Reducing CO2 by Low-cost Solar Hot Water System Located in Condominium Veranda

Copryright The Building Research Institute, Tokyo Gas Co.

The Building Research Institute, an independent administrative agency, and Tokyo Gas Co., a major natural gas utility in Japan, announced earlier in 2008 that they have jointly developed a low-cost water heating system for installation on condominium balconies. The system, which they named the Next Generation Solar Hot Water Supply System, consists of solar panels and a water heater. In February 2008, they conducted an experimental demonstration of a prototype, which attracted much interest.

Heating water is the biggest factor of a household's energy consumption, accounting for about 30 percent, so energy saving devices that can efficiently heat water are eagerly welcomed. The system, designed specifically for condominium use, is a combination of a water heater and solar panels fixed to the balcony.

Water heated by the solar panels is stored in a tank, and when the temperature of the water in the tank is above a preset level, water is supplied to the household from the tank directly, with no need for the gas heater to be ignited. Even when the water temperature drops below the preset level, the water in the tank is still warmer than tap water, meaning less gas is consumed to heat the water than usual. The prototype experiment established that heating water efficiency could be improved by 13 percent on average to a maximum of 20 percent. For example, for a four-member family, gas costs can be reduced by about 10,000 yen (about U.S.$95) per year.

While the price of a conventional solar panel water heating system including a water heater ranges between 200,000 yen (about $1,900) and 500,000 yen (about $4,800), the institute and the company aim to sell new systems consisting of two solar panels, a water tank with additional items, and a water heater for about 100,000 yen (about $950). They plan to start commercial production of this system for condominiums by March 2009, making it the first integrated solar panel-gas water heater for condominium in Japan. In the near future, they plan to develop a similar system for individual houses and also a larger scale system for use in condominiums.

- Building Research Institute
http://www.kenken.go.jp/english/index.html

Posted: 2008/12/18 06:07:54 AM