Koji Okada
Design Director, Architectural Design Department
NIKKEN SEKKEI LTD, Tokyo

Hirotaka Kubo
Mechanical Engineer
Nikken Sekkei Ltd, Tokyo

New Through-Wall Units Set a Precedent for High-Rise Conditioning Efficiency

This project is the first tall office building in Japan to span over railway tracks, with large floor plates and high environmental performance as design requirements. The challenges of MEP design were to achieve robust redundancy, effective and flexible office space, occupant comfort, and energy conservation at the same time, through holistic, integrated design. To achieve this, a new perimeter through-wall unit (TWU), utilizing exhaust heat recovery, was developed to achieve independent cooling and heating, plus ventilation for each office area, in consideration of comfort and good air quality. The TWUs installed in the perimeter enclosure are harmonized with the outer-braced structure and combined with few interior columns, allowing good views and a compact core, with a high effective floor area ratio at 84.3 percent.

A conventional TWU can neither exhaust indoor air nor recover heat from exhaust indoor air. The new TWU developed for this project added an operating function to exhaust indoor air to the outside, and to recover waste heat from indoor exhaust air by way of a heat pump compressor in each unit, enhancing A/C efficiency. In order to discharge indoor air from the exterior walls, a detailed study of the complex wind pressures applied to the exterior walls of the high-rise building was carried out. As a result of simulations and full-scale experiments, special slit openings and chambers were provided in the exterior panels, and a differential pressure sensor was installed between the indoors and outdoors, ensuring stable exhaust performance.

The new TWUs’ development of new chambers and dampers into standard equipment, combined with its integration into exterior walls, is highly economical, and can be generally applied to high-rise buildings.

This awards category sponsored by: