Self Build - North Wiltshire

[knobblycats]

Hi all,

 

My wife and I are about to put in a planning application for our self-build in North Wiltshire. We live in a 1950's farm cottage - dispel any bucolic imagery, it's very ugly and it leaks water and air like a sieve! It is, however, in open countryside with great views and a large (1200sqm) plot. The plan is to do an almost entirely DIY build in the garden before demolishing the existing cottage.

 

We want to get the new build up to passive house standards but not bothering with the certification. Will likely be using ICF on insulated slab.

 

I want to move us almost entirely onto electric, including for heating and hot water. We already have 2 electric cars, a Leaf and a Skoda Enyaq and I'm looking forward to advice and debate on the best way to achieve all electric in a low-cost way!

 

Attached are the plans that we're soon submitting to planning (already gone through pre-application). Any thoughts or advice would be much appreciated. 

[ToughButterCup]

First off, welcome. And good luck with the application.

Your plan is exactly the same as ours. I love your design: we nearly chose one very similar. 

 

We built in Durisol (DIY Max) And what fun we had ??  As many downs as ups. Nestled inside now, wind whistling round our withers, nice and warm, no heating on at all.

Not finished yet - its relentless, and I'm getting a bit fed up - mostly tiredness - after 5 years non-stop work except for the odd weekend in Glasgow. I realise thats a very selfish thing to say - many would donate their eye teeth to have the chance I have been given. 

 

Use the search box on this site for DURISOL, that should give you a good insight to the ups and downs of the material and processes.  There are other excellent ICFs each with their own characteristics. I would use Durisol again - but mainly because I know what to look for and what the pitfalls are.

 

Good luck with the application,

Ian

[Bitpipe]

Quite a few here are all electric, if your build is of a passive standard then your heat requirement will be low so low temp UFH plus a ASHP would work well. Has the advantage of running in reverse in summer to cool your GF. 

 

PV will help also - you have a nice south elevation that would work well with in roof panels.

 

 

 

 

 

[jack]

Nice looking project.

 

I'd definitely be looking into getting three-phase power onsite if you have two electric cars and are considering running your house solely on electricity.

[JohnMo]

Your heat demand should be low, if going passive or close too.  Others have just Willis heater's, for UFH, e7 for DHW.

 

Would be worth doing some cost benefit analysis, compare ASHP.  What ever you do keep UFH control simple, no weather compensation, simple  or single thermostat etc.

 

Good luck, you will learn a lot. I can recommend Durisol also.

  

[knobblycats]

@ToughButterCup thank you for the warm welcome!

 

@Bitpipe and @JohnMo interesting you both mention UFH - I'm all for keeping things simple and had actually thought about not having UFH at all! Where would be the best place on this forum to start a thread on heating?

 

@jack good point, I've eyeballed our supply pole and there's definitely 4 cables so here's hoping we can get three phase easily enough!

[JohnMo]

I would go to that specific place on the forum have a good old read, loads of good info.

 

Best thing about UFH, is nothing on the walls.  200mm of PIR insulation in floor, polythene over, clip tubing to insulation, screed over. Design with a free copy of loopcad or get suppliers to do it for you.  Once you get your head around it very easy to do.  Me and wife did ours.

[jack]

2 hours ago, JohnMo said:

What ever you do keep UFH control simple, no weather compensation, simple  or single thermostat etc.  

 

My setup is nearly as simple as it can be - single thermostat, single downstairs zone - but I do find weather compensation to help. I run 25 degrees when the temperature is above (from memory) 7 degrees, with a linear rise to 28 degrees as the temperature drops to 0 degrees. Could be my imagination, but I found that running at 25 degrees fixed would leave the house feeling a bit cool during a long cold spell. 

 

It adds almost no complexity. I set the curve once on the main ASHP controller, and haven't really looked at it again in several years.

[jack]

51 minutes ago, knobblycats said:

 

@Bitpipe and @JohnMo interesting you both mention UFH - I'm all for keeping things simple and had actually thought about not having UFH at all! 

 

UFH is definitely something I wouldn't be without in a well-insulated house, especially downstairs. 

[Thorfun]

5 hours ago, knobblycats said:

Any thoughts or advice would be much appreciated. 

welcome. my advice is to keep us updated with progress! we love a good self-build on here. ?

 

[Bitpipe]

2 hours ago, knobblycats said:

 

@Bitpipe and @JohnMo interesting you both mention UFH - I'm all for keeping things simple and had actually thought about not having UFH at all! Where would be the best place on this forum to start a thread on heating?

 

As said above, if you build to passive standards your house will have quite a low heat requirement.  

 

Low temp UFH is therefore an ideal method to deliver that heat requirement.

 

If you have an insulated slab, the UFH pipes are fixed to the mesh ahead of the slab pour and the slab is heated as a single zone. Saves cost on another layer of insulation & screed etc.

 

If you use an ASHP, this can be reversed in summer and the slab can be cooled to just above the dew point. If this is not of interest there are other ideas above on how to generate the heat for the UFH and also your domestic hot water (DHW).

 

Your bedrooms should not require separate heating but you can make provision and install later if required. Nice to have warm bathroom floors if tiled (low power electric ufh is good option here) and towel rads for warm towels. 

 

MVHR is a must in a passive standard house as you'll have high degree of airtightness through use of ICF and will likely spec decent windows without trickle vents etc. While MVHR is not good at moving heat around (very low airflow) it does ventilate very efficiently with minimal heat loss. You can consider introducing additional heat (or cooling) to the MVHR system, just be aware that at best it will act as a trim and not the main source of warmth.

[Adrian Walker]

On 08/12/2021 at 12:11, knobblycats said:

Hi all,

 

My wife and I are about to put in a planning application for our self-build in North Wiltshire. We live in a 1950's farm cottage - dispel any bucolic imagery, it's very ugly and it leaks water and air like a sieve! It is, however, in open countryside with great views and a large (1200sqm) plot. The plan is to do an almost entirely DIY build in the garden before demolishing the existing cottage.

 

We want to get the new build up to passive house standards but not bothering with the certification. Will likely be using ICF on insulated slab.

 

I want to move us almost entirely onto electric, including for heating and hot water. We already have 2 electric cars, a Leaf and a Skoda Enyaq and I'm looking forward to advice and debate on the best way to achieve all electric in a low-cost way!

 

Attached are the plans that we're soon submitting to planning (already gone through pre-application). Any thoughts or advice would be much appreciated. 

 

 

 

 

Welcome to BuildHub and good luck with your application,  the design and build to passive house standards is a good choice.

 

I presume that you have used an architect to develop your ideas? Has your house been modelled in PHPP? Your form factor could be a little squarer, but with lots of insulation that shouldn't be a major problem.  ICF comes in many versions, but I would look at Velox rather than Durisol or Isotex if you don't want the hassle with airtightness.  Depending on your ground conditions Foamed Glass might be a good  way to achieve an insulated slab.  For DHW (Domestic Hot Water)I would have a look at Sunamp, charged using off-peak electricity. UFH would be a sensible solution for space heating with the option for cooling using an ASHP.  Your heating requirement are going to be minimal.  I presume that you have a large PV array?