ᐅ Which type of heating system is recommended for a KfW 55 energy-efficient house?
Created on: 28 Aug 2011 21:12
A
amazingbee
Hello! We are currently planning a house and, since this is not something you do often, we have many questions. Due to the development plan for our plot, we are required to build a KfW 55 energy efficiency house and are now unsure about what type of heating system we need. Builders have given us different advice!
Is it possible to install a standard gas condensing boiler combined with solar water heating, or do we have to use geothermal or air-source heat pumps?
I would appreciate any answers!
Is it possible to install a standard gas condensing boiler combined with solar water heating, or do we have to use geothermal or air-source heat pumps?
I would appreciate any answers!
EveundGerd1 Jun 2015 21:39Frank78 schrieb:
You are mixing the energy saving ordinance standard with the heating technology.
.For me, the building envelope and heating system belong together. They have to match.
Frank78 schrieb:
Here, “amazingbee” is aiming for the KfW 55 standard.Which they are trying to achieve with a gas heating system.
That’s why I suggested considering reconsidering the KfW 55 standard and choosing a different one.
Tomorrow I will calculate the costs of our gas condensing boiler in the new build including connection and so on. The last gas condensing boiler in 2008 (existing building) cost €3,800 including installation, without hot water.
L
Lebensprojekt1 Jun 2015 23:05Frank78 schrieb:
Another "can't be true" comment – I’ve already had that from a lady here in the forum recently. Do I come across as that unbelievable?
Let’s take the Viessmann Vitocal 343-G as an example, so we’re not referring to a cheap unit. COP of 4.6.
Price including a 200l (53 gallons) hot water storage tank: €8500 (gross)
Add either a surface or horizontal ground collector.
Material price around €900 for the pipes plus antifreeze and distributor... let’s generously say €1700.
That makes €10,200 plus the excavator plus beer and sausages for the helpers installing the collector.
So about €11,000? €11,500?
Subtracting a €4,000 subsidy leaves around €7,000–7,500. For a cheaper heat pump, even less.
I think a gas boiler + storage tank + flue system + gas connection costs at least the same, even though I haven’t had one quoted – tell me where you usually land! Installation and connection costs should be roughly the same.
If you definitely want or have to drill, of course, that changes things – for me that would have added a whopping €10,000 to the total cost...The gas system is included as standard in the offer from the builders (all builders I’ve dealt with).
Additional costs are about €5,000 (gas connection, tank installation, groundwork). I can tell you about tank rental and so on once I find my note with the offer details again.
Oh, and a gas boiler itself costs about €4,000 depending on the brand.
Now I have a question myself, as we are very interested in this too.
We are planning to build to the KfW 70 standard (which is mandatory). We are using an air-to-water heat pump from Wolf (BWL 1A).
Now we are considering going straight to KfW 55, since we thought that with 36.5cm (14 inches) Poroton T9 bricks, triple-glazed windows, and insulated basement, floor slab, and ceiling, the additional effort may not be that significant.
Why this consideration? Because we want to reduce the monthly electricity and heating costs of the heat pump or the general household energy consumption.
From my perspective, there are the following options:
1) Combine a KfW 55 building envelope with an air-to-water heat pump. This should reduce consumption, saving money on the heat pump operation and primary energy demand.
2) Combine a KfW 70 building envelope with a ground-source heat pump using trench collectors or boreholes. More expensive, but lower electricity costs for the heat pump operation.
3) KfW 70 with air-to-water heat pump plus photovoltaics on the roof including storage. Probably the most expensive solution, or similarly priced as option 2, but with self-generated power and the possibility to supply other household consumers with self-produced electricity, thus lowering electricity costs.
In summary, our goal is to reduce monthly electricity expenses in the most efficient way possible.
At the moment, I am leaning toward option 1. However, we do not want mechanical ventilation with heat recovery (MVHR)... would we have any chance without it?
Who can clarify these questions for us? The builder or can only an energy consultant provide certainty? We would like to have this clarified before signing the contract.
What would you do?
We are planning to build to the KfW 70 standard (which is mandatory). We are using an air-to-water heat pump from Wolf (BWL 1A).
Now we are considering going straight to KfW 55, since we thought that with 36.5cm (14 inches) Poroton T9 bricks, triple-glazed windows, and insulated basement, floor slab, and ceiling, the additional effort may not be that significant.
Why this consideration? Because we want to reduce the monthly electricity and heating costs of the heat pump or the general household energy consumption.
From my perspective, there are the following options:
1) Combine a KfW 55 building envelope with an air-to-water heat pump. This should reduce consumption, saving money on the heat pump operation and primary energy demand.
2) Combine a KfW 70 building envelope with a ground-source heat pump using trench collectors or boreholes. More expensive, but lower electricity costs for the heat pump operation.
3) KfW 70 with air-to-water heat pump plus photovoltaics on the roof including storage. Probably the most expensive solution, or similarly priced as option 2, but with self-generated power and the possibility to supply other household consumers with self-produced electricity, thus lowering electricity costs.
In summary, our goal is to reduce monthly electricity expenses in the most efficient way possible.
At the moment, I am leaning toward option 1. However, we do not want mechanical ventilation with heat recovery (MVHR)... would we have any chance without it?
Who can clarify these questions for us? The builder or can only an energy consultant provide certainty? We would like to have this clarified before signing the contract.
What would you do?
The energy consultant should be more objective, although whether that helps if the construction manager has no idea how to install the proposed option is debatable.
In my opinion, a ground source heat pump makes you more independent from electricity price fluctuations in the long run compared to an air source heat pump, since a ground source heat pump generally requires less electricity to produce the same amount of heat.
In my opinion, a ground source heat pump makes you more independent from electricity price fluctuations in the long run compared to an air source heat pump, since a ground source heat pump generally requires less electricity to produce the same amount of heat.
@Lexmaul: When exactly did you apply for the Bafa subsidy?
As far as I understand, you have to do that before commissioning anything (drilling?).
Unfortunately, our general contractor has no knowledge about geothermal energy.
For our KfW 55 standard, we also opted for a brine heat pump with ground drilling.
As far as I understand, you have to do that before commissioning anything (drilling?).
Unfortunately, our general contractor has no knowledge about geothermal energy.
For our KfW 55 standard, we also opted for a brine heat pump with ground drilling.
S
Sebastian7916 Aug 2015 13:41The drilling may already have been done – the important thing is that you haven’t signed any contract regarding the heating system yet. The application must be accompanied by an offer for the heating system.
My application was only submitted last week because I was waiting for the new heating system from Vaillant.
My application was only submitted last week because I was waiting for the new heating system from Vaillant.
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