ᐅ Controlled residential ventilation or demand-controlled ventilation – any experiences?

Shism schrieb:
....It has to be calculated individually...

Where exactly is it calculated individually? Most people just skip the few € planning costs!

Best regards

Where is individual calculation even done? Most people just skip the few € of planning costs!

Well, when it comes to mechanical ventilation with heat recovery, there are various factors that need to be calculated... starting with the supply and exhaust air flow rates, the placement of the vents, the impact on sizing the heating system, insulation of the ductwork to prevent condensation, and so on...

My main point here was an economic feasibility calculation.
If someone says upfront that they want a mechanical ventilation system with heat recovery simply because they like the idea of not having to ventilate manually, then the economic aspect becomes less important.
But if someone installs mechanical ventilation with heat recovery because they believe it will save them money in the long term, then playing with the numbers can be worthwhile...
The same goes for someone who wants some sort of automatic ventilation but is wondering if the extra cost of a full mechanical ventilation system with heat recovery is justified...

Shism schrieb:
Well, when it comes to controlled residential ventilation, there are various factors that need to be calculated or considered... this starts with the supply and exhaust air volumes, the placement of the vents, effects on the sizing of the heating system, insulation of the ducts to prevent condensation, and so on...

Correct! The better a building is insulated, the more significant the impact of controlled residential ventilation with heat recovery on the overall energy balance.

Shism schrieb:
...I was initially referring to a cost-effectiveness calculation... If someone installs a controlled residential ventilation system with heat recovery because they believe it will save money in the long run, then it can be interesting to play around with the numbers...

When it comes to one’s budget, it’s best not to gamble. Controlled residential ventilation with heat recovery cannot be considered separately from the other building systems. The overall context is important! It is not uncommon for controlled residential ventilation with heat recovery, in addition to providing extra comfort, to have investment effects through its influence on the standard heating load and room heating demand. Heating surfaces become less expensive, and it may be possible to choose a heat generator with one heating capacity level lower (especially interesting for heat pumps), etc.

Shism schrieb:
...Also for someone who wants some form of automatic ventilation but is now considering whether the extra cost for a full controlled residential ventilation system with heat recovery is justified...

Regardless of how one values comfort financially, the overall situation will always be decisive in each case. Those who truly have the time to ventilate daily by opening windows as needed can certainly do so. There is no mandatory requirement for controlled residential ventilation with heat recovery, even though ventilation system vendors often like to suggest otherwise! Window ventilation is recognized as an acceptable ventilation method according to [1946-6], provided minimum moisture protection is ensured. However, user behavior is often noticeably different. In the morning, rooms are quickly aired out, and in the evening, people return indoors! This creates a completely different system condition.

Best regards.

Window ventilation has been recognized as an acceptable ventilation method since 1946-6, provided that the minimum moisture protection is ensured. However, user behavior is usually quite different. In the morning, ventilation occurs in short bursts, and in the evening, people close up again! A completely different system condition!

That is exactly why I believe it makes sense to have an automatic ventilation system in every new build, which ensures a certain minimum air exchange and increases ventilation when humidity is high. Window ventilation then becomes no longer a compulsory task to be done several times a day but can be done on demand, like "in the old days."

There is no mandatory requirement for mechanical ventilation with heat recovery, although ventilation system sellers often suggest otherwise!

That is precisely what bothers me. Many do not take any ventilation alternative seriously. It is as if mechanical ventilation with heat recovery is the only option, and everything else is seen as silly and associated only with disadvantages... Then it is also claimed that the investment costs are recovered in no time.

Correct! The better a building is insulated, the more significant the influence of mechanical ventilation with heat recovery is on the overall energy balance.

and the higher the percentage share of the mechanical ventilation’s electricity and maintenance costs in the "heating costs."

When it comes to your own money, you shouldn’t take unnecessary risks. Mechanical ventilation with heat recovery is not independent from the rest of the building systems. The overall context is important! Mechanical ventilation with heat recovery often produces investment effects beyond added comfort, due to its influence on the standard heating load and room heating load. Heating surfaces become cheaper, and, if applicable, a heat generator can be sized one level lower (especially interesting for heat pumps), and so on.

You do have to play the game depending on the situation... simply because you cannot know everything! For example, price developments for oil/gas/electricity, etc. Also, the assumed lifespan of a mechanical ventilation system can play a role in whether it ever pays off economically. But of course, there are also solid facts that must be considered: potential heating savings, financing, maintenance, and operating costs. Essentially, even the geographic location has a strong impact (average temperatures, solar radiation, etc.).

Since, in our case, heating optimization (or savings potential) through mechanical ventilation more or less does not apply (district heating...), the calculation was simpler for us personally. Heat recovery, especially considering our heating costs, was completely uneconomical. Comfort remains a factor, but we decided to invest the saved money in other things that, in the end, provide us with more comfort.

Shism schrieb:
....Since in our case the heating optimization (or potential savings) through controlled ventilation is more or less eliminated (district heating...) the calculation was simpler for us personally.

Energy generation or supply generally has nothing to do with its utilization.

Best regards.

The generation or supply of energy generally has nothing to do with its utilization.

That’s not what I meant ;P

However, there is no saving potential in the sense that I could, for example, choose a "smaller" heat pump or operate it in a "better" range...

I simply receive my xxxx kWh of thermal energy delivered directly to my home, and I don’t have the efficiency of a heating system that I could positively influence through controlled residential ventilation.

If the heat recovery then saves me 5,000 kWh (5,380,000 BTU) per year, then that’s exactly the saving I get—no additional cost-saving effects like someone with a heat pump might have...