Designing architectural facilities that harmonize with the "new normal office"

Located close to Kanazawa Station in Kanazawa City, Ishikawa Prefecture, Hirooka Terrace is a new-normal tenant office building that aims to go beyond the boundaries of conventional urban offices and provide new value to workers. By harmonizing the space created by the architectural plan with the functions provided by the facility plan, the building has achieved Nearly ZEB certification under BELS, making it a pioneering building in environmental design for high-rise tenant office buildings.
This time, we will look at this project from the perspective of MEP Engineering.

The semi-outdoor terrace that opens onto the main street is the symbol of "Hirooka Terrace." From the early planning stages, we held repeated discussions with the architectural and electrical designers about whether we could use this facade as a functional environmental device. Kanazawa has a Sea of Japan climate, and is characterized by heavy rainfall, especially in the winter, and many long windy days. For this reason, a typical terrace that is fully open would be strongly affected by the wind and rain.

Therefore, in order to create a semi-outdoor space that can also function as a workspace, we examined the layout and configuration of the atrium, glass, mesh fence, and wooden louvers that form the terrace. At the same time, with the aim of improving the indoor environment and contributing to energy conservation, we also conducted in-depth examinations to ensure that a comfortable airflow is taken in from the terrace on the windward side of natural ventilation (gravity ventilation using the stairwell), and to reduce direct solar radiation and direct light, thereby reducing heat load and glare. Through this type of complex facade engineering, we viewed the terrace and indoor space as a single unit, aiming to optimize the total design across the thermal, light, and wind environments.

After minimizing the heat load of the entire building, we then consider ways to generate energy. Currently, there are very few examples of large-scale buildings like this one that have achieved Nearly ZEB. One possible reason for this is that the space required for energy generation is extremely limited.
Therefore, this plan has been designed to minimize the installation of equipment on the roof by providing a facility balcony on each floor, and to use the roof as a dedicated space for energy generation.In addition, the eaves of the terraces located in various places are made of photovoltaic glass integrated into the building material, in order to maximize energy generation throughout the building.

In constructing the heat source system, we made maximum use of well water, a local resource. A water-cooled heat pump chiller that uses well water heat is used as the main heat source, achieving highly efficient operation even in seasons when outside air conditions are harsh. In addition, during the intermediate seasons when outside air conditions are good, the attached air-cooled heat pump chiller is operated as the main unit, minimizing the power required for the well water pumping pump. This combination minimizes energy consumption throughout the year, while providing a stable supply of medium-temperature chilled water at 12°C in the summer, as well as chilled water at 7°C mainly for backup purposes, and hot water at 45°C in the winter.
For the air conditioning and ventilation of the standard floor offices, the specifications and configuration are such that the main secondary unit is a desiccant outdoor air conditioning unit with built-in total heat exchanger, which in summer is able to handle the latent heat load of the introduced outside air and human bodies using only medium-temperature chilled water produced by a water-cooled heat pump chiller, and the remaining sensible heat load is handled by a small packaged air conditioner with a small amount of refrigerant charge. Through these measures, we have maximized the efficiency of the heat source and air conditioning (minimizing operational carbon) while also taking whole-life carbon into consideration. In addition, we are also taking various other measures, as shown in the diagram below.

Exposed wood reinforced formwork lumber (MI deck) has been used throughout the building. Compared to typical deck formwork, the carbon fixation in wood is expected to reduce the building's overall ​_CO2 emissions by approximately 2%. In addition, by eliminating ceiling materials and minimizing ceiling-surface equipment for a simple structure, we are promoting carbon neutrality through resource conservation.
On the other hand, the design presented great challenges as the equipment, ducts, and pipes, which are often hidden in the ceiling, were now exposed.Even at the on-site stage, we worked closely with the contractor to come up with ideas for the equipment layout that would make the finish look more beautiful, the routes for the ducts and pipes to be deployed, and the specifications for the heat-retaining finish, in order to aim for a sophisticated space where the warmth of wood coexists with the equipment.

Dehumidifying radiant panels that use well water heat are installed on the elevator transfer route leading to the office floors, and the air is gently conditioned by flowing medium-temperature chilled water at 12 °C in the summer and warm water at 45 °C in the winter. In the summer, chilled water at 7°C is supplied only during rush hour, resetting the heat history accumulated during the commute and providing the value of "being able to start work in comfort."

As ICT technology, including the use of cloud computing, rapidly evolves, the role expected of building equipment is expanding more than ever. In addition to traditional considerations for general operational management, it is becoming increasingly important to consider "a system that allows the building itself to be continuously updated," taking into account people's movements, daily usage, and future technological advances.
Taking advantage of the unique feature of Hirooka Terrace, which is connected to the adjacent Hokkoku Bank Head Office by a connecting corridor, a portal site was created as a soft initiative that can be used by workers at both facilities. By centralizing facility information and services, a comfortable workplace is provided.
For example, tenants at Hirooka Terrace are allowed to use the cafeteria at the bank's main branch, but physical distance can be a bottleneck, and there is a risk that they may not use it as expected. To address this issue, we used AI cameras to analyze people flow and display heat maps to visualize congestion and length of stay in real time. Furthermore, by utilizing accumulated data to display estimated waiting times and congestion forecasts, we can evolve the system to be more user-friendly.

These services are supported by an integrated network that can flexibly respond to future technological advances and the addition of new facilities. Just as smartphones can be easily updated, we have created a system that allows building facilities to continue to evolve, and we are also considering expanding this to bank headquarters in the future.
Furthermore, when it comes to building operation and management, labor saving and operational efficiency are essential amid a declining working population. Therefore, by digitizing daily equipment inspections and enabling data storage and report output on an app, an efficient and uniform inspection work scheme has been realized.
Through these efforts, we aim to create a smart building where users and managers can work comfortably and efficiently, and which will continue to evolve into the future.