Hello everyone, the title already describes the problem. Approximately 20% humidity in all living and sleeping rooms. We moved in about two weeks ago. That can’t be normal, right? I expected such low humidity only after 2-3 years, but not right from the start...
The first night in the house was really horrible. On top of that, we have been dealing with colds and coughing the whole time. We now have a humidifier running all night in the bedroom (starting in the evening, about 12 hours total) and wake up with around 35-40% humidity.
Could something be set incorrectly in the mechanical ventilation system with heat recovery, or is this low humidity normal in a new house?
What can we do? Apart from the bedroom, we don’t notice it being a problem in any other room. Enthalpy exchangers are supposed to increase humidity by a maximum of 5%, right?!
Thanks for your feedback and best regards
The first night in the house was really horrible. On top of that, we have been dealing with colds and coughing the whole time. We now have a humidifier running all night in the bedroom (starting in the evening, about 12 hours total) and wake up with around 35-40% humidity.
Could something be set incorrectly in the mechanical ventilation system with heat recovery, or is this low humidity normal in a new house?
What can we do? Apart from the bedroom, we don’t notice it being a problem in any other room. Enthalpy exchangers are supposed to increase humidity by a maximum of 5%, right?!
Thanks for your feedback and best regards
W
WilderSueden5 Mar 2023 22:30motorradsilke schrieb:
What’s still missing is the calculation of how much the mechanical ventilation system itself consumes.
I did a bit of research and found figures between 200 and 500 kWh per year. So even assuming 200 to 500 kWh for ventilation, I would save around 300 kWh, which is about 60 euros per year. It wouldn’t pay off in my lifetime, even if electricity prices rise. What are you comparing this against? Your 2 air changes per day, or the 5+ air changes you get on a low setting, which you should have at minimum?
M
motorradsilke6 Mar 2023 05:48WilderSueden schrieb:
What are you comparing? To your 2 air changes per day or the 5+ air changes you get on low setting and should have at a minimum? Who says I should have at least that many?
I use the values from my heating load calculation done by an energy consultant (a quarter of my heating energy demand). This is apparently considered sufficient by experts.
And that’s not even entirely accurate—I simply took the electricity consumption of my heat pump, which also includes domestic hot water heating. If I subtract that, there is probably almost no economic advantage left for the controlled residential ventilation system.
If YOU see controlled residential ventilation as a comfort benefit, that’s fine. That is subjective and certainly true.
It is not necessary, it does not pay off financially, and I assume that the majority of houses currently being built do not have it. Although the impression here might be different, this forum does not represent most home builders.
W
WilderSueden6 Mar 2023 08:34You should have received a ventilation plan from your designer that specifies how often ventilation is required.
Otherwise, try using a major search engine to look up recommended air exchange rates or minimum ventilation rates. You’ll often find a rate of 0.5 air changes per hour or 12 per day. I also consider that quite high, but with windows alone, you won’t even come close to that. Two air changes are definitely far too few. Even in older buildings with less airtight windows, tenants can run into problems with dampness if they only ventilate twice a day.
Otherwise, try using a major search engine to look up recommended air exchange rates or minimum ventilation rates. You’ll often find a rate of 0.5 air changes per hour or 12 per day. I also consider that quite high, but with windows alone, you won’t even come close to that. Two air changes are definitely far too few. Even in older buildings with less airtight windows, tenants can run into problems with dampness if they only ventilate twice a day.
M
motorradsilke6 Mar 2023 10:27WilderSueden schrieb:
You should have received a ventilation plan from your designer that specifies how often you need to ventilate.
Otherwise, try searching online for the recommended air exchange rate or minimum air exchange. You will commonly find 0.5 air changes per hour or 12 per day. I also think that’s quite high, but with just windows, you won’t even come close to that. Two air changes are definitely far too few. Even in older buildings with less airtight windows, tenants can have problems if they only ventilate twice a day and moisture builds up. I just checked my ventilation plan. The minimum requirement for moisture protection is 0.1. That matches my routine of ventilating twice plus keeping the bedroom window open at night and opening doors several times during the day.
W
WilderSueden6 Mar 2023 10:43This is the wrong section. I have looked up the three relevant ventilation levels for you. Moisture protection refers to the ventilation you need when you are on vacation. You need to look at the nominal ventilation, which is for everyday use with people in the house, cooking, showering, and so on. And I can assure you that this will be much more than 0.1 air changes per hour.
The core of the standard DIN 1946-6 is the distinction of four ventilation levels with different intensities, which we explain to you here in more detail:
Ventilation for moisture protection (FL)
This ventilation level aims to provide sufficient ventilation of the building depending on the respective thermal insulation level. The goal is to prevent building damage caused by moisture even when the occupants are temporarily absent and moisture loads are reduced, for example, when drying laundry indoors is intentionally avoided. This means: a ventilation system designed accordingly must operate independently of the user.
Reduced ventilation (return air)
This ventilation level must also be largely independent of the user. It must ensure that even when occupants are temporarily absent, for example due to work commitments, the ventilation meets minimum hygiene standards and building protection requirements.
Nominal ventilation (NL)
The so-called nominal ventilation refers to the air supply needed to maintain hygiene and health standards as well as building protection when the dwelling is in regular use. The nominal ventilation level can partially involve the occupant actively in the ventilation concept, for example through manual window ventilation.
The core of the standard DIN 1946-6 is the distinction of four ventilation levels with different intensities, which we explain to you here in more detail:
Ventilation for moisture protection (FL)
This ventilation level aims to provide sufficient ventilation of the building depending on the respective thermal insulation level. The goal is to prevent building damage caused by moisture even when the occupants are temporarily absent and moisture loads are reduced, for example, when drying laundry indoors is intentionally avoided. This means: a ventilation system designed accordingly must operate independently of the user.
Reduced ventilation (return air)
This ventilation level must also be largely independent of the user. It must ensure that even when occupants are temporarily absent, for example due to work commitments, the ventilation meets minimum hygiene standards and building protection requirements.
Nominal ventilation (NL)
The so-called nominal ventilation refers to the air supply needed to maintain hygiene and health standards as well as building protection when the dwelling is in regular use. The nominal ventilation level can partially involve the occupant actively in the ventilation concept, for example through manual window ventilation.
motorradsilke schrieb:
This works for me with ventilating twice plus keeping the bedroom window open at night and opening doors several times a day.plus working in the garden, plus sitting on the terrace with doors open for hours 😉Similar topics