Hello,
We built a passive house and moved in around Easter. Unfortunately, we experienced an almost unbearable summer. Despite shading, the indoor temperature stayed above 26°C (79°F) almost continuously, even at night.
We have a ventilation system from Paul (Novus 450) with an active ground-source pre-cooling feature. The ventilation is not yet properly adjusted; it currently operates at about 30% higher airflow than necessary. The problem is that no matter the supply air temperature, the vents deliver roughly 0.5°C (0.9°F) less than the room temperature. Even with the active bypass engaged and supply air reduced to 16°C (61°F), the room temperature remains at 22.9°C (73°F) (our current indoor temperature without additional heating is 23.5°C (74°F)). The technician measured the values and said it was not optimal but still acceptable. However, I find that hard to believe, since we are sweating every night and don’t even get cooler air into the house overnight. Has anyone experienced something similar? Thanks for any help...
Best regards,
Thorsten
We built a passive house and moved in around Easter. Unfortunately, we experienced an almost unbearable summer. Despite shading, the indoor temperature stayed above 26°C (79°F) almost continuously, even at night.
We have a ventilation system from Paul (Novus 450) with an active ground-source pre-cooling feature. The ventilation is not yet properly adjusted; it currently operates at about 30% higher airflow than necessary. The problem is that no matter the supply air temperature, the vents deliver roughly 0.5°C (0.9°F) less than the room temperature. Even with the active bypass engaged and supply air reduced to 16°C (61°F), the room temperature remains at 22.9°C (73°F) (our current indoor temperature without additional heating is 23.5°C (74°F)). The technician measured the values and said it was not optimal but still acceptable. However, I find that hard to believe, since we are sweating every night and don’t even get cooler air into the house overnight. Has anyone experienced something similar? Thanks for any help...
Best regards,
Thorsten
Thorsten_J2 Oct 2017 22:16I understand that the controlled residential ventilation system can’t cool the entire house, but if the pre-cooled air is heated back up to room temperature inside the ducts, then the summer bypass seems pointless, or am I mistaken? At least some cooler air should reach the rooms.
According to Paul, the temperature increase should be a maximum of 1-2 degrees Celsius (2-4 degrees Fahrenheit). I just wanted to hear how others are experiencing this.
As active cooling, we have 100 meters (330 feet) of ground loop with a pump and a cooling element placed after the first supply air filter. At the same time, this also works as heating in winter.
According to Paul, the temperature increase should be a maximum of 1-2 degrees Celsius (2-4 degrees Fahrenheit). I just wanted to hear how others are experiencing this.
As active cooling, we have 100 meters (330 feet) of ground loop with a pump and a cooling element placed after the first supply air filter. At the same time, this also works as heating in winter.
We have the same problem here: outside 30°C (86°F) in summer, inside the room 26°C (79°F) despite shading. Schwörerhaus's recommendation is to turn off the controlled ventilation system between 9 a.m. and 9 p.m. during the day... At night, open all the windows and set the ventilation to exhaust mode.
Well, as I already mentioned, I don’t see a problem. Without active shading and/or cooling in the summer, modern and well-sealed houses will heat up and stay warm because that is essentially what they are designed for.
The sun is simply there, and once the heat is inside, it stays in the house. That is exactly what the insulation, ETICS (External Thermal Insulation Composite System), or whatever system you have on the house is for.
The controlled ventilation system is primarily intended for air exchange, and it does that. However, warm outside air adds an additional factor that heats the house in summer besides the sun. Pre-cooling the air slightly through a ground heat exchanger or brine system can reduce the temperature by a few degrees, but this only marginally delays the time it takes for the house to warm up. Once the heat is inside, it simply remains.
At least with the bypass, the outside air (regardless of its temperature) enters without bringing the house’s heat back inside through the heat exchanger, which is definitely something you want to avoid in the summer.
The sun is simply there, and once the heat is inside, it stays in the house. That is exactly what the insulation, ETICS (External Thermal Insulation Composite System), or whatever system you have on the house is for.
The controlled ventilation system is primarily intended for air exchange, and it does that. However, warm outside air adds an additional factor that heats the house in summer besides the sun. Pre-cooling the air slightly through a ground heat exchanger or brine system can reduce the temperature by a few degrees, but this only marginally delays the time it takes for the house to warm up. Once the heat is inside, it simply remains.
At least with the bypass, the outside air (regardless of its temperature) enters without bringing the house’s heat back inside through the heat exchanger, which is definitely something you want to avoid in the summer.
Thorsten_J3 Oct 2017 12:24Mycraft schrieb:
...
At least with the bypass, outside air gets inside (regardless of its temperature) without the heat from the house being transferred back through the heat exchanger, which is definitely not desired in summer.Exactly, that’s what I mean, but the air in the bypass still seems to be warmed by up to 10°C (18°F) in the duct (up to room temperature), which strikes me as odd.
Why? If your duct is located within the heated building envelope and has no active cooling, why would cooler air come out of it?
If the air has been cooled previously by the brine heat exchanger but then passes through a device at around 26°C (79°F) and through ducts also at 26°C (79°F), the air will be warmed up again. Once it reaches the room air, the temperature equalizes anyway, resulting in a homogeneous environment.
If the air has been cooled previously by the brine heat exchanger but then passes through a device at around 26°C (79°F) and through ducts also at 26°C (79°F), the air will be warmed up again. Once it reaches the room air, the temperature equalizes anyway, resulting in a homogeneous environment.
Thorsten_J14 Oct 2017 06:12Ok, thank you for your answers. However, I had expected at least slightly cooler air to come out.
Why do I have an expensive ventilation system with a heat exchanger and bypass if the heat capacity of air is low anyway and everything is heated up in the duct? Sounds almost like a perpetual motion machine.
Why do I have an expensive ventilation system with a heat exchanger and bypass if the heat capacity of air is low anyway and everything is heated up in the duct? Sounds almost like a perpetual motion machine.
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