Steel posts and thermal bridging
bigvibes
| Posted in Green Products and Materials on
I’m in Italy, planning an addition to build a 400 sq ft solarium that will be mostly windows with 3 posts framing the structure. I am looking for the most sustainable material and don’t have many options where I live so am considering recycled steel.
I’m concerned about the thermal bridging issues with steel but I’m also wondering how big of a deal it would be as it would only be the outside corner posts and one in the middle. The rest is windows. Any thoughts on whether I’d lose a great amount of energy heating this? Any other issues with steel I should think about? thanks
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Replies
They don’t sell wood posts near you?
Yeah, it's pretty rare in residential construction that a post has enough vertical load to require steel. Sometimes there's an issue if your worried about seismic loads with getting a good connection, a post welded to a beam is pretty solid.
They do, and I would like to use it, but in my particular situation there were issues with it.
I was advised against it as the type of finish I wanted to use would crack when set on wood, but I just found a way yesterday to alleviate that potential problem, so I will now be going with wood.
bigvibes,
The energy loads in a typical solarium are overwhelmingly dominated by the glass and frames. I wouldn't worry about the posts much.
The dollar savings for eliminating the thermal bridging in a solarium is the same as it would be in a double-wall assembly.
DC,
Yes of course - and you can make that same argument about every component, big or small, in the room, but you have to look at context. I took his question not to be about simple ROI, but whether the loss was significant enough to spend time trying to alleviate.
My experience with solariums is that the huge amount of glass means trying to manage solar gain and heat loss through that dwarfs any other concerns. Whether it pencils out to thermally isolate the posts or not is in the weeds.
If the question were, "how do I make my solarium more energy-efficient," then the answer would be "make the windows smaller," in a heartbeat. But that's not the question that was asked.
DC,
" I’m also wondering how big of a deal it would be as it would only be the outside corner posts and one in the middle. The rest is windows. Any thoughts on whether I’d lose a great amount of energy heating this?"
The question was whether the heat loss through the posts is a significant part of the heat loss. I don't think it is.
I read those same words and come to a different conclusion. "Any thoughts on whether I’d lose a great amount of energy heating this?" doesn't say anything about heat loss relative to the rest of the building.
I'm a believer that people should do anything that makes economic sense to conserve energy. Just because a building is wasteful doesn't mean it should be more wasteful than it needs to be to accomplish its design goal.
Thanks, that's what I was wondering about. I shouldn't be too concerned with a small detail like that when I should focus on ensuring the right type of windows and frames.
One thing I would be worried about with steel post is condensation. It is a perfect condensing surface and if any wood is attach I think it could potentially saturate. If you have ever lived with non thermally broken metal windows your will understand.