A protestant church is standing at a rich green residential area at a 10-minute walk from the Shonan beach. The meetinghouse of the 50-year old church became too small and it came to a decision that a new church would be constructed on a new site. People related to the church said, "We wish to have a chapel appropriate to give praise to the Lord."The words of the Bible are read, and heard in service.
*Six roofs
The composition of construction was a one-storied building with a restrained height so that it might harmonize with a low-rise residential area and aimed at creating space appropriate to prayer and worship with the six curved surface roofs at different heights, which allowed natural light to pour down between those roofs. A message got across that six roofs means the first to sixth day from the Creation in the Bible genesis and worship manifests the seventh day.
*Direct sunlight and skylight are manipulated according to the time zones.
Direct sunlight was inappropriate for the time zone of service, but considering that direct sunlight was appropriate for the time zone except for service, this construction was designed to create a space of skylight during the time zone for service (10:30-12:00 in Sunday morning) and direct sunlight during other time zones. So, light was simulated at intervals of 30 minutes on the representative days in 12 months and manipulated according to the time zones. As a result, the time zone for service comes to create a space under a soft skylight throughout year. If service comes close to finishing time, direct sunlight begins to draw a ray of light on the wall surface. Dynamic alterations take place that direct sunlight changes to the state of one line in the afternoon and further takes another form to pour down like shower at around three o'clock.
*Ribs of sound and light
Uneven longitudinal ribs were carved at random rhythm to the exposed RC concrete wall of the chapel, and dark gray acoustic boards were placed between the ribs. Conflicting requirement arrived at a solution through striking a balance, by making it easy to hear priests' preach and Bible Readings with concave acoustic boards, and the sound of ecclesiastical music such as hymns with RC convex surfaces. Flutter echo reduces by random rib pitches. Contrast of dark gray concave surfaces against light stands out a light gray brightness of direct sunlight shooting the convex surfaces. Based on the idea that modern church construction has to provide a space to enable the Bible Readings, it came up to mind that the state of direct sunlight shooting through a dark space became a reality in a bright, not dark space.
*Direct moonlight
Under the sky of Shonan, we participate in a service, read and hear the words of the Bible and have the time for pray in a space under dynamic direct sun light in the afternoon. Direct moonlight shoots through a pitch-dark chapel at night of the full moon. Time and space like this harmonizes with the regional nature and scenery and hopefully people come to love the construction.
*Outdoor terra-cotta cross
Reverenced Furuya picked up 5KG sand by hand in the premises of the previous church and a terracotta cross was made being burned, mixed with the sand. This is because that I wanted to interweave the 50 years' history of Shonan Christianity association and the congregation's desires in it.
*Open rainwater pipe
Slits were installed on the outside wall at the lowest position of circular arc to make it open rainwater pipes. As a result, it could be enjoyable to see rain flow in the gutters and leaves don't block the gutters in spite of abundance of pine leaves.
*Direct sunlight and prayer
Space where direct sunlight reveals various expressions according to times is suitable for one person's or several people's prayer. In the afternoon after prayer, it becomes a space for prayer by the small number of people and direct sunlight changes the number of the ray from one to two or three and its angle by the minute.
*Skylight and service
The words of the Bible are read, and heard in service. It is inappropriate that the Bible and people are exposed to sunlight during service. Skylight is appropriate for service. The space is secured for skylight during service from 10:30 a.m. to 12:00 a.m.
*Chapel after noon
Only one ray of thin direct sunlight shoots through the chapel when hymn is sung toward the end of service
*The Creation relief tile
Under the six roofs, relief tiles in the motif of the hand of God for the six-day Genesis are buried on the north-south walls. Unbaked tiles were engraved with original pictures from Genesis and burned one by one. The tiles were colored with transparent thin blue with the image of morning haze. The pictures of six days were delicately different in design between south and north, and added the enjoyment to find a picture not only in the chapel but in various rooms including the anteroom, rest room, baby room and pastors' room.
*Structural design
Structural design was based on box frame type reinforced concrete construction with sufficient amount of wall 300mm thick in a longitudinal direction and thin steel moment frame on the short side direction. Curved slabs in the curvature for one side of 250mm in thickness that composes the roofs functions as beams using the curvature of the slab, and resists the horizontal force as part of steel moment frame. Void slabs were adopted for curved slabs, used to efficiently span them and the wall on the short side direction was given complete structural slits so that it might be relieved from the burden of a horizontal force.
ARCHITECT: TAKESHI HOSAKA / TAKESHI HOSAKA ARCHITECTS
STRUCTURAL ENGINEERS: HITOSHI YONAMINE / OVE ARUP & PARTNERS JAPAN Ltd
ACOUSTICS: AYAKO HAKOZAKI / NAGATA ACOUCTICS
PHOTOGRAPHER: KOJI FUJII / Nacasa&Partners Inc.
CLIENT: SHONAN CHRIST CHURCH
Site: 416.50 m2
Building area: 175.96 m2
Floor area ratio: 175.96 m2
Building height: 6656 mm
No. of floors: 1F
Planning phase: February 2013 - October 2013
Construction phase: November 2013 - June 2014
Construction nature: Reinforced Concrete (RC)
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Statement of acoustic engineers:
Ayako Hakozaki / NAGATA ACOUCTICS
Among the acoustical design requirements for the sanctuary, a focus was made on ensuring that the congregation would be able to hear the sermons clearly. To this end, the reverberation of the space was limited to an appropriate level and measures were taken to inhibit the occurrence of undesirable echoes.
Architecturally, the sanctuary’s ceiling was planned to be the exposed underside of the building’s curved concrete roof. From an acoustical design perspective, this curved shape provides abundant early sound reflections to the sanctuary uniformly. On the other hand, since the side walls of the sanctuary were designed to be parallel, smooth concrete surfaces could result in undesirable echoes. Furthermore, we needed to add sound absorbing material to the side walls to avoid excessive reverberation. For both of these, a pattern of vertical ribs with a random periodicity was created on the concrete side walls. And between the ribs, strips of sound absorbing black urethane foam were inserted. In the sanctuary, the pastor's speech could be heard clearly and easily throughout the space, while the hymns could be heard softly.
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Statement of structural engineers:
Kazuma Goto, Kanae Hagiwara, Hitoshi Yonamine, Tokyo
The curved as-cast concrete roof is a one of the striking feature of the Church, in the quiet neighbourhood, located in Shonan area where is along the coast of Sagami Bay in Kanagawa, Japan. This church provides approximately 175m2 and has single storey with RC structure. Arup was consulted about structure and lighting environment .
Associate with the hexameron in the Creation of Genesis, the architect, Hosaka Takeshi was inspired and designed the “six” roofs.
The characteristic 6 curved slab is designed not only architectural reason but also it provides structural, acoustic, and lighting benefits.
By steric effect from their curvature, the roof can span 7.6m length only with 250mm thickness and in each curved slabs, there’re void tube which reduces the weight of the structure. In the case of the seismic, especially their spanning direction, the shear wall with 300mm thickness and the curved slabs behaves as if moment frame structure since the girder slab has stiffness for the direction.
The both side of each roof, there’re gaps in order to taken in natural sunlight. They brighten the space of chapel with daylighting and it secures sufficient supply of illuminance. Therefore, the daylight from the opening is enough to be able to fill the space with bright natural light during the daytime. The opening is also designed to avoid the direct sunlight during the time of worship.
The curves provide us to avoid intensive the sound of carol and sermons.
Having curvature, the sunlight reflects spreads into the room and it is blighter than the case of flat slab. Even the moonlight falls to the inside and leads us to fantastic world.
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