Suitable sun tunnels for a bathroom

[Smallholdertoo]

We are due to start building a highly insulated 1.5 storey detached annexe in July. 

 

The downstairs wet room of approx. 4m2 is due to be lit by a small Velux in the roof at the edge of an upstairs. bedroom.

I now need to use this area in the bedroom behind a bulkhead for MVHR pipes. My wife wants to have natural light in the wet room so she is suggesting a sun pipe. For me this will only work if it is well insulated  otherwise condensation, due to cold bridging, may be a problem.

 

We will have a number of Velux's on the roof so I thought that perhaps a Velux sun tunnel may work. However, these have a basic u-value of 2.9w/m2/k, though they do an insulation kit which drops the u-value to 1.8w/m2/k but only for the 14" version which would be too large for the size of the room. Has anyone used a Velux sun tunnel in a bathroom environment? and if so was there a condensation issue?

 

Or does anyone have any other suggestions?

 

 

Edited March 21 by Smallholdertoo
duplicated image

[SteamyTea]

6 minutes ago, Smallholdertoo said:

Or does anyone have any other suggestions

I did some work for Monodraught back in the 1990s.  They were decent to deal with.

[Smallholdertoo]

59 minutes ago, SteamyTea said:

I did some work for Monodraught back in the 1990s.  They were decent to deal with.

Many thanks I will contact them on Monday

[SteamyTea]

2 minutes ago, Smallholdertoo said:

Many thanks I will contact them on Monday

Let us know how you got on.  I often think about sunpipes, still have some prototype bit kicking about.

[Smallholdertoo]

On 21/03/2025 at 20:56, SteamyTea said:

Let us know how you got on.  I often think about sunpipes, still have some prototype bit kicking about.

Contacted Monodraught. They agreed that their Sunpipe is not designed to be airtight, 

 

Solatube however do have a passiv house standard version of their product that has 0.5w/m2k u-value and gaskets to ensure that airtightness. So I am probably going down this route.

[SteamyTea]

1 minute ago, Smallholdertoo said:

They agreed that their Sunpipe is not designed to be airtight

I think they use the lack of airtightness to control condensation, they are/were an HVAC company really.

 

Have you thought of making your own, it is only a periscope after all.

[Smallholdertoo]

11 hours ago, SteamyTea said:

I think they use the lack of airtightness to control condensation, they are/were an HVAC company really.

 

Have you thought of making your own, it is only a periscope after all.

In a word No! Although it s only a periscope of sorts , it needs to be a1rtight and thermally functional and aesthetically attractive both internally and out. Maybe worth the effort if i needed 5. Thanks for your help.

Edited March 26 by Smallholdertoo
Minor wording change