I'm really confused! Please help

[Juj]

Hi,

I'm not entirely sure if this post belongs here but there are several components that I think I should consider as part of one solution: Heating and Hot Water.

 

You may be familiar with my project from the introductions forum but I'll present you with my circumstances in any case.  I currently have a Combi Boiler heating our traditionally constructed 2700sq.ft bungalow and providing hot water to 2 showers (right now we use 14000 kWh Electricity and 48907 kWh Gas per annum!).  We will be updating the current building with thicker loft insulation and better windows, but will still use rads to heat this portion of the house when we complete the renovation.

 

 The new part of the house will add around 6000sq.ft and will be built to much better u values using ICF walls and SIPS roof.  Here's where I'm confused, I don't know what the best system will be that can provide loads of hot water (7 showers), heat UFH in the new part and also heat the rads in the old part.  I'm further confused by mhrv, I've heard this is a necessity in ICF homes, but then heard the speaker at the homebuilding show at NEC state that they're pointless for homes over a certain size.  I'm open to installing an ASHP but I'm not sure whether it's necessary or even beneficial when I have the option of mains gas.  Lastly, I've a good size roof pointing SE without any shading to speak of so we could potentially generate a considerable amount electricity, but I would have to consider the regulations of having a system over 4kWh and the costs associated, also factoring potential battery storage over and above Sunamp if this too makes sense to use. I don't have a clue where the feed in tariff comes in to all this!

 

There will also be a detached annexe of around 800sq.ft and we will most likely go with UFH and 1 shower, I'm not sure how this should be incorporated in to the overall scheme or whether I should treat it separate.

 

I know its probably a good idea to speak with an energy solutions firm and will most likely speak with Stratford Energy Solutions who have been recommended to me, however, I also know that they may have commercial interests that don't take in to account all of the factors we self builders consider.    

 

Edited April 4, 2018 by Juj
Forgot to mention Annexe

[Nickfromwales]

Ok, so DHW is a big part of this picture. 

When you say 7 showers, how many occupants will there be to use them ? 

[Ferdinand]

The regulations and costs for solar are likely to be an issue at 10kWp, not 4. I have 9.98 and they just included all the extra admin in the price that did not feel too expensive. Cost for black panels and backgrounds with Solaredge and as 3 separate arrays some easy some hard was about £11.75k in Jan 2016 all in.

 

Play the game right with saving on the tiles for a new roof and you should save a good chunk off that.

 

I think you are within range, so I will PM the details of my supplier.

 

It feels to me that you probably want a distributed solution for water heating, and to transfer the energy around via electricity or gas rather than hot water, certainly to the annexe. Several Distributed Sunamps?

 

A monopitch on the annexe angled to catch the sun might give you a full 10kWp solar install in that one place. I make 800 sqft plus a roof pitch big enough for about 40 pv panels, which is 10kWp as near as dammit. If it is single storey or even a ground style array on a flat roof that will also hugely simplify any maintenance should you need it.

 

F

 

 

Edited April 4, 2018 by Ferdinand

[Nickfromwales]

8 minutes ago, Ferdinand said:

Several Distributed Sunamps?

Maybe, but also the option to fit a couple of Rinnai tankless gas water heaters. 

Pro :

capital cost

 

Con :

flue penetration

annual inspection 

[Juj]

53 minutes ago, Nickfromwales said:

Ok, so DHW is a big part of this picture. 

When you say 7 showers, how many occupants will there be to use them ? 

@Nickfromwales There are 6 adults and 3 kids, kids are still young so could possibly 1 more? This is the forever house so cost over the long term is important, but so is being able to get it done in the first place!

[Juj]

@Ferdinand Mounting the solar panel on the annexe is an interesting idea, I'd not thought of it since the main building has a much larger roof area.  If it's possibly it would certainly be easier to maintain and would most likely save me costs of having integrated panels in the main roof.  Do you know if there is a solar panel that could double up as a  roof panel so that I could forgo another roofing solution or am I making this trickier than it needs to be?

 

[Ferdinand]

5 minutes ago, Juj said:

@Ferdinand Mounting the solar panel on the annexe is an interesting idea, I'd not thought of it since the main building has a much larger roof area.  If it's possibly it would certainly be easier to maintain and would most likely save me costs of having integrated panels in the main roof.  Do you know if there is a solar panel that could double up as a  roof panel so that I could forgo another roofing solution or am I making this trickier than it needs to be?

 

 

If you dig around eg on @JSHarris‘s blog Jeremy costed his in-roof solar panel system. I think if you go for solar tiles the efficiency roughly halves. Jeremy's is in a conservation area. 

 

The cost efficient in roof solar are roof membranes plus panels and minus the cost of tiles which are not then needed.

 

F 

 

[Nickfromwales]

29 minutes ago, Ferdinand said:

 

If you dig around eg on @JSHarris‘s blog Jeremy costed his in-roof solar panel system. I think if you go for solar tiles the efficiency roughly halves. Jeremy's is in a conservation area. 

 

The cost efficient in roof solar are roof membranes plus panels and minus the cost of tiles which are not then needed.

 

F 

 

+1. Scrap the roof tiles and use the solar setup as your covering. ?

[Juj]

13 minutes ago, Nickfromwales said:

+1. Scrap the roof tiles and use the solar setup as your covering. ?

Just so that I'm getting this right, I can use a large array of solar panels in place of a roof covering (EDPM etc.) I've never actually seen a solar roof take up the entire roof, normally its bordered by normal roof tiles.  I'll have to look through @JSHarris blog in more depth.

[Jeremy Harris]

These entries show the in roof PV system:

 

http://www.mayfly.eu/2013/11/part-twenty-two-roofing-and-mvhr-and-a-quick-video/

 

http://www.mayfly.eu/2014/01/part-twenty-six-the-scaffolding-comes-down-at-last/

 

And here are some photos of the in roof PV system being fitted and the completed front elevation, which looks on to a GII listed building and is inside an AONB and Conservation Area, so we had a fair few planning issues over putting PV on the roof:

 

 

 

[Ferdinand]

30 minutes ago, Juj said:

Just so that I'm getting this right, I can use a large array of solar panels in place of a roof covering (EDPM etc.) I've never actually seen a solar roof take up the entire roof, normally its bordered by normal roof tiles.  I'll have to look through @JSHarris blog in more depth.

 

it is not quite in place of. But you do not need the tiles or similar behind the area where the panels go.

 

So you would have your waterproof Edpm membrane, with panels over, but tiles round the edge only.

 

Here is J’s blog. It is worthwhile reading from end to end.

http://www.mayfly.eu/

 

F