Structural engineer for a passive house basement

[WisteriaMews]

Can anyone recommend a structural engineer they have used for a passive house basement? Ideally in the south east London / Kent area.

 

We're currently designing a passive house and the planners are pushing us towards a basement as they want a limited structure above ground.

 

Thanks.

[Thorfun]

We used TSD for our basement. They’re based in Ireland (we’re not) but that didn’t bother them or us. 
 

@Bitpipe used a UK based SE for their basement but I found them a bit pricey. 
 

have an extensive read of the basement sub forum as there’s lots of info on there

Edited May 27, 2023 by Thorfun
Added bit about sub forum

[WisteriaMews]

Thanks. I've had a read through some threads and saw recommendations for TSD but they weren't specific to Passive House and looking at their website they didn't mention that as an area covered, but I will get in touch with them.

[Conor]

You don't need a passive house engineer. There's very little relationship between calculating the loadings of a building and insualtion. It's your architect that needs to be on the ball with things like efficient form, cold bridging etc.

[SteamyTea]

2 minutes ago, Conor said:

There's very little relationship between calculating the loadings of a building and insualtion

The arithmetic and science, once reduced to the SI system is very similar.

They all tend to use kg, metres, seconds and temperature.

[saveasteading]

If anything it is likely to be over-insulated. Earth 2m down is generally a constant temperature (is it 16°C?) and most earth is a poor conductor,  but I haven't seen an insulation brochure that mentions that. 

Someone here will know if Passivhaus mention it. 

Passivhaus should be advising against basements because of the extra material and earth removal required.  Perhaps this is a more holistic sustainability issue than their energy model, but I would be interested to know.

 

Design a basement structurally, in parallel design how to keep it dry, then insulate the inside. And start saving.

[Thorfun]

1 hour ago, saveasteading said:

then insulate the inside

we insulated outside ours

[Nickfromwales]

46 minutes ago, Thorfun said:

we insulated outside ours

Far better option AFAIC and saves on precious GIA.

2 hours ago, saveasteading said:

Earth 2m down is generally a constant temperature (is it 16°C?) and most earth is a poor conductor,  but I haven't seen an insulation brochure that mentions that. 

I thought closer to 13^o? I would not want the entirety of the basement concrete to be at exactly that temp and then to have to try to mitigate retrospectively / internally. Seems a no-brainer to dig a bit wider and drop 200/300mm of EPS around / underneath.

 

 

At depths of 2m and more, the ground temperature does not deviate very much from the average summer/winter surface temperatures (around 8° to 12°C [46ºF to 54ºF] in the UK depending on location). At this depth, there is an enormous store of heat that can be usefully tapped for heating in the winter.

Edited May 27, 2023 by Nickfromwales
Snippet from the 'net added

[saveasteading]

A good point about building a very expensive basement then using up floorspace. 

That will work especially if you like plain walled brutalism.

[markocosic]

On 27/05/2023 at 17:41, saveasteading said:

Passivhaus should be advising against basements because of the extra material and earth removal required

 

Why so?

 

Digging a half storey hole to get your foundations below the frost line, allow entry of your water services etc that are buried two meters deep in cold parts of the world, building a basement in it, and levelling the spoil around the house to raise the ground floor up out of the summer mosquito altitude, is a great idea in many parts of the world!

[saveasteading]

2 hours ago, markocosic said:

Why so?

Because the earth needs to be transported away and disposed of. Lots of diesel. Then it fills a valuable space in landfill, or goes on a farmers field, (probably under the radar) making it unproductive.

 

Then a basement is a heavy structure using much more material than an above ground floor.

 

So it is a commercial decision to get more housing on expensive land  but not sustainable...hence should be contrary to passive house principles.

 

[markocosic]

2 hours ago, saveasteading said:

Because the earth needs to be transported away and disposed of. Lots of diesel. Then it fills a valuable space in landfill, or goes on a farmers field, (probably under the radar) making it unproductive.

 

If you're disposing of the earth.

 

Reread the description and I'm describing what folks do here in the cold flatlands.

 

Digging out a half storey; building from below the frostline (which they'd need to do anyway); then banking the excavated earth up against the house so that ground floor ends up half a storey above the surrounding land. 

 

Free of mosquitoes. With a view. Free of water on the ground floor etc.

 

 

In the cities there's also an argument for it. Half basements for the cars, pushbikes, strollers, electric wheelchairs etc. In the space that you've had to dig down to for footings. Aartments above them. Density the city without losing amenity. Does involve muckaway though. But meh if that building is still there in 100+ years.

 

 

Also meh if it's that basement that saves you a  from Russian invasion etc. Check out Finland for planning policies that consider legitimate military interests. They've got some of the world's most over specified underground parking/gyms/bats etc all in the name of good effing luck if you make it past the swamps sunshine.

 

 

 

 

[IanR]

3 hours ago, saveasteading said:

So it is a commercial decision to get more housing on expensive land  but not sustainable...hence should be contrary to passive house principles.

 

PassivHaus principles do not relate to the carbon "foot-print", sustainability, waste, pollution or really any aspect of construction method. It's a building performance standard that relates to the completed building, with comfort at its core.

 

Probably why it has succeeded where the Code for Sustainable Homes which tried to cover everything from construction through to end of life fell by the wayside as it was far too complicated.

[saveasteading]

6 hours ago, IanR said:

building performance standard that relates to the completed building, with comfort at its core

 I thought maybe i've not been paying attention. So I've checked their website. Aplogies for the grey background.

This reads to me  as carbon, especially energy, first and comfort second, but perhaps comfort sells more buildings.

 

As an estimate, I'd say that a basement construction creates 5 x the carbon,  than the average.

 

I'm not against most of the passivhaus principles.

THe Bedzed project  (similar principles) was a serious inspiration to me. 

 

Check out the monetary cost of a basement too, in some detail, before committing.

 

 

 

Buildings are a significant culprit of carbon emissions – accountable for 35% of total global energy consumption. Backed with over 30 years of international evidence, Passivhaus is a tried & tested solution that gives us a range of proven approaches to deliver net-zero-ready new and existing buildings optimised for a decarbonised grid and augmented for occupant health and wellbeing.

[IanR]

4 hours ago, saveasteading said:

 This reads to me  as carbon, especially energy, 

 

Yes, but for the completed building in day to day use. Not the construction of the building.

Edited July 22, 2023 by IanR

[saveasteading]

9 hours ago, IanR said:

Not the construction of the building.

Edited 9 hours ago by IanR

Interesting. Any idea Why not? They either care about carbon or don't. 

[Thorfun]

10 minutes ago, saveasteading said:

Interesting. Any idea Why not? They either care about carbon or don't. 

could it be that the carbon usage of a poorly built house over it's lifetime pales in to comparison to the carbon usage of a passivhouse regardless of it's construction?

 

(please note I have no data to back up that theory)

[SteamyTea]

1 hour ago, Thorfun said:

please note I have no data to back up that theory

It might be in here.

 

https://www.iea.org/reports/global-status-report-for-buildings-and-construction-2019

 

39% of global emissions, 11% is the construction of the buildings.

So around 4% is the building.

 

Not really an issue if the building lasts 40 years.

[IanR]

1 hour ago, saveasteading said:

Interesting. Any idea Why not? They either care about carbon or don't. 

 

That's harsh.

 

Carbon foot-print for construction versus building performance are two entirely different processes that are not compatible for being captured within a single control system. Yes, the PH Institute could run a separate "Standard" for construction, but so could anyone else. It's generally better for companies to focus on their expertise though than attempt to be all things to all (wo)men.

 

I'd also say that if they were too prescriptive with regards construction method there would be a lot less buildings constructed under PH principles. Not everyone wants to build sustainably sourced timber-frame houses using only natural insulation.
 

I'd say that's also why PH targets are based on area/volume rather than occupancy. ie. to not dictating that the home owner should only allow xm² per occupant.

[joe90]

Very interesting, the Romans invented concrete which is energy/carbon intensive and some of their stuff is still standing, so not bad in the scheme of things. With my own Passive esk building I used concrete and PIR for slab and insulation but Rockwall insulation elsewhere as I wanted to limit my “plastic” use as much as I could. The building uses very little energy to heat and keep comfortable so overall better for the environment long term 🤷‍♂️

[IanR]

17 minutes ago, joe90 said:

the Romans invented concrete which is energy/carbon intensive and some of their stuff is still standing, so not bad in the scheme of things.

 

And there are many 500 year old timber frame buildings still standing, but that's not the norm.

[SteamyTea]

1 hour ago, joe90 said:

the Romans invented concrete which is energy/carbon intensive and some of their stuff is still standing

Most of the caves people lived in are still around as well.

1 hour ago, joe90 said:

I wanted to limit my “plastic” use as much as I could.

Why, it is a fantastic material. Polypropylene can last centuries, is dirt cheap, so cheap that it is not worth recycling, it is one of the easiest to recycle as well.

It is not really the material that is the problem, it is how it is applied.

[joe90]

 

41 minutes ago, SteamyTea said:

Most of the caves people lived in are still around as well.

Well no one “built” those.
 

 

Disadvantages of polypropylene:

• It has a high thermal expansion coefficient which limits its high temperature applications.
• It is susceptible to UV degradation • It has poor resistance to chlorinated solvents and aromatics.
• It is known to be difficult to paint as it has poor bonding properties.
• It has a high flammability.

no 4 is probably why it’s not good as house insulation (rockwall is a very fire resistant material).

[SteamyTea]

10 minutes ago, joe90 said:

no 4 is probably why it’s not good as house insulation (rockwall is a very fire resistant material).

https://www.ineos.com/globalassets/ineos-group/businesses/ineos-olefins-and-polymers-usa/products/technical-information--patents/ineos-engineering-properties-of-pp.pdf Auto-ignition Temperature	340°C
Energy Required for Ignition	2500 k/m2
Ignition Temperature	420°C
Minimum Radiant Flux for Ignition	20 kW/m2
Smoke Specific Extension Area	380-610 m2.kg
Soot Yield	0.06-0.09 kg soot/kg

 

So a little better than pine which auto ignites around 300°C

https://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html

 

 

[saveasteading]

2 hours ago, SteamyTea said:

a little better than pine which auto ignites around 300°C

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