ᐅ Decentralized Mechanical Ventilation – Yes or No? Pros and Cons?
Created on: 26 Feb 2016 13:15
N
nils1985
Dear Forum,
We are currently planning our new build, and I have now received the scope of work from our builder. First of all: one thing is certain, a central heat recovery ventilation system is out of the question because it is too expensive.
The basic data for our single-family house:
130 sqm (1,400 sq ft), underfloor heating on the ground floor and in the bathroom (upper floor), radiators everywhere else, all windows with roller shutters (thermally insulated roller shutter boxes with half-shells).
[U]According to our scope of work, the following is to be installed:[/U]
"Decentralized ventilation system Lunos e² with heat recovery (up to 90%), very low power consumption (only 0.09 watts / sqm (0.008 watts / sq ft) thanks to direct current), and a 10-year warranty on the ceramic heat exchanger. Fully integrated into the exterior wall. Exhaust fans as AB 30/60."
[U]Our wall construction is as follows:[/U]
- Double-shell facing masonry – total thickness of 45 cm (18 inches).
- Inner leaf – 17.5 cm (7 inches) thick aerated concrete blocks as plan bricks, WLZ 0.10, compressive strength PP2, brand Ytong.
- 14 cm (5.5 inches) hydrophobic (water-repellent) core insulation boards KDII with staggered joints, WLG 035.
- 2 cm (0.8 inches) air gap.
- 11.5 cm (4.5 inches) facing brick.
- U-value is approx. 0.16 W/m²K.
- Triple-glazed insulating glass as thermal insulation glass (Ug value 0.7 W/m²K).
Is it really necessary to install a heat recovery ventilation system? I know it prevents mold and ensures controlled air exchange. But is it really required? I am rather skeptical about it. I have already been in several houses (built from 2013 onwards) without heat recovery ventilation and haven’t noticed anything negative.
So far, the disadvantages outweigh the benefits for me (just my own opinion):
- Increased energy use (electricity, heat loss).
- Holes in the wall.
- Noise from external influences and the ventilation system itself.
- Energy loss during winter.
- Higher temperatures in the bedrooms during summer.
If we decide to go with a decentralized heat recovery ventilation system, how many fans would be needed? Where would it be advisable to install them?
Thank you in advance for your effort and opinions!!!
We are currently planning our new build, and I have now received the scope of work from our builder. First of all: one thing is certain, a central heat recovery ventilation system is out of the question because it is too expensive.
The basic data for our single-family house:
130 sqm (1,400 sq ft), underfloor heating on the ground floor and in the bathroom (upper floor), radiators everywhere else, all windows with roller shutters (thermally insulated roller shutter boxes with half-shells).
[U]According to our scope of work, the following is to be installed:[/U]
"Decentralized ventilation system Lunos e² with heat recovery (up to 90%), very low power consumption (only 0.09 watts / sqm (0.008 watts / sq ft) thanks to direct current), and a 10-year warranty on the ceramic heat exchanger. Fully integrated into the exterior wall. Exhaust fans as AB 30/60."
[U]Our wall construction is as follows:[/U]
- Double-shell facing masonry – total thickness of 45 cm (18 inches).
- Inner leaf – 17.5 cm (7 inches) thick aerated concrete blocks as plan bricks, WLZ 0.10, compressive strength PP2, brand Ytong.
- 14 cm (5.5 inches) hydrophobic (water-repellent) core insulation boards KDII with staggered joints, WLG 035.
- 2 cm (0.8 inches) air gap.
- 11.5 cm (4.5 inches) facing brick.
- U-value is approx. 0.16 W/m²K.
- Triple-glazed insulating glass as thermal insulation glass (Ug value 0.7 W/m²K).
Is it really necessary to install a heat recovery ventilation system? I know it prevents mold and ensures controlled air exchange. But is it really required? I am rather skeptical about it. I have already been in several houses (built from 2013 onwards) without heat recovery ventilation and haven’t noticed anything negative.
So far, the disadvantages outweigh the benefits for me (just my own opinion):
- Increased energy use (electricity, heat loss).
- Holes in the wall.
- Noise from external influences and the ventilation system itself.
- Energy loss during winter.
- Higher temperatures in the bedrooms during summer.
If we decide to go with a decentralized heat recovery ventilation system, how many fans would be needed? Where would it be advisable to install them?
Thank you in advance for your effort and opinions!!!
B
Bieber081529 Feb 2016 22:03BeHaElJa schrieb:
I also think it largely depends on the sensitivity of the person It is primarily a matter of interpretation and design.
Here, the distinction is always made only between central and decentralized systems. Does anyone have experience with a central exhaust system with heat recovery combined with decentralized wall vents for the supply air?
We recently looked at this system at friends’ house and thought it was good. Not audible. Hardly noticeable even at maximum level.
We recently looked at this system at friends’ house and thought it was good. Not audible. Hardly noticeable even at maximum level.
S
Sebastian791 Mar 2016 07:10If you can't hear anything at the maximum setting, in my opinion something might be wrong.
@Tomtom
I have a Wolf CWL 300, and you can only hear it at full power. Of course, many factors play a role, but I am specifically referring to the noise at the valves from a distance of 1-2 meters (3-6 feet) during normal operation, which means 80-150 cubic meters per hour (cbm). Naturally, you can also hear 150 cbm at night, but my system is continuously controlled and usually runs at about 70-80 cbm at night, which is not audible.
Central exhaust with supply air vents should be understood as you described: they are basically simple exhaust systems where the air flows back in without heat recovery, either through window frame gaps or separate supply air openings in the wall—so basically a workaround.
I have a Wolf CWL 300, and you can only hear it at full power. Of course, many factors play a role, but I am specifically referring to the noise at the valves from a distance of 1-2 meters (3-6 feet) during normal operation, which means 80-150 cubic meters per hour (cbm). Naturally, you can also hear 150 cbm at night, but my system is continuously controlled and usually runs at about 70-80 cbm at night, which is not audible.
Central exhaust with supply air vents should be understood as you described: they are basically simple exhaust systems where the air flows back in without heat recovery, either through window frame gaps or separate supply air openings in the wall—so basically a workaround.
tomtom79 schrieb:
How is this supposed to work if it draws cold air into the room without first warming it through a heat recovery ventilator? That doesn’t make sense. Quote from another forum:
"Exhaust air system with decentralized supply air.
The air initially flows cold into the rooms through decentralized openings. However, in good systems, you don’t feel any draft because the cold air quickly mixes with the warm room air.
The heat recovery takes place within the exhaust air system.
There is an exhaust air heat pump that extracts energy from the warm exhaust air and transfers it, for example, to a heating buffer, a domestic hot water tank, or both."
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