SUSTIE—ZEB-related technology demonstration building

Offices are expected to be sustainable. From the perspective of reducing the environmental impact, ZEB (Net Zero Energy Building) has been attracting attention, and a certification system has been established. The aim is to create a building where the total of energy generation and consumption through renewable energy is zero, so that all energy consumed during building operation can be covered by renewable energy. On the other hand, wellness is also required in offices to ensure the health and comfort of workers. A certain range of thermal environment is required regardless of the season. Reducing the environmental impact and improving health and comfort are both important from the perspective of sustainability, but they can be somewhat contradictory. If energy conservation goes too far, the environment tends to become hot/cold, but that is not good. This project aims to show that ZEB and wellness can be achieved at a high level.

The building, commonly known as "SUSTIE," is a demonstration building where employees themselves act as test subjects to accelerate the development of ZEB and wellness-related technologies. It was planned from the beginning to achieve both the platinum rank of WELL certification and the S rank of CASBEE-WO certification, along with ZEB. Moreover, while most ZEBs are small-scale, under 2,000 m2, this facility is medium-sized, over 6,000 m2 and four stories high. As the building size increases, energy consumption increases, making it more difficult to achieve ZEB, but this was positioned as a prototype with ZEB in mind.

ZEB is not achieved by simply improving insulation performance. It is the result of integrating various technologies. In order to create a prototype that would be easily accepted by the market, we did not use special technologies, but instead focused on arranging general-purpose technologies. First, we adopted a plan that is long from east to west, which is suitable for energy conservation. It is difficult to receive western sunlight from a low altitude, and the eaves can save sunlight from the south, which is high altitude. A large opening in the glass curtain wall on the north side allows ample natural lighting from the north. Facing that curtain wall is the atrium that runs through the first to fourth floors, which is the greatest feature of this facility. Cooling/heating the entire atrium, which holds a huge volume of air, is disadvantageous in terms of energy conservation, and at first glance it seems like a contradictory plan, but this was the key to achieving both ZEB and wellness.

The use of renewable energy is essential for ZEB. In many cases, solar panels are installed, but because an area according to the size of the facility is required, a large site is needed. However, in SUSTIE, which aims to be a prototype, all solar panels are installed on the building so that it can be done on a normal site, not in such a special situation. In order to maximize that area, we aim to maximize the building area. The insertion of a void played a part in this.

Of course, this atrium is a useful mechanism for creating richness and diversity in the workspace, which contributes to wellness. However, there is no denying the disadvantages to the thermal environment. That's why we adopted "mitigated air conditioning." This is the idea that it is not necessary to air-condition all spaces equally, and the temperature setting can be changed depending on the purpose. The atrium is used for communication and meetings, which are not used for long periods of time, so the temperature setting is set lower than in other areas, and localized air conditioning is provided in conjunction with radiant air conditioning using water-type heating and cooling panels.