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.
P
Pinkiponk23 Jul 2020 08:19DaSch17 schrieb:
I totally agree with you. Personally, I would also prefer gas. However, in most new residential areas—like ours—gas lines are unfortunately no longer being installed.
So the only options left are air source heat pumps, air-to-water heat pumps, or ground source (geothermal) heat pumps...It might be worth considering the topic of liquefied petroleum gas (LPG). In our case (a gap in an older development), natural gas is available, but if there is enough space, I would also consider LPG for new construction.@Bookstar is (unfortunately) right in practice, especially if you don’t take care of things early enough.
For a heat pump that runs well and efficiently, it requires initiative, due to most heating installers lacking motivation or expertise.
That means:
Getting a proper heating load calculation done.
Designing the underfloor heating based on the heating load calculation with a maximum supply temperature of 32 degrees Celsius (90°F).
Probably installing wall heating in the bathrooms.
Having balanced heating circuits with about 80 meters (260 feet) per circuit.
Omitting buffer tanks and bypass valves.
Adjusting and balancing the system during the first winter.
Often, the problem starts with the heating load calculation because experienced installers still estimate. This leads to oversized units being installed.
The underfloor heating design is the same. Nobody wants to invest the time.
Additionally, heating installers often add a large markup to the heat pump price, which makes the heat pump much less attractive.
If you follow the points above, you end up with a heating system that requires no further adjustments after the first winter and is extremely low maintenance. This keeps follow-up costs very manageable. If you don’t have a fireplace, you won’t need to see the chimney sweep again, you can save the basic gas fee, and disconnect the gas connection as well.
Replacing the heat pump many years later is also very simple—just a few cables and two pipes.
However, despite all optimizations, @Bookstar’s system does not seem to run very well. Aside from that, supplying hot water with solar power isn’t free, as the solar thermal system had to be purchased and installed.
Conclusion: I’m an interested layperson and would anyway pay attention to the above conditions to stay flexible in the future. For me, only a heat pump would be an option in a new build.
Gas is easier, though. Planning mistakes by the heating installer don’t have as much impact on operating costs.
For a heat pump that runs well and efficiently, it requires initiative, due to most heating installers lacking motivation or expertise.
That means:
Getting a proper heating load calculation done.
Designing the underfloor heating based on the heating load calculation with a maximum supply temperature of 32 degrees Celsius (90°F).
Probably installing wall heating in the bathrooms.
Having balanced heating circuits with about 80 meters (260 feet) per circuit.
Omitting buffer tanks and bypass valves.
Adjusting and balancing the system during the first winter.
Often, the problem starts with the heating load calculation because experienced installers still estimate. This leads to oversized units being installed.
The underfloor heating design is the same. Nobody wants to invest the time.
Additionally, heating installers often add a large markup to the heat pump price, which makes the heat pump much less attractive.
If you follow the points above, you end up with a heating system that requires no further adjustments after the first winter and is extremely low maintenance. This keeps follow-up costs very manageable. If you don’t have a fireplace, you won’t need to see the chimney sweep again, you can save the basic gas fee, and disconnect the gas connection as well.
Replacing the heat pump many years later is also very simple—just a few cables and two pipes.
However, despite all optimizations, @Bookstar’s system does not seem to run very well. Aside from that, supplying hot water with solar power isn’t free, as the solar thermal system had to be purchased and installed.
Conclusion: I’m an interested layperson and would anyway pay attention to the above conditions to stay flexible in the future. For me, only a heat pump would be an option in a new build.
Gas is easier, though. Planning mistakes by the heating installer don’t have as much impact on operating costs.
I’m not a fan of liquid propane gas. You have the tank issue, higher fuel costs compared to natural gas, and then it has to be transported to you by ship and truck. All in all, not ideal—better to go with a regional option like a pellet heating system.
I think my heating system is running pretty well by now. An average of 60 euros per month is about typical, though it could certainly be better. I’m satisfied, though, as a lot depends on how you use the heating. We like it warm, and a new building takes a few years to fully dry out. So the costs will probably go down a bit over time.
I think my heating system is running pretty well by now. An average of 60 euros per month is about typical, though it could certainly be better. I’m satisfied, though, as a lot depends on how you use the heating. We like it warm, and a new building takes a few years to fully dry out. So the costs will probably go down a bit over time.
@Joedreck perfectly sums up what I wanted to add. When calculating the heating demand, please don’t deceive yourself. Schwörerhaus used standard values, meaning the living room at 21°C (70°F), the bedroom I believe 19°C (66°F), and so on. Honestly, that’s too cold for me. I always sit at home in winter wearing shorts and a T-shirt; I don’t want to use blankets. So, our consumption is probably 20-30% higher than comparable houses set at a “room temperature of 23°C (73°F).” I wasn’t aware of the impact; at that time, I didn’t know anyone who had installed an air-water heat pump. I only went by hearsay and what the salespeople said. If I had known about this forum back then, I would have chosen gas, even though I’m personally a bit reluctant about it. It also annoys me a little because I’ve been on the internet since 1996 and was already registered in various forums, where you really get very informative posts directly from users, not salespeople.
What is the average annual energy consumption of an air-to-water heat pump?
Would 3,000 kWh per year be realistic? How can this be calculated?
*KfW 40 Plus standard, 180 m² (1,940 sq ft) living area, fireplace, underfloor heating, controlled mechanical ventilation, constant temperatures of 21-22°C (70-72°F) in all rooms, and 23-24°C (73-75°F) in the bathrooms (total 21 m² / 226 sq ft)
Of course, this depends on the manufacturer and model among other factors. But there should be some kind of general rule of thumb, right?
Would 3,000 kWh per year be realistic? How can this be calculated?
*KfW 40 Plus standard, 180 m² (1,940 sq ft) living area, fireplace, underfloor heating, controlled mechanical ventilation, constant temperatures of 21-22°C (70-72°F) in all rooms, and 23-24°C (73-75°F) in the bathrooms (total 21 m² / 226 sq ft)
Of course, this depends on the manufacturer and model among other factors. But there should be some kind of general rule of thumb, right?
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