The total amount of energy required in the life of a house is 53,000 eu. This is equivalent to the energy contained in the food that one person would consume over the course of their life if they lived for 145 years!

Housing consumes energy. We will examine the life-cycle energy of housing, i.e. the total amount of energy required for construction, maintenance, and scrapping. Let's assume that we live in a wooden house with a total floor area of 100 square meters for 30 years. To begin with, a large amount of energy is required to produce wood, concrete and other construction materials. Next, carpenters assemble these materials, build the house, provide maintenance services for 30 years, and finally scrap the house. This entire process consumes a total of 106 million kcal or 53,000 eu, which is equivalent to the energy contained in the food that one person would consume over the course of their life if they lived for 145 years! This amounts to 4.85 eu per day, or in the case of a family of four, a little over 1 eu per person. In other words, we consume the same amount of energy for housing as we do for food.

Of the total energy consumed, approximately 76 percent, or three quarters, is accounted for by the manufacture of building materials and construction. Therefore the longer we use a house, the more energy we conserve. This calculation is based only on the house itself and does not include the energy required for furniture, home furnishings, kitchen goods, household appliances, information equipment, electricity, gas, kerosene, and so on. The energy required for housing accounts for only about 8 percent of the total life-cycle energy of all the above-mentioned and other elements in our household activities.

Another element not included in this calculation is the energy required for disposal of construction waste generated through scrapping. The amount of waste resulting from dismantling a wooden house is equal to the household waste generated in 60 years. According to a book written by Norihiro Mitsuhashi of the Nihon Keizai Shimbun, building a house that lasts for 200 years using 100-year old wood helps to fix carbon dioxide, which in turn prevents global warming. Therefore, we can best contribute to environmental conservation by utilizing houses as long as possible.

Ever since the construction of houses was begun on the fire-devastated land of postwar Japan, the housing situation in large cities has been poor and the houses are often referred to as "rabbit hutches." To create a richer society, we must continue our efforts to improve the housing situation. We do not have to forgo better housing for the sake of the environment; all we have to do is break away from the conventional practice of building and scrapping.