The story behind the birth of Air Cycle House

Air Cycle House mean Air circulation type housing.

Air cycle house
“Touch the flowing air”
It was born from the traditional Japanese legend.

Even after wood is used in buildings
If the wood is always in contact with the flowing air
It doesn’t rot and can live its life.

At the time of 1977, the buildings became airtight as the energy saving of homes began, the insulation of houses began, and the spread of aluminum window frame progressed.
As a result, the danger of wood rot, such as the foundation, progressing at a considerable speed has become a hot topic in newspapers and magazines.

The representative was a wood-rotting fungus called “Namidatake” that occurred under the floor of a new house in Hokkaido.
The photo of the underfloor covered with pure white fungus was shocking.

At that time, the soil was exposed under the floor, and the current measures such as soil cover and soil concrete were not taken to prevent moisture. Damage such as attracting termites has expanded.

As a countermeasure, various methods were proposed and tried by the public and private sectors.
We have come to the Japanese tradition of “touching the flowing air.”

“Touch the flowing air” is
As the word says, even after construction, if air is constantly flowing around the wood, it will not be damaged by wood-rotting fungi, and termites will not easily nest.

It is also proved by the air-dry moisture content.

The moisture content that is settled down after the wood is left in nature is called the air-dry moisture content. It is said to be about 15% in Japan and about 11% in Europe.

When the water content of wood exceeds 25% at all times, the activity of rotting fungi becomes active, and termites also like water, which is a dangerous situation.

If the wood is exposed to the flowing air, the moisture content of the wood will settle down to about 15% even outside where it is exposed to rain and dew.

Air cycle house were born from the idea that if there was constant air flowing around all the wood, there would be no fear of rotting.

It was in 1977.

In fact, the moisture content of the wooden foundations and other parts of the air cycle housing at university institutions has settled down to around 10% over the long term.

The old Japanese building was called ShinKabe, and it was exposed without being hidden in the wall.
It was always “touching the flowing air”.

The current building has become Ookabe and is hidden inside the wall, and glass wool, which is a heat insulating material, has entered the wall to save energy, and air has stopped flowing inside the wall.

At that time, measures against humidity on the ground surface under the floor were not good enough, so the damage represented by Namidatake mentioned above occurred.

Air Cycle House regains air flow into the wall,
underfloor and space on the first and second floors,
in the cabin space on the ceiling.
By devising how to assemble the wooden structure.
For all wooden structural materials that support the building.
We succeeded in “touching the flowing air”.

Insulation had to be removed from the wall in order to “touch the flowing air.”
To that end, PAC has developed its own exterior insulation.
It was in 1977.

If you want to “touch the flowing air”, warm the air in winter,cool air in summer.

From that thought
It can be said that it is the first full-scale passive solar in Japan.
It has developed into a PAC house.



Passive Air Cycle

An acronym for Passive Air Cycle.

Japanese Page


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