Bio-Solar House in Thailand
The biogas unit produces cooking gas from household waste. It was adapted from research from Kasetsart University and the Department of Alternative Energy Development and Efficiency in Thailand's Ministry of Energy. Still in its testing phase, the biogas unit's effectiveness has not yet been calculated, but it can be modified in the future if necessary.
The house harvests an average of 20 to 25 gallons (80 to 100 liters) of water per day. The air conditioning unit produces 8 gallons (30 liters) of condensation water daily. Dew and rain, which vary by season, are collected from the roof to make up the balance. Water is filtered and stored in a tank with a capacity of 950 gallons (3600 liters). Wastewater from the kitchen, showers, carport, and washing machine is filtered and reused for irrigation.
On the roof of the 1900-square-foot (180-square-meter), three-bedroom house are 670 square feet (62 square meters) of solar cells capable of generating 22 kilowatts. The system can store energy for three days. A comparable, conventional house would require 15 times more area in solar cells.
The air conditioning unit has a capacity of 9000 Btu and can operate around the clock. At peak capacity it consumes 6.45 kilowatts. On average, the system produces a surplus of 15 kilowatt-hours per day.
The sun powers all equipment, including the pumps for the oval-shaped swimming pool. A modified personal computer linked to dozens of sensors controls the system. This computer, installed on the landing between the lower and upper floors, enables the occupants to monitor and adjust the equipment. They can control the temperature and humidity in all the rooms and read the outdoor wind speed. The system shows if any of the sliding windows are opened, and how far.
A Personal Crusade
The designer and occupant of this self-reliant bio-solar house is Soontorn Boonyatikarm, professor of architecture at Chulalongkorn University. Two years ago, he secured a budget of about US$12.5 million (50 million Bhat) and put together a multidisciplinary development team of students and faculty in architecture, engineering, and science.
Soontorn had long had an interest in ecologically responsible architecture. But personal circumstance provided additional impetus for the project. His wife suffers from pulmonary problems, and needs isolation from the notoriously polluted Bangkok air. The answer was a virtually airtight house in which the air is continuously filtered.
Another reason to develop a self-sustaining house was basic economics. Thinking ahead to his retirement, with a lower income, Soontorn was concerned about the high utility bills he had been paying. He calculated that the additional investment needed for the bio-solar house (40 percent more than a conventional house of this style) would pay for itself in seven years. The thought of never paying another utility bill was most appealing.
Developing the bio-solar house was a multidisciplinary project and involved a combination of material science, civil engineering, and biotechnology. To minimize energy requirements — a basic concern in a solar-powered house — the research team spent long hours testing materials for walls, floors, roof, and glass for their capacity to reduce the cooling load.
The roof, which absorbs most of the heat, is made of metal. Between the roof and the one-foot- (30-centimeter-) thick insulation is an air duct, allowing the wind to ventilate the heat absorbed by the roof. The garden has several artificial mounts designed to direct the wind toward the house.
While the house has windows on all four sides, eaves and recessed windows prevent the sun from shining directly into most of the interior. At no time of the day does the sun enter the main house directly. To further reduce heat gain, all windows and doors have triple-paned ("heat-stop") glass.
The only room receiving direct sunlight is what Soontorn calls the "green room," a square, glass-encased space that cantilevers over the swimming pool. The extended part of the floor is made of glass, providing an unobstructed view of the water. At night, when the room is lit, it seems to float above the pool.
Prototype for a Nation
Soontorn claims the house is 14 times more energy-efficient than a conventional house. Moreover, he says, the house embodies a "philosophy of modern living," based on economy, technology, environmental preservation, and social values without sacrificing comfort. This comfort extends to air quality, cooling, lighting, and acoustics despite the reduced load on the environment.
Building a virtually airtight house required a high degree of workmanship, something not readily available in Thailand. Soontorn joked that it would have been easier to build the house with German workers. "But the proof-of-concept is here. We can now build a bio-solar house for anyone who wants one."
The cost of this house was about US$75,000 (3 million Bhat), not including the cost of the solar panels, which are imported and whose economic competitiveness is hampered by high import duties. Soontorn hopes the government will soon reduce these duties.
Even so, he is convinced that Thailand could benefit enormously if the technology were applied on a large scale. Without the swimming pool, his house would have come within the normal price range of new houses in his country today.
Soontorn estimates that if Thailand built 300,000 such houses, the country would not need any additional power stations. But he is not optimistic about support from the Thai government and plans to promote the technology with developers both in Thailand and other countries.
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Jan Krikke is a journalist from the Netherlands, currently based in Thailand, who writes about Asian technology.