ᐅ Is a ventilation system cost-effective? Does it save money?

Hello dear community,

we have installed a decentralized ventilation system from Südwind (Ambientika smart). The advantages, such as always having fresh air, fewer pollen particles inside the house, and noise protection thanks to closed windows, are really appealing. However, the costs for purchasing and installing the units are definitely not cheap!

The contractor told us that we can save on heating costs and that the investment pays off within 10 years. Is that possible? I mean, these systems – even with heat recovery – still consume electricity, and we still need to heat the house, right? On top of that, there are maintenance costs (new filters, etc.).

Has anyone done a detailed calculation or has knowledge about the numbers?

Hello,

Technically, it is true that a decentralized ventilation system with heat recovery noticeably reduces ventilation losses, which affects heating costs. However, the effect is often less than what brochures promise, especially in houses that are not thoroughly renovated. Electricity costs, filter replacements, and initial investment should not be overlooked, as they impact the overall calculation. Without generous assumptions, a payback period of about ten years is possible but tends to be tight in reality – more realistically, you should expect 12 to 15 years, depending on the building.

If these systems are purchased solely for the expected savings, disappointment is not unlikely. Comfort, air quality, and pollen filtration usually outweigh the savings effect.

Schnackischnak

LarsBr80 schrieb:

Hello dear community,

We have installed a decentralized ventilation system from Südwind (Ambientika smart). The benefits like always having fresh air, fewer pollen particles inside the house, and noise reduction through closed windows are really attractive. However, the costs for purchasing and installing the units are not cheap!

The contractor told us that we would also save on heating costs, and that the investment would pay off within 10 years. Could that be true? I mean, these systems—even with heat recovery—still consume electricity, and we still need heating, right? Plus, there are maintenance costs (new filters, etc.).

Has anyone done a detailed calculation or has an informed opinion on the numbers?

It’s quite difficult to calculate this precisely. How often and for how long would you have opened windows or patio doors, and at what outside temperatures? If you can specify that for your situation and house, you could estimate how much heating energy would have been lost through ventilation. Lots of assumptions involved.

What is the power consumption of the fans? Mine use about 7 watts per hour during continuous ventilation. With six units, that adds up to around 363 kWh of electricity.

If I assume you only save about 20% on heating costs and look at my actual consumption for my 120 sqm (about 1,300 sq ft) house, I save roughly 260 kWh electricity for the heat pump (last year, the heat pump’s electricity consumption for heating was about 1,026 kWh according to the meter). So financially, the ventilation system would not pay off, at least not in terms of direct savings.

Still, I would install it again for the benefits you mentioned—especially as someone who suffers from grass pollen allergies.

According to studies, in new construction, a (central) mechanical ventilation system with heat recovery can save around 40% of heating costs. However, due to overall low heating costs, it is often not a very profitable financial investment.

I agree that the ventilation system will not pay off through direct savings on heating costs from ventilation alone.

However, I also believe that houses could no longer be built as well insulated and especially as airtight without a ventilation system. Overall, it therefore makes a larger contribution than just reducing ventilation losses.

LarsBr80 schrieb:

We installed a decentralized ventilation system from Südwind (Ambientika smart). [...] However, the costs for purchasing and installing these units are not cheap! [...] I mean, these devices—even with heat recovery—still use electricity, and we still have to heat the house, right? [...] Has anyone done a detailed cost analysis or has knowledge about the figures?

Why did you choose a decentralized solution (are we talking about an existing house?)?
A decentralized mechanical ventilation system is primarily a retrofit solution or intended for situations where only a minority of rooms are equipped with mechanical ventilation. The concept of heat recovery works best (and most efficiently) with a central mechanical ventilation system. A decentralized mechanical ventilation system mainly provides increased comfort (especially for people who work outside the home and cannot ventilate properly during the day). On its own, it will not be cost-effective.
The exact opposite of “cost-effective” applies when a decentralized mechanical ventilation system is selected for a new build: a future owner will expect the more modern central mechanical ventilation system, which would then need to be retrofitted (which is unnecessarily expensive due to construction reasons).

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LarsBr80 schrieb:

The craftsman told us that we would also save on heating costs and that the effort would pay off within 10 years.

There are assumptions about prices, price trends, usage behavior, consumables, opportunities, etc., which sometimes make this kind of payback calculation possible, and sometimes not.

LarsBr80 schrieb:

Has anyone actually done the math or knows about the numbers?

Of course I have done such calculations, and almost everyone here tends to make their own system look favorable.
We made the numbers look good for a masonry heater. You have a good and reliable heating system with low operating costs that won’t fail you. You’ve already invested that money. Forget recalculating over 8, 10, 15, or 20 years and just enjoy your home.