One of our main bugbears with used houses is the obsession with a southern exposure. Though we perfectly understand the rationale–Japan is in the northern hemisphere and thus a southern facade provides more natural heating in the wintertime–we can’t fathom the insistence of builders and designers that all rooms in a house will face south and all “utilities,” meaning bathrooms and kitchen, will be located on the north side of the structure. Given the normally small plots of land in Japan, this results in a kind of domino distribution: all houses in a development “face” south, which inevitably means facing the “north” side of your neighbor. When we’ve asked builders about orienting a house toward the west or even north in order to take advantage of some attractive natural feature of the land, we’re invariably met with consternation and concern. It’s entirely possible, they say, but inadvisable. Some things just aren’t done.
Our reasons for shunning southern exposures are mostly aesthetic, but a recent article in the Tokyo Shimbun suggests that maybe southern exposures are not economical or even healthy. The University of Tokyo Engineering Department built an experimental house on the roof of one of its buildings to study the effect of direct sunlight on interior environments. Like almost all modern Japanese housing, the part of the building facing south had large plate glass windows so as to allow more light in. On sunny winter days when the exterior temperature was 10 degrees C, the interior temperature was as much as 35 degrees C, which is actually bad for the people who live there. In essence, the large windows make it difficult to control the interior temperature, which means the home owner may actually use more energy. According to the professor in charge of the project, it depends on the type of glass that is used, but in most houses the windows allow visible and near infrared light to pass into the house, where it is reflected off of the floor in the form of far infrared light, warming the room. Far infrared light cannot pass back out the window and thus more heat is trapped in the room. Direct sunlight contains a great deal of energy. Moreover, at night, when temperatures drop even further and there is no sunlight, more heat escapes from the house because of these big windows.
The experiment was mainly carried out to study the effectiveness of large windows, but what we took away from the article was that the merit of a southern exposure is a myth. The professor said that the kind of direct sunlight that enters the house through these large windows is also bad for the eyes, since it is incredibly bright. Inside, there will be areas of high contrast, and the pupils of the eye will adjust in reference to the brightest areas, thus making other areas too dark to see. Tasks such as reading or watching TV strain the eyes when there is too much direct sunlight. The professor suggests smaller windows that are positioned in such a way as to take advantage of “scattered light,” meaning atmospheric light that is indirect but still bright enough to illuminate the interior without the need for artificial lighting. He even said the windows can be put on the north side of the house since scattered light does not diminish depending on the direction. We can testify to this finding since our last apartment was on the northwest corner of the building, meaning we got very little direct sunlight. However we received plenty of indirect light and never had to turn on any lamps in the daytime anywhere in the apartment. And because our orientation was unpopular, we actually paid less rent than people who rented apartments on the south and east sides of the building.
So the next time we meet a builder or developer who snorts at our desire for a northern or western exposure, we’ll cite the University of Tokyo study, though we’re pretty sure it won’t make a difference.