News 18-04 (No.364)
Issued : April 25, 2018
The New Shizuoka Prefecture Mt. Fuji World Heritage Centre
By Keiji Oguchi
Mt. Fuji World Heritage Centre [Photo: Hiroyuki Hirai]
World Heritage Centre viewing Real Mt. Fuji behind
[Photo: Hiroyuki Hirai]
Last year, on December 23, 2017, the Shizuoka Prefecture Mt. Fuji World Heritage Centre opened. From ancient times, the Japanese people have honored Mt. Fuji as a spiritual place and national symbol, perhaps because of its symmetrical, curved shape, elegant slope and singular location surrounded by lowlands. Japanese poetry and other literature describes the mountain’s beauty and the feelings it evokes. Paintings and other art forms have depicted its graceful form. In 2013, UNESCO officially recognized Mt. Fuji as a World Heritage Site and as “a sacred place and source of artistic inspiration.”
Mt. Fuji straddles the borders of Shizuoka Prefecture and Yamanashi Prefecture and both prefectures maintain a Mt. Fuji World Heritage Centre. The subject of this article is the new Shizuoka Prefecture Mt. Fuji World Heritage Centre. In the words of the centre’s director, the “mission of the centre is to facilitate a deeper examination of Mt. Fuji, to broadly communicate its beauty and traditions to people in Japan and overseas, and to help ensure that its elegant appearance and unparalleled cultural value are preserved for future generations.” (This is a direct quote from the director’s message on the centre’s website.)
<< Location of the Centre >>
The location chosen for the Shizuoka Prefecture Mt. Fuji World Heritage Centre is in the prefecture’s Fujinomiya City. To enter the compound of the centre, visitors pass next a large Japanese Torii gate, the traditional entrance structure of Japanese Shinto shrines. From the Torii gate, a 300 m. (984 ft) path to the north arrives at Fujisan Hongu Sengen Taisha, which is a Grand Imperial (Shinto) Shrine and Japanese National Treasure. Beyond it, on clear days, visitors can see Mt. Fuji in the distance.
The shrine’s grounds include Wakutama Ike (literally, “Gushing Jewels Pond”) where pure mountain spring water from Mt. Fuji abundantly and consistently fills the pond before continuing downstream to the prefecture’s Suruga Bay on the Pacific Ocean Coast. These waters from Mt. Fuji flow along one side of the World Heritage Centre.
<< Shigeru Ban’s Unique Architectural Design and Nagata Acoustics’ Role >>
Section Drawing of Exhibition Wing and North Wing
The architectural design of the centre is the brainchild of Pritzker-prize winning architect Shigeru Ban and his firm, Shigeru Ban Architects. His winning design concept for the center was selected through an open competition of proposals held by Shizuoka Prefecture in 2014. Mr. Ban designed the centre to have three buildings: an Exhibition Wing; a North Wing; and, a West Wing. In particular the eye-catching Exhibition Wing has the unique shape of an inverted cone covered with a façade made of thick wood latticework in a diamond pattern.
Inside the Exhibition Wing, a sloped, spiral corridor wraps around and up the interior’s windowless perimeter, with a time-lapsed video of a climb up Mt. Fuji projected on the corridor’s walls. Visitors watch the video as they climb up the spiral corridor. The intention is to create a virtual media experience that simulates the climb from Suruga Bay to the top of Mt. Fuji. In addition, the building has a number of exhibition floors that can be accessed from the spiral corridor where visitors can learn about Mt. Fuji’s history, its natural environment, its influences on culture and art and the mountain’s role in the Japanese religious belief system. Finally, when visitors arrive at the top of the corridor and enter the observation hall, through a window at this level can be seen the iconic elegance of the real Mt. Fuji perfectly framed by the window in the most well-known picture postcard view of the mountain.
In front of the Exhibition Wing Mr. Ban located a shallow, but expansive pool of water. On clear days the Exhibition Wing’s inverted cone shape reflects in the water, creating a conic image in the water that mirrors the shape of Mt. Fuji seen against the backdrop of the real mountain visible in the distance. On these clear days, a visitor standing at the south side of the centre can enjoy a view of four “Mt. Fuji” images—the real mountain in the distance, its inverted image in the shallow pool, the inverted cone of the Exhibition Wing and the flipped image of the Exhibition Wing that, shaped like Mt. Fuji, is reflected in the shallow pool.
At Mr. Ban’s request, Nagata Acoustics provided consulting services for the room acoustics of the Exhibition Wing’s inverted-cone-shaped interior. We also provided sound isolation consulting and architectural room acoustics design for the Video Theatre in the north wing.
<< Acoustics in the Exhibition Wing >>
Interior Perimeter Spiral Corridor
As part of our acoustics consulting for the Exhibition Wing, we considered whether visitors to the space would experience a whispering-gallery wave sound phenomenon. If this phenomenon were to occur, visitors walking in the spiral perimeter of the inverted-cone-shaped Exhibition Wing, or standing in one of the exhibition spaces on this wing’s floors, would have the confusing experience of hearing sounds emanating from places unseen or unable to be determined by the person hearing them. We prepared a simple 3D geometrical acoustic model and ran simulations that confirmed our hypothesis that the combined effect of sound travelling along the inverted conical wall surfaces, lower surfaces of the corridors and the large ceiling would result in sound focusing on the exhibition floors and in the corridors.
Because the walls of the spiral corridor serve as the projection surface for the video of the Mt. Fuji climb, these surfaces needed to have a very smooth finish. To mitigate the sound reflecting characteristic of the smooth upper wall surfaces, we installed acoustic tiles on the back surfaces of the corridor and on the large ceiling. The travertine pattern of the visible side of the acoustic tiles lacks visual appeal, but due to the low light levels in the spiral corridor of the Exhibition Wing the pattern is inconspicuous and mostly not noticed by visitors. We also wanted to install the acoustic tiles along the back surfaces of the exhibition floors that can be accessed from the spiral corridor, but these exhibition spaces are well lit and the final decision of the project team was to install a smooth surface in these locations.
In this wing the fan from the projector adds a masking noise to the overall acoustics. The combination of our installation of acoustic tiles and the fan’s masking noise resulted in the space being free of any undesirable whispering-gallery wave sound phenomena.
<< The Video Theatre >>
The 74-seat Video Theatre boasts a 265-inch screen so that even on the cloudy days that hide a view of the real Mt. Fuji, visitors to the centre can enjoy a magnificent view of Mt. Fuji on the screen in 4K resolution. The theatre has the following interior finishes: a carpeted floor; walls typical of Japanese cinemas with a layer of drywall covered first with a layer of glass wool and then with a kind of damask material; and, a ceiling of non-conbustable paper pipes arranged to create an “undulating ceiling” pattern.
It was my expectation that the sound scattering caused by the paper pipes would make this interior design element also a sound absorbing element, but we also ensured that the space would have sufficient sound absorption by affixing a layer of glass wool directly below the ceiling slab. With this acoustic design feature, sound that passes through the paper tubes toward the ceiling will be absorbed by the layer of glass wool. Overall, the centre’s Video Theatre has the same kind of minimal reverberation characteristic as do most recently built cinema theatres.
I made my last visit to the centre shortly before the completion of construction. Water had not been added to the shallow pool on that day and the skies were unfortunately dismally overcast, so I saw only the inverted Mt. Fuji-like shape of the inverted-conical Exhibition Wing, but neither the real Mt. Fuji nor any of the pool reflections. I hope to visit the centre again soon so that I can enjoy a view of the real Mt. Fuji and see the reflections of the mountain and the Exhibition Wing as well.
Bancho Church’s New Building Opens with the Mission Statement “Open for All”
By Ayako Hakozaki
Bancho Church Building Exterior
Front of the Sanctuary Interior
Bancho Church has a 132-year history from its original opening in 1886, during Japan’s Meiji Era. The church belongs to the United Church of Christ in Japan, a Protestant denomination and derives its name from the church’s original location in the Fourth Bancho of Tokyo’s Chiyoda Ward near Kojimachi Station.
Bancho Church’s new building uses a site in Chiyoda Ward’s Sixth Bancho, near the original church building’s location. The church moved into its new location in February and held its first worship service in the new building on February 11, 2018. On March 18, 2018, the congregation held a dedication ceremony for the new building.
<< Project Overview >>
Tezuka Architects designed the new church building and oversaw its construction. Satohide Corporation served as the project’s general contractor. Nagata Acoustics performed acoustical consulting services for the building’s sanctuary during the design and construction phases of the project, including room acoustic design, sound isolation and noise control design.
This was the third church project designed by Tezuka Architects on which we participated. The previous two projects were Chigasaki Sion Christian Church and Higashiyahata Christ Church. However, on the previous projects we participated only in the design phases of the projects. This was our first experience collaborating with Tezuka Architects through the construction phase of the church project.
<< Highlights of the New Church Building >>
Detail of Sanctuary Wall Plaster Treatment
The serene appearance of the new Bancho Church building’s architecture blends well with the location’s surroundings. The building’s full-height, glass entrance doors visually express the church’s desire to welcome all who wish to enter its space. At the outset of this project, the church shared its fundamental mission statement in writing with the project team. The statement reads: “Value our connection with the local community in the spirit of being Open for All.” The architects developed an architectural design that expresses this mission of the church.
When a person steps into the church sanctuary after passing through the entrance doors and foyer, they come into a space with ceilings that rise three-stories high and where light from skylights fills the room. The space evokes a desire to simply stand quietly in the space. A feeling of being softly enveloped in the space is created by the hand-plastered finish on the ceilings and walls, the work of master plasterer Mr. Naoki Kusumi. Some of the small skylights have stained glass panels of orange or yellow hues, adding subtle shades of color to the basic white of the sanctuary’s walls and ceiling. Ms. Chiemi Inoue made the stained glass panels and donated them to Bancho Church for the new building. In addition to the panels used as skylights, Ms. Inoue created a number of stained glass panels for the exterior wall of the stairway that leads from the foyer to the second floor. The stained glass panels reflect colorful light into the building.
The cross that graced the old church building now hangs on the wall of the front of the new sanctuary and the old church’s sacrament table has been installed below the cross to serve as a table for the sanctuary’s bible. In this way, the church connected its history with its new location and building.
The rear wall of the sanctuary has a pipe organ balcony. A pipe organ is scheduled to be installed in the balcony in December, 2018.
<< The Sanctuary’s Room Acoustic Design >>
Vertical Surface below a Skylight
We developed our acoustic design for the sanctuary with two equally important key priorities. One of the key priorities was to design a space where sermons and other speech can be heard clearly throughout the sanctuary’s seating. The other key priority was to create a space of rich acoustics for pipe organ music and hymnal singing. In addition, it might be considered an additional significant requirement that we needed to develop a design that would not detract in any way from the sanctuary’s sublime ambiance.
The walls and ceiling of the Bancho Church sanctuary were constructed using reinforced concrete. In this rectangular space, the opposing walls of the sanctuary appear to be parallel to each other but, in fact, three of the walls are slightly angled so as to prevent undesirable flutter echoes.
For Mr. Kusumi’s plaster finish over the concrete wall and ceiling surfaces, we requested that his finished work have as much surface depth variation as possible. From the acoustic design perspective, this implementation would best promote the generation of soft sound reflections. The variations in Mr. Kusumi’s plaster finish can be felt by touch and when a person moves their hand along the wall the surface variations can be felt. At the lower portion of the walls the variations are more subtle and become larger towards the upper portions of the walls.
The process to select the plaster finish began with Mr. Kusumi preparing multiple samples that had both a variety of textures and different variations of surface depth. The architect selected a plaster finish based on his design requirements and Nagata Acoustics participated in the selection to confirm the appropriateness of the finish from the acoustic design perspective. When the concrete installation of the sanctuary’s concrete walls and ceiling were complete and scaffolding removed, a large sample of the selected plaster finish was brought into the space and placed so that light from the skylight shone on it. The project team again reviewed its decision and gave final confirmation of the selected finishing treatment.
For sound absorption needs in this space we adopted measures to prevent an excess of reverberation. Firstly, we installed glass wool in the louvered ceiling under the organ balcony’s overhang. For this implementation we specified that the glass wool be installed with an air space behind it to obtain sound absorption of low frequency sound. During our acoustic design process we also considered using glass wool on the vertical surfaces directly below the skylights. Installing glass wool on these surfaces would have required us to use in this location a different plaster than the one applied throughout the rest of the sanctuary by Mr. Kusumi. We decided to prioritize the visual quality of how these surfaces look when light from the skylights shines on them. Accordingly, we did not install glass wool in this location and these surfaces have the same plaster finish as the rest of the sanctuary.
Another sound absorbing consideration of our room acoustic design concerned the timing of installation of the pipe organ because it will be a large sound absorbing element in the sanctuary but is not yet installed. In the current state before the installation of the organ, the space’s acoustics are a bit too lively. As a temporary means of reducing the reverberation characteristic during this time period, we used the seat cushions from the old church and spread them along the floor of the pipe organ balcony.
<< The Important Role of the Sound System >>
Microphone of the Sound System
As the final topic I wish to share here about the sanctuary’s room acoustics, I will highlight the indispensable role of the sound system for this project which required both rich acoustics and clarity of speech. After the church took occupancy of the building, the vendor that designed and installed the sound system, Eizo System Co., Ltd., came to the church to explain how to adjust and use the sound system. Nagata Acoustics also participated in this gathering and confirmed with the client that the objective of clarity of speech had been achieved.
The sound system has Pipeline loudspeakers, which were selected because this model is known for obtaining clarity of speech in spaces with long reverberations times and, overall, the sound system performed as intended. However, the boundary microphone (a microphone with wide directionality installed on the surface of the pulpit) picked up reverberations from the space, resulting in a small loss of speech clarity. We tested substituting a gooseneck-style microphone for the boundary microphone. This change improved the clarity of speech in the sanctuary and the gooseneck-style microphone became the permanent solution.
During the sound amplification tests with the microphones, church representatives who participated in the tests by speaking at the pulpit told us that when they use the gooseneck microphone they are careful to face it and speak into it. It makes sense that the shape of the gooseneck-style microphone causes speakers to be careful about using it effectively. During the worship service and dedication that followed the sound system test, each person who used the microphone similarly spoke into it in a way that—considering the comparatively long reverberation time of the space—consistently achieved easily understand amplified speech through the sound system.
<< Memorable Words by Pastor Yokono >>
At the first worship service in the new church building, Pastor Yokono spoke these words to the congregation, “As we move into the new church building, I think we will be confused by various changes. It’s natural to feel this way and for the most part, and as you will maybe agree, time will resolve these feelings.” When we embark on something new, the person embarking on the new endeavor may forget that change can make a person feel confused and become worried by the confusion. The pastor’s words remain in my heart.
After the dedication, some members of the congregation told me that they enjoyed the sanctuary’s acoustics during hymnal singing. On the other hand, the clarity of speech may have confused some people comparing to the old church.
The pipe organ by Jäger & Brommer Orgelbau will be completed in December, 2018. Its installation will result in yet a new change to the sanctuary’s acoustics and the sound amplification in the space will likely also be affected. I hope that the acoustics in Bancho Church’s sanctuary will become a source of strength for the church and the people who pray there.
Nagata Acoustics Inc.
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