Green Architecture: Passive designs and lighting

Architects and engineers can design buildings that dramatically save on power consumption. There are two main types of energy-efficient design, active and passive. These terms are also used to describe the way solar energy is harnessed, and this topic will be covered at a later date.

As the words suggest, the main difference between the two types is that passive designs take advantage of natural effects due to their position, orientation, and so on, whereas active designs employ utilities that directly change energy usage, such as solar water heaters and reverse-cycle air conditioning. This can be confusing because solar water heaters are in fact examples of passive uses of solar power, because the sun's energy is merely trapped and used to heat water, rather than being converted directly into electricity. In the realm of building and construction, however, the word passive refers to physical, not mechanical, designs.

The main features of passive designs allow maximum natural sunlight in, while controlling heat. In some climates it is better to warm the house and this means that lots of sunlight entering a building is good all year round. In other climates it is cold in winter but hot in summer, so designs must try to let lots of winter sunlight in, but somehow block it in summer, so as not to heat the inside of the building. In tropical regions the main concern is to keep heat and humidity from staying outside.

Generally buildings are now oriented east-west, following the sun's path, with few windows in the north and south sides. Although windows in the north-south sides will still allow some light to enter, it is easier to insulate walls than windows. Skylights are good examples of passive designs, acting as ceiling lights in the daytime.

The "Tower in the Park" scheme popular in cities such as New York and parts of Germany in the late 1950s to early 1970s set tall apartment buildings dotted strategically around grassy areas. The idea was to prevent other tall buildings from blocking natural sunlight getting to other buildings, as well as to create a community, "garden within the city" feel. In general the psychological hopes of the designers were dashed, with the gardens either unused or only frequented by dealers, but these blocks still get plenty of natural sunlight.

In Berlin, long before this, apartment buildings were commonly designed in a square, with an inner courtyard. It was hoped at first that the inner courtyard, surrounded by only three or four stories of residences, would give people privacy and natural sunlight. However, poor orientation and no variation in height meant that while the front sections of the blocks were well-lit and warm, sunlight into the back sections was blocked on both sides, by the front part of the building, and by the apartment blocks they were back to back with. Soon the dim and cold back sections were relegated to low-income earners. If the front sections had been built lower than the back, say about one or two stories, light could have entered the courtyard and the rear apartments. Otherwise it would have been best to build in a U-shape, eliminating the rear section altogether.

Go To Page: 1 2

Articles in this Topic    Discussions in this Topic