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The Rozak House was specially designed by Troppo Architects to function in Darwin’s tropical environment.

Darwin is located on the northern coast of Australia, called the Top End. There are basically two seasons, the “Dry” season from April through September, and the “Wet” season from October through March. The dry season has highs of 32c, lows of 17c at night, and no rain for six months; it’s very comfortable during the day and a bit chilly at night. All of Darwin’s rain (about 2 meters of it) is saved up for the wet season, with highs of 36c and lows of 22c, compounded by 90% humidity. This makes it very hot and humid during the day, but mostly comfortable at night.

Not only does it rain during the wet season, but Darwin is visited by cyclones, some of which have done terrific damage. In Darwin, time is divided into two eras, pre-cyclone and post-cyclone. The cyclone is Cyclone Tracy, which on Christmas Eve 1974 basically destroyed the town, leveling most of Darwin’s houses. The winds were so strong they blew off the wind gauge at the airport, so no one is really sure if it was a category four or five cyclone. To top matters off, people were so engrossed in Christmas and jaded by previous false alarms, that most people stayed around town, oblivious of the cyclone until it bore down upon them. Needless to say, Cyclone Tracy affected the psyche of Darwin for many years – especially house designs…

Before cyclone Tracey, houses generally didn’t have air conditioning, relying on ceiling fans and ingenious design to keep people cool. They were elevated, long and narrow, and had as many louvered windows as possible. This allowed the breeze to easily flow through the house, cooling it off. (Elevated houses had a few other advantages, such as flood and fire protection, and they made it more difficult for insects and snakes to get inside.) During the day elevated houses are about 2 degrees cooler than the outside air temperature, and at night they’re about 2 degrees warmer. This meant that during the hottest time of the year (the wet season) fans would need to be on between 1:00 PM and 6:00 PM for people to be comfortable. During the rest of the day, and during the dry season, fans were rarely used.

After the cyclone tore apart the elevated houses that people sheltered in, the population acquired an understandably large fear of cyclone wind damage. For the next few years any new houses were basically bunkers. They were low to the ground with cement blocks, core-filled to withstand the impact of flying debris. Large louvered windows were reduced to small holes that would keep out flying missiles. Locals “affectionately” call them “hot boxes” because they’re always hot inside. During the wet season the cement blocks heat up and never really cool off; the inside is 32c during the day and 31c at night. Opening the windows help, but there aren’t many to open. Air conditioning is required.

Since Tracey, Darwin has largely expanded through subdivisions built en-masse by developers, who have continued to propagate-cement block houses. They’re cheaper to build than cyclone-coded elevated houses. More can be crammed into an acre. (Houses with lots of louvers not only get better breezes, but they make it easier hear one’s neighbors.) And (I say cynically) no one really knows if you didn’t core fill the walls. “Core filling” involves putting reinforcing bar in the cement-block cavities and then filling the entire wall with concrete. Concrete can be quite expensive. I’ve heard enough anecdotes to believe that many walls are not core filled like they should be. To make matters worse, most people living in Darwin are transplants from the cooler southern climates in Australia. Developers design their houses so they look like the houses the transplants have left behind. Such designs tend to be inappropriate for the climate. One common “feature” is wall-to-wall carpeting, which gets very moldy up in Darwin and is completely inappropriate. Red roofs are also common because they mimic the ceramic tile from southern Australia; all roofs in Darwin are steel to withstand cyclones, and because of the intense sunlight, silvery or white coloring would be the most energy efficient choice.

The net result of all this is that most new houses in Darwin consume huge amounts of electricity to power their air conditioners and hundreds of thousands of liters of waters to maintain a green lawn and palm trees. (Only a few palm trees are are native to the area, but people think that because it’s in the tropics they must have a yard full of palms.) The houses aren’t well designed for the climate. Poor design costs money. During the wet season, a “hot box” uses about $100-$200 electricity per month. A traditional house without air conditioning and without a watered garden uses $30 to $50.

This phenomena isn’t unique to Darwin. I’ve seen it in the US, where new houses in Phoenix (a desert) have virtually the same design as those built in Seattle (almost a temperate rain forest).