According to contractor Shimizu Corporation, the new headquarters it opened in Tokyo open this week stands as the world’s most emission-free building.
With no clear certification standard for zero-energy buildings, however, it is hard to verify the claim. What is clear is that there are a number of highly energy efficient and CO2-reducing features that are not common in traditional large buildings.
One such technology is an air conditioning system that makes use of radiant heat. Water hoses run under ceiling boards like capillary vessels. By controlling the temperature of the water circulating in the hoses, the temperature of the ceiling board surface is controlled. As a result, a surface temperature of about 20 degrees absorbs the heat of people working in the office through a radiant effect. This system can reduce CO2 emissions by 30 per cent compared to conventional air conditioning systems.
The lighting system also makes use of energy-efficient technology. Light-emitting diode (LED) lighting has been fully adopted and is controlled by motion sensors. Energy used for lighting during the day is generated by photovoltaic (PV) panels placed in the outer walls. The PV panels take up about 2,000 square metres and generate 84,000 kwh of power per year.
In addition, window shades have been installed, which angle automatically to follow the path of the sun and optimize natural light into the working space. This is said to reduce CO2 emissions by 90 per cent compared to standard lighting systems.
The overall result is that the building emits only 38 kg/m2 of CO2 per year, 62 per cent less than the average Tokyo building.
Shimizu is aiming to reduce emissions even further and have set a target to reduce CO2 emissions by 70 per cent through fine tuning of air conditioning and lighting facilities as well as adopting further energy saving systems by the end of 2015. Finally, the company plans to offset the remaining emissions by creating emission rights to realise a Zero Emission Building (ZEB).
In a marketing statement, Shimizu said the building’s environmentally-friendly measures are “sure to increase the demand for construction of buildings like the new Shimizu Headquarters.”
With zero-energy buildings still an emerging area and only a small piece of the total global building industry, Shimizu’s claims may be somewhat optimistic with respect to the current market. Time will tell whether their building is as emission-free as they say, and whether that helps usher in a new generation of zero-emission buildings.