INSIGHTS

2023.01.05

MEP Engineering designers talk. Environment and Facility Idea Note Vol. 05

Creating a more comfortable, smarter, greener office

Kayabacho Green Building

MEP Engineering designers talk. Environment and Equipment Idea Note TOP

Achieving both comfort and energy efficiency through the integration of exterior, lighting, and air conditioning

Kayabacho Green Building is the first tenant building in Japan to introduce multiple cutting-edge environmental technologies that will revolutionize the office environment, aiming to create a more comfortable, smarter, and more environmentally friendly office. These efforts are expressed in the main facade and office spaces, and various cutting-edge technologies such as radiant air conditioning and intelligent lighting systems are introduced intensively, and the design reduces energy consumption (CO2 equivalent) by approximately 45% compared to general office buildings.

The process of creating a next-generation office that combines comfort and energy efficiency.
Kayabacho Green Building: The first tenant building in Japan to actually implement a variety of cutting-edge environmental technologies.

Eco Grid

To block sunlight from entering the rooms, the vertical grid elements that characterize the exterior are solar shading louvers. This blocks sunlight almost all day from the autumn equinox to the vernal equinox, and from 9am onwards in the summer, reducing the burden on the air conditioning. The horizontal elements also function as light shelves, and together with the gradient blinds, efficiently introduce daylight into the rooms, illuminating the ceiling, ensuring sufficient brightness even when the office illumination is reduced.

Eco Grid: Shielding louvers and light shelves improve the environmental performance around windows.

Maisonette ventilation

Cold air is introduced through the louvers at the bottom of the three-span window in the center on the north side, and warm air inside the room is exhausted through the natural ventilation windows at the top of the atrium. Since each floor is self-contained, the pressure difference between each floor is equal, and the ventilation volume is constant.

Air flow around the perimeter counter (left) and around the windows (right). Each floor of the office is provided with a complete open atrium, and natural ventilation is achieved by utilizing the difference in height.

Visualization

We have introduced a system that not only displays energy usage, but also encourages workers to take energy-saving measures and makes the results of those efforts visible.

Real-time energy usage is displayed on monitors on each floor.

4 lighting systems

Eco-friendly next-generation lighting system

This building uses LED lighting throughout and has four different lighting systems, including a system that can change the brightness (illuminance) and color of the light (color temperature).
By creating a comfortable working space based on each of these concepts, intellectual and labor productivity will be improved while energy savings will also be achieved by reducing or turning off unnecessary lighting.

Intelligent Lighting System

By individually adjusting ceiling lights and providing the necessary luminance and color temperature in the necessary places, you can create the lighting environment that each worker prefers. You can also reduce or turn off unnecessary lights to save energy.

Task Ambient Lighting System

The overall brightness is ensured by using ceiling lighting (ambient lighting) with lower luminance than normal, while task lighting ensures the brightness required for workers' hands.

Task lighting image

Human Sensor System

While the entire room is lit at a constant illuminance and color temperature, a occupancy sensor installed on the ceiling is used to dim or turn off the lights on a zone-by-zone basis when no one is present.

Presence Sensor

Hybrid radiant air conditioning

Radiant air conditioning provides a comfortable office space with little air current, quietness and even temperature, while transporting cold and hot energy by water instead of air, which efficiently transfers heat and saves energy. In addition, generating and storing cold energy at night reduces the peak load of daytime air conditioning power consumption.

This is the first time in Japan that a "hybrid radiant air conditioning system" has been installed in a tenant building. This system combines conventional radiant air conditioning with "structure thermal storage," which stores and reuses cold heat in the concrete ceiling and other structures (structure).
Outside air treatment unit and radiant air conditioning panels installed on the roof.

Designer's Voice

Designer

Electrical MEP Engineering Department / Joined in 2002

Hiromitsu Mizutori

Hiromitsu Mizutori

In pursuit of improved productivity and energy efficiency in the office, we have adopted four lighting systems, including lighting that automatically changes brightness and color in accordance with the biorhythm of the day, and lighting that allows the brightness and color to be freely adjusted to suit personal preference.
Even after the building was completed, we received the Facility Encouragement Award from the Institute of Electrical Installation Engineers of Japan thanks to the cooperation of the residents, who compiled an evaluation of the actual operation through questionnaires and measurements. I also have fond memories of working with Professor Miki of Doshisha University, who helped us from planning to operation, and the students who helped with measurements and data organization.
*Affiliation at the time of project assignment

Designer

Mechanical MEP Engineering Department / Joined in 2009

Sunsuke Nakamura

Shunsuke Nakamura

Aiming to create a next-generation office building, we collaborated with Mitsubishi Estate and gradually scaled up the building, from an 80m2 experimental office to a 360m2 demonstration office, accumulating knowledge and introducing cutting-edge air conditioning and lighting technologies that were not yet widespread at the time, to the Kayabacho Green Building, which was finally put into practical use.
This was the first attempt in Japan to install radiant air conditioning throughout a commercial rental office using a system ceiling, and we had some very difficult times getting started, but the positive feedback we received from many people after completion was a great encouragement to us as MEP Engineering.
*Affiliation at the time of project assignment

Data

Property Name

Kayabacho Green Building
location

1-7-3 Nihonbashi Kayabacho, Chuo-ku, Tokyo (address)
Site area

387.43㎡
Total floor area

2,869.95㎡
scale

10 floors above ground, 1 floor below ground, 2 floors in the penthouse
height

46.65m (maximum height)
Completion

May 2013
Main Applications

Office, parking lot
Design and Construction Supervision

Mitsubishi Jisho Sekkei Inc.
Construction

Maeda Construction (architecture), Kyudenko (intelligent lighting systems, etc.), Toyox (radiant air conditioning systems)
Awards
  • 27th Institute of Electrical Installation Engineers of Japan Award
  • Winner of the 17th JIA Environmental Architecture Award

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Update : 2022.11.10

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