Why daylight? How much light is enough?

More light
It turns out that roof windows provide at least twice as much light as vertical windows of the same size and three times as much light as dormer windows of the same size; see chart.
Roof windows also allow for greater variation in light intensity, which increases the visual interest of the room.



Better light distribution
Furthermore, it is clear that roof windows ensure a higher brightness of walls than windows in dormers and facade windows, leading to a smoother transition between the high brightness of the window filling and the adjacent wall, thus reducing the risk of glare.

“The new generation of roof windows offers up to 18% more glazing area.”

Rule 1/10 is not enough!
Often, when addressing the quantity of natural light, we resort to the simplifying 1/10 rule of glazed area to the room area. It should be noted that a facade window as the sole source of natural light will not meet the standard requirement for deeper or wider attic rooms. Such rooms need to be supplemented with a roof window to meet the requirement of ČSN 73 0580-2 Natural light in residential buildings for sufficient daylight and its uniformity in the assessed room. When using triple glazing, especially in renovations, we must not forget the lower light transmission and design a larger glazed area.

More at www.velux.cz in the expert section.