New build energy efficiency "must haves"

[Olly P]

We are designing our 275 sqm self build dormer 1.5 storey 4/5 bed bungalow set in a just under 4 acre field. We are planning on living here for the rest of our lives and would like the dwelling to be well insulated,and have some energy efficient systems such as MVHR and possibly a ground source heat pump, may be triple glazing to reduce the running costs. 

 

With out  going all out "eco home" (we are wanting to build a traditional design with a few modern elements) what would be the the must have energy saving systems that you would suggest? 

[gravelld]

No systems or bling, just fabric first - highly insulated, best windows you can afford, low air permeability. If you get that right then I'll grant you the MVHR bling ? 

 

But you probably won't need much in the way of heating, so a GSHP might be overkill. You're better off putting the £20k-odd that costs into the fabric.

 

All completely possible with traditional design.

[ragg987]

The biggest impact is from a fabric-first approach - ensure there is a high-level of insulation (walls, floor, roof) and air-tightness, then the rest is less critical. Though once you have a high-level of airtightness then you will need some active ventilation - e.g. MVHR.

 

4 minutes ago, Olly P said:

With out  going all out "eco home" (we are wanting to build a traditional design

The two are not mutually exclusive - you can have an eco traditional home. It is attention to detail that will make the difference.

[ProDave]

You have the basics in mind already.  Good insulation. Good air tightness (mostly attention to detail) Triple glazing is not much more than double, concentrate on finding a quality window supplier.  The one you will get some discussion about is the heat pump.  Most of us concluded an air source heat pump is better value. Not quite so efficient but a LOT cheaper to install and less maintenance.

 

Also consider solar PV. That is harder to justify now without any FIT to subsidise it but a couple of us have done cheap DIY installs.

[SteamyTea]

PV on the roof can save you cash on tiling, so my still be worthwhile.

I am intrigued by the concept of eco bling.  Seems to mean anything connected to the internet.

 

A heap pump is hardly a new idea.  I don't think they are blingy.

 

[joe90]

I agree with all the above comments particularly insulation and airtightness. Like you I wanted a traditional looking build and in our case a “cottage”. Ours is traditional build, brick and block (I hate render) but with 200mm cavity full filled and 300 in the warm roof. Despite the roof being “I” beam construction I inserted false beam ends to make it look like an old roof would be. We have UFH with ASHP which is easy and cheap(ish) to instal. Our windows were hand made locally and are double glazed (but very near triple in u value and we are in a mild part of the country. Might not be everyone’s cup of tea but we are very pleased with the result.

[Olly P]

 

Looks fantastic joe90 you should be very proud of your build ????.

We were also thinking of a wide cavity for increased insulation and warm roof construction.

 

 

It's worth mentioning that gas  water and electricity are on site so energy generation isn't essential. Very interesting about the GSHP vs ASHP, as we have enough room for GSHP I was advised to go for it but if ASHP is cost efficient then i think that's the way to go.

 

Solar PV DIY, something I am interested in. Any links to suppliers? 

 

Thanks all for the helpful comments. 

 

 

[nod]

2 hours ago, gravelld said:

No systems or bling, just fabric first - highly insulated, best windows you can afford, low air permeability. If you get that right then I'll grant you the MVHR bling ? 

 

But you probably won't need much in the way of heating, so a GSHP might be overkill. You're better off putting the £20k-odd that costs into the fabric.

 

All completely possible with traditional design.

Great answer 

Absolutely agree We we’re so looking forward to heating up the 150 square metres of porcelain on the ground floor 

In reality we hardly have the UFH on The radiators on the first floor where on for half a day testing But haven’t been switch on since moving in last December 

I would agree Fabric of the build is everything 

[ProDave]

7 minutes ago, Olly P said:

 

Looks fantastic joe90 you should be very proud of your build ????.

We were also thinking of a wide cavity for increased insulation and warm roof construction.

 

 

It's worth mentioning that gas  water and electricity are on site so energy generation isn't essential. Very interesting about the GSHP vs ASHP, as we have enough room for GSHP I was advised to go for it but if ASHP is cost efficient then i think that's the way to go.

 

Solar PV DIY, something I am interested in. Any links to suppliers? 

 

Thanks all for the helpful comments. 

 

 

Have a look at my thread about DIY solar PV

 

Re ASHP / GSHP.

 

For a GSHP you have to bury a lot of pipework in the ground.  Even though I had my own digger at the time, I decided it was a LOT of work.  then you have to fill that pipework with quite a lot of brine.  I worked out the pipe and brine would cost more than the actual heat pump.

 

An ASHP you just site close to the building and connect 2 pipes and some cables.  a LOT easier and a lot cheaper.

 

Ssomebody worked out that although a GSHP was more efficient, but the difference was small and the saving in energy over it's lifetime would never pay for the additional install costs.

 

There is another subtle difference.  A GSHP puts the works inside the house, so you might get noise problems (like having a large fridge running for a lot of the time)  But an ASHP puts the works outside so far less likely to be heard inside the house. 

[PeterW]

GSHP is only worth it if you go for RHI and then making the house air tight and fabric first becomes pointless as it reduces your payments .... 

 

Go for min 150 cavity - blown beads are good. If you can get 350mm deep rafters then Warmcell in the roof is good for both heat and sound insulation. 

 

Seriously consider using in roof PV as the cost is about £30/Sqm more for in roof PV to slate, and about £50/sqm for tiles. Becomes a real no brainer

[NSS]

Probably goes without saying, and with a 'traditional' design you may not intend to have a lot of glass, but worth considering what effect solar gain may have. A well insulated near airtight home can easily overheat.

[Oz07]

@joe90 stainless wall ties or composite out of interest?

[Conor]

12 hours ago, Olly P said:

 

It's worth mentioning that gas  water and electricity are on site so energy generation isn't essential. Very interesting about the GSHP vs ASHP, as we have enough room for GSHP I was advised to go for it but if ASHP is cost efficient then i think that's the way to go.

 

 

Gas usually come up on top in terms of cost over heat pumps. Obviously you have the carbon emissions aspect that requires deeper consideration. But can't get around fact that mains gas is (currently) 3-4x cheaper than electric, and gas boilers are much cheaper than heat pumps and have proven reliability and predictable service costs. 

 

I think it will swing the other way in a few years time, but in my case I'm going for gas as it's a much lower capital outlay and there's little difference in running costs. Possibility to change to heat pump in the future will be there tho.

 

 

12 hours ago, Olly P said:

 

 

[joe90]

2 hours ago, Oz07 said:

@joe90 stainless wall ties or composite out of interest?

 

Interesting, the composite were sooo expensive I did some back of fag packet sums and the thermal bridge for the stainless ties I found was minimal so went with stainless.

[SteamyTea]

41 minutes ago, joe90 said:

Interesting, the composite were sooo expensive I did some back of fag packet sums and the thermal bridge for the stainless ties I found was minimal so went with stainless.

There has been talk that stainless steel ties can cause cold spots, which may cause localised condensation.  Though I suspect that this is an over rated problem.

 

[joe90]

1 hour ago, SteamyTea said:

There has been talk that stainless steel ties can cause cold spots, which may cause localised condensation.  Though I suspect that this is an over rated problem.

 

 

Because of our wider cavity the stainless ties are in the mortar for the min distance allowed (forgot what this was) so any small amount of coolness is dispersed. I had no indication of cold spots during this last winter.

[Olly P]

Had the quotes back from British gas and electricity north west. £475 plus vat for gas...... £6700 for electricity!! ?. They say this is down to a road closure to carry out the connection ( although the gas connection will be crossing the road too) 

 

So far we have on the short list of must haves in energy efficiency terms; wider cavities, UFH and ASHP.  We will be running a log burner too and have a tree surgeon friend who gets us logs virtually FOC so that will be a source of heat in the winter.

Edited May 15, 2019 by Olly P

[gravelld]

If you're talking log burners then that's another area you should research thoroughly (if efficiency is your aim).

 

The trouble with log burners is what they are doing when they aren't running. If you have a standard open flued burner it's basically exhausting heat out of your house on a 24/7 basis.

 

So instead you need a room sealed log burner. I believe there are some certifications around these about retaining their seals over many years use. You will need to run a duct to connect the log burner to the outside. Someone else will be able to fill you in on more detail with these.