ᐅ Is it possible to install air conditioning as an upgrade if a mechanical ventilation system with heat recovery is already installed?
Created on: 8 Aug 2021 07:32
M
McEgg
Hello,
we live in a KfW55 house with a controlled mechanical ventilation system. Since it gets too warm for me in the summer, I would now like to add air conditioning units.
I am planning a total of four units: in the three bedrooms upstairs and in the open living, dining, and kitchen area on the ground floor.
I have looked at units from Gree and would choose 2.7 kW units for the upstairs rooms and a 5.3 kW unit for the ground floor, based on the room sizes.
Now to the main question:
Does it make sense to install air conditioning if we already have a controlled mechanical ventilation system? Do the air conditioning units generally need to be sized larger because the ventilation system removes the cool air too quickly? Or does the controlled mechanical ventilation system prevent the rooms from cooling down effectively in the first place?
we live in a KfW55 house with a controlled mechanical ventilation system. Since it gets too warm for me in the summer, I would now like to add air conditioning units.
I am planning a total of four units: in the three bedrooms upstairs and in the open living, dining, and kitchen area on the ground floor.
I have looked at units from Gree and would choose 2.7 kW units for the upstairs rooms and a 5.3 kW unit for the ground floor, based on the room sizes.
Now to the main question:
Does it make sense to install air conditioning if we already have a controlled mechanical ventilation system? Do the air conditioning units generally need to be sized larger because the ventilation system removes the cool air too quickly? Or does the controlled mechanical ventilation system prevent the rooms from cooling down effectively in the first place?
H
hampshire8 Aug 2021 11:04I have great understanding of your project and do not criticize the installation of an air conditioning system in any way.
How illogical are our building regulations focused on energy saving when they mainly address heat loss during the cold months but hardly consider heat removal in the warm months? The energy saved in winter is then spent on additional air conditioning in summer because it’s no longer possible to cool the houses once the heat has built up inside. Isn’t there a smarter way to approach this already at the regulatory level?
How illogical are our building regulations focused on energy saving when they mainly address heat loss during the cold months but hardly consider heat removal in the warm months? The energy saved in winter is then spent on additional air conditioning in summer because it’s no longer possible to cool the houses once the heat has built up inside. Isn’t there a smarter way to approach this already at the regulatory level?
McEgg schrieb:
The figures come from the building permit / planning permission documents.Ah, so you don’t actually know if that’s even correct. 😎I’m wondering how it can get (too) warm in your house at all. The upper floor only has windows at the gable ends (west/east).
The south side has an overhang.
Are the awnings at least hanging in the meantime? 😉
Even if this “summer” you mostly have to use them as rain protection.
H
hampshire8 Aug 2021 11:30driver55 schrieb:
I wonder how it can even get (too) warm inside your house. The upper floor only has windows on the gable ends (west/east).
The south side has an overhang.Possible factors: Factor A: The roof insulation becomes "warmed through" after several sunny days.
Factor B: In everyday living, windows are often left open frequently and for long periods, causing heat to accumulate in the bedrooms upstairs.
Factor C: The east and west windows are not shaded when exposed to sunlight. Radiant heat enters freely and cannot escape well due to good insulation.
It might be a good idea to route supply and exhaust air for a controlled ventilation system through underground piping – this way the incoming air could be naturally cooled without any energy consumption.
McEgg schrieb:
So, the bedrooms are about 20m² (215 sq ft) each with a ceiling height of 2.73m (9 ft). The area on the ground floor is approximately 55m² (592 sq ft) with a ceiling height of 2.63m (8.6 ft).
These figures come from the building permit documents. How does the heat enter the house? Do you have large windows, etc.?
For just a few warm days like this year, it should be enough to close the bedroom windows tightly in advance using roller shutters and similar measures.
hampshire schrieb:
How illogical are our building regulations for energy saving, focusing almost entirely on heat loss during the cold months but hardly addressing heat gain in the warm months? The energy saved in winter is often used in summer for additional air conditioning, since it becomes impossible to cool the house once the heat gets inside. Isn’t there a smarter way to approach this starting with the regulations?I’ve been saying this for a long time… but…The biggest problem today is the lack of thermal mass in houses, not just the half-hearted shading. And, of course, the assumption that “the house is insulated.” Obviously, a lot of people just switch their brains off at this point.
hampshire schrieb:
It might not be a bad idea to run supply and exhaust air for a controlled ventilation system through pipes buried underground – that way the incoming air could be naturally pre-cooled without energy use.That often causes hygiene problems though, which is far from ideal.@McEgg
Based on experience:
With today’s construction methods, a 3.5 kW unit should be sufficient for your living area, and the smallest possible—ideally a 2.0 kW unit—for the bedrooms.
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