SunPipes in Passivhaus? Saw it in Build the Dream.

[TheMitchells]

Did anyone see the Build the Dream programme from a couple of weeks ago. It was the one where she built a huge house over the stables.  But what surprised me was the house she was sent to see which was built I think in 2008 and was the first Passivhaus in Scotland.  They had two sunpipes into the dressing room to give extra light.  But I didn't think you would be able to use Sunpipes in a Passivhaus?  Am I wrong? 

We have one fitted into our upstairs hall and it works very well, giving us as much light as quite a large window.  We have wrapped insulation around the pipe within the cold attic, but I would not have thought it was airtight.  Any ideas?

[ProDave]

We have a sun pipe in our house and it does its function of illuminating an otherwise dark space very well. But I agree it would take a lot of detailing to get it completely air tight, and it is bound to increase heat loss.  I guess the question is whether the gain from lighting a dark space is worth perhaps a slight reduction in the building's performance?

[Jeremy Harris]

Our neighbour has one in their extension.  It's forever getting damp with condensation inside, that on bad days drips down inside the house.  The problem seems to be that the outer dome gets very cold, and warmer, moister, air from inside can get inside the tube, then condense on the dome and run down the sides.

I doubt it's even vaguely airtight, and most probably isn't that thermally efficient, either.

[SteamyTea]

I made some prototype stuff for Monodraught a few years back.  I designed a system to get around the condensation, and insect problem.  It was too expensive to compete in the market place.

I remember having a conversation with SarahSW (what happened to her, the building seems stagnant if it is the one I drive past a lot) about making a DIY solution with a couple of mirrors.  They are only periscopes after all.

I still have a couple of contacts with the company I worked for then and may be able to help if anyone fancies a DIY solution.

But I suspect that an LED light panel is the real answer.  I still want to see if Jeremy's ones upset my delicate eyesight (and I am passing pretty close to his on Monday).

Edited June 17, 2016 by SteamyTea

[ProDave]

No condensation trouble with ours, it passes through a cold roof space so would be a prime candidate for such a problem. Ours is a "solar tube" if that helps,  It is just a steel tube with a very highly polished mirror finish to the inside surface, a plastic dome and flashing at the roof end, and a fairly flat round fitting at the ceiling end, not unlike the cover of a round 2D type light fitting (I have lost count of how many times guests have asked about the "light" on the landing and how to turn it off)

A big improvement in our case could be mader by lagging the tube as it goes up through the cold loft, and some sealant to seal the ceiling fitting to the ceiling would help.

I will digress to the condensation issue. It is something I have never understood.  Our present timber framed house is absolutely bone dry. You can hang wet washing in the utility room on the "pulley" and it makes no difference. You can bath or shower and there's rarely any codensation on the mirrors.

Now our previous house was a 1930's semi with solid 9" brick walls. So it was obviously a poorly insulated house. It had run of the mill UPVC double glazing. We never had condensation on the windows, but any cold surface, like a toilet cistern full of cold water, would be dripping with condensation after a bath or a shower.

Now the house was heated so it was warm and comfortable.  What puzzles me comparing the two houses is why did the 1930's house have so much moisture in the air it condensed on a cold toilet cistern, yet the new house doesn't. It can't be the amount of moisture produced by the occupants, so the extra moisture must have come from the fabric of the building.  I can well see in a "damp" house like that, a solar tube might have problems with condensing moisture.

[TheMitchells]

12 hours ago, ProDave said:

No condensation trouble with ours, it passes through a cold roof space so would be a prime candidate for such a problem. Ours is a "solar tube" if that helps,  It is just a steel tube with a very highly polished mirror finish to the inside surface, a plastic dome and flashing at the roof end, and a fairly flat round fitting at the ceiling end, not unlike the cover of a round 2D type light fitting (I have lost count of how many times guests have asked about the "light" on the landing and how to turn it off)

A big improvement in our case could be mader by lagging the tube as it goes up through the cold loft, and some sealant to seal the ceiling fitting to the ceiling would help.

I will digress to the condensation issue. It is something I have never understood.  Our present timber framed house is absolutely bone dry. You can hang wet washing in the utility room on the "pulley" and it makes no difference. You can bath or shower and there's rarely any codensation on the mirrors.

Now our previous house was a 1930's semi with solid 9" brick walls. So it was obviously a poorly insulated house. It had run of the mill UPVC double glazing. We never had condensation on the windows, but any cold surface, like a toilet cistern full of cold water, would be dripping with condensation after a bath or a shower.

Now the house was heated so it was warm and comfortable.  What puzzles me comparing the two houses is why did the 1930's house have so much moisture in the air it condensed on a cold toilet cistern, yet the new house doesn't. It can't be the amount of moisture produced by the occupants, so the extra moisture must have come from the fabrric of the building.  I can well see in a "damp" house like that, a solar tube might have problems with condensing moisture.

That's pretty much as I have found - never had any problems of condensation and it goes through a cold attic.  However, we too have a timber framed house, built by the Americans in the 1980, we think, for personnel at the local RAF station. They (the Americans) are still there and half the estate was sold off 20 years ago, when I bought it.  We never have any problems with condensation and half an hour after a shower, the room is completely dry and there isn't a fan anywhere.  Our clothes dry overnight, without any heating and again no condensation.  We assume the house has a vapour barrier that allows the moisture to escape.  Its a great system and hence part of the reason we want to build in timber.

[SteamyTea]

When I lived in Bucks, I had a house build for the USAF, built in the late 50's I think.  It cost next to nothing to heat and had lots of glass.
  It was 'thermolite' cavity and brick.

Strange how they knew how to knock them up cheaply and quickly back then, and now we ponce about for years to get a place built.

Does your place have a wider than UK standard front door?

[TheMitchells]

yes, the doorways are all wider and the light switches are  at waist height.  Its a great house with lovely spacious rooms.  I have just been looking at the sunpipe we used and the company (Solartube) now do a similar system but designed with better thermal and acoustic properrties, designed for Passivhaus apparently.  We paid £552 in 2010 and the basic model look to be around the same price now. 

I was wondering if anyone has any other experiences of sunpipes that are a little cheaper?