ᐅ Multi-day Power Outage as Currently Experienced in Berlin: Risks for Heating Systems and Water Pipes?
Created on: 6 Jan 2026 10:01
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Pianist
Good day!
As you probably know from the news, there is currently an extended power outage in the southern part of Berlin, which started on Saturday and is expected to last until Thursday. This makes me wonder: what impact does a multi-day power outage have on building systems when outside temperatures are below freezing?
Let’s assume that a house in an unprepared state would no longer be habitable by usual standards. The fresh water system can be drained, and the local water supplier can be asked to shut off the supply line in the street. This should take care of that aspect. But what about the circulation water in the heating system? It’s unlikely that every radiator or underfloor heating loop can be completely drained reliably.
How long does it take for a well-insulated house, constructed with materials that have good thermal mass, to freeze enough that there is a risk of heating pipes bursting? The consequences would be severe, potentially requiring the removal of the screed…
So, let’s assume minus ten degrees Celsius (14°F) and a week without power. Are there any experience reports from previous events?
Matthias
As you probably know from the news, there is currently an extended power outage in the southern part of Berlin, which started on Saturday and is expected to last until Thursday. This makes me wonder: what impact does a multi-day power outage have on building systems when outside temperatures are below freezing?
Let’s assume that a house in an unprepared state would no longer be habitable by usual standards. The fresh water system can be drained, and the local water supplier can be asked to shut off the supply line in the street. This should take care of that aspect. But what about the circulation water in the heating system? It’s unlikely that every radiator or underfloor heating loop can be completely drained reliably.
How long does it take for a well-insulated house, constructed with materials that have good thermal mass, to freeze enough that there is a risk of heating pipes bursting? The consequences would be severe, potentially requiring the removal of the screed…
So, let’s assume minus ten degrees Celsius (14°F) and a week without power. Are there any experience reports from previous events?
Matthias
Pianist schrieb:
How long does it take for a well-insulated house, built with materials that have good thermal mass, to become that thoroughly cold, our ancestors used to know this.
Explained today, every person produces about 100W of heat. If you have 5 to 20 people living in the house, like in the past, it will never freeze inside at -10°C (14°F).
It will get chilly without a stove, but no frost.
Invite visitors over; their houses will be colder than yours 😉
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Neuer von Da7 Jan 2026 00:49I would simply light the fireplace.
In the long run, without ventilation, the humidity might cause damage after a few days.
But there are still windows...
Oh, revise the roller shutters—they don’t open without power, so that means 2 emergency windows.
Most homeowners have supplies for a few days, and the refrigerator is the winter storage.
Cooking can be done with a gas bottle grill or a camping stove.
Electricity and lighting come from batteries, etc.
We could live like this for about 1 to 2 weeks at most.
The most important thing is probably always having supplies on hand.
In the long run, without ventilation, the humidity might cause damage after a few days.
But there are still windows...
Oh, revise the roller shutters—they don’t open without power, so that means 2 emergency windows.
Most homeowners have supplies for a few days, and the refrigerator is the winter storage.
Cooking can be done with a gas bottle grill or a camping stove.
Electricity and lighting come from batteries, etc.
We could live like this for about 1 to 2 weeks at most.
The most important thing is probably always having supplies on hand.
I don’t have any roller shutters; only the patio door is secured from the inside at night and when I’m away with a security grille. Although it would be unlikely for anyone to get through anyway, this way nobody is even tempted to try, and no damage is caused. I also don’t have a fireplace or stove because I didn’t want to manage firewood, and a floor plan without a second chimney wasn’t an option.
So, in my opinion, there are only two options: either a fully reliable backup power supply to maintain normal operation, or you leave the house and only want to prevent frost damage.
So, in my opinion, there are only two options: either a fully reliable backup power supply to maintain normal operation, or you leave the house and only want to prevent frost damage.
Experience report:
We are currently building a KFW40 house. The structure is up with windows installed and exterior roof insulation; we are now installing the insulation between the rafters. The screed and underfloor heating have not yet been installed. There are still several holes in the external walls, and the door to the less insulated basement is only covered with a bedsheet.
During the day, we heat from outside using a construction heater to about 13°C (55°F) to ensure the plaster dries properly and working conditions are comfortable. We have several temperature and humidity loggers set up, so we can closely monitor how the temperature behaves at the moment.
At night—when the heating is off for approximately 14 hours—we lose an average of 1°C (1.8°F). When it was around -11°C (13°F) outside during the night, the temperature inside dropped by 1.2°C (2.2°F) by morning. When the nighttime temperature is close to 0°C (32°F), the temperature drop is only about 0.8°C (1.4°F).
We are currently building a KFW40 house. The structure is up with windows installed and exterior roof insulation; we are now installing the insulation between the rafters. The screed and underfloor heating have not yet been installed. There are still several holes in the external walls, and the door to the less insulated basement is only covered with a bedsheet.
During the day, we heat from outside using a construction heater to about 13°C (55°F) to ensure the plaster dries properly and working conditions are comfortable. We have several temperature and humidity loggers set up, so we can closely monitor how the temperature behaves at the moment.
At night—when the heating is off for approximately 14 hours—we lose an average of 1°C (1.8°F). When it was around -11°C (13°F) outside during the night, the temperature inside dropped by 1.2°C (2.2°F) by morning. When the nighttime temperature is close to 0°C (32°F), the temperature drop is only about 0.8°C (1.4°F).
The house also doesn’t freeze through quickly. It takes time. At risk initially are only the exposed pipes that haven’t been drained.
If you have a gas grill and maybe two gas cylinders instead of one, you can still cook during a power outage. Many households have a hot water tank of around 200 liters (50 gallons) that supplies fresh water. You might be able to fill a bathtub, or maybe not.
A few candles provide light. I have a 2 kW generator for the essential appliances, just in case. With 40 liters (10.5 gallons) of fuel, it lasts a long time.
If you have a gas grill and maybe two gas cylinders instead of one, you can still cook during a power outage. Many households have a hot water tank of around 200 liters (50 gallons) that supplies fresh water. You might be able to fill a bathtub, or maybe not.
A few candles provide light. I have a 2 kW generator for the essential appliances, just in case. With 40 liters (10.5 gallons) of fuel, it lasts a long time.
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