Hello,
we would like to build a one-and-a-half-story single-family house with about 125 sqm (1,345 sq ft) plus additional development space in the attic. Without a basement but with a 9 m (30 ft) garage.
We have a plot of land in sight, which we hope to reserve by May. We have already had several appointments with construction companies, including TaC, a developer from Krefeld, and one from Sonsbeck. I feel increasingly uncertain. Both developers offer roughly the same concept, but their prices differ significantly. One says that a ventilation system is not necessary for a KfW 55 solid construction house, while the other says it is very important. I am completely confused. Intuitively, the developer from Sonsbeck was our favorite—until we saw the cost estimate.
It is just too expensive! With TaC, the costs are within our budget, but opinions about the company are mixed.
Does anyone have experience in the NRW area?
Best regards
we would like to build a one-and-a-half-story single-family house with about 125 sqm (1,345 sq ft) plus additional development space in the attic. Without a basement but with a 9 m (30 ft) garage.
We have a plot of land in sight, which we hope to reserve by May. We have already had several appointments with construction companies, including TaC, a developer from Krefeld, and one from Sonsbeck. I feel increasingly uncertain. Both developers offer roughly the same concept, but their prices differ significantly. One says that a ventilation system is not necessary for a KfW 55 solid construction house, while the other says it is very important. I am completely confused. Intuitively, the developer from Sonsbeck was our favorite—until we saw the cost estimate.
It is just too expensive! With TaC, the costs are within our budget, but opinions about the company are mixed.
Does anyone have experience in the NRW area?
Best regards
T
toxicmolotof3 May 2017 17:28Caspar2020 schrieb:
When you ventilate, the 1.2kWh is simply lost. Thanks to heat recovery, it isn’t. That aspect shouldn’t be overlooked. What exactly is being overlooked? For you, the 1.2kWh is definitely lost too. Or does the mechanical ventilation system run with love?
C
Caspar20203 May 2017 17:33Yes; air and love. No, but the energy is actually used to warm up the fresh air. In other words, the heating system has less work to do to bring the air back to room temperature.
You really have to consider the overall energy balance.
By the way, the energy loss that occurs when you follow the recommended values for manual ventilation described in a DIN standard is actually even higher.
You really have to consider the overall energy balance.
By the way, the energy loss that occurs when you follow the recommended values for manual ventilation described in a DIN standard is actually even higher.
The energy consumption is probably mostly due to the fan. There is no preheating involved, at least not intentionally.
The amount of heat energy recovered is a different matter. Someone clever could certainly calculate it (or anyone with a mechanical ventilation system with heat recovery can check their heating load calculation), but it is doubtful that it covers the costs.
You can take it a step further. Mechanical ventilation with heat recovery reduces the heating load, which may allow for a smaller heat pump, shallower boreholes for geothermal energy, etc., saving on investment. Nevertheless, it still probably won’t be economically viable in practice.
Some people also save on basement windows thanks to the mechanical ventilation system, and so on.
The amount of heat energy recovered is a different matter. Someone clever could certainly calculate it (or anyone with a mechanical ventilation system with heat recovery can check their heating load calculation), but it is doubtful that it covers the costs.
You can take it a step further. Mechanical ventilation with heat recovery reduces the heating load, which may allow for a smaller heat pump, shallower boreholes for geothermal energy, etc., saving on investment. Nevertheless, it still probably won’t be economically viable in practice.
Some people also save on basement windows thanks to the mechanical ventilation system, and so on.
T
toxicmolotof3 May 2017 19:43@Caspar2020
The overall energy balance looks like this:
With controlled mechanical ventilation: 1.2 kWh of electricity for ventilation plus 16% of 1.2 kWh for heating
Without controlled mechanical ventilation: 1.2 kWh for heating
So, from this very simplified perspective, I do not see an energy advantage.
The overall energy balance looks like this:
With controlled mechanical ventilation: 1.2 kWh of electricity for ventilation plus 16% of 1.2 kWh for heating
Without controlled mechanical ventilation: 1.2 kWh for heating
So, from this very simplified perspective, I do not see an energy advantage.
The calculation is fundamentally incorrect. The savings come from the thermal energy recovered from the ventilated indoor air. With an open window, this energy is lost 100%, and additional heating is required. A mechanical ventilation with heat recovery system returns 84% or more of the thermal energy to the room, depending on the model.
However, this has nothing to do with the approximately 1.2 kWh of electricity needed to operate the mechanical ventilation system for one day.
However, this has nothing to do with the approximately 1.2 kWh of electricity needed to operate the mechanical ventilation system for one day.
B
bierkuh833 May 2017 20:07I also don’t understand why people here are talking about opponents of controlled residential ventilation... I haven’t seen anyone like that in this thread so far... For me personally, it’s just important to EMPHASIZE that controlled residential ventilation is not mandatory. It has advantages if you have it.
For example, I recently had my monthly advance payment from the utility for the heat pump adjusted, logically based on last year’s consumption. €53 per month for 145m² (1560 ft²). If I now generously calculate a 20% saving and ignore ongoing operating costs, where does that leave me? Exactly... increased comfort, fine. Automatic mold in the house without it? No. Alright, that’s enough.
And some of the explanations and comparisons made here seem very much like they come from a clip school. Sorry, dealing with that really annoys me.
For example, I recently had my monthly advance payment from the utility for the heat pump adjusted, logically based on last year’s consumption. €53 per month for 145m² (1560 ft²). If I now generously calculate a 20% saving and ignore ongoing operating costs, where does that leave me? Exactly... increased comfort, fine. Automatic mold in the house without it? No. Alright, that’s enough.
And some of the explanations and comparisons made here seem very much like they come from a clip school. Sorry, dealing with that really annoys me.
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