For Efficient Use of Energy Resources
The prevailing economic development paradigm leads to higher energy consumption. Yet the fact that supplies of the fossil fuels used as energy sources are finite means these should be used carefully. Below we outline energy-saving activities involving offices and homes that aim to reduce emissions of carbon dioxide (CO2), a substance thought to be implicated in global warming.
Japan's Ministry of the Environment launched Cool Biz for the Japanese public in the summer of 2005 as a campaign to prevent global warming. In the campaign, offices are encouraged to set thermostats on air-conditioning systems at 28 degrees C during the summer months and allow workers to wear casual clothing. The Cool Biz approach has since been adopted widely by households as well as offices.
The Cool Biz campaign has proven highly effective in reducing energy usage. A research report shows that the typical office building in Tokyo has achieved an energy reduction of approximately 17% by raising the preset temperature of air-conditioning system thermostats from 26 degrees C to 28 degrees C.
Besides raising the preset temperature, Cool Biz also promotes:
- Turning off unneeded cooling equipment
- Cutting out sunlight using blinds, curtains and balcony plants
- Minimizing the opening or closing of doors and windows
- Sprinkling water on streets, sidewalks, etc.
As well as lighter garments, wearing clothes made from linen, wool or other cooler textiles can make you feel more comfortable during the summer. Hot or spicy foods can also lessen the need for air conditioning by making you perspire. A personal fan and a water bottle are other useful items to adjust conditions for individuals.
Cool Biz denotes general lifestyle changes for saving energy in the summer.
After the success of Cool Biz, Warm Biz began as its winter equivalent to extend the global warming prevention benefits of saving energy. The Warm Biz campaign is more effective than Cool Biz since the campaign term is longer and temperatures inside and outside differ significantly during the period.
In the Warm Biz campaign, businesses are urged to heat offices only to 20 degrees C during the winter months (thermostats are set to 19 degrees C in all government and public agency offices). Lowering the temperature of offices from 23 degrees C to 20 degrees C achieves energy savings of approximately 20%.
The basic principle advocated under Warm Biz is to put on additional clothing when it is cold so that excessive use of heating appliances can be avoided. People who feel the cold are encouraged to dress warmly or to use a blanket to cover their knees while at work.
One tip for keeping office spaces warm is to place partitions in front of doors to block draughts of cold air from doors. Another is to open the blinds in the daytime to allow the sun's heat into the room, shutting them at night to prevent the room temperature from dropping sharply. Using small fans for short periods can also be effective to circulate the warmer air that tends to rise and collect near the ceiling.
Households can also save energy in winter by layering clothes and only using the heating when necessary. Keeping your feet warm is a good way to prevent feeling cold. Such lifestyle changes can help lessen the reliance on heaters.
A comfortable house has always been one that stays cool in summer but warm in winter. The energy-saving house aspires to this same ideal. The important thing is to design the house so that external heat does not enter during summer and internal heat does not escape during winter. An effective way of creating this kind of comfortable housing is to use airtight materials to build walls, floors and roofs and to install double-glazed windows for greater insulation. External blinds or shutters fitted to the windows can further boost the effect by shading the house from the sun in summer and trapping the heat inside in winter.
Another approach is to take advantage of the characteristics of plants. For example, growing grass or other perennial plants on the roof or vines on the outside walls can help to cool the building in summer because transpiration by the plants releases heat into the ambient air. In winter, the same action helps to retain heat inside the house.
Traditional Japanese house building techniques ensure appropriate ventilation. By allowing natural air flow in the house, this approach ensures that heat circulates throughout the house and helps to minimize temperature variation within each room. Modern construction methods achieve a similar effect through the inclusion of multiple stairwells and ventilation outlets.
Proactive use of renewable energy sources is also important. Solar photovoltaic panels and solar thermal systems can both play a role in realizing significant energy savings.
Heat pumps, which can extract heat from the air for heating or cooling purposes, are set to be one of the key technologies for creating a low-carbon society. Heat pumps generate no CO2 emissions during operation because there is no fuel combustion. Like solar or wind power, the heat extracted from the air is renewable energy. Since the power consumed by the heat pump device for heating or cooling is much less than the thermal energy extracted from the air, heat pumps contribute to a net energy saving. Heat pump technology is already incorporated into many household appliances.
An air conditioner is a typical example of a heat pump in action. During cooling, heat is extracted from the room by the indoor unit and emitted to the outside by the outdoor unit. To heat the room, heat is extracted from the outside air by the outdoor unit and then the indoor unit uses it to create a warm flow of air.
Electric water heaters fitted with heat pumps are also a common example of this technology in action. Compared with conventional fuel-burning water heaters, some of these products can achieve energy savings of approximately 30% and cut CO2 emissions in half despite the emissions when generating electricity. Other household appliances that incorporate heat pump technology include washer/dryers and refrigerators.
Heat pump-based household appliances are familiar but crucial tools to prevent global warming. Wider adoption of such products would be friendly to the environment.
A combined heat and power (CHP) system (also called cogeneration system) recycles waste heat produced when generating electricity using primary energy such as oil and natural gas so that waste heat can be utilized to heat water or for air-conditioning purposes. This can boost the energy efficiency of the overall system to extremely high levels in the 70-80% range. A CHP system also cuts CO2 emissions significantly compared with just generating electricity from primary fossil fuel sources.
Many developments are now installing CHP systems, including leisure facilities, hotels, hospitals and factories. In recent years, residential CHP systems for households that supply electricity and hot water have also appeared on the market in Japan. Greater adoption of such products would help to boost energy efficiency.
