Planning a brand new system for a new build

murphaph

Hi all,
We're living over in Berlin and next summer we're going to build a well insulated (Roof 0.178, walls 0.147, windows 0.7 and floor 0.205 W/m²K), airtight house on the outskirts of the city. We're at the preliminary stages of planning this house but we know we'll be going the prefab house route (hence the known U values-most prefab manufacturers here will hit those figures).

Roof will be full length pitched roof around 45% pitch and facing more or less south or slightly south west. Approx 100m² of roof space available for use on sunny side.

The plan in my head is the following:

Ground source heat pump (not sure if bored or horizontal collector buried 1.5m below surface. The site we have bought is 922m² and rectangular so it's big enough for that option. The house will only take up a footprint of around 100m² as it'll have a cellar. Total living area around 200m² including cellar which will be livable,

Photovoltaic panels on roof to power the heat pump during the day and heat up external large volume, low heat loss buffer tank which can be used either to provide DHW or UFH with energy.

Ventilation with heat recovery also.

My thought process is as follows...

In Germany there's 20 years left to run on the guaranteed price per kWh but it's sinking year on year. Currently it's €0.17 but electricity is expensive here, around €0.28/kwh so anyone who installs a new system today is financially better off if he can use the solar produced, rather than selling into the grid.

Seeing as it's more lucrative to use as much of the electricity generated ourselves, we come to the idea of somehow storing that energy. The batteries are still not a mature enough technology in my eyes and are relatively expensive compared to a system without them. So, as an alternative to batteries I think it might make sense to use the electricity at midday (when we're usually all out of the house at work/school) to drive the heat pump and charge the buffer tank for use in the evenings.

What are your thoughts on such a setup?

Condenser

You need to take advantage of the Smartgrid which is being rolled out across Germany at the moment as you can purchase electricity for your heating at opportune times which will reduce the cost of running the system. The right heat pump can even choose the tariff for you and when to run.
I'd talk to a company called GeoSolar who would be a very large installer in the Berlin area.


Supplementing with PV is also a very good option in Germany and your heat pump can control this too.

murphaph

Cheers for the tip Condenser. We will be limited in who we can select for the install because we have decided to do everything through the housebuilder. More expensive that doing the bits individually but my other half was not in favour of building at all and could only be persuaded if we took a turnkey solution where we only have 1 point of contact no matter what the issue,

I'm tending towards a company called fingerhaus.de and they supply as one of their packages the Viessmann 222-G with the smart controller you mention which can decide to use the PV energy at noon (while we're at work) to charge the hot water tank, the heating circuit buffer tank or to simply heat the heating circuit (or passively cool it in high summer).

For our size property they charge €12,950 for the 100m deep bore hole (they don't state if the cheaper horizontal collector is an option), the heat pump and the underfloor heating itself and fitting of course. I think that's an ok price.

Wrt the smartgrid...is there any point in that AND a smart heat pump control which can intelligently use your own PV energy after all other electrical consumers in the house have been satisfied? It currently and in future will make more sense to use your own PV energy because of the falling feed in tariffs here (falling to keep in line with rapidly falling PV equipment prices) so we'd be looking to use washing machines and any other non-time sensitive loads during the afternoon when the PV provides its peak output. We therefore wouldn't want our washing machine to switch on at 3am to avail of cheaper wind energy from the grid like our neighbour who has no self generation capability. Maybe I'm missing something here?

Condenser

The very latest units will decide which tariff to pick from which supplier on any given day so you can purchase from suppliers that are oversupplying at that particular time. When you need the heating on will vary depending on the weather so saying exactly when you'll use the electricity is difficult to predict, in some cases it might be cheaper to use the power from a supplier than use your own.


I assume the price you received is an additional cost on top of what a standard house with gas boiler system would cost (i.e. the gas system costs 10k but the heat pump is an additional €12K) as I know a 100m bore around Berlin would generally set you back €4,500 to €5,500 depending on the driller. You couldn't even buy the material for the installation at the price you mentioned.

murphaph

Condenser wrote: »

The very latest units will decide which tariff to pick from which supplier on any given day so you can purchase from suppliers that are oversupplying at that particular time. When you need the heating on will vary depending on the weather so saying exactly when you'll use the electricity is difficult to predict, in some cases it might be cheaper to use the power from a supplier than use your own.


I assume the price you received is an additional cost on top of what a standard house with gas boiler system would cost (i.e. the gas system costs 10k but the heat pump is an additional €12K) as I know a 100m bore around Berlin would generally set you back €4,500 to €5,500 depending on the driller. You couldn't even buy the material for the installation at the price you mentioned.

As far as I understand it no, the company would normally charge €20,950 for the bore, heat pump + UFH so the €12,950 is a special price (probably a loss leader for them but I'm sure they've done their sums and make it up somewhere else). If you choose their standard condensing boiler option + 2 solar panels (hot water) + UFH + basic ventilation system (no heat recovery) it's currently €8,100. Some of these prefab house manufacturers include a basic boiler as part of the base price but not this crowd. They specialise in renewables in their builds (apparently in Germany 37% of new builds use renewables generally but with them it's 85%...it's kind of their focus).

http://www.fingerhaus.de/unternehmen/aktuell/aktionen/energieplus/

I suppose you can't really say the geothermal solution they offer for 13k is really the price because you have to build the rest of the house with them to get that price. It's hidden somewhere else if it's impossible to provide that package for 13k, it must be.

We will absolutely keep the smart meter in mind now (it's on my list) and will ask them about it when we go for quotes (the site purchase is going through now so don't want to hex anything!).