Architecture, Indoor Environment, and Antiaging Medicine

Buildings can be broadly divided into commercial buildings, represented by offices, and residences. The former are often active during weekdays, while the latter are often passive (relaxing) during nights and holidays. Recent research has revealed the impact on the health of residences where people spend a lot of time in a passive state. One major example is the Sick House Syndrome, which became a social issue in the 1990s. From the 1980s, there were reports of people falling ill inside houses and buildings, and this phenomenon began to be publicized. In the 1990s, it was covered in general newspapers and quickly became a social issue. In 2000, a large-scale epidemiological survey conducted by the government showed that chemical substances in indoor air were causing health problems. More precisely, it was inferred that these were the cause because a large number of volatile substances were detected at much higher concentrations than outside. In 2003, when the Building Standards Law was revised, measures against Sick House Syndrome were introduced, and the installation of mechanical ventilation systems and the restriction of the use of building materials containing formaldehyde were explicitly stated. Since then, the number of people suffering from Sick House Syndrome has decreased, suggesting that these measures have had some effect. In fact, the airtightness of houses had started in the 1970s. Windows that used to be made of wood frames with glass were replaced with aluminum sashes, and earthen walls and wooden floors and ceilings were replaced with plywood and gypsum board, greatly reducing gaps (unintentional airtightness), but this was not widely recognized. There is a value called “ventilation rate (times/hour)” that shows how much the air inside a building is replaced in an hour. In traditional earthen-wall houses in our country, it is said to be more than 10 times/hour, but in concrete apartments, it can be less than 0.3 times/hour, and the same amount of indoor generation as before can easily exceed the allowable amount. Since 2003, intentional airtightness has been implemented, and on top of that, the installation of planned ventilation, a device that forcibly exchanges indoor and outdoor air (0.5 times/hour), has been made mandatory. It can be said that unintentional airtightness is the main cause of Sick House Syndrome, and the solution is intentional airtightness. Currently, there are about 60 million existing houses in Japan, but only about 10% of them have been intentionally made airtight. Approximately 80% are unintentionally airtight (the remaining 10% are as leaky as houses in the Edo period).