Bachelor’s thesis in Architecture - Urban Oasis

URBAN OASIS High School Fine Arts Building, Oxford Mississippi Walking along the straight outer walls of the musical high school a path suddenly opens up and let the visitors into an oasis, filled with vivid vegetation and calm water streams.

With a stepping exterior facade students and bypassers can easily sit down and enjoy the environment while waiting for the school concert to begin.

The school has been divided into three parts, each with its own purpose, separated to minimize disturbance between the volumes.

To connect the volumes and effortlessly move between them, an underground passage is available.

The exterior facade expression echoes through the entire school. The rehearsal rooms and the auditorium has been designed to comply with the exterior facade.

Concept

Site analysis

1 km 100 m

The concept proceeds from dividing a volume and separate the noisy facilities from each other. Each part is then adjusted for its functions and connected with an underground passage. Between the volumes an oasis has been created to give the students a place to socialize and hang out during breaks. Levels have been added to the exterior facade, both to make diffusive walls and also to enable seats in the oasis.

The site is surrounded by different sources of noise. An airport is located one kilometer north west of the school and two high trafficked roads enfold the site in the opposite direction. An outdoor practicing marching band and people talking outside the school also need to be taken into consideration.

When all the noise sources are summarized, a wall with STC-50 value is enough to keep a required Noise Criteria 15 in the auditorium, the most sensitive room.

15 m 1 km

gypsum board 13 mm concrete 125 mm mineral wool 13 mm concrete 38 mm

2 km

band rehearsals

auditorium black box

separating the noisy facilities to prevent disturbance from each other by splitting the box

Noise sources

Worst case scenario Sound pressure level in the Auditorium

Sound pressure level on site [dB]

exterior STC-50 wall detail

[dB] SPL level on site Reference STC-50 NC15 curve Predicted level

Cars People on site Marching band Aircraft

A wall with a value of STC-50 will be enough to block noise from the outside and keep Noise Criteria 15 in the auditorium.

These calculations do not take the shielding of the buildings into account and therefore it is even more likely that a STC-50 value for the wall is enough.

the height of each volume is adapted by its function tilting walls to create a better spatiality and let the sunlight in between the volumes

Frequency

[Hz]

The urban oasis creating an urban oasis connecting the separated volumes by an underground path

By having a stepping shape of the exterior walls the reflecting sound is scattered. That contributes to a better acoustic environment in the oasis.

By having volumes embracing the oasis, only a small amount of outside sound is leaking through the openings. This results in a more silent environment inside.

Frequency

[Hz]

Reverberation time - Lobby

Lobby

[s]

The lobby has a great volume to generate a magnificent feeling for the visitors. Wood panels on the walls combined with a leaning roof prevents flutter echo and a pour sound environment. The reverberation time is approximately 0.8 seconds which is good for this type of halls.

Frequency

adding levels for a more vivid facade and acoustical advantages

[Hz]

panel width: 42 mm air gap: 10 mm

lobby panels The main sound source in the lobby will be people talking. An average frequency for speaking is roughly 1kHz. This frequencies and below will penetrate the panel through the 10 mm wide air gaps and get absorbed by the glass wool. The wood panels has an absorption factor of approximately 50 %.

section A-A 1:200

underground passage between the three volumes

0

5

10

15

1-200

I II III

The oasis

Illustration 2

Plans

underground passage that connects the three separated volumes

1:500

Rooms

Noise Criteria

1. Main lobby 2. CafĂŠ 3. Restrooms 4. Mixing position 5. Orchestra pit 6. Stage 7. Scene shop 8. Loading dock 9. Practice room 10. Small band rehearsal room 11. Storage 12. Office 13. Electrical room 14. Black box 15. Social area 16. Cleaning room 17. Ventilation shaft 18. Mechanical room 19. Dressing room 20. Marching band rehearsal room 21. Choir rehearsal room 22. Balcony lobby

NC-40 NC-35 NC-35 NC-15 NC-15 NC-15 NC-40 NC-30 NC-25 NC-30 NC-20 NC-40 NC-35 NC-25 NC-25 NC-40

Plan -1

-8.0 m

private balcony for the students to join the fuss at the oasis

Ground plan +0.0 m

Plan 1 +7.8 m

B

7

8

ill. 2 8

9

9

6

9

9

3 15

9 3

10 3

Auditorium balcony +4.2 m

5

9 19

19 3

3

3

12

17 11

12

11 11 12

ill. 3

9

ill. 4

3

4 21

2

13

9 20

17 22

3

A

3

A

1 15

9

16

3

N

2 11 12

17

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3 15

sightline to the auditorium entrance from the main road of the school

3

wall perforated with windows to let the audience outlook the oasis during intermissions

3 8

tight intimate walking path along the stretch of water to the centre of the oasis

B

0

Social areas Private

Black box The black box is a theatre with a very simple design, which makes it a flexible space. The black box is capable of endless new configurations, allowing people to exercise their creativity.

the urban oasis, a place for both the students and bypassers

Public private area at level 2 for the students auditorium lobby in two levels lounge combined with entrance at level 1

social area and lobby next to the black box

Reverberation time - Black box

Black box- ex. 2

Stage along one wall, seats in semicircle formation

Stage along short side.

Curtains shielding off space, which could be used for storage

10

15

1-500

[s]

To achieve this requirement the lighting system is put onto flexible girders, the seats is moveable and the stage is moveable both sideways and in height.

Also the space is changeable with curtains to shield off parts of the volume, which then can be used for storage.

The reverberation time is around 0.9, good for monologues and other theatrical performances.

Black box- ex. 1

5

Black box- ex. 3 Frequency

[Hz]

Storages are put in the middle of the building, separating the noisy rooms from each other.

Raised stage in the middle, surrounded by seats

hardwood floor 9 mm plywood 19 mm air gap/studs 45 mm vibration isolation pads concrete 100 mm

gypsum 18 mm concrete 80 mm mineral wool 75 mm

air gap 25 mm concrete 60 mm mineral wool 25-100 mm diffusive panels

hardwood floor 9 mm plywood 19 mm air gap/studs 33 mm mineral wool 24 mm concrete 100 mm gypsum 18 mm

STC-50 floating floor 1:20 The floor between the band rehearsal and entrance at level 1 is a heavy floating floor construction with a STC- value of 50 which is enough to keep NC-40 in rooms at entry level and NC-25 in the choir rehearsal room.

hardwood floor

floating floor and wall

chipboard

1:20 hardwood floor section B-B

15 mm

19 mm

elastomer foam concrete

The wall contains an air gap which prevents vibrations to pass through the wall. Combined with a floating floor and blocking storage rooms, the rehearsal rooms will not disturb each other.

12 mm

50 mm

100 mm

1:20

The floor in the marching band rehearsal room contains a soft layer of elastomer foam to make it comfortable to walk on.

I II III

Auditorium

Marching band rehearsal room

Illustration 3

Illustration 4

Auditorium

Marching band rehearsal room

Reverberation time Opera mode Concert mode Speech mode

[s] The auditorium is the core of the school and the most displayed room for visitors. The interior walls are made of wood, perceived as a warm and living material. The ceiling is adjustable and reminds of the exterior facade. It gives a vivid expression to the auditorium with an exciting play of light.

The band rehearsal room is designed with diffusive walls that scatter the reflecting sound. By using a wall with approximately 50% absorption the estimated reverberation time is 0.7 seconds, which establishes good conditions for a marching band.

[s]

The auditorium needs to have changeable acoustics since it is supposed to handle many different types of performances. By having an adjustable ceiling and a flexible back wall the volume can be changed to suit different acoustical occasions. The ceiling panels are suspended with wires. The length of the wires can be adjusted with computerized system for optimal acoustics.

Diffusive wall in two dimensions A

A-A B

B

Following pictures show three different modes and the acoustics of these.

Frequency [Hz] A

speech mode

Reverberation time - Marching band rehearsal room

concert mode

opera mode

d2

B-B

d1

A marching band generates much sound over a large range of frequencies, though its spectrum peaks around 300 Hz. For these walls to be diffusive its irregularities, d1 and d2 must be at least a quarter wavelength deep.

Therefore the depth of the walls needs to be at least 0.3 meters.

Frequency

Choir rehearsal room

[Hz]

Reverberation time - Choir rehearsal room [s]

Lowered ceiling and dropped back wall.

Closed orchestra pit.

Ceiling raised and orchestra pit open.

The choir rehearsal room needs to have changeable acoustics for different occasions. Diffuse walls are required and a longer reverberation time is wanted. By using a wall with about 15% absorption the reverberation time is estimated to 1.2 seconds which is reasonable for singing. By having slidable curtains on each wall the reverberation time can be modified to a value one find suitable. The roof is leaning 7o to prevent flutter echo.

Raised orchestra pit, gives extra rows of seating. Stage shell is placed on stage.

Clarity - C80 C-80 dB 15

No curtains Changeable RT using curtains

To ensure an undisturbed and quiet environment for the choir room it is well separated from the percussion and marching band rehearsal rooms.

The choir students have easy access to the single practice rooms and to a common room located on the other side of the building.

5

Frequency

[Hz]

0

wall with diffusive pattern

-5

High clarity in speech mode helps the audience to hear the speaker clearly.

Average clarity in opera mode, which works for both singing and music

slanted ceiling to prevent flutter echo

Relatively low clarity in concert mode.

Strength - G 15

G dB

10

5

0

Small volume gives high strength.

Strength is low throughout the auditorium in opera mode.

Strength relatively high. Stage shell increases the sound from performing band

individually adjustable curtains for variable acoustics

Speech Transmission Index - STI 0.8

0.7

0.6

All seats have a good STI which indicates a high easiness of speech listening.

Practice rooms

STI -

At smaller events in the auditorium a decreased volume is convenient for improved acoustics.

One step in reducing the volume is to lower the sub ceiling into a back wall. This is made possible with a wire attached to the back wall and a joint at the end of the balcony which makes the sub ceiling able to rotate. Removable chairs let the back wall drop all the way down to the floor.

prevent disturbance between practice rooms with blocking rooms

7 o splayed walls to prevent flutter echo

individual ventilation branches, prevents flank transmission

detail, changeable acoustics - 1:100

0

corridor between band rehearsal room and practice rooms to minimize disturbance

removable chairs 1

2

3

1-100

band rehearsal room

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