Ventilation

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Contents

IntroductionMechanical VentilationNatural VentilationGround Coupled Heat ExchangersFrench Regulations

INTRODUCTION

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Importance

Assures quality of air:Removes pollutants, excess moisture

Adds fresh air

Effects of moisture:Degrades material

Leads to mould…

…which can irritate asthma, allergies…

Or leads to dust mites

Can improve comfort: air is precooled / preheated

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Source: www.dampserve.com

Source: Wheat 2010

Condensation due to single glazing, can be removed by ventilation

Pollutants (1)

Indoor air 10x more polluted (Haut 2011)

Moisture due to cooking, showering, washing machine, breathing…People: Smoking and breathing Gases emitted from

Building elements, materials (slow release)

Cleaning products, candles, insecticides, cosmetics, toiletries, perfumes…(rapid release)

Animals 5Sources: www.searsoutlet.com, enchanteur.com.my, Gaynor 2014, http://greenplanetethics.com explosionhub.com,

Pollutants (2)

Radon Natural radioactive substance

Enters buildings, can cause lung cancer over a long period of time

Volatile organic compounds

Can evaporate at ambient temp.

Eg formaldehyde…

Products have eco labels ...

Paints, shampoo, clothes… 6

EUEcolabel The

Blue Angel

French VOC labelling

Infiltration

NOT THE SAME as ventilationUncontrolled air leak(s)In the past, partly would have refreshed airAs buildings are more airtight, real focus on ventilation

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Air leaking into houseAir leaking out

Plumbing stack vent

Bathroom vent

Electrical outlet

Dryer vent Dryer

vent

Kitchen fan

Recessed lights

Attic hatch

Source: www.gabuilderenergyservices.com

Ventilation characteristics

Described by: Ventilation rate: amount of air provided

Airflow direction: overall direction in a building

Air distribution/ airflow pattern: parts of space air enters and leaves

8Airflow distributionSources from top: Zhao 2007, Mentor Graphics 2009

Airflow rate: contourDirection: arrows

Air Characteristics

Air moves from high pressure to low pressureComposition of atmosphere:

Not exhaustive list

Do not confuse: inhaled

and exhaled air.

Exhaled: 16% Oxygen,

4% Carbon Dioxide9

High pressure

Low pressure

Nitrogen; 78%

Oxygen; 21%

Argon; 1% Carbon Dioxide; 0%

Composition of atmosphere

Exercise:

Please link the names and descriptions

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Name Description

COV Controlled air flow

Infiltration Harmful compounds released into the air at an ambient room temperature

Ventilation Has 21% Oxygen

Exhaled air Has 4 % Carbon Dioxide

Inhaled air Uncontrolled air flow

Exercise:

Please link the names and descriptions

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Name Answer

COV Controlled air flow

Infiltration Harmful compounds released into the air at an ambient room temperature

ventilation Has 21% Oxygen

Exhaled air Has 4 % Carbon Dioxide

Inhaled air Uncontrolled air flow

Types of ventilation

MechanicalBased on fans

Rooms positively or negatively charged

Inlets primary rooms (living room)

Extractors in bathrooms and kitchens

NaturalUses difference in pressure/temperature for airflow

Relies on location: prevailing wind, climate…

Mixed mode (Hybrid)Adds fans to natural ventilation

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Source: www.brookvent.co.uk

Natural ventilation based on wind

Mechanical ventilation - pro’s and cons

ReliableCan use filtersCan choose airflow path

Hospital: infected air drawn away

May not work: equipment failure, utilities interruption, poor maintenance, incorrect managementInstallation and maintenance costsUses fossil fuels? (electricity)

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Pollen filterSource: Zehnder 2014

Natural ventilation - pro’s and con’s

Energy efficientProvides high ventilation rates more economicallyAdditional effect: more daylightCombined with natural coolingMaintenance low, but important (efficiency, pathogens)Variable: climate, wind, temperatureFilters can’t be usedHard to accurately model: occupant closes/opens door 14

Planned performance

Actual performance (closed window)

Mixed mode - pro’s and con’s

Suitable for most weather/ climatesEnergy savingFans can be noisyExpensiveDifficult to design

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Source: Connection 2014

MECHANICAL VENTILATION (MV)

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MV: exhaust only (single flow)

Vents in living room, bedroom etc.: windowsAir extracted in kitchen/bathroom: fanBuilding under negative pressureDoors have to have 1cm gap

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Source: Unelvent 2014

Air travels: dry to humid areaUnregulated, so: heats house in summer, cools in winterCan cause backdrafting in combustion devices

Exhaust only: humidity controlled

Single flow can be also humidity controlledUseful: varies flow on occupationTwo types in France:

Hygro A: extract air humidity regulated

Hygro B: extract and supply air humidity regulated

Hygro B more efficientBoxes, vents and ducts identical for two systems: easy to upgrade 18

Entry : humidity controlledSource: degriffelec.com

Entry : unoccupied

Small level of humidity

Minimal speed

Entry : occupiedSource: Econology 2008

High level of humidity

Elevated speed

MV: Supply only

Some countries, air only pumped inLeaves through gaps or ventsBetter control of flow than exhaust onlyGood in hot countriesCan cause moisture problems in cold climates: humid air infiltrates building elements

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Source: Energy.gov 2012

MV: Double flow (1)

Inlet and extract ductsPressure is balanced OR positivePositive stops outside air infiltrating in humid countriesCan have open fires inside Heat recovery systemNoisy:

Fan silencers

Install fans on structural walls

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Source: Unelvent 2014

Outlet connection

Continuously welded casing

Inlet connection

Flow optimised tailsAcoustic baffles

Aerodynamic inlet

Source: dB Noise Reduction Inc. 2014

MV: Double flow (2)

System should be inside heated volume. If outside

reduction in efficiency

causes condensation

INSULATE WELL

Important: airtightness and correct installationMaintenance (cleaning filters, studies confirm often incorrect performance…)Filters for higher air quality

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Source: Firestone 2011

Heat recovery system

Up to 95% efficientThermal loss reducedSmall electricity demandHigher acoustic comfortBypassed in summer: fresh air

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Exterior Interior

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Warm stale air

Cold fresh air

Heat recovery unit

Cold stale air

Warm fresh air

Good for extreme climatesCan be combined with a ground source heat exchanger

Cost of ‘hygro B vs double flow ’

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Graphic compares primary energy consumption; for heating and fansTwo climatic regions: Nancy (N), Nice (S)Heating use is always smaller for heat exchanger

Nice: Cost effective to use extract onlyNancy: Heat exchanger is better

Double flow

Double flow

Mechanical ventilation energy consumption

Fan use Fresh air heating energy use

Source: Effinergie

Hygro B

Hygro B

Heat Recovery

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LG Vent Axia

Casto

Stiebel EltronNather

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Ventilation pipes

Pipes

Dampers and measuring units

Roof hoods

Others…Efficient closing on standstill fan

Bend with cleaning access

Exhaust vent

Flow meter

Fire damper

Roof hood

Source: http://www.lindab.com

Exercise: Ventilation systems

Why is an exhaust only ventilation system negatively pressurised?

Why is a double flow ventilation system either balanced or slightly positively pressurised?

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Exercise: Ventilation systems ANSWER

Why is an exhaust only ventilation system negatively pressurised?

Air travels from an area of high pressure to an area of low pressure. The fan creates negative pressure, forcing air to be sucked into the building.

Why is a double flow ventilation system either balanced or slightly positively pressurised?

It is positive as air is being pumped in, so pressurises building.

If supply and exhaust fans are of equal capacity, pressure is balanced.

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Maintenance of ventilation systems

Ventilation systems lose efficiency, become noisyClean system every 5 yearsHire companies. Use:

Negative airflow: vacuum cleaner

2500-5000 cubic feet per minute speed.

Home vacuum cleaner: 100-150 CFM

Some use truck

Change filters yourself 1-3 times a year

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Source: http://www.absolutecleanstl.com

Specific advice (Ademe guide)

Air dampers: once a yearExtract vents with electric closing mechanism: wipe with damp clothInverter: dust. Life: 3-5 yearsOccupancy sensor: wipe lense with soft clothMore info: « Guide pratique sur la modulation des débits de ventilation dans le tertiaire »

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Sources: http://formation.xpair.com/voirCours/grilles_registres_caissons.htm,

Maintenance (2)

All parts need a clean: Air vents

Filters

Inlet and outlet

Furnace

Fan

Bactericide, Biocide, fungicide…debatable

More info: http://legitimedepense.telequebec.tv/occurrence.aspx?id=412

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Source: TCEM 2014

NATURAL VENTILATION

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Natural Ventilation (NV)

Stack effect: hot air risesCross ventilation: wind driven ventilationGlazed openable surfaces also support heating/cooling

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Misato-Matchi, Japan. Source: Top: Winchip 2011, Bottom: Institute for Building Environment and Energy Conservation 2008.

Wind tower/wind catcher (1)

Wind gets drawn in: Persian architecture, Arabic architecture…

33Source: DPChallenge 2014

Wind tower/wind catcher (2)

Wind tower in Cairo (left), multidirectional in Bahrain (right)

34Source: Elgendy 2014

Wind Cowl

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Sources: Autodesk 2011, BDa ZEDfactory

Images: BedZed developmentInlet and outlet connected to heat exchanger. Wind drives system instead of fan.

Higher speed = lower pressure. Air goes from high pressure to low pressureSo…cowl aides air being pulled out of building

Cooling tower

Air travels opposite way to wind towerHot air drawn in, cooledOnce warms up, exitsUsed to use wet sheets to cool. Design uses damp pads

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Cooling tower in Utah. Source: Lawrence 2011

Wind rooftop turbine

Uses windPulls air out of atticRemoves moisture, important in winter when roof elements are cold (condensation, frost, mould…)Check sufficient quantity of air entering building

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Source: http://aaaefficiency.com

Venturi ventilation

Easy to install Uses wind and hot air rising

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Venturi ventilation installation (1)

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Remove cap shingles

Cut slot

Centre vent on roof

Source: Air Vent Inc.

Venturi Ventilation installation (2)

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Nail first section

Cut final section to right length

Nail cap shingles in placeMore details: www.airvent.com/pdf/installation/VenturiVentPlus-install.pdfSource: Air Vent Inc.

Design Techniques

Rules of thumbE.g. Cross ventilation

Occupants near window shouldn’t feel discomfort

Air will pick up pollutants as it travels

Room length < 5 x floor-ceiling height

Accurate simulation hard, depends on wind speed and directionCan use Computer Fluid Dynamics (CFD) 41

Masdar Headquarters, Abu DhabiSource: Elgendy 2010

CASE STUDIES

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Inland Revenue, Nottingham, UK

Shallow plans for cross ventilation and daylightStack ventilation Exposing thermal MassLower floors: naturally ventilatedTop floor: lightweight, roof ventsWindows:

Triple glazed

Blinds, Light shelves and louvres

NV assisted with fans, can be preheated in winter

43Source: Bottom: Fine Art America 2014

Inland Revenue, Nottingham, UK (2)

44Source: Santamouris 2013

Jean Marie Tijbaou, New Caledonia

Cultural centreHot, humid climateOptimised for NVLocated on hilltopFacing south prevailing windFew trees south, lots in east and west to funnel windNear water, coolsWind from sea has to rise, cools further 45

Source: Piano 2014

Cultural centre Jean Marie Tijbaou

46Source: Piano 2014

Namba Parks, Japan

Old stadiumReintroducing greeneryNaturally ventilatedShopping centre with many facades exposed to the elementsGardens: trees, waterfalls, rocks, vegetable patch…

47Source: Yoneda 2014

Embrace House, Solar Decathlon project

Designed by Danish studentsFront glazing opens for natural ventilationNatural daylight

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Source: Grozdanic 2014

Mali’s Falatow Jigiyaso Orphanage, Africa

OrphanageVents in each building form part of NV strategy

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PV, waste water treatment, solar gain, thermal mass…

Exercise:

True or false?

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Statement Answer

Stack ventilation can only be used for rooms facing the prevailing wind

Natural ventilation supports designs which use natural daylight

Natural ventilation cannot be used in cities due to noise pollution.

Exercise:

True or false?

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Statement Answer

Stack ventilation can only be used for rooms facing the prevailing wind

False. It relies on hot air rising, usually in a tower above the main part of the building.

Natural ventilation supports designs which use natural daylight

True. For example: large glazed facades can have parts which open. Can’t do with heavyweight material.

Natural ventilation cannot be used in cities due to noise pollution.

False. Although the design will heavily be influenced by this fact, there are many dampers/measures which can be used which enable at least partly to use natural ventilation

GROUND COUPLED HEAT EXCHANGER

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Ground coupled heat exchanger

Uses ground temperature (1.5m below surface)In summer, cools airIn winter, warms airAir used directly for ventilationAir blown into building in pipes

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Pipes 2m underground, 2% slope, 50m long

20/22º

24/26º

Air inlet35ºC

Condensation

By-pass

Compressor

Mechanical ventilation

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Components

Air entryFilter,

1m above ground

Stainless steel

PipesDiameter: 160-250mm

Air must circulate at least 20s

Airtightness important (water, bacteria)

Smooth walls

Rigid, polypropylene for heat transfer

Source: Magdelaine 2014

Pipe layouts (1)

Several different pipe layouts

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Building wall Building wall

Air inlet

50m pipe

Condensing unit

Air inlet

2x 25m pipe

« Y » section joining 2 pipes

Condensing unit

Pipe layouts (2)

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Building wall

Air inlet

Condensing unit

« Y » section joining 2 pipes

0.8m

Building wall

0.8m

2%

Condensing unit Air inlet

Distribution pipe

Radon

Radioactive: starts as uranium 238, then decomposes ->gasFound in all soils Dangerous if breathed inCan’t be removed from lungs, continues to decompose thereAfter smoking, 2nd cause of cancerAirtightness of ventilation important

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Average radon concentration in households per department (Bq/m3)Source: IRSN 2013

January 2000

Legionnaires Disease

Thrives in 25-43ºC. Damages lungsExchanger insulated from ground waterReason important to remove condensationCondensation happens at dew point temperatureThis is influenced by temperature and relative humidity

58Sources from top: Gaur 2012, BIMC Hospotal 2014

FRENCH REGULATIONS

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Acoustic Regulations

Residential noise limit: “Arrêté du 30/06/1999 relatif aux caractéristiques acoustiques des bâtiments d’habitation”

Ventilation system < 30dB in main rooms,

<35dB in kitchen

60Source: http://langlopress.net/homeeducation/resources/science/content/support/illustrations/Decibel%20Range/Decibel%20Range%20Chart.jpg

Acoustic regulations (2)

Type of building Continuous function

Intermittent function

Library, data centre, medical centres, restrooms

33dB 38dB

Teaching premises, music rooms, ateliers, administrations, dining areas, multipurpose rooms

38dB 43dB

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« Arrêté du 25 avril 2003 » relative to limiting noise in pedagogical environements

French thermal regulations

RT2012Bbio: double flow ventilation system with 50 % heat recovery

Cmax : 50 kWhep / m2 .an, includes primary energy

Air flow minimum per room type

Airflow at extract and inlet units (“article 64.1 de règlement sanitaire départemental type”)

RT2020: energy positive buildings62

Minimum airflow

ARRÊTÉS - 24 MARS 1982 - 28 OCTOBRE 1983General extract airflow:

If humidity regulator is included:

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Number of habitable rooms

1 2 3 4 5 6 7

Minimal total airflow (m3/h) 35 60 75 90 105 120 135

Minimal total airflow in kitchen (m3/h)

20 30 45 45 45 45 45

Number of habitable rooms

1 2 3 4 5 6 7

Minimal airspeed (m3/h) 10 10 15 20 25 30 35

Examples of extract airflow

Number of main rooms

Kitchen (m3/h)

Bathroom (m3/h)

1 75 15

2 90 15

3 105 30

4 120 30

5 + 135 30

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General notes

RT2012 bans natural ventilation for collective housingMechanical system = choice otherwiseOpening windows is acceptable ventilation Energy use of ventilators is limited

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Exercise: Regulations

True or false?

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Statement Answer

French regulations mandate mechanical ventilation

There exists limits for the total airflow of a building

Having humidity controlled ventilation enables lower ventilation rates

Natural ventilation cannot be used for hospitals

Exercise: Regulations

True or false?

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Statement Answer

French regulations mandate mechanical ventilation

False

There exists limits for the total airflow of a building

True

Having humidity controlled ventilation enables lower ventilation rates

True

Natural ventilation cannot be used for hospitals

False. It cannot be used for collective housing.

Bibliography (1)

Wheat, S. 2010http://www.theecologist.org/green_green_living/home/685646/turning_our_victorian_terrace_into_an_ecohome_part_six_ventilation.html

Gaynor, K. 2014. http://blog.kerrygaynormethod.com/3-of-the-most-common-excuses-for-smoking-debunked/

Zhao, Y. 2007. http://www.paladinoandco.com/thought-leadership/comparison-of-measured-airflow-rates-at-selected-locations-in-a-naturally-ventilated-full-scale-building-with-simulated-results-from-computational-fluid-dynamics/

Mentor Graphics 2009. http://hpac.com/archive/cfd-aids-school-districts-utilization-thermal-displacement-ventilation

Zehnder 2014. http://www.archiexpo.com/prod/zehnder/heat-recovery-controlled-mechanical-ventilation-60528-649562.html

Connection Online 2014. http://www.build.com.au/mixed-mode-hybrid-ventilation

Haut, P. de. 2011. Chauffage, isolation et ventilation écologiques. Eyrolles: Paris.Unelvent 2014.

http://www.unelvent.com/vmc-simple-flux-hygroreglable.html Econology 2008.

http://www.econology.fr/blog/2013/06/26/vmc-simple-flux-hygro-entrees-air-bouches-hygro/dB Noise Reduction Inc. 2014. www.dbnoisereduction.com/technical_data_and_specifications/tds01_rectangular_silencers.php?p=vns Firestone 2011.http://greencomplianceplus.markenglisharchitects.com/technical/ventilation/new-ventilation-systems-todays-airtight-homes/

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Bibliography (2)

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Energy.gov 2012 http://energy.gov/energysaver/articles/whole-house-ventilation

Institute for Building Environment and Energy Conservation 2008.http://www.ibec.or.jp/jsbd/L/index.htm

DPChallenge 2014. http://www.dpchallenge.com/image.php?IMAGE_ID=673696

Elgendy, K. 2014http://www.carboun.com/sustainable-design/a-california-building-revives-traditional-middle-eastern-designs/

Autodesk 2011http://sustainabilityworkshop.autodesk.com/buildings/stack-ventilation-and-bernoullis-principle

BDa ZEDfactory www.zedfactory.com/loadreduction.pdf

Lawrence, R. G. 2011. http://www.motherearthnews.com/green-homes/student-built-earth-block-home-brings-natural-cooling-to-navajo-reservation.aspx#axzz38wCgR03j Elgendy 2012

http://www.carboun.com/sustainable-design/masdar-headquarters-the-first-positive-energy-building-in-the-middle-east/

Fine Art America 2014http://fineartamerica.com/featured/nottingham--inland-revenue-building-yhun-suarez.html Santamouris, M. 2013. Environmental Design of Urban Buildings: An Integrated Approach. Earthscan: London

Bibliography (3)

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Magdelaine, P. 2014. http://www.notre-planete.info/ecologie/habitat/puits_canadien.php

Piano, R. 2014http://pzarch14.wordpress.com/2012/11/15/jean-marie-tjibaou-cultural-center-renzo-piano/

Yoneda, Y. 2014http://inhabitat.com/japans-namba-parks-has-an-8-level-roof-garden-with-waterfalls/namba-parks-japan-jerde-partnership-2/

Grozdanic, L. 2014. http://inhabitat.com/danish-students-embrace-house-for-two-boasts-a-super-energy-efficient-double-envelope/

IRSN 2013http://www.irsn.fr/FR/connaissances/Mediatheque/pages/Detail_Mediatheque.aspx?GuidWeb=2c2a9274-9106-41cf-b110-445981d4784e&GuidList=46306625-d53e-464d-9750-4113c34c8065&GuidItem=10&Cible=1&imgId=467a23db-0d7e-484f-8890-da26f97c175e|24

Gaur, D.C. 2012.http://topnews.net.nz/content/222078-legionnaires-disease-taking-its-toll-auckland

BIMC Hospital 2014http://www.bimcbali.com/news-update/legionnaire%E2%80%99s-desease.html

TCEM 2014http://www.tcem.fr/nettoyage-gaines-ventilation-tuyauterie-canalisation-tcem.asp

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