STEM Community Challenge

Dr Steve Dorney 16 July 2011

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Plan for today• Background

• Bay House School/Vestas/ISVR – siting wind turbines

• ALNS/ISVR Consulting/Creative Partnerships – room acoustics

• The HESTEM “Project brief” document

• Have a go …

• Link to HESTEM curriculum change – environmental engineering consultancy

• Future: energy management; waste management

3

Locating a wind turbine• Loci – see worksheet

• Applying technical, legal and social criteria

• Design and build at scale on school site

• + real-life example/issue

• - measurable but invisible impact on school/community

• - no legacy

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Room acoustics• 3 way project

– Consulting experience for University students

– Free professional assessment of spaces

– Pupils involved in measurement, design and implementation

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Four projects undertaken

• Investigation of Speech Intelligibility in The BLA Room The Hartley Library

• Investigation of the Acoustics of a Science Classroom Mayfield School, Portsmouth

• Noise Impact Assessment at a Proposed Skateboard Park Site Greatness Community Association

• Investigation of the Acoustics of a School Canteen Admiral Lord Nelson School, Portsmouth

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ALNS Stage 1 – measure/report

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ALNS Stage 2 – upgrade skills and knowledge

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ALNS Stage 3 – design & test

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ALNS Stage 4 – select, revise and implement

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Room acoustics• Broad range of maths and science

• Applying technical, legal and social criteria in tangible (audible!) scenario

• Realistic prototyping process

• + real-life example/issue

• + measurable and high impact on school/community

• + environmental and learning legacy

The sample HESTEM brief• www.sonicwonders.org

Have a go …

Time (s)

Pre

ssure

(Pa)

Decay is exponential

Reverberation time: time for pressure to decay by a factor of 1000 (60dB)

RT60 = 3 x RT20 If it’s too long …

The reverberation time of St Paul’s cathedral (at 500Hz) when empty of people is

A. 3 seconds

B. 7 seconds

C. 11 seconds

D. 15 seconds

kVR

A

A is the equivalent area of perfectly absorbing material (in m2)

The internal volume of St Paul’s Cathedral is 152,000m3 and its reverberation time when empty of people is 11 seconds. Calculate:

i. The equivalent absorption area when the cathedral is empty

ii. The reverberation time when full (2000 people) where each person has an equivalent absorption area of 0.4m2

Sabine’s formula

where 0.161k s m

The reverberation time of St Paul’s cathedral (at 500Hz) when full of people is

A. Less than 4 secondsB. Between 4 and 6

secondsC. Between 6 and 8

secondsD. Longer than 8 seconds

Predicting absorption area

1 1 2 2 n nA S α S α S α

where are absorption coefficients …

Equivalent absorption area,

Material Absorption coefficient, Cost

Carpet 0.05 £10 per m2

Ceiling tile 0.5 £40 per m2

Thick curtains 0.35 £7 per m2

Linoleum 0.02 £2 per m2

Seating Equivalent absorption area Cost

Plastic seats 0.1m2 each £20 each

Upholstered seats 0.8m2 each £55 each

kVR

A

where 0.161k s m

Challenge 2• The reverberation time of this room, if unfitted and unoccupied, would be 3

seconds, say. What is the most cost effective way of fitting it out (including 50 chairs) so as to halve the reverberation time (still unoccupied)?

Challenge 3• Acoustic ceiling tiles are chosen as the sole solution to halve the

reverberation time, and the headmaster needs to decide what proportion of the ceiling to have treated. Find an expression for the reverberation time as a function of cost and plot (sketch) the graph.

Challenge 1• Estimate the volume of this room.

(for V=1350m3)

0 2000 4000 6000 8000 100000

0.5

1

1.5

2

2.5

3

3.5

Cost (£)

Re

verb

era

tion

tim

e (

s)

1

ay

bx

Of form

19

Plan for today• Background – community/uni links via STEM?

• Bay House School/Vestas/ISVR – siting wind turbines

• ALNS/ISVR Consulting/Creative Partnerships – room acoustics

• The HESTEM “Project brief” document

• Have a go …

• Link to HESTEM curriculum change – environmental engineering consultancy

• Future: energy management; waste management