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Community and Q&A

Adding a (second) lower “lens” to a tall skylight shaft

maxwell_mcgee | Posted in Interior Design on

Hi all,

As part of a new house we’re building in CZ5, we have four skylights located towards the centre of our house plan to bring light into an otherwise very dark space. The skylight shaft for these skylights ends up being very tall — it’s close to 8′ between the ceiling plan and the top of the roof as these skylights cut through the tallest part of the unconditioned attic. 

We’re a bit concerned about the aesthetic of these super tall skylight shafts, and our architect has suggested that we should install a second pane of glass as a “lens” closer to the ceiling plane to reduce the perceived height.

My concern is that this may create a weird microclimate in the shaft and I haven’t come across any reading materials that explain the building science associated with this type of situation. Our mechanical engineer will design in some ventilation into this space, including intake to a dedicated dehumidifer (supplemental to heating/cooling via ducted heat pumps). But is that enough?

Is a pane of glass as a “lens” okay or do we instead need to be thinking about something like a decorative metal screen or grille that allows for almost unfettered air movement through this area? Let’s assume for a moment that the shaft will be well detailed and the skylight itself will be triple pane, high performance glass (likely Lamilux product from 475)

I’m including a link to an image of an example of some company that designs these type of “lenses” to illustrate what I’m describing. 


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  1. walta100 | | #1

    I get a lot more light from my sun tunnels than skylights that are 4 times larger.

    They may make them larger than this 22 inch model.


  2. Expert Member
    BILL WICHERS | | #2

    I had some very deep/high skylight wells similar to what you describe (I had two around 6 feet or so), and they had frosted panes of glass in the bottom that sat on a lip around the edge. I didn’t have moisture issues in the shafts, but you do need to air seal and insulate the entirety of the exterior of the shafts. Paint the interior bright white.

    Note that you can install some linear lights vertically in the shafts and use them for lighting in the evening. The idea is to use the lights “reflectively”, so that you get a diffuse light out the bottom glass and not a direct beam.


  3. Expert Member
    ARMANDO COBO | | #3

    I've found that if you flare/angle the skylight chase at the ceiling, it will bring more light and provide a more visually interesting views in the room.

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