1. BSCI 9060 – Advanced Acoustics Project
Measure of Sound Pressure at Building Envelope
Herman Kwok

2. Introduction
 Wikipedia:
Green Roof - a roof of a building that is
partially or completely covered with
vegetation and a growing medium
Purpose - absorbing rainwater, providing
insulation, creating a habitat for wildlife,
and helping to lower urban air
temperatures and mitigate the heat island
effect.
 …and Sound Attenuation

3. Green Roof
2 types of Green Roof
Intensive roofs - thicker and can
support a wider variety of plants such
as shrubs and even trees
Extensive roofs - light layer of
vegetation, low-growing plants such as
Sedum Species

4. Proposal
 Noise Attenuation across Green Roofs
 Collect Sound Pressure Level
measurements along green roofs
 Acoustical Façade Load
 Identify Relationships and Patterns

5. Location
Great Northern Way Campus
BCIT Green Roof Research Facility

7. BCIT Green Roof Research Facility

8. BCIT Green Roof Research Facility
 1065 sq.ft.
 3 different sections of flat roofing with identical
area
 2 of them are green
 Centre section is a typical flat roof with no
vegetation, aka reference roof
 Green roof on the east side named GR1 has 75mm
(3") growing medium
 GR2 on the west side has 150 mm (6")
 Roofing assembly is fitted with weather poles,
thermal couples, heat flux transducers, and soil
moisture metres.

11. GR1 East Side 75mm Medium

12. GR2 West Side 150mm Medium

13. Reference Roof

16. Results
 150mm medium had the greatest attenuation in
the low frequency range (16hz to 200hz)
 75mm medium had the greatest attenuation in the
High Frequency range (250hz to 8000hz)

18. Weaknesses & Error Factors
 Neighboring warehouse boom box was present
 Large brick warehouse diffracted a lot of the noise
generated by the omni-directional speaker
 West side contained a non-vegetated slope and a
concrete wall
 Larger area of experimental roofs may be needed
 Traffic noise from the Great Northern Way
 Outside temperature fluctuated from around 12
degree Celsius to 3 degree Celsius

22. Reference
 [1] Renterghem T. V. & Botteldooren D. (2008). Green Roofs
for Quietness. Ghent University, Department of Information
Technology, Acoustics group, Belgium
 [2] Connelly, M. & Hodgson, M. (2008). Sound Transmission
Loss of Extensive Green Roofs. Living Architecture Monitor,
Fall 2008, Pg. 24-29.
 [3] Button, D. (June 2008). Green Roof Solves Loud Noise
Problem for Tasmania University Union. Jaws Architects
 [4]
http://commons.bcit.ca/greenroof/research/infrastructure-
research/bcit-green-roof-research-facility-vancouver/
 [5] http://commons.bcit.ca/greenroof/faq/what-is-the-bcit-
centre-for-architectural-ecology/
 [6] http://www.greenroofs.com/projects/pview.php?id=731

23. THANK YOU