:12
In my opinion, that depends on many factors, such as the orientation and sunlight.
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garfunkel
4 Jun 2016 22:14
Hello, yes, that’s true. But you still need a way to predict whether enough windows will be installed to achieve brightness level x or how it will be with the planned design.
tomtom794 Jun 2016 22:15
The regional building code states that in Baden-Württemberg, the window area must be about 1/10 of the floor area.

The transmission value (TL value) then tells you how much light passes through the glass.

Now, theoretically, you could plan for 20m² (215 sq ft) of window area with a TL of 70% light transmission.
However, you rarely need that much, or do you not want to place any furniture?
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garfunkel
4 Jun 2016 22:29
Hello Tom, the room example was just a thought experiment on my part 😉

What is the TL value, and how is the 70% calculated?
How much lighting is needed for a bright room?
And what is generally defined as bright?

I once read that an office space requires 500 lux (regardless of natural or artificial light) and a workstation with small electronic components needs 800 or 1000 lux.

Based on this, without being able to assess it exactly, I would say that 1000 lux can be considered bright.
tomtom794 Jun 2016 22:33
The TL value indicates how much sunlight passes through, and this information is provided with your windows.

I can’t answer your question specifically, but too much window area without shading in summer will cause the house to overheat significantly. So, blinds or shutters are essential.