ᐅ Ventilation system in a new build: yes or no?

Gartenbau schrieb:
... I am an engineer and understand enough about thermodynamics to know that heat recovery is sensible.

The question is whether “sensible” refers to functionality or economic efficiency. Operating the ventilation system of a restaurant (on the Zugspitze) without heat recovery would probably not be economical. For a single-family house with an average outdoor temperature of 10°C (50°F) during the heating season, it would likely not be cost-effective. I think this is now clear. It simply depends on the energy balances.

Gartenbau schrieb:
... General consensus on controlled residential ventilation: very comfortable, but if you don’t have it, airing the rooms is sufficient—as long as you’re not too lazy to do it.

I agree with the first opinion; the second one, as already mentioned, only under certain conditions!

Gartenbau schrieb:
... Can you list some factors for and against it?

The necessities are partly explained in DIN 1946-6, among other sources.

Gartenbau schrieb:
... What other factors are there?

For example: location → environmental noise, cooling with night-time outdoor air in summer! In such cases, window ventilation is only suitable in very quiet surroundings. The Energy Saving Ordinance has caused some problems concerning summer thermal insulation in exposed locations, especially in attics.

Gartenbau schrieb:
... The heat losses due to warm air are the same when ventilating manually or with a controlled ventilation system without heat recovery, as long as the walls do not cool down during ventilation.

Only if the air exchange rate is exactly the same.

Gartenbau schrieb:
... why some believe it simply doesn’t work without it.

That always depends on the perspective. Those who appreciate the comfort and are willing and able to pay for it will hardly argue against it. The same applies to vendors. Those who don’t have such a system and experience problems are usually reluctant to admit they may have made a mistake. However, not every single-family house must have controlled residential ventilation.
In conclusion: Forum posts cannot replace professional advice and should only be considered as encouragement for further measures.
Best regards.

Yes, there are many reasons in favor of it. However, €uro still needs to calculate whether it will actually be worthwhile.

Cost Efficiency

What are some rough (!!) benchmark values for the heating energy demand of a new 160 sqm (1,722 sq ft) house without a basement for 4 people? Also, how much electricity does a mechanical ventilation system with heat recovery typically consume per year? Please avoid answers with unclear or unspecified conditions. Rough estimates are fine if needed...

I would like to get a general idea of the potential annual savings from heat recovery. Would it be around $10, $100, or $500?...

A small side question: Is it possible to turn off the mechanical ventilation system in summer if you want or are able to sleep with the windows open?

Hello,

Based on our calculations and experience, the values for heating energy demand, or more accurately final energy demand, are as follows:
For a well-insulated house, around 65 kWh/m²/a (21,000 BTU/ft²/year). The ventilation system saves about 12 to 18 kWh/m²/a (4,000 to 6,200 BTU/ft²/year) with an efficiency of 80% (90% is already achievable), at a self-consumption of approximately 4.5 kWh/m²/a (1,400 BTU/ft²/year). These values reflect our experience and are given here only as guidelines. For a specific building project, the figures are always calculated in advance, since architecture and solar heat gains also play a significant role.

Of course, the mechanical ventilation can be turned off if you prefer to sleep with windows open. From experience, however, this is rarely done anymore:
- no more mosquitoes at night
- no noise inside the home
- it feels like fresh air all night long

But basically, it is possible. For example, if there is a party and windows are open, the system should be turned off then.

PenK schrieb:
Of course, you can turn off the mechanical ventilation system if you want to sleep with the windows open. From experience, however, people rarely do this anymore:
- no more mosquitoes at night
- no noise inside the house
- it feels like fresh air all night long
But basically, if there’s a party and all the windows are open anyway, then the system should be turned off.

Well, we currently live in the city and sleep with the window open. We are moving far out and building on a traffic-calmed street, so noise will probably be less of an issue. For example, I like it when the wind rustles through the trees or the birds sing.
The question is whether to run the ventilation system at all, since it consumes electricity, especially when you can sleep with the window open and during the day the patio door is open all the time anyway, and it’s warm enough that you don’t need to recover heat (I already have the heating turned off in my poorly insulated, pre-war apartment).

Of course, then just turn off the ventilation. We also live at the end of a private road. It’s a wonderful feeling to have the window open. Please make sure to have a switch installed in the bedroom that allows you to turn off the entire system. Otherwise, you will always have to go back to the control unit, which is usually located in the reference room (mostly the living room). Remote controls are available. You could also have it controlled by a timer so that the system runs during the day, which makes sense when you are at work.

When it is very warm in summer, we keep the windows closed and cool our apartment, using an additional duct to cool the bedroom a bit more. To support cooling the house, we turn off the system early, air out the whole house with the cool morning air, and then close the windows again. The blinds lower automatically when exposed to direct sunlight.