Tuesday, 19 March 2013

Different thermal aesthetics

The basic idea behind our house is that heat is insulated, so the temperature stays within a comfortable range throughout the year. A little can be added in the winter. A little could be taken away in the summer.

Japan is hot in the summer, and cold in the winter, so measures often need to be taken to both heat and cool. This is the case in many places. In the UK and northern climates, overheating is usually not a problem, but heating is needed for much of the year. In tropical climates, heating is never really needed, but the temperature is too high for much of the year.

So a number of different thermal aesthetics are possible.

One approach is to design for the summer, aim to reduce excessive temperatures, then provide extra heating available for the winter.

Another approach is to design for the winter, aim to keep temperatures high, then provide extra cooling for the winter.

Commonly in Japan, buildings are designed for spring and autumn, so heat needs to be added in the winter, and cooling needs to be provided for the summer.

Ideally, a building should be designed for the whole year, so that it will not get too hot in the summer, and not get too cold in the winter. This is possible, but needs thermal insulation and thermal mass. Insulation and thermal mass both cost money, and calculations of the cost and benefit seem to be highly skewed against high capital costs and towards high running costs. In fact calculations are usually not even made, and capital costs are kept as low as possible without even considering running costs.

Heaters in Japan are often portable kerosene stoves, which can be moved into place and cleared away when the seasons change. Heating is not part of the building itself, but something that can be added later. This makes the buildings much more simple. Since the fuel is kerosene, filled from a tank, there is no need for fuel lines into the building. Just electric cables to pump in fuel and keep the fans running. This approach can lead to much lower fuel consumption, if heat is just provided where and when it is needed. Although fuel efficiency in modern western buildings is much higher, fuel consumption can also be much higher since the whole building is kept at a high temperature the whole time, while there may only be a couple of people in one or two rooms some of the time.

The traditional wisdom in Japan is that windows can be opened in the summer. As everyone knows, or soon finds out, opening windows doesn't work when it's in the thirties outside. Especially with some of the modern building techniques and their emphasis on cosmetics and cost cutting. So air conditioners are usually also installed.

The air conditioner is an effective device in the scenario of low-cost high-turnover buildings. They are usually wall or ceiling mounted so they take up little or no floor space. As a heat pump, they can cool buildings in the winter as well as heating them in the summer. In addition they can remove humidity from the air. This seems to me to be an example where the electronics industry is making up for deficiencies in the building industry.