ᐅ Newly built apartment (KfW-55 standard) cannot be cooled below at least 25 °C.
Created on: 21 Aug 2022 08:52
F
Forsberg21
Hello,
I have rented out a new apartment (built in 2021, KfW-55 standard). The tenant recently informed me that since spring, the indoor temperatures have consistently been at least 25°C (77°F) or higher. On warm days, it even reaches up to 28°C (82°F), although she keeps all the aluminum shutters closed during the day (no home office). Cross-ventilation at night doesn’t bring the temperature below 25°C (77°F). She is asking for advice on how to cool the apartment down a bit during the summer.
What could be causing this?
The apartment has a decentralized ventilation system and underfloor heating, which is naturally turned off in summer.
The apartment faces southwest and has large window areas.
Could it be that the ventilation system continuously brings in warm outside air on hot days, causing the temperature to rise so much?
Should the ventilation system be turned off during the day?
But why doesn’t the apartment cool down at night, even though there seems to be cross-ventilation and the nights are cooler?
Do you have any tips? I am a bit overwhelmed.
Best regards,
Robert
I have rented out a new apartment (built in 2021, KfW-55 standard). The tenant recently informed me that since spring, the indoor temperatures have consistently been at least 25°C (77°F) or higher. On warm days, it even reaches up to 28°C (82°F), although she keeps all the aluminum shutters closed during the day (no home office). Cross-ventilation at night doesn’t bring the temperature below 25°C (77°F). She is asking for advice on how to cool the apartment down a bit during the summer.
What could be causing this?
The apartment has a decentralized ventilation system and underfloor heating, which is naturally turned off in summer.
The apartment faces southwest and has large window areas.
Could it be that the ventilation system continuously brings in warm outside air on hot days, causing the temperature to rise so much?
Should the ventilation system be turned off during the day?
But why doesn’t the apartment cool down at night, even though there seems to be cross-ventilation and the nights are cooler?
Do you have any tips? I am a bit overwhelmed.
Best regards,
Robert
KingJulien schrieb:
But that’s a Pyrrhic victory. To achieve a minimal amount of evaporative cooling, you increase the humidity, which also makes it feel clammy.
A fan is completely sufficient.
By the way, I do the exact opposite. In summer, I run the dehumidifier and accept the slight warming it causes for pleasantly dry air 😉 Don’t underestimate the perceived temperature (dew point). I would strongly advise against using towels or ice cubes, even though it is physically correct and does indeed produce evaporative cooling.
OWLer schrieb:
The perceived temperature (dew point) should not be underestimated. I would also strongly advise against the towel or ice cube method, even though it is physically correct and actually creates evaporative cooling.It always depends on what one personally finds comfortable or uncomfortable. For example, I find a fan blows too much air, which I do not find pleasant. I personally prefer using a damp cloth instead.But of course, the humidity level will increase.
Today is August 26th, in this hellish month (today it is raining for the first time, the temperatures have been crazy, always clear blue skies, everything dried out).
The split air conditioner has cooled the bedroom for 12 hours every night, and also occasionally the office and living room.
A KFW55 house is otherwise a nightmare in summer. I understand your tenant; it is unbearably warm, and it’s hard to sleep well.
Energy consumption: 56 kWh over 24 effective days (we were away for 2 days).
Costs: 2.33 kWh/day = 0.7€ per day.
I would definitely choose to buy a split air conditioner again.
The fear of dry air has not come true; luckily, I haven’t ordered power-hungry humidifiers yet. After 12 hours of air conditioning in the bedroom, the humidity is still above 50%.
Soon I will even heat with it – it’s actually cheaper than gas plus underfloor heating…
The split air conditioner has cooled the bedroom for 12 hours every night, and also occasionally the office and living room.
A KFW55 house is otherwise a nightmare in summer. I understand your tenant; it is unbearably warm, and it’s hard to sleep well.
Energy consumption: 56 kWh over 24 effective days (we were away for 2 days).
Costs: 2.33 kWh/day = 0.7€ per day.
I would definitely choose to buy a split air conditioner again.
The fear of dry air has not come true; luckily, I haven’t ordered power-hungry humidifiers yet. After 12 hours of air conditioning in the bedroom, the humidity is still above 50%.
Soon I will even heat with it – it’s actually cheaper than gas plus underfloor heating…
G
Georgian201927 Aug 2022 01:10KfW70 with a solid 36.5cm (14.4 inches) wall and double-glazed windows: the indoor temperature is usually around 23 degrees Celsius (73°F). When it was often above 30 degrees Celsius (86°F) outside, the living room sometimes reached 25 degrees Celsius (77°F) because the patio door was frequently open. Otherwise, at least one window is tilted open at night, and in the early morning, when it's 17-19 degrees Celsius (63-66°F), the house is ventilated. During the day, shutters on the south and west sides are kept closed.
I now understand why I didn’t build a KfW55 or 40... basically a plastic house with a ventilation system.
I now understand why I didn’t build a KfW55 or 40... basically a plastic house with a ventilation system.
Georgian2019 schrieb:
KfW70 with a 36.5cm (14 inch) solid wall and double-glazed windows: generally around 23 degrees Celsius (73°F) inside the house. When it was often over 30 degrees Celsius (86°F) outside, the living room sometimes reached 25 degrees Celsius (77°F) because the patio door was frequently open. Otherwise, at night at least one window is tilted open, and early in the morning with 17-19 degrees Celsius (63-66°F) outside, the house is ventilated, then shutters on the south and west sides remain closed during the day.
I know why I didn’t build KfW55 or 40... that would be a plastic house with a ventilation system. Cool, that sounds normal.
How is the heating and hot water supply for you? How many kWh per year?
Georgian2019 schrieb:
I already know why I didn’t build a KfW55 or 40 house... basically a plastic house with a ventilation system.Timber frame construction with wood fiber insulation boards is not like a plastic bag. Always these generalizations… if one thing is bad, everything is bad…Similar topics