ᐅ New Single-Family Home Built to KfW55 Standard – Which Heating System to Choose?
Created on: 19 Jul 2020 12:19
T
Traube348
Hello everyone,
I have read many articles and would now like to benefit from the extensive knowledge of the members here.
A brief overview of my building project:
- Single-family house with approximately 160sqm (1,722 sq ft) of living space
- No basement, 2 full floors with an unfinished attic
- Relatively large window areas and an open-plan design with a staircase in the living area
- Underfloor heating throughout the house with tile flooring
- KfW 55 standard with timber frame construction
- A wood-burning stove will be installed
Unfortunately, I have little experience in this area and rely on recommendations from others regarding heating.
On the ground floor, we have a utility room of 8sqm (86 sq ft) where we would like to accommodate all the technical equipment.
The builder recommends installing a central ventilation system, which we would like to do.
Now to my question:
There is a gas connection in our building area, and a friend told me we should definitely heat with a gas boiler. To meet the KfW standard, according to the energy consultant, we still need to install 9sqm (97 sq ft) of solar panels on the roof.
A heating engineer friend advises: choose an air-to-water heat pump – split system Weishaupt LS 8-BREK – so you can avoid the solar requirement.
I have requested quotes for both options from different heating engineers, and they come out roughly the same in price.
Since I have heard many statements opposing air-to-water heat pumps, I tend to prefer gas.
However, the main challenge is the limited space in the utility room. In addition to the heating system, the two-flue fireplace, and the ventilation system, the electrical control cabinet as well as the washing machine and dryer are also planned to be located there.
Is there anyone who has faced a similar space issue?
What would you recommend?
Thank you very much in advance for your help.
I have read many articles and would now like to benefit from the extensive knowledge of the members here.
A brief overview of my building project:
- Single-family house with approximately 160sqm (1,722 sq ft) of living space
- No basement, 2 full floors with an unfinished attic
- Relatively large window areas and an open-plan design with a staircase in the living area
- Underfloor heating throughout the house with tile flooring
- KfW 55 standard with timber frame construction
- A wood-burning stove will be installed
Unfortunately, I have little experience in this area and rely on recommendations from others regarding heating.
On the ground floor, we have a utility room of 8sqm (86 sq ft) where we would like to accommodate all the technical equipment.
The builder recommends installing a central ventilation system, which we would like to do.
Now to my question:
There is a gas connection in our building area, and a friend told me we should definitely heat with a gas boiler. To meet the KfW standard, according to the energy consultant, we still need to install 9sqm (97 sq ft) of solar panels on the roof.
A heating engineer friend advises: choose an air-to-water heat pump – split system Weishaupt LS 8-BREK – so you can avoid the solar requirement.
I have requested quotes for both options from different heating engineers, and they come out roughly the same in price.
Since I have heard many statements opposing air-to-water heat pumps, I tend to prefer gas.
However, the main challenge is the limited space in the utility room. In addition to the heating system, the two-flue fireplace, and the ventilation system, the electrical control cabinet as well as the washing machine and dryer are also planned to be located there.
Is there anyone who has faced a similar space issue?
What would you recommend?
Thank you very much in advance for your help.
DaSch17 schrieb:
We were told that with an oversized photovoltaic system, you produce more electricity than you can use, and that excess is essentially lost when the battery storage is full (especially during the warmer months). Also, I once read somewhere that the ratio of battery storage to photovoltaics should be roughly 1 kWp = 1 kWh.
So, should we rather opt for a larger photovoltaic system?What is supposed to be lost? Everything you don’t use is actually paid for! Unless you take some silly storage subsidy that requires you to limit output to 50%. Also keep in mind that a larger system produces more energy even under low light conditions, which increases your self-consumption rate. That’s especially important in winter.
I would save the money on the battery entirely and just install as much photovoltaic capacity as possible. In a few years, vehicle-to-home (V2H) / vehicle-to-grid (V2G) technologies will be available, and then your car will provide storage with significantly higher capacity.
DaSch17 schrieb:
We were told that with an oversized photovoltaic system, you produce more electricity than you can use, and this surplus is basically lost once the battery is full (especially during the warmer months). I also read somewhere that the ratio of battery storage to photovoltaic capacity should be around 1 kWp = 1 kWh.
So, would it be better to install a larger photovoltaic system after all? Ratio of photovoltaic to storage: photovoltaic ≥ storage, preferably "larger"
“Overproduction”: There are actually two types of this...
Instead of the usual 70% maximum feed-in to the grid, you have 50% due to a subsidy. This means, specifically, that if you have 10 kWp on your roof, you are allowed to feed a maximum of 5 kW into the grid. You need to consume 5 kW inside your home (heating, oven, stove, hairdryer, etc.) and/or charge your battery with 5 kW ("soft setting"). You can only do this until the battery is full. Once it is full and you cannot absorb 5 kW, the inverter reduces the output power so that not the full 10 kW is “produced,” but only about 7 kW. In this case, you lose 3 kW of potential output.
Alternatively, if you have 9 kWp installed on the roof but your inverter can only deliver 8 kW AC output, the difference of 1 kW is sometimes lost. Since you don’t get full sunlight every day or an ideal generation curve, you can calculate a small percentage of loss and estimate how much money is lost per year. A slightly undersized inverter tends to be more efficient at partial load (for example, when it’s cloudy).
There are forums online where this is discussed in much more detail…
Heinz2k schrieb:
Unless you use one of those stupid storage subsidies where you have to throttle down at 50%.Don't you have to do that as well if you want a subsidy without storage? At least, that was the case last year.
Heinz2k schrieb:
I would completely save the money on the storage battery and instead maximize everything you can. In a few years, V2H/V2G will be available, and then you’ll have your storage in the car with significantly larger capacity. You probably mean decades. Sorry, but V2H/V2G is still just a vision for the future.
blackm88 schrieb:
Isn’t this also required if you want funding without storage? At least that was the case last year.I don’t know of any current funding program that doesn’t require a storage system; otherwise, the 70% rule applies to all.
Mycraft schrieb:
You probably mean decades. Sorry, but V2H/V2G is still a thing of the future.I’m not so pessimistic about that. e3dc is making progress, and the ID3 should theoretically be able to do it as well (as are many Asian cars). If we take the energy transition seriously, we can’t avoid seeing electric vehicles as grid-supporting elements. I think the main obstacle right now is political will, not technical capability. Sorry for the off-topic.
Similar topics