ᐅ Ventilation with heat recovery?

Hello everyone,

I have a question about the system offered by Schwörerhaus (also described on their website):

As I understand it, air is extracted from the kitchen, bathroom, and toilet, and fresh air, warmed by the exhaust air and heating wires, is supplied to the living room and bedroom.

Warm air comes from above.

Does it really work that the kitchen and bathroom still stay warm in winter? Apparently, no warm air is supplied there, at least not directly.

I actually thought it would be best if warm air were supplied from below, since cold air tends to stay near the floor.

Is the overall air circulation effective enough for this to work?

Overall, the system seems to use only air-to-air heat exchange combined with electric heating (to cover the remaining heating demand after the heat exchanger). Would it be possible to significantly reduce the electricity consumption by adding a groundwater heat pump, or is that no longer worthwhile in these areas?

Is this system a sort of standard, or do other passive houses use completely different methods?

Thank you
insgruene

Hello,

insgruene schrieb:
..As I understand it, air is extracted from the kitchen, bathroom, and WC, and fresh air warmed by the exhaust air and heating wires is supplied to the living and bedrooms.

This cross-ventilation with transfer areas is mainly used in mechanical ventilation with heat recovery. The difference here, however, is that the entire heating output is delivered through the ventilation system. Spaces with different temperature levels are therefore only feasible to a limited extent. In addition, air is a poor "energy storage medium" or "transporter." This approach requires correspondingly low heating loads and very careful planning and sizing.

insgruene schrieb:
..Does it really work that the kitchen and bathroom are still warm in winter? Apparently, no warm air is supplied there, at least not directly.

The warm air comes from the transfer areas. In such applications, I always plan supply and exhaust air for each room and no transfer areas!

insgruene schrieb:
..And I actually thought that it would be best to supply warm air from below since cold air stays at the floor.

With proper building design, temperature gradients are negligible because this is not an old building with poorly insulated floors, walls, and ceilings, and room heights above 2.5m (8 ft 2 in).

insgruene schrieb:
..Is the total air circulation really efficient enough for this to work?

With proper planning, this can work. With mistakes, it becomes very uncomfortable!

insgruene schrieb:
..Could the share of electricity demand be reduced even more by using a groundwater heat pump, or is that no longer economical in these areas?

It is possible, but whether the effort is worthwhile is questionable. This can be calculated based on the actual energy demand.
Don’t forget hot water preparation!

Best regards

Thank you very much!

That doesn't sound very trustworthy as a concept...

How does this work in other passive houses?

In some way, I have to supply energy in the winter. What other options are there, and who offers something robust that won't lead to huge electricity bills even in extreme winters?

Best regards
insgruene

Hello,

insgruene schrieb:
...That doesn’t sound very trustworthy as a concept...

With supply and exhaust air in each room and precise planning, the basic principle is definitely feasible.

insgruene schrieb:
...In some way, I have to supply energy in winter. What other options are there, and who offers something robust that doesn’t lead to massive electricity bills even in extreme winters?

I wouldn’t choose the house or the provider based only on the building services. You can also use a traditional water-based heating system (underfloor heating) combined with an air source heat pump. It all depends on the specific figures, for example the heating load. By the way, the capacity requirement for domestic hot water production will likely exceed the heating load.
If in doubt, the provider’s documents/calculations can be reviewed by a professional ;-)

Best regards

Not for the building services only, but also to some extent 🙂

I’m just surprised that it’s called a Passive House, because I actually understand that term differently.

At Town & Country, they offer underfloor heating with a groundwater heat pump and solar collectors on the roof, which is more in line with "passive," at least according to my understanding.

Thank you very much for your explanations!
insgruene

insgruene schrieb:
...I’m just surprised it’s called a Passive House, because I actually understand that term differently.

PH basically means that very little primary energy is consumed. Also, there is a significant difference between primary energy and final energy, which is what the consumer actually pays for. 😉

insgruene schrieb:
..
At Town & Country, they offer underfloor heating with a groundwater heat pump and solar collectors on the roof, which comes closer to "passive," at least in my understanding.

Most likely, Town & Country is more focused on their own budget than on the builder’s. 😀

Best regards.