BSCI 9060 – Advanced Acoustics Project

Measure of Sound Pressure at Building Envelope

Herman Kwok

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

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

Proposal

Noise Attenuation across Green Roofs

Collect Sound Pressure Level measurements along green roofs

Acoustical Façade Load

Identify Relationships and Patterns

Location

Great Northern Way Campus

BCIT Green Roof Research Facility

BCIT Green Roof Research Facility

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.

GR1 East Side 75mm Medium

GR2 West Side 150mm Medium

Reference Roof

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)

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

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

THANK YOU