It is estimated that only about 4% of Japanese people live in homes that are at least minimally warm.

It is estimated that only about 4% of Japanese people live in homes that are at least minimally warm.
Recently, the table below has often appeared in presentations by Japanese professors of thermal environment.

Japan's current housing stock is said to be approximately 50 million units.
Of these, only 5% meet the 1999 standards (next-generation energy conservation standards).
Unfortunately, most detached houses are simply energy-efficient.
The room temperature is not ideal. Therefore, people who live in such houses do not feel satisfied with the "warmth".
The reality is that it's hard to have your voice heard.
First, I wanted to know what the ratio of detached houses to condominiums was among the 50 million units.
So I looked into it and found that
Detached houses: 27.5 million units: 56%
Tenement houses: 1.33 million units: 2%
20.7 million apartments: 42%
I was able to find the following data.
Of the 5% of next-generation energy-efficient detached houses, only 5% are able to live in a reasonable temperature range.
Even a conservative estimate would be that it's only around 20%.
So, 27.5 million households x 5% x 20% ≒ 280,000 households
The number that is calculated is:
The results show that only one in 100 detached houses can maintain a decent level of heat.
It expresses what I mean. It mostly matches my own feelings too.
Next are apartment buildings. (There are few tenement houses, so I will omit them.)
In the case of an apartment, it depends on whether it is a room on a middle floor, facing south, new or old.
The warmth changes considerably.
Here, we needed to look at the distribution of floors and number of units in the actual apartment buildings.
The distribution rate is different for condominiums and rental apartments, but on average,
Considering this, a 4-story building with 20 units is the average or middle-class image of an apartment building.
understood.
It's easier to understand if you think of it as five rooms on one floor, with four floors each.
In this case, approximately 30% of the rooms on the middle floor can be called middle rooms.
Next is the orientation. If the main opening faces south, the apartment is quite
It will be warmer, but not all rooms face south.
From my experience, it's about 50% facing south, 20% facing east, 20% facing west, and 10% facing north.
Of course, the warmest part of this is the 50% that faces south.
Finally, the age of the building is simply half of the newer existing apartments.
In other words, I came up with a rough classification that 50% is warm.
Multiplying all of these together gives
20.7 million households x 30% x 50% x 50% = 1.55 million households
This is the result.
Even though there are fewer apartments than detached houses, people live in warm homes.
That means there are about five times as many people.
If we add up the 280,000 detached houses and 1.55 million condominiums, the total comes to 1.83 million.
The result is 3.6%. Rounded up, it becomes 4%!!
This is where the title comes in: "It is believed that only about 4% of Japanese people live in homes that are at least minimally warm."
This led to the following conclusion.
It is difficult to define the minimum level of warmth,
"Housing that does not threaten the lives of the elderly"
"Housing that doesn't rob you of your health just by living in it"
"A home that can heat the entire house at reasonable utility costs"
"A house I would be happy to live in"
None of this is quantitative, but I think that's about it.
Although this is a very rough calculation, I don't think it's far off the mark.
By the way, the number of vacant houses in Japan right now is 7 million, which is 14%!
The call is for the use of stocks...