Passiv house costs.

[garrymartin]

38 minutes ago, -rick- said:

A lot of custom one-off homes will tend to be in the more expensive as the customers will want nice things like big windows, overhangs, lots of corners and detail or simply to squeeze a lot into a difficult site. Meeting the passivhaus standards then will add a lot more cost than a simple box.

Spot on. Passivhaus is only of near-equal cost parity if the building was designed to be Passivhaus from the beginning, including principles of form factor. If someone has designed a home, and then tries to make it Passivhaus, then you are almost in retrofit territory, which of course costs more.

 

18 minutes ago, saveasteading said:

I was thinking of one-offs as most on BH are.

I think you can do one-offs too at significantly less than 30% increase in costs, but as above, you need to design from the outset.

 

The garage door is a great example earlier in this thread. It looks like the architect/designer didn't consider this at the outset, and possibly made the fire *and* airtightness barrier/boundary the same, causing the requirement for an airtight and thermally efficient fire door, which was very costly. Separating those elements (fire/airtight) at the design stage may have resulted in signficantly less cost. It may not have been possible given site or design constraints, but just one example.

[Gone West]

3 hours ago, -rick- said:

An example of cost saving might be that if you meet passivehaus standards, especially in a compact home, your heating demands are tiny so you can skip the expensive heat pump install and just put in a couple of small electric heaters.

Exactly. We designed and built our last place to PH standards. It was around 130m2 and was heated with a towel rail in each of the three bathrooms and an EASHP built into the MVHR came on when the weather was very cold. The whole house was kept at 23C 24/7. Very low energy costs.

Edited 13 hours ago by Gone West

[MPx]

14 hours ago, Oz07 said:

I've been thinking about this. Not an ideal solution but one which should pass? Have a non fd rated passiv level insulated door opening into your hallway, and a fire doorset immediately behind opening into the garage. Depending what is stored in the garage after sign off you may want to remove fd? If the garage size and position of opening allows you may even like to build a small stud lobby within the garages. Insulated door into house, fire line the stud and fire door on the stud going into garage?

Yes, as our walls will be some 400mm thick we could support a double door withing the aperture and we considered the FD on the garage side and the passive door in the hall, but what a pain to use, exacerbated by the self close on the fire door.  

 

12 hours ago, -rick- said:

 

The problem you describe here is one that has come up several times on this forum (for people who are just trying to be energy efficient, not building to passivhaus standards). Integrated garages impose a lot of extra costs that aren't obvious when the architect first draws them. That said, they are often the only option in many plots.

Integral garage a part of our brief.  Drive in and enter the house out of the weather.  

 

So part of the design.  But as it doesn't appear to be possible to make an operational garage airtight or thermally efficient it has to be outside the envelope.

 

Building control also working against us.  Nonsense requirement to have a 150mm step between garage and hall - no doubt mitigating risks that no-one has ever seen materialise.  Working opposite to the requirement to have a level entry to the front door.  By definition there must be a step or slope if the garage is 150mm lower so "level" is not a possible outcome.  We're just trying to make sure we're able to manage life with mobility issues should that come to pass - but hopefully it wont!

Edited 4 hours ago by MPx