Structural engineer for a passive house basement

[SteamyTea]

1 minute ago, saveasteading said:

But pine forms a charred layer which then protects the core.

Only when the heat source is removed I think.

Keeps pumping in the energy and it will burn, how bonfires work.

Though if you have a cable (most likely thing to cause isolation to burn) at 200°C+, you have bigger problems.

 

I picked polypropylene as it is one of the cheapest and long lasting plastics there is, and it is easily recyclable, just heat it up a bit and squeeze it though a nozzle.

The point is, the embodied energy in building a house is probably equivalent to 5 years of running the household.

We get very hung up on concrete for environmental reasons, mainly it accounting for 3 to 4% of global CO_2e emissions, but when you think it can be there for 1000 years, the embodied energy/carbon is effetely zero.

The main problem is that it is not often there for 1000 years.

Purely as an aside, the worlds largest recycled material is asphalt.  Nearly 100 million tons in the USA alone.

[saveasteading]

18 minutes ago, SteamyTea said:

Only when the heat source is removed I think.

Keeps pumping in the energy and it will burn,

Energy and oxygen. In a modern house it should be contained to a room and fizzle out.

Tests at BRE show that even lightweight  studwork survives the 1 or 2 hour requirement of the bldg regs. 

They start the realitic tests using timber with lots of air gaps ( a bonfire) , then  spread it to furniture etc, lots of paper and plastic.

In lab tests they just use gas blowers. I've stood on the other side...its very hot and a bit scary.

 

A bonfire of structural sized timber will take hours to burn right through.  A bit of PIR on the top (in the interests of science)  will be gone in minutes.

[SteamyTea]

Just now, saveasteading said:

In a modern house it should be contained to a room and fizzle out.

I a modern design, shouldn't insulation be in an airtight cavity anyway, with firebreaks.

As I said earlier, it is how you use materials, not really the material, that is important.

Not as if we really want to go back to exclusively using only plant fibres and animal products to built houses.

 

Many years ago British Steel designed houses that were bolted together.  I think there may be a case for modular housing that can be relocated easily in the future.  Maybe not in the UK, we have a very strange relationship with housing, but in the developing countries, which also happen to be at the real pointy end of climate change, certainly.

I thought of this as I heard about some African women and children that were waking for 3 hours a day to get water from a well.  Why not move the village to the well.

[joe90]

5 hours ago, SteamyTea said:

Why not move the village to the well.

Abode is difficult to move.

[saveasteading]

4 minutes ago, SteamyTea said:

Why not move the village to the well

I expect there is a good reason for being where they are. I wonder if anyone on here has experience and  can advise on this interesting matter.

 

6 minutes ago, SteamyTea said:

modern design, shouldn't insulation be in an airtight cavity anyway, with firebreaks.

 

That was meant to be my point. The fire runs out of oxygen.

But timber doesn't melt and spread itself. The worst fire damage I have seen was from a polystyrene ceiling. 

[SteamyTea]

1 minute ago, saveasteading said:

The worst fire damage I have seen was from a polystyrene ceiling

It can be made fireproof, as can polyurethanes.

 

We had to send of 3 samples or any new foam that was moulded for fire testing.  Could send 3 samples of the same batch and 2 would fail.

With furniture, the biggest improvement was in the fabrics, not the foams.  Oddly, back in the 80s, car seats did not have to be fire resistant.  They may now.

[saveasteading]

Just now, SteamyTea said:

Oddly, back in the 80s, car seats did not have to be fire resistant.

Oddly, car fuel tanks in the 80s were made of steel and didn't go on fire. Now made of plastic, so the multiple explosions in car parks, beloved of film producers, is now feasible.

[SteamyTea]

2 minutes ago, saveasteading said:

Oddly, car fuel tanks in the 80s were made of steel and didn't go on fire. Now made of plastic, so the multiple explosions in car parks, beloved of film producers, is now feasible.

Plastic fuel tanks are designed to deform in a collision.  Steel ones used to split, and corrode after a relatively short time.

Much safer now.

Aviation kerosene is very hard to set alight unless atomised properly.

 

 

[saveasteading]

54 minutes ago, SteamyTea said:

Plastic fuel tanks are designed to deform in a collision.  Steel ones used to split, and corrode

It is a long time since I designed a multi-storey car park. I do recall though it being mentioned in the codes or a lecture that multiple car fires simply didn't happen as shown in films. Hence that car parks were often over-designed for fire risk. Then that was quietly withdrawn with the use of plastic tanks as fire can spread quickly.

Balancing individual car risk against communal ones (car parks and motorway pileups must be a tricky balance.  

[saveasteading]

On 27/05/2023 at 15:11, Conor said:

There's very little relationship between calculating the loading of a building and insulation. It's your architect that needs to be on the ball

I would expect some Engineers' practices to be very happy to do both. It is Building Science. For a purely Structural Engineer there would be a lot of reading up to do on insulation, but the science is easy enough. But there is probably one in a practice of 10 that is into it. This might result in a neatly integrated and practical design.

Controversially I suggest that Architects practices tend to be more individual and linear in their work and sublet these secondary specialities to other consultants.

[saveasteading]

On 22/07/2023 at 11:51, markocosic said:

here in the cold flatlands.

Half a storey, no muck away , and provides additional insulation to the ground floor. OK I am sold.

 

You must need some serious pumping to keep it dry, if you have a wet season between the permafrost and the summer.

[markocosic]

43 minutes ago, saveasteading said:

You must need some serious pumping to keep it dry, if you have a wet season between the permafrost and the summer.

 

The upper 1/2 storey drains to adjacent land; pretty quickly.

 

The lower 1/2 storey yes. Fortunately the flatlands are typically sand. Once you're through the silt/clay/peat cap it drains freely. 🙂

 

Not everywhere is the same; but passive house shouldn't make this assumption for you IMO.

[Bitpipe]

The sum total of our passive basement design was thus - design a basement structure, specify EPS grade that it sits on (EPS200 for us) and EPS to the sides (EPS 70) and ensure that this external vertical insulation layer meets the insulation layer from the above ground dwelling.

 

Airtightness is easy, just need to lap the internal membrane from above down onto the basement wall below and tape. Spec PH grade windows & doors for basement and you are done.

 

Ours has no heating and it always a comfortable 20 degrees. If I was doing it again, I'd have openable windows for more rapid cooling in as it can get quite warm when a few people in there.