ventilation. contents introduction mechanical ventilation natural ventilation ground coupled heat...
TRANSCRIPT
Ventilation
2
Contents
IntroductionMechanical VentilationNatural VentilationGround Coupled Heat ExchangersFrench Regulations
INTRODUCTION
3
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
4
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
7
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
10
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
11
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
12
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)
13
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
15
Source: Connection 2014
MECHANICAL VENTILATION (MV)
16
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
17
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
19
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
20
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
21
Source: Firestone 2011
Heat recovery system
Up to 95% efficientThermal loss reducedSmall electricity demandHigher acoustic comfortBypassed in summer: fresh air
22
Exterior Interior
22
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 ’
23
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
24
LG Vent Axia
Casto
Stiebel EltronNather
25
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?
26
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.
27
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
28
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 »
29
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
30
Source: TCEM 2014
NATURAL VENTILATION
31
Natural Ventilation (NV)
Stack effect: hot air risesCross ventilation: wind driven ventilationGlazed openable surfaces also support heating/cooling
32
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
35
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
36
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
37
Source: http://aaaefficiency.com
Venturi ventilation
Easy to install Uses wind and hot air rising
38
Venturi ventilation installation (1)
39
Remove cap shingles
Cut slot
Centre vent on roof
Source: Air Vent Inc.
Venturi Ventilation installation (2)
40
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
42
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
48
Source: Grozdanic 2014
Mali’s Falatow Jigiyaso Orphanage, Africa
OrphanageVents in each building form part of NV strategy
49
PV, waste water treatment, solar gain, thermal mass…
Exercise:
True or false?
50
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?
51
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
52
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
53
Pipes 2m underground, 2% slope, 50m long
20/22º
24/26º
Air inlet35ºC
Condensation
By-pass
Compressor
Mechanical ventilation
54
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
55
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)
56
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
57
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
59
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
61
« 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:
63
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
64
General notes
RT2012 bans natural ventilation for collective housingMechanical system = choice otherwiseOpening windows is acceptable ventilation Energy use of ventilators is limited
65
Exercise: Regulations
True or false?
66
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?
67
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/
68
Bibliography (2)
69
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)
70
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
71