How people survived at -30 °C without batteries and gas boilers

A resident of Harbin, the world's largest city with an extremely cold climate, told The Conversation how traditional heating methods helped people survive freezing temperatures of -30°C and why these solutions are relevant again amid the energy crisis and climate change.

Harbin is located in the north-east of China. Temperatures regularly drop to -30 °C in winter and rarely rise above -10 °C in January, even on the warmest days. At the same time, about six million people live in the city, and for a long time they did without central heating in the form familiar to Europe.

The author, now an architecture and construction researcher in the UK, notes that the traditional heating systems used in the region for centuries could offer the world more energy-efficient and sustainable ways to keep warm - especially now that heating bills are rising and winters are becoming less predictable.

A warm bed instead of a warm house

A key element of living in the cold was the kang, a massive bed made of tamped earth and bricks built into the house. Its history goes back at least two thousand years.

The kang was connected to the kitchen cooker: when food was cooked in the house, hot air travelled through channels under the bed, heating the whole structure. Thanks to its large mass, it retained heat all night, even if the air in the room remained cold.

Unlike central heating, the system did not use energy to heat the entire room. Only the surface where people sat or slept, covered with thick blankets, was heated. At the same time, there was almost no need for additional fuel - the fire was lit for cooking anyway.

According to the author, from the engineering point of view, the kan was an extremely efficient solution: without pumps, radiators and unnecessary heat loss, but with a long and stable effect.

East Asian philosophy of heat

A similar approach existed in other East Asian countries. Korea used ondol, a hot air underfloor heating system. Japan introduced kotatsu, a low table with a blanket and a heater to warm the feet and lower body.

The general principle was the same:
warm the person, not the whole house.

Even clothing played a key role. Warm, handmade cotton jackets complemented the architecture and kept you warm without wasting energy.

Europe knew this - but forgot

The author reminds us: Europe once used localised heating systems too. Ancient Rome used hypocausts - heating floors with hot air. In the Middle Ages, walls were covered with thick tapestries and sleeping areas were made as draught-proof as possible.

In the 20th century, however, central heating replaced all this, heating the whole house to the same temperature - even if there is only one person in the house. As long as energy was cheap, the model worked. But today it is becoming less and less sustainable, especially in the poorly insulated homes that characterise the UK and a number of other countries.

Lessons for the future

In the author's view, new technologies - heat pumps and renewables - are indeed important. But they will only be as effective as possible if we use heat wisely and rethink the very notion of comfort.

Traditional systems like cana show:
heat is not necessarily high air temperature,
but the deliberate contact of heat with the human body.

In the context of climate change and energy instability, such ideas may become relevant again - already in a modern, safe and technologically advanced version.