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Tokyo Main Office Building Annual Energy Consumption Greatly Reduced Compared to Old Building

Verifying large energy-conserving effects in an office building!

March 9, 2010Takenaka Corporation

Takenaka Corporation (President: Toichi Takenaka) has compared the annual energy consumption of the Tokyo Main Office Building (located in Koto-ku, with a total floor space of 29,747 square meters) with the average annual energy consumption between 2002 and 2004 of the old building (located in Chuo-ku, with a total floor space of 36,847 square meters). The results showed that in the first year, 2005, there was a total reduction of 34 percent (specific consumption* 19 percent), and five years later in 2009, there was a total reduction of 47 percent (specific consumption of 35 percent).
In addition to using nature for natural ventilation, natural lighting, and heat-collection ducts, the Tokyo Main Office Building also uses many environmental technologies such as a hybrid air-conditioning system using natural winds, a highly-efficient heat source system, and sensors to control the lighting in order to realize a massive 34 percent reduction in 2005. (*Specific consumption: annual energy consumption per square meter of the total floor space)

~Exterior appearance of the Tokyo Main Office Building~

In 2005, when the company began using the Tokyo Head Office Building, a working group was established to optimize the operation of the building, and up to now, continuous improvements have been made. During that period, over 20 improvements have been made to conserve energy, including extensions being made to the natural ventilation operation controls, readjustments being made to the heat source system operation, and the operation period for the heating system during winter being shortened. As a result, the annual amount of energy consumed during 2009 was a 20 percent reduction compared to 2005. Takenaka has verified that along with hardware-related measures such as the use of nature, energy-conserving designs, and the use of the latest, highly-efficient equipment, detailed attention to software in the management stage is effective in the promotion of energy conservation.
The company plans to continue to introduce additional cutting-edge technology in the building in the future aiming at continual management improvements, and the further reduction of energy consumption.

<Outline of the energy-conserving measures taken at the Tokyo Main Office Building>

Hardware-related measures including building design and energy-conserving air conditioning(before building use)

  • Reduction of the building heat load (Low-E glass, reduction of openings in the exterior walls + installation of light courts)
  • Use of nature(natural winds, natural ventilation, heat-collection ducts, use of rainwater)
  • Hybrid air-conditioning system using natural winds, optimal operation control by zone
  • Highly-efficient heat source system, large temperature difference air conditioning heat delivery system
  • Highly-efficient lighting, dimmer control

Building management-related measures(while building is use)

  • Optimization of the hybrid air-conditioning system control
  • Optimization of the heat source cold water temperature
  • Readjustments made to the heat source system operation
  • Shortening of the heating system operation period during winter
  • Adjustments to the illumination intensity when light bulbs are simultaneously changed
  • Partial implementation of “Light Biz”(an energy-conserving lighting code)
  • nstalling remote lighting controls for different areas and the strict turning-off of unnecessary lights (program-controlled), etc.

Revisions to the Rationalization in Energy Use Law from April 1, 2010 will require companies which consume 1,500 kiloliters of energy (crude oil equivalent) or more per year to manage their energy consumption and make continuous efforts to reduce consumption. It is expected that many companies will become subject to this law.
With new construction work, Takenaka can make proposals for the latest CO2-cutting buildings. With existing buildings, the company can make management-improvement proposals, energy-conserving refurbishing proposals by floor, energy-conserving refurbishing proposals for an entire building, and energy-conserving proposals using next-generation technologies.
Based on the actual results achieved with the Tokyo Main Office Building, the company plans to meet the wide energy-conserving needs of its clients with effective proposals.