ᐅ Ventilation in New Construction (Central vs. Decentralized), Noise Disturbance
Created on: 20 Jun 2016 20:41
K
Kiri123
Hello everyone,
I am currently considering the ventilation system for our planned new build (details: Kfw 70, 2 full floors + basement + unheated attic, hipped roof, 200m² (2,150 sq ft) living space). We live in a rural area and like to keep the windows open sometimes, so we don’t necessarily have to rely entirely on mechanical ventilation.
I am torn between a central controlled mechanical ventilation system with heat recovery, a central exhaust with decentralized supply air, and decentralized supply/exhaust with heat recovery. My requirements are:
• Ventilation of bathrooms (master bathroom, children’s bathroom without windows, and guest toilet without windows) with demand-controlled ventilation based on usage
• I want to avoid having to open windows every few hours while still maintaining high indoor air quality
• Not too noisy, as I am very sensitive to noise when trying to sleep
• I am also sensitive to dry air; for example, I cannot tolerate air from air conditioning or sports halls very well
Below are the pros and cons of each system as I see them:
Central Controlled Mechanical Ventilation with Heat Recovery
+the most mature system
-expensive (I estimate about 10,000 to 13,000 Euros)
-more complex planning, including suspending and boxing in ducts
-(I heard from a provider of decentralized ventilation systems: as soon as I turn up the ventilation in the living room, more warm air is blown into the bedroom – not desirable)
-the indoor air quality in the prefabricated houses with controlled ventilation that we visited was always poor. That makes me skeptical
Central Exhaust with Decentralized Supply Air
+cheaper (maybe 2,000 to 3,000 Euros?)
+should meet minimum requirements
-energy wasted (or can I reuse the heat energy somehow? I am planning to install an air-water heat pump for heating and hot water production. Maybe the heat can be used here in a useful way). I was advised against a complete exhaust heat pump. Perhaps combined exhaust/fresh air heat pumps exist?
-cold air from decentralized supply? (I have read that with proper planning this is no problem because the supply air mixes “appropriately” with the existing indoor air)
-somewhat contradicts the idea of energy-efficient houses. Still, it’s probably more efficient than constantly having windows tilted open.
Decentralized Ventilation with Heat Recovery
+If I simply install one of these ventilators in the living-dining area, the master bathroom, and the children’s bathroom (+ exhaust in the toilet), the minimum requirements should be met. I estimate about 3,000 Euros (1,000 Euros per unit)
-if I want to cover all other rooms to avoid window ventilation entirely, it gets more expensive (maybe ~8,000 Euros) and:
-I would have many holes in the building envelope
-I hesitate to install these devices in bedrooms or children’s rooms because I think they may be too noisy.
Could you please help me with the decision? Maybe by sharing your experience or confirming or disproving some of my points? I would also like to see different ventilators in practice. Do you have any tips? I heard it might be possible somewhere in Berlin, but I live in the postal code area 5xxxx.
I look forward to your opinions.
Kiri
I am currently considering the ventilation system for our planned new build (details: Kfw 70, 2 full floors + basement + unheated attic, hipped roof, 200m² (2,150 sq ft) living space). We live in a rural area and like to keep the windows open sometimes, so we don’t necessarily have to rely entirely on mechanical ventilation.
I am torn between a central controlled mechanical ventilation system with heat recovery, a central exhaust with decentralized supply air, and decentralized supply/exhaust with heat recovery. My requirements are:
• Ventilation of bathrooms (master bathroom, children’s bathroom without windows, and guest toilet without windows) with demand-controlled ventilation based on usage
• I want to avoid having to open windows every few hours while still maintaining high indoor air quality
• Not too noisy, as I am very sensitive to noise when trying to sleep
• I am also sensitive to dry air; for example, I cannot tolerate air from air conditioning or sports halls very well
Below are the pros and cons of each system as I see them:
Central Controlled Mechanical Ventilation with Heat Recovery
+the most mature system
-expensive (I estimate about 10,000 to 13,000 Euros)
-more complex planning, including suspending and boxing in ducts
-(I heard from a provider of decentralized ventilation systems: as soon as I turn up the ventilation in the living room, more warm air is blown into the bedroom – not desirable)
-the indoor air quality in the prefabricated houses with controlled ventilation that we visited was always poor. That makes me skeptical
Central Exhaust with Decentralized Supply Air
+cheaper (maybe 2,000 to 3,000 Euros?)
+should meet minimum requirements
-energy wasted (or can I reuse the heat energy somehow? I am planning to install an air-water heat pump for heating and hot water production. Maybe the heat can be used here in a useful way). I was advised against a complete exhaust heat pump. Perhaps combined exhaust/fresh air heat pumps exist?
-cold air from decentralized supply? (I have read that with proper planning this is no problem because the supply air mixes “appropriately” with the existing indoor air)
-somewhat contradicts the idea of energy-efficient houses. Still, it’s probably more efficient than constantly having windows tilted open.
Decentralized Ventilation with Heat Recovery
+If I simply install one of these ventilators in the living-dining area, the master bathroom, and the children’s bathroom (+ exhaust in the toilet), the minimum requirements should be met. I estimate about 3,000 Euros (1,000 Euros per unit)
-if I want to cover all other rooms to avoid window ventilation entirely, it gets more expensive (maybe ~8,000 Euros) and:
-I would have many holes in the building envelope
-I hesitate to install these devices in bedrooms or children’s rooms because I think they may be too noisy.
Could you please help me with the decision? Maybe by sharing your experience or confirming or disproving some of my points? I would also like to see different ventilators in practice. Do you have any tips? I heard it might be possible somewhere in Berlin, but I live in the postal code area 5xxxx.
I look forward to your opinions.
Kiri
Sebastian79 schrieb:
An open window seems to provide more cooling at night than a mechanical ventilation system with a bypass... you can believe that or not.That is indeed true, as an open window simply allows much higher airflow. We also fell into the misconception that the ventilation system cools the house in summer. The ventilation system is designed to reduce the need to open windows in winter and to prevent moisture levels that encourage mold growth. New houses are so well insulated that just the radiant heat from two people can warm up a room overnight. My PC can raise my office temperature from 21°C (70°F) to 25°C (77°F) within two hours, even though the ventilation system is running at two-thirds capacity.
For summer, you should consider other solutions than a ventilation system, such as windows with integrated mosquito screens or an actual air conditioning unit.
Payday schrieb:
This is really true, as an open window simply allows for more airflow. We also fell into the misconception that the ventilation system cools the house in summer. The ventilation system is designed to reduce the need for airing in winter and to prevent moisture levels that promote mold. I would absolutely agree with that!
Payday schrieb:
My heat pump can heat my office from 21°C (70°F) to 25°C (77°F) within 2 hours Wow, what kind of heat pump do you have? :-O
@BastianB: I was about to write the same... then I did some googling... so to raise the air temperature in a room (20 m² (215 ft²)) by 5 degrees, you don't even need to run 100 watts for an hour.
Of course, this is a bit simplified since you also heat all the building components to some extent – but yes, if no heat escapes, you can warm the space "superficially" pretty quickly (like with a fan heater).
20 m² (215 ft²) * 2.5 m (8.2 ft) = 50 m³ (1,765 ft³) – air requires about 1 joule per gram per kelvin, or 1 kJ per kilogram per kelvin. Air weighs roughly 1.2 kg per cubic meter, so that’s 300 kJ for 50 m³ and 5 °K (5 K). 300 kJ is about 85 Wh.
Of course, this is a bit simplified since you also heat all the building components to some extent – but yes, if no heat escapes, you can warm the space "superficially" pretty quickly (like with a fan heater).
20 m² (215 ft²) * 2.5 m (8.2 ft) = 50 m³ (1,765 ft³) – air requires about 1 joule per gram per kelvin, or 1 kJ per kilogram per kelvin. Air weighs roughly 1.2 kg per cubic meter, so that’s 300 kJ for 50 m³ and 5 °K (5 K). 300 kJ is about 85 Wh.
S
Sebastian7912 Aug 2016 16:32We also sometimes leave windows open at night despite having a ventilation system with a bypass function.
At least with Helios, the system does not work against this and does not increase wear as a result.
At least with Helios, the system does not work against this and does not increase wear as a result.
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