Cairn Homes Properties Ltd. Blake's Noise Impact Assessment
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Cairn Homes Properties Ltd. Blake’s Noise Impact Assessment Report Ref Issue 1 | 6 November 2017 This report takes into account the particular instructions and requirements of our client. It is not intended for and should not be relied upon by any third party and no responsibility is undertaken to any third party. Job number Job number Ove Arup & Partners Ireland Ltd Arup 50 Ringsend Road Dublin 4 D04 T6X0 Ireland www.arup.com Cairn Homes Properties Ltd. Blake’s Noise Impact Assessment Contents Page 1 Introduction 1 2 Methodology 2 2.1 Introduction 2 2.2 Assessment Methodology 2 2.3 Sound reduction values 2 2.4 Monitoring methodology 3 3 Baseline Environment 6 3.1 Introduction 6 3.2 Attended 6 3.3 Unattended 7 3.4 Adjusted monitoring data 8 4 Impact Assessment 8 4.1 Introduction 8 4.2 Glazing type 1 – 4mm/12mm/4mm 9 4.3 Glazing type 2 – 6mm/12mm/6mm 9 4.4 Glazing type 3 – 10mm/12mm/6mm 10 4.5 Glazing type 4 – 10mm/12mm/6mm 11 5 Conclusions and Recommendations 11 6 References 12 Report Ref | Issue 1 | 6 November 2017 | Arup \\GLOBAL\EUROPE\DUBLIN\JOBS\254000\254226-00\4. INTERNAL\4-03 DESIGN\4-03-02 CONSULTING\NOISE\BLAKES NOISE\BLAKES INWARD NOISE ASSESSMENT REPORT ISSUE 2.DOCX Cairn Homes Properties Ltd. Blake’s Noise Impact Assessment Executive Summary Cairn Homes Properties Ltd. intends to apply for planning permission for development of student accommodation and residential buildings at the Blake’s site, Stillorgan, Co. Dublin. A noise impact assessment has been undertaken in order to predict the glazing type requirements for compliance with relevant internal noise limits. Baseline noise surveys were undertaken at five locations at the site boundary over daytime and night-time in order to capture the noise levels on site. Measured noise levels were dominated by traffic noise. Predictions of internal noise levels were made based on the sound reduction values from various types of glazing (all double paned). These levels are compared to internal noise limits, to ensure compliance. The assessment has demonstrated that the desired intrusive noise levels can be achieved using a standard double glazing unit such as Glazing Type 2. As the detailed design progresses and final glazing selections become available, they will be reviewed to ensure that they provide an equivalent (or better) level of performance. This is expected to provide sufficient sound reductions to achieve good compliance with the internal noise design levels. It is proposed to provide a standby generator at the location of the ESB substation to the south of the site. The generator is standby and only operates in the event of power failure and during testing. 1 Introduction Cairn Homes Properties Ltd. intends to apply for planning permission for development at the Blake’s Site in Stillorgan, Co. Dublin. The site is bound to the north by the Lower Kilmacud Road, to the east by the N11 dual-carriageway, to the west by The Hill Road and to the south by a privately owned residence and garden. The development will consist of the demolition of the existing buildings, associated infrastructure and car parking areas on the site to allow for the construction of student accommodation and residential buildings. Ancillary retail, restaurant/café and public spaces are also proposed. This noise impact assessment has been prepared to form part of the planning application for the Blake`s development. The purpose of this report is to assess the requirements for glazing types along the façades of the proposed development to ensure that internal noise design levels are complied with. This is achieved by undertaking baseline noise monitoring and applying reduction factors at specific frequencies, based on design standards. The predicted internal noise levels are then compared to appropriate standards and compliance is stated. Report Ref | Issue 1 | 6 November 2017 | Arup Page 1 \\GLOBAL\EUROPE\DUBLIN\JOBS\254000\254226-00\4. INTERNAL\4-03 DESIGN\4-03-02 CONSULTING\NOISE\BLAKES NOISE\BLAKES INWARD NOISE ASSESSMENT REPORT ISSUE 2.DOCX Cairn Homes Properties Ltd. Blake’s Noise Impact Assessment The focus of this report is on the noise transfer into the proposed building through windows, with some discussion on vents. These will be the main sources of environmental noise transfer into the building. The assessment also considers the potential impact of the proposed generator on adjoining residential property. 2 Methodology 2.1 Introduction This section outlines the assessment methodology, including the noise design levels, the sound reduction values applied in the impact assessment and the baseline monitoring methodology. 2.2 Assessment Methodology The assessment undertaken predicts the internal noise levels that would be expected in a building based on baseline data with specific glazing reduction factors applied. These factors are based on the type of glazing used i.e. single, double, pane thickness etc. and are taken from BS 6262:2005 Part 2 Glazing for buildings – Code of practice for energy, light and sound outlines sound reduction. The calculated internal values were then compared to design levels for various land uses presented in BS 8223:2014 Guidance on sound insulation and noise reduction for buildings. The assessment considers four scenarios, all double glazed of varying thickness. 2.2.1 Noise design levels BS 8233 specifics noise design levels for each type of property use. Table 1 outlines design level ranges that are applicable to the proposed development. Table 1: Noise design level ranges for varying land uses/activity Primary land use Activity Design level range (dB) LAeq,T Residential Daytime resting (Daytime) 35 Night-time sleeping (Night-time) 30 Education Work requiring concentration 35-40 2.3 Sound reduction values BS 6262:2005 outlines sound reduction values that can be applied to external noise levels in determining internal noise. The reduction values outlined are based on the type of window glazing applied to the building and are a function of the glazing type, thickness and gap spacing. The use of glazing presents a worst case façade for noise reduction with higher reductions being achieved through other facades e.g. blockwork, insulation products. Report Ref | Issue 1 | 6 November 2017 | Arup Page 2 \\GLOBAL\EUROPE\DUBLIN\JOBS\254000\254226-00\4. INTERNAL\4-03 DESIGN\4-03-02 CONSULTING\NOISE\BLAKES NOISE\BLAKES INWARD NOISE ASSESSMENT REPORT ISSUE 2.DOCX Cairn Homes Properties Ltd. Blake’s Noise Impact Assessment Sound reduction values are applied to each third-octave sound pressure level obtained from monitored data. BS 6262 states that “for general building acoustics, the octave frequency bands are 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz”. Therefore, these octave bands have been selected for the application of reduction values. Table 2 presents reduction levels based on the installation of double glazing, in accordance with BS 6262, as double glazing is proposed for the development. Table 2: Double glazing sound reduction levels. Double glazing One third-octave band centre frequency (Hz) resultant sound Glass width / cavity reductions (dB) width / glass width 125Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 4mm/12mm/4mm 21 15 25 36 39 31 6mm/12mm/6mm 23 18 29 39 33 40 10mm/12mm/4mm 24 22 32 37 44 42 10mm/12mm/6mm 25 29 34 39 37 46 2.4 Monitoring methodology 2.4.1 Introduction A baseline noise survey was undertaken on the 8 and 9 of May, 2017 in order to quantify the existing environment. The survey was conducted in general accordance with ISO 1996: Acoustics – Description, measurement and assessment of environmental noise (Part 1 & Part 2) (ISO, 2003 & 2007). Cognisance was also given to the Guidance Document Guidance Note for Noise: Licence Applications, Surveys and Assessments in relation to Scheduled Activities (NG4), (EPA, 2012). This document provides overall guidance on carrying out noise surveys including setting up the noise meter, time periods, and survey lengths. Daytime is defined as 07:00 to 19:00, evening time as 19:00- 23:00 and night time is defined as 23:00 to 07:00. 2.4.2 Survey locations Five monitoring locations (N1-N5) were chosen along the proposed development boundary in order to quantify the baseline noise environment for the site. These locations are representative of the worst case receptors in terms of noise exposure i.e. due to the close proximity to the N11 national road and the R825 link road, or both. Long term (24-hr) monitoring was carried out at the eastern boundary of the proposed development. Long term monitoring was unable to be undertaken along the northern boundary of the proposed development as no suitable safe location Report Ref | Issue 1 | 6 November 2017 | Arup Page 3 \\GLOBAL\EUROPE\DUBLIN\JOBS\254000\254226-00\4. INTERNAL\4-03 DESIGN\4-03-02 CONSULTING\NOISE\BLAKES NOISE\BLAKES INWARD NOISE ASSESSMENT REPORT ISSUE 2.DOCX Cairn Homes Properties Ltd. Blake’s Noise Impact Assessment could be obtained. Short term monitoring was carried out at this location instead and is deemed sufficient for the purposes of this assessment. These five locations are presented in Figure 1. The monitoring location coordinates are presented in Table 4. Table 4: Monitoring Locations Monitoring Long term / Coordinates Location short term Easting Northing N1 320269 227999 N2 320322 228018 Short term N3 320352 228029 N4 320322 228017 N5 Long term 320380 227987 Figure 1: Noise monitoring locations © BingMaps2017 2.4.3 Instrumentation A Brüel & Kjær 2250 Light Class 1 Sound Level Meter was utilised to carry out the noise assessment. This meter complies with the International Electrotechnical Commission (IEC) Specification for Sound Level Meters. The noise meter was calibrated before and after each measurement using a Brüel & Kjær 4231 Acoustic Calibrator.