Hello everyone,
We just had a conversation with the company responsible for our heating and plumbing installation.
First of all – we are building a large single-family house with a basement, two full floors, and a hipped roof with a 22° (22 degrees) pitch. Wall construction is 17.5 cm (7 inches) sand-lime brick, insulation with mineral wool, plus a brick façade.
We are building according to the 2012 Energy Saving Ordinance (EnEV 2012) and are not aiming to achieve a higher standard.
Our original plan was:
- Gas heating with underfloor heating on all levels, no wall-mounted radiators, and a central mechanical ventilation system with heat recovery.
Now, after the discussion, I’m totally confused. The company recommends:
- Heating via an air-to-air heat pump, solar thermal for hot water, plus gas to support hot water
- Underfloor heating only on the ground floor and first floor, excluding children’s rooms and bedrooms (to avoid overheating during sleep), with the rest heated by wall-mounted radiators on a second heating circuit
- No mechanical ventilation system with heat recovery due to noise issues
I can understand reconsidering the mechanical ventilation system because of potential constant noise and airflow, so we might want to think that over.
But I’ve never heard of combining a heat pump, gas, and solar thermal in one system!
Solar thermal is said to be uneconomical anyway, especially with a roof pitch of only 22° (22 degrees), right? We also don’t have a direct south-facing roof orientation. Does anyone have links or information about the economic viability?
Our main priorities are comfort; cost and economic efficiency are not the primary focus, but I don’t want to end up building something completely pointless either. The problem is, we need some sort of renewable energy source to comply with the Energy Saving Ordinance. The thermal protection report is not available yet, but I definitely need some concrete information for the next meeting. It would be great if someone could help!
We just had a conversation with the company responsible for our heating and plumbing installation.
First of all – we are building a large single-family house with a basement, two full floors, and a hipped roof with a 22° (22 degrees) pitch. Wall construction is 17.5 cm (7 inches) sand-lime brick, insulation with mineral wool, plus a brick façade.
We are building according to the 2012 Energy Saving Ordinance (EnEV 2012) and are not aiming to achieve a higher standard.
Our original plan was:
- Gas heating with underfloor heating on all levels, no wall-mounted radiators, and a central mechanical ventilation system with heat recovery.
Now, after the discussion, I’m totally confused. The company recommends:
- Heating via an air-to-air heat pump, solar thermal for hot water, plus gas to support hot water
- Underfloor heating only on the ground floor and first floor, excluding children’s rooms and bedrooms (to avoid overheating during sleep), with the rest heated by wall-mounted radiators on a second heating circuit
- No mechanical ventilation system with heat recovery due to noise issues
I can understand reconsidering the mechanical ventilation system because of potential constant noise and airflow, so we might want to think that over.
But I’ve never heard of combining a heat pump, gas, and solar thermal in one system!
Solar thermal is said to be uneconomical anyway, especially with a roof pitch of only 22° (22 degrees), right? We also don’t have a direct south-facing roof orientation. Does anyone have links or information about the economic viability?
Our main priorities are comfort; cost and economic efficiency are not the primary focus, but I don’t want to end up building something completely pointless either. The problem is, we need some sort of renewable energy source to comply with the Energy Saving Ordinance. The thermal protection report is not available yet, but I definitely need some concrete information for the next meeting. It would be great if someone could help!
Would a domestic hot water heat pump also be an option in the case of the original poster? Would it then be possible to do without solar panels? And would that also make sense from a cost perspective?
If the building is left unfinished over the winter to freeze and dry out – would that be a problem without a mechanical ventilation system, aside from comfort considerations?
If the building is left unfinished over the winter to freeze and dry out – would that be a problem without a mechanical ventilation system, aside from comfort considerations?
Heating Load Calculation – Note: This is a simplified explanation for non-experts. The heating load is calculated based on the specific construction project, location, and individual comfort temperature (for the entire house; for individual rooms this is only possible to a limited extent – maximum 2-3°C (4-5°F) difference), among other factors. Using this data, the proper heating system and, for example, the spacing of underfloor heating pipes can be determined.
I consider gas heating combined with a controlled mechanical ventilation system with heat recovery to be a good and straightforward solution. Controlled mechanical ventilation also provides very good comfort beyond the first two years.
This solution should be more affordable even when installed by an external builder than the above-mentioned patchwork work done by the uncle at a "friendship price," and almost certainly with lower ongoing costs.
I consider gas heating combined with a controlled mechanical ventilation system with heat recovery to be a good and straightforward solution. Controlled mechanical ventilation also provides very good comfort beyond the first two years.
This solution should be more affordable even when installed by an external builder than the above-mentioned patchwork work done by the uncle at a "friendship price," and almost certainly with lower ongoing costs.
B
Bieber081512 May 2015 20:38I have gone through a similar learning process. We have now decided on an air-to-water heat pump. I am adding controlled residential ventilation with heat recovery mainly for comfort reasons. With the standard insulation specified in the construction specifications (so nothing particularly special), we are still achieving KfW 70 standards. The alternative would have been gas and solar thermal. I asked about that intensively, but the heat pump that the builder usually installs (which other people are already living with and managing just fine) is not more expensive (in fact, it’s usually cheaper) upfront than gas plus solar thermal (assuming the gas connection is only for heating, which would then be eliminated since cooking is done electrically). Without the requirement for solar thermal, I probably would have chosen gas, but that is not an option here… or it does not reduce the investment costs.
I would definitely not install two systems. Underfloor heating is different from the traditional radiators that have been used for ages, but different does not automatically mean worse. Overall, the comfort and well-being in a modern, energy-efficient house with underfloor heating (and ideally controlled residential ventilation) is likely to be significantly higher than in an 1980s new build with radiators under the windows. Don’t let yourself be confused about that.
So, choose the solution that is common on the market, simple (not two systems), and can be legally implemented. From my point of view, that’s the heat pump. Either an air-to-water heat pump or a ground-source heat pump (ground loops, if you are willing to allocate the land permanently, or geothermal energy if you want to go for drilling and can afford it).
I would definitely not install two systems. Underfloor heating is different from the traditional radiators that have been used for ages, but different does not automatically mean worse. Overall, the comfort and well-being in a modern, energy-efficient house with underfloor heating (and ideally controlled residential ventilation) is likely to be significantly higher than in an 1980s new build with radiators under the windows. Don’t let yourself be confused about that.
So, choose the solution that is common on the market, simple (not two systems), and can be legally implemented. From my point of view, that’s the heat pump. Either an air-to-water heat pump or a ground-source heat pump (ground loops, if you are willing to allocate the land permanently, or geothermal energy if you want to go for drilling and can afford it).
The heat load calculation is also important for the correct sizing of the heating system and, for example, the heat source in geothermal applications. Most technologies are financially worthwhile only if they are well coordinated with each other – for instance, photovoltaic systems combined with a brine-to-water heat pump designed for self-consumption.
EveundGerd12 May 2015 21:24Is the home's energy standard really sufficient for a heat pump?
I remember colleagues who had to rely on electric resistance heating in winter, which was expensive, because they found the technology "interesting" back in 2008, but the building envelope was not suitable for it.
I remember colleagues who had to rely on electric resistance heating in winter, which was expensive, because they found the technology "interesting" back in 2008, but the building envelope was not suitable for it.
B
Bauexperte12 May 2015 22:01EveundGerd schrieb:
Is the house’s energy standard really sufficient for a heat pump? Sure. Double-layer masonry works, it will probably achieve something closer to KfW 70 than KfW 85 anyway; as long as the house isn’t built on bare beams, of course.
EveundGerd schrieb:
I remember colleagues who had to use expensive backup heating with an electric heating element in winter because they found the technology "interesting" in 2008, but the building envelope wasn’t suitable. They probably had an air-to-air heat pump, which is only cost-effective in a passive house. If it’s an efficiency house 70 or 55 standard, then the electric heating element comes into play.
Regards, Bauexperte
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