Pavilion facility planning that realizes "short circulation"

This time we will be introducing the Mitsubishi Group Pavilion, Mitsubishi Pavilion, at the 2025 Osaka-Kansai Expo. With one basement floor and two aboveground floors, the structure is constructed with a diamond-shaped building and an inscribed rectangular building covering an elliptical semi-underground space that has been leveled like a mortar. Here we will introduce an example of the low-tech methods that are unique to a pavilion, a temporary building that will only be in operation for six months.

Due to the nature of the Expo pavilion, it will be dismantled after six months of operation, so we aimed to minimize the environmental impact and waste. We decided to limit the insulated "complete interior space" to the bare minimum, and to narrow down the areas that require air conditioning and lighting. This plan is aimed at pursuing sustainability through simple methods rather than advanced technology.

Therefore, the air conditioning system for the area used by visitors is configured with only one compact air conditioner (heated by chilled water supplied by the Expo Association). Only enough space has been reserved within the air conditioner's machine room to allow for minimal maintenance. This is because, given the short operation period of just six months, it is assumed that there will be no equipment updates or equipment being brought in or out during that time. These measures have maximized the spatial efficiency of the pavilion. Additionally, the back office rooms have individual heat sources, each with a room air conditioner. Again, as a plan for short-term operation, although the site is surrounded by seawater, a standard-spec outdoor unit has been installed, rather than the specifications required for areas exposed to sea breezes.

Additionally, the "standby" and "post-show" areas, which correspond to the traffic flow before and after the video experience that is the main content, are open-ceiling spaces that let in natural light through the transparent polycarbonate exterior walls, and we decided not to install lighting fixtures anywhere other than in the passageways. Generally, lighting fixtures in open-ceiling spaces require the erection of scaffolding for maintenance, but this plan makes such work unnecessary, while also considering ease of building maintenance.

In this pavilion, power is supplied to each location from an outdoor substation, but due to the limited operation period, this substation is leased. The electricity supply is planned to be a simple system with separate supply systems for each purpose so that the visual and audio of the exhibition content and back office related power are not mixed, minimizing the scope of the impact in the event of a power system problem.

The "Waiting Park" is shaded from the sun by the upper building that covers it, and the cool air that comes through the excavated ground and the cool breeze from the sea flow in comfortably. It is open to all visitors as a cool, well-ventilated waiting space.

The building's only compact air conditioner, as mentioned at the beginning, is installed in the machine room on the first floor. By taking in outside air from the "waiting park" directly below, it is not only possible to lower the temperature of the outside air taken in and save energy, but also to minimize the length of the ducts, thereby reducing materials and transport capacity, making it a rational and economical plan.

Portable fans have been installed to help circulate the air, but they are actually the same ones used at construction sites. The lighting is also the same equipment used at construction sites, and will be available for use at other construction sites after the exhibition ends. By using reusable products for the air conditioning and lighting equipment, we have made it easy for visitors to understand the concept of "small resource circulation," or short circulation.

When Architectural Design on a regular site, MEP Engineering will generally gather information about the infrastructure of the site from government documents and on-site surveys. MEP Engineering will also take the lead in deciding the location of the infrastructure in consultation with each infrastructure agency.

However, for this Expo site, the Expo Association (Japan Association for the 2025 World Exposition) is developing the infrastructure from scratch, and the location of the infrastructure was specified for each pavilion site from the beginning. Having the location of the infrastructure specified means that the infrastructure route and space to the building are regulated. MEP Engineering has a large impact on the architectural plan, so by coordinating with all departments as one, we were able to achieve a plan that was efficient.

When constructing this Expo, the Expo Association issued guidelines such as design requirements and construction conditions. However, because the design of Mitsubishi Pavilion took place earlier than other private pavilions, some guidelines were still under consideration in the early stages of design, and we repeatedly checked the consistency of the contents as we proceeded with the design. Even after construction began, the guidelines were revised and new ones were issued, so we made various adjustments as needed, such as catching up on information and reviewing facility specifications, right up until the building was completed.

In addition to face-to-face meetings on-site, we also utilized web conferencing to ensure smooth communication, which allowed us to resolve each issue one by one.

Although we struggled to gather all the information necessary for MEP Engineering, we feel that the fact that we were able to have the honor of being the first private pavilion to be completed is a result of the unity of all our departments.