A housing shortage in Japan in the 1950s was becoming a big social
concern as the people concentrated in large cities. The Japan Housing
Corporation was established in 1955, before the existence of large
apartment complexes, to tackle the shortage by building urban housing in
quantity. Over the next 50 years or so, the corporation was reorganized
several times in response to varying demand for housing and ongoing
regional developments. In 2004, the Urban Development Corporation merged
with the Urban Areas Development Division of the Japan Regional
Development Corporation to form the Urban Renaissance Agency (UR).
Today, it owns nearly 770,000 rental housing units nationwide (about 1.4
percent of all units in Japan), providing housing for almost 1.7
million people (about 1.3 percent of the population).
Fighting Global Warming through Housing
The average amount of carbon dioxide (CO2), a major cause of global
warming, emitted annually per household in Japan is about 5.5 tons.
Aware of this, UR decided to employ innovative technologies to improve
household energy efficiency, because over 60 percent of household
emissions (not including transportation) are to produce the energy
needed for air conditioning, water heating, and electrical appliances.
One of the most effective of the various measures employed by UR is
the use of improved insulation materials, resulting in more efficient
air conditioning and reduced indoor moisture condensation during the
winter and general mustiness in rooms. The heat-insulating properties of
materials used in newly built housing complexes comply with the
next-generation energy saving standards set out in the most recent Law
Concerning the Rational Use of Energy. By the end of fiscal 2006, UR had
built roughly 10,000 houses under these new standards, resulting in an
estimated reduced energy consumption for air conditioning equivalent to a
CO2 emissions reduction of about 350 tons per year. Mr. Satoshi Nomura
from UR's Urban Environment Planning Office said, "I believe that the
heat-insulating properties of our rental housing complexes are the best
in Japan."
Another pillar of the measures employed by UR in its rental housing
is the introduction of high-efficiency appliances. Resource consumption
is reduced by installing latent heat recovery heating and hot water
systems, which reuse exhaust heat, and more energy efficient facilities.
This measure is applied not only in newly built housing complexes but
also in older ones. When old ones are renovated, the appliances are
replaced with more energy efficient ones and new heat insulation
materials.
"We have continued to improve the environmental quality of our
housing over the past 50 years," said Mr. Nomura. "Some residents, for
example, had complained that their units were prone to condensation and
mold, so we used updated technology and materials to solve these
problems, developed jointly with private businesses, while also
contributing to efforts to prevent global warming."
UR uses ingenuity and innovative technologies in their housing to
further reduce environmental impacts. Some of them were pioneered by the
agency, such as a super water-saving toilet system, a residential
fuel-cell cogeneration system, a garbage compost system, and a peak
alarm cabinet panel that gives an audible warning when electricity is
overused.
Buildings Designed and Built for Long Life
UR also addresses the structure of new buildings from an environmental
perspective. For example, its new KSI Housing design is built using the
skeleton-infill (SI) construction method, in which the structure of the
building (skeleton) is separate from the interior and room layout
(infill).
The "KSI Housing" design, a UR-version of the skeleton-infill housing
method, has a strong frame to increase its durability. The concrete
layers around the steel rebar used in posts and beams, for example, are
one-centimeter thicker than in standard buildings. This strong frame
allows these buildings to last up to 100 years.
In the KSI Housing design, with its floor slab separated from the
infill, the partition walls are built after the floor is completed. This
makes it easy to move walls or to add new walls even after the entire
building has been finished. In addition to the capability of changing
room layout, it is also possible to connect two or more adjoining
apartment units to make extended larger unit. Such flexibility in design
provides the ability to cope with future changes in lifestyles and
demand through remodeling, avoiding the need for buildings to be
demolished, and thus extending their service life.
Mr. Nomura said, "Construction costs are relatively high, but the KSI
housing will be beneficial to residents in the long run because both
its lifecycle cost and carbon dioxide emissions will be reduced.
Overall, the physical quality of our rental housing is pretty high."
It's also interesting to see how UR rebuilds its aging housing
complexes. For example, the demolition of old buildings generates a
large amount of concrete debris, estimated to be about 33 cubic meters
per unit (two rooms and an eat-in kitchen) in a reinforced concrete
building. Since 1992, UR has been recycling waste concrete on-site,
whenever possible by crushing it into pieces. The crushed concrete is
then used as material for grounds improvement, in the foundations of new
buildings, and for roadbeds, depending on the size of the pieces. The
rate of recycling concrete debris is now as high as 99 percent.
After many years of use, buildings need to be rebuilt because of a
decrease in structural strength due to deterioration of the concrete,
and obsolete facilities and equipment that don't comply with improved
technical or living standards. Since UR is scheduled to rebuild a large
number of housing complexes, its efforts to increase the recycling of
construction waste will greatly contribute to saving resources.
Improving the Environment in the Process of Urban Development
UR's housing estates are huge, and such large-scale developments often
have substantial impacts on the environment. To avoid this, UR has made
every effort possible to minimize changes to the topography of its
development sites. Furthermore, it has launched new initiatives that
help improve the natural environment of the areas in and around the
sites. One of UR's initiatives is to create certain types of natural
habitat, or "biotopes."
"In setting up a biotope in our project site, the most difficult
thing is keeping the balance between the residential and natural
environment," said Ms. Kyoko Ikeda, of UR's Urban Environment Planning
Office. For example, as a lot of people don't like insects and worms,
too many of them in a biotope may draw complaints. To solve such
problems and create consensus on the importance, preservation, and
unitization of a biotope before creating it, UR holds study meetings and
workshops with experts and residents in housing complexes, local
communities, and local non-profit organizations. Such step-by-step
communication and planning helps residents see the value of having a
biotope. In one local community, for example, a new non-profit
organization was established to manage theirs. To create not only
housing but also a better residential environment, this initiative is
being promoted while encouraging resident participation.
A typical example of UR's rental housing complexes is Sunvarie
Sakurazutsumi in Musashino City, Tokyo, which includes about 1,500 units
on 44,000 square meters of land. The complex, first built in 1959, was
renovated in 1999. There are natural features in the surrounding area
that are high in biological value and potential, including Tamagawa
Josui, a waterway constructed in 1654 to supply water to Edo, the Sen
River, which is about 21 kilometers in length, and Koganei Park of Tokyo
with an area of 78 hectares.
As urbanization proceeded in Musashino over time, however, green
spaces that provide habitat became separate and scattered about like
stepping-stones. To preserve the existing greenery and promote further
greening, UR used the renovation of Sunvarie Sakurazutumi as an
opportunity and based its planning on the city's basic plan for greenery
promotion. Utilizing existing clusters of trees and the Sen River in
the residential area helped create a green network.
The riverbed, which had been lined with concrete, was renovated by
arranging natural rock and wooden piling to be like a natural river
again. Balancing with the natural vegetation of the surrounding area,
trees were planted to create a thicket, bushes were added, and a pond
was constructed. Creating a biotope in this way is the key to
successfully creating a green area with water features, while also
providing habitat for many kinds of living things and a place where
people can come to relax.
As time goes, the need for new housing arises. In particular, the
need to employ an environmental perspective has occurred in many
different fields since the Kyoto Protocol was adopted in 1997.
Mr. Nomura said, "We have to have a broader perspective to evaluate
how we can consider the environment within limited budgets. In
collaboration with the private sector, sometimes differences in demands
happen. We must have a thorough dialogue with stakeholders, such as
local governments and private-sector housing builders, in order to
achieve some common understanding. It is difficult to build 100-percent
environmentally friendly housing, but we believe that we may be able to
change today's standard specifications in housing by improving as much
as we can."
The environmental activities of the Urban Renaissance Agency reflect
the present era we live in, while also showing us a valuable direction
in designing and building housing for the future.
(Written by Yuko Kishikami)
