Plant Noise Breakout Assessment

Subject: Plant noise breakout assessment Date: 15 August 2013 Job No: Ref AAc\230750-00\TN01

1 Introduction

Arup has been requested to undertake an assessment of noise breakout from building services plant associated with the proposed conversion of part of the existing Manx Telecom Data Centre in the Isle of Man. This assessment demonstrates that noise breakout to the nearest noise sensitive receivers complies with the planning criteria, as set out below.

2 Planning criteria

Approval of the Reserved Matters planning application Ref 13/00726/REM for conversion and extension of the existing Manx Telecom Data Centre has been granted with the following acoustic condition.

1. Noise levels resulting from the proposed development, once operational, at the surrounding school, office and meeting room shall not exceed $35\mathrm{dBL}_{\mathrm{Aeq,1hr}}$ internally and $45\mathrm{dBL}_{\mathrm{Aeq,1hr}}$ externally and at the nearest residential premises shall not exceed $30\mathrm{dBL}_{\mathrm{Aeq,1hr}}$.
2. Prior to commencement of the works on site in accordance with the approved document, further details of the acoustic surrounding must be approved by the Planning Authority and thereafter the surrounds erected in accordance with these details.

Figure 1 shows the location of the proposed site with the noise receivers mentioned in the planning condition identified. Figure 1: Data centre site and nearest noise sensitive receivers

3 Plant noise assessment

Plant Item	Lw/Lp	Octave Band Centre Frequency, Hz	dB(A)
63	125	250	500	1k	2k	4k	8k
Pop Room DX Condensers	Lp at 1m	51	53	52	49	44	42	40	31	51
Office DX Condenser	Lp at 1m	43	45	47	42	39	33	27	19	44
CRAC unit DX Condenser	Lp at 5m	46	36	42	44	42	37	30	28	45
Dry air coolers	Lw	56	68	71	78	79	76	74	67	83
Circulating Pumps P1/P2	Lp at 1m	66	65	67	65	66	73	58	50	70
Circulating Pumps P3/P4	Lp at 1m	71	70	72	70	71	78	63	55	75
Transformers	Lw	-	-	-	-	-	-	-	-	67
Packaged Emergency Generators
Inlet	Lw	89	81	66	50	42	41	49	53	68
Outlet	Lw	88	82	68	48	39	40	48	60	69
Enclosure	Lw	95	92	86	86	79	73	68	45	86

Figure 2 below shows the plant associated with the data centre. Sound power noise levels of each noise source are given in Table 1. Figure 2: Data centre plant locations

Table 1: Plant item noise levels, dB

Two modes of plant operation have been assessed as detailed below;

Normal operation plant

• 2 Pop Room DX Condensers
• Office DX Condenser
• 1 CRAC unit DX Condenser
• 1 Dry Air Cooler
• Circulating Pump P1
• Circulating Pump P3
• 1 Transformer

Emergency operation plant

• As normal operation plus
• 1 Packaged emergency generator

Emergency operation of plant will only occur during instances of total power failure to the site and it is anticipated that this will be a very infrequent occurrence. The emergency generation plant will be tested for 10 minutes each month and this will be scheduled to occur at times of day when the background noise is at its highest thus lessening the effect on nearby noise sensitive receivers.

Local screening has been provided to the noisiest piece of plant equipment that being the dry air coolers as shown in Figure 2. A solid screen 3m high having a surface mass of 12kg/m² will be erected in the location shown providing screening to the school and residential receivers.

The Planning Condition stipulates criteria for both commercial and residential premises and a worst case assessment of noise from the plant at the closest noise sensitive receivers falling into these categories has been undertaken. The closest receivers have been identified as Ballacottier Primary School and Farmhill Meadows. Noise levels at the Restart Unit will be lower than those at the School due to screening afforded by the existing buildings and it is also further distant than the school. The assessment allows for all plant operating at full duty simultaneously for normal operation.

A summary of the assessment results is shown in Table 2. Spreadsheets for each assessment are shown in Figure 3 to 6 at the end of this assessment.

Location	Normal plant operation	Emergency generator mode
Planning criterion (dBA)	Calculated worst case plant noise level, (dBA)	Planning criterion (dBA)	Calculated worst case plant noise level, (dBA)
Ballacottier Primary School	45	39	Not stipulated in the conditions	46
Farmhill Meadows	30	30	Not stipulated in the conditions	38

Table 2: Calculated worst case plant noise to nearby receivers

4 Conclusions

An assessment of noise breakout from plant associated with the external plant compound for the converted data centre has been undertaken. The assessment has been undertaken for the worst case scenario where all plant operates at full duty simultaneously.

The assessment shows that the existing plant selections together with local screening do not exceed the limiting level at the nearest noise sensitive receivers for normal operation plant.

Noise levels during emergency operation of generators have been calculated and presented for consideration but as this occurs very infrequently the anticipated effect to the nearby receivers is deemed to be insignificant.

Figure 3: Assessment of breakout noise to Ballacottier Primary School during normal operation of plant

ARUP Consultants in Acoustics • Vibration • Venues • AudioVisual

15-Aug-13

15-Aug-13

15-Aug-13

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Nature of Work	Length (inm) Volume	Degree (inm) Count
mm	mm/s	31.5	63	125	250	500	1k	2k	4k
Noise level at Ballacottier Primary School from building services plant emergency operation
	20	20	31.5	63	125	250	500	1k	2k	4k	8k
CEAC into DS Condenser B Lp at 3m	Distance to School = 40m		61		46	36	42	44	42	37	30
Distance correction for a point source from 3m to 40m	Ratio of Distances - Point Source	40.0 m	3.0 m		-10	-10	-10	-10	-10	-10	-10
1	Freefield Lp at school		27		27	17	23	27	23	18	11
	Office DS condenser Lp at 1m	Distance to School = 30m		43		40	45	43	41	38	32
	Distance correction for a point source from 1m to 30m	Ratio of Distances - Point Source	30.0 m	1.0 m		-32	-32	-32	-32	-32	-32
2	Freefield Lp at school		13		8	13	21	8	6	9	-5
	Pup power DS condenser 2 and 3 Lp at 1m	Distance to School = 37m		53		50	55	53	34	40	41
	Distance correction for a point source from 1m to 37m	Ratio of Distances - Point Source	37.0 m	1.0 m		-33	-31	-31	-31	-31	-31
	Correction for 2 units					3	3	3	3	3	3
3	Freefield Lp at school		25		22	28	27	28	17	13	9
	Dry air cooler B Lw	Distance to School = 82m		53		54	60	71	78	79	76
	Distance Correction (Hemispherical)		42.0 m	3 m		-40	-40	-40	-40	-40	-40
	Barrier Atom2003W/12.2 Equations; Path Diff.: 0.88 m, Do 1.2 m, He 2.6 m, Do 41 m, He 3.5 m		3.0 m	0.08 m		-3	-6	-6	-7	-9	-11
4	Freefield Lp at school		33		16	12	24	30	26	23	26
	Transformer Lw	Distance to School = 36m		67
	Distance Correction (Hemispherical)		42.0 m	3 m		-40	-40	-40	-40	-40	-40
5	Freefield Lp at school		25
	Chilled Water Pumps P1-P2 Lp at 1m	Distance to School = 51m		70		66	65	67	65	66	73
	Distance correction for a point source from 1m to 51m	Ratio of Distances - Point Source	51.0 m	1.0 m		-34	-34	-34	-34	-34	-34
	Barrier Atom2003W/12.2 Equations; Path Diff.: 1.22 m, Do 2 m, He 0.5 m, Do 44 m, He 3.5 m		3.0 m	1.22 m		-9	-11	-13	-16	-19	-22
6	Freefield Lp at school		23		23	24	20	17	13	17	-3
	Chilled Water Pumps P3-P4 Lp at 1m	Distance to School = 51m		75		71	76	72	76	71	76
	Distance correction for a point source from 1m to 51m	Ratio of Distances - Point Source	51.0 m	1.0 m		-34	-34	-34	-34	-34	-34
	Barrier Atom2003W/12.2 Equations; Path Diff.: 1.22 m, Do 2 m, He 0.5 m, Do 44 m, He 3.5 m		3.0 m	1.22 m		-9	-11	-13	-16	-19	-22
7	Freefield Lp at school		20		18	25	25	20	18	22	4
	Generator Inlet Lw	Distance to School = 43m		68		89	81	66	30	42	41
	Distance Correction (Plano Source) - Point Source Region		45.0 m			-43	-41	-41	-41	-41	-41
	Leaves Directivity Horizontal Angle 90°, Vertical Angle 90°		3.0 m	3.0 m		2	0	-13	-13	-13	-13
8	Freefield Lp at school		27		36	46	13	-4	-13	-13	-6
	Generator Outlet Lw	Distance to School = 46m		69		88	82	60	48	39	40
	Distance Correction (Plano Source) - Point Source Region		46.0 m			-43	-41	-41	-41	-41	-41
	Leaves Directivity Horizontal Angle 90°, Vertical Angle 90°		2.1 m	2.3 m		3	2	-2	-13	-13	-13
9	Freefield Lp at school		29		50	63	24	-6	-15	-13	-6
	Generator Casing Ln.rad	Distance to School = 44m		86		93	92	86	86	79	73
	Distance Correction (Parallelepiped): A.12 m, B.2.5 m, C.5 m		44.0 m			-44	-44	-44	-44	-44	-44
10	Freefield Lp at school		40		33	48	42	42	38	29	23
	Total Resfield Lp at school (logarithmic addition of 1 to 10)		40
	Façade correction (dB)		3
	Noise level outside school		46
Calculation Checking Record
SerialPad Version 4.13.6
Check Type
Check No
Class

Check Type	✓	Check Result	✓
	Initial Date		See Comments
Date		Intervention		Revision Required

Figure 4: Assessment of breakout noise to Ballacottier Primary School during emergency operation of plant

Job No. 230750-00

Date 2013

Date 15-Aug-13

Date 15-Aug-13

15-Aug-13

Plant noise breakout assessment

15 August 2013

AAc\230750-00\TN01 Figure 5: Assessment of breakout noise to Farmhill Meadows during normal operation of plant

Name	Length (mm/Volume)	Degree Band Counts	Sequence
dB	dB(A)	31.5	63	125	250	500	1k	2k	4k	8k
1	CRAC unit DX Condenser B Lp at 3m	Distance to Farmhill Meadows = 118m	41	46	36	42	44
Distance correction for a point source from 1m to 118m	Ratio of Distances - Point Source	118.0 m	-27	-27	-27	-27
2	Freehold Lp at Farmhill Meadows	18	18	8	14	16	14
Office DX condenser Lp at 1m	Distance to Farmhill Meadows = 116m	41	40	43	43	41
3	Distance correction for a point source from 1m to 116m	Ratio of Distances - Point Source	116.0 m	-41	-41	-41	-41
Freehold Lp at Farmhill Meadows	4	4	4	2	8	4
4	Pop exam DX condensers 2 and 3 Lp at 1m	Distance to Farmhill Meadows = 112m	53	50	55	53	54
Distance correction for a point source from 1m to 112m	Ratio of Distances - Point Source	112.0 m	-41	-41	-41	-41
Correction for 2 units	112.0 m	1.0 m	3	3	3	3
Freehold Lp at Farmhill Meadows	15	15	17	18	18	7
5	Dry air outlet B Ln	Distance to Farmhill Meadows = 117m	83	56	68	73	78
Distance Correction (Homospherical)	117.0 m	3	-49	-49	-49	-49
Barrier Ation(50/99/13.2 Equation), Path Diff: 0.07 m, Dx:1.2 m, Hs:2.6 m, Dr:116 m, Ht:1.5 m	3.0 m	0.07 m	-5	-5	-6	-7
6	Freehold Lp at Farmhill Meadows	18	3	13	18	22	21
Transformer Ln	Distance to Farmhill Meadows = 107m	67
7	Distance Correction (Homospherical)	107.0 m	3	-49	-49	-49	-49
Freehold Lp at Farmhill Meadows	14	14
Freehold Water Pumps P1/P2 Lp at 1m	Distance to Farmhill Meadows = 123m	70	66	65	67	65
8	Distance correction for a point source from 1m to 123m	Ratio of Distances - Point Source	123.0 m	-42	-42	-42	-42
Barrier Ation(50/99/13.2 Equation), Path Diff: 1.21 m, Dx:2 m, Hs:0.5 m, Dr:114 m, Ht:1.5 m	3.0 m	1.21 m	-9	-11	-13	-16
Freehold Lp at Farmhill Meadows	11	11	16	13	12	7
9	Cocktail Water Pumps P5/P4 Lp at 1m	Distance to Farmhill Meadows = 123m	71	71	70	73	70
Distance correction for a point source from 1m to 123m	Ratio of Distances - Point Source	123.0 m	-42	-42	-42	-42
Barrier Ation(50/99/13.2 Equation), Path Diff: 1.21 m, Dx:2 m, Hs:0.5 m, Dr:114 m, Ht:1.5 m	3.0 m	1.21 m	-9	-11	-13	-16
Freehold Lp at Farmhill Meadows	19	19	21	19	17	12
10	Total firefield Lp at Farmhill Meadows (logarithmic addition of 1 to 7)	27
Facade correction (dB)	3
Noise level outside Farmhill Meadows	76
Planning criterion	10	Therefore the plant noise level complies with the planning condition
Calculation Checking Record	Check Type	Check Result	✓
Small Check		OK
Check No	Green Zone	Yes Comments
Date	Intermediate	Revision Required

Figure 6: Assessment of breakout noise to Farmhill Meadows during emergency operation of plant

ARUP Consultants in Acoustics • Vibration • Versace • AudioVisual
Job No. 230750-00
Date: 15-Aug-13
Date: 15-Aug-13
No. Manx Telecom Ltd
Length: 15-30
Noise level at Farmhill Meadows from building services plant emergency operation
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