Passiv house costs.

[Oz07]

https://www.bbc.co.uk/news/articles/cg5l3z7p922o

 

Just reading this article they claim building to passiv standard is 5% extra for houses (semi) and 2% (flats). I wonder why they don't include detached. 2 and 5% seem unbelievable to me. Perhaps detached is a lot higher? Don't forget all the boffin work that goes into designing these houses and understanding how all the different elements will interact. 

 

They talk of the new future homes standard next March. I will ask AI what the implications will be.

[Oz07]

Seems that institution is a trade body. Its basically propaganda that article. 

 

Interestingly the changes don't seem too extreme to me. U value targets are similar. Airtightness is ok don't think I've ever been over 3. It does appear to be more aggro so hopefully I can get planning and b regs sorted before March. 

 

Wonder how these changes will effect the housebuilding targets. 

[-rick-]

With the current building regs, meeting passivhaus standards isn't that much of a leap (assuming you are building with quality/well finished detail in mind).

 

It used to be our regs were way way weaker and now they are not. The cost of building houses has gone up a lot also and the added cost of insulation, better windows, etc, becomes a smaller part of the overall budget.

 

I can see the cost of doing the paperwork/documentation to get certified as potentially being the main additional cost of going passivhaus with some (more optimal*) designs.

 

* ie, the existing design for the house is a relatively energy efficient shape, with reasonable glazing (heat loss and heat gain perspectives), already has MVHR planned, etc.

[JohnMo]

51 minutes ago, Oz07 said:

Don't forget all the boffin work that goes into designing these houses

Self build pays for that each time, as they are generally one offs. A developer should only pay once for multiple houses.

[Oz07]

6 minutes ago, JohnMo said:

Self build pays for that each time, as they are generally one offs. A developer should only pay once for multiple houses.

Yes always gonna be more expensive for one offs. Then again I suppose there is the flip side where clever folk like yourself can work out all these interactions themselves. 

 

The AI was saying we do not have enough highly skilled trades to complete enough houses. Sloppy bricklayers with insulation, rough joiners or not enough engineers familiar with heat pumps. I can believe it. 

[-rick-]

4 minutes ago, Oz07 said:

The AI was saying we do not have enough highly skilled trades to complete enough houses. Sloppy bricklayers with insulation, rough joiners or not enough engineers familiar with heat pumps. I can believe it. 

 

Indeed, standards are getting tougher which should in time lead to better quality (for any project) but lack of labour availability makes things difficult whatever you are doing. The good contractors generally know what they are worth given availability.

Edited 2 hours ago by -rick-

[Oz07]

32 minutes ago, -rick- said:

With the current building regs, meeting passivhaus standards isn't that much of a leap (assuming you are building with quality/well finished detail in mind).

 

It used to be our regs were way way weaker and now they are not. The cost of building houses has gone up a lot also and the added cost of insulation, better windows, etc, becomes a smaller part of the overall budget.

 

I can see the cost of doing the paperwork/documentation to get certified as potentially being the main additional cost of going passivhaus with some (more optimal*) designs.

 

* ie, the existing design for the house is a relatively energy efficient shape, with reasonable glazing (heat loss and heat gain perspectives), already has MVHR planned, etc.

I'm not sure about that. The u values above are surely not going to be anywhere close to passiv?

 

I get what you are saying though the regs have come on a lot in the last 20 yrs. I think they are at about the right level now for mass market homes. Keeping in mind end users. There is nothing against individual builders going the extra mile if they want to, or if they think it will help increase value (doubtful)

[-rick-]

Just now, Oz07 said:

I'm not sure about that. The u values above are surely not going to be anywhere close to passiv?

 

0.18 is the regs

 

Depending on the house I've read that 0.15 might be all thats needed to meet passivhaus (there isn't a specific number as passivhaus is more about the overall heat loss which is affected by windows, air tightness, etc)

 

It's not much difference in the quantity of insulation (another 50mm)?. The detailing is stricter and really once you are in this range air tightness matters much more. If you focus on that you need less insulation.

[MPx]

Well we're finding it hugely expensive so I'm not surprised its not viable commercially.  Our passive house is going to cost way more to build than it will be worth on the market thereafter.  Latest example:  We have an integral garage.  Garage outside the passiv envelope, hallway inside.  Door from garage to hall very nearly impossible to source.  You can buy any number of FD30 rated fire doors for a few hundred quid as required by BC in that location.  You can buy quite a few doors adequately rated for thermal efficiency and airtightness and they cost low thousands.  But try to find a door that covers both angles and that's a tad harder.  After a 6 month search I've found two companies who will make me one.  One for £7k the other £8k.  That's a lot of money for one internal door!

[Oz07]

27 minutes ago, -rick- said:

 

0.18 is the regs

 

Depending on the house I've read that 0.15 might be all thats needed to meet passivhaus (there isn't a specific number as passivhaus is more about the overall heat loss which is affected by windows, air tightness, etc)

 

It's not much difference in the quantity of insulation (another 50mm)?. The detailing is stricter and really once you are in this range air tightness matters much more. If you focus on that you need less insulation.

My last place was built to those u values with good airtightness (less than 1 I think on the normal test) and mvhr and I wouldn't of thought it was anywhere close to passiv. I remember doing at energy used per sqm thread on here years ago at the time. 

[mjc55]

How long though before houses are being built by robots?

 

https://www.bbc.co.uk/news/videos/cgljl9zp47xo

 

They will work 24 hours a day, to exacting standards.  I would imagine that passive would be easy for them to achieve.

 

I used to think that it was the trades that would benefit from AI as they will still have jobs whilst others won't - now I am not so sure. 

[Oz07]

33 minutes ago, mjc55 said:

How long though before houses are being built by robots?

 

https://www.bbc.co.uk/news/videos/cgljl9zp47xo

 

They will work 24 hours a day, to exacting standards.  I would imagine that passive would be easy for them to achieve.

 

I used to think that it was the trades that would benefit from AI as they will still have jobs whilst others won't - now I am not so sure. 

I wouldn't hold your breath. I'm sure it is coming eventually but surely we are talking decades rather than years