By Chris Hogg
BBC Tokyo correspondent
If you live in Japan, the chances are you live in a small space in a city.
Space-station technology is inspiring the Japanese homes of the future
Eight out of 10 people here live in urban areas, and six out of 10 own their own home.
But Japan is going through a period of rapid and profound change.
The population is in decline and ageing fast. Fewer people mean more space, of course.
The average floor area of a typical home increased from 60 square metres in 1963 to 94 square metres in 2003.
But it causes problems too.
"Small towns throughout the country are losing young people who are gravitating to the larger cities," says James Lambiasi, an architect who works here in Tokyo.
"The towns are dying while Tokyo booms with new condominiums. These 'condos' are mainly geared towards 'dinks' (double income no kids).
"And as competition increases, so does the amount of amenities on offer - on-site gyms, dog showers off the lobby, you name it".
Harutaka Oribe, another architect, agrees that the Japanese, in particular single, working women with a lot of money to spend, have acquired a taste for luxurious living.
"Kitchens and bathrooms used to be pushed into the corner in almost all living spaces in Japan," he points out, "but now dinner parties are becoming popular, especially among young, single, working women, and kitchens are becoming one of the most important factors when choosing where to live."
What about real innovation though?
'Home of the future'
Houses made of aluminium are attracting a lot of interest. Aluminium frames last a long time - almost 100% of the metal can be recycled and even if it is, it does not lose its strength.
They are lightweight; they don't need harmful preservatives to stop deterioration... the list goes on.
Toyota Homes showed their vision of the home of the future at the Expo 2005 in Aichi last year.
Features included an indoor swimming pool that could be used as a water-storage tank during water shortages, and solar cells set into the walls to imitate the process of photosynthesis in plants, so that the whole house could be used to generate power.
You park your hybrid electric car inside the lobby to charge it, or if there's a power cut, you can power up the home off the car battery.
Serkan Anilir is working at the University of Tokyo on plans for a new type of home which takes such environmental concerns even further.
He wants to create an "infrastructure-free house" using technology inspired by biology to try to reach the point where it no longer relies on energy or other services from outside.
"Water and energy are the two key elements of human life," he says.
"Within two years we hope to come up with new concepts for energy and water recycling."
The design would be guided by work already in progress on building space stations. The aim is the same - to create a living environment that's totally self-reliant.
"Our first prototype will be for use after disasters," the researcher says.
"Japan is not ready to cope with a major natural disaster. The challenge for us is to persuade people that this concept is the best way to deal with the problem."
The difficulty, he says, is that the construction industry is not interested in long-term vision, just short-term profits.
That's why the best work to challenge the norms of housing design is going on in the universities.
His comments are echoed by the architect James Lambiasi.
"The Japanese pre-occupation with amenities has obscured a lot of really innovative thinking," he says.
"Much more money is spent on paying a famous actor to do a commercial to advertise a property than will ever be paid to an architect to design something truly innovative."