sustainable workplace in practice c f leung senior manager building & energy efficiency and...
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Sustainable Workplace in PracticeC F Leung
Senior Manager
Building & Energy Efficiency and Indoor Air QualityBusiness Environment Council
4 August 2011
Essentials of a healthy workplace
Indoor Environmental Quality
Presentation Overview
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• On average, adults spend more than 90% of time indoors.
• Better IEQ protect our health, contribute to our comfort, improve productivity, increase profitability and value of the property, and attract and retain more tenants.
• Poor IEQ may lead to discomfort and illness, more sick leave and higher absenteeism, weaken our competitiveness.
Essentials of a Healthy Workplace
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• Acute health and comfort effects that appear to be linked to time spent in a building;
• No specific illness or cause can be identified.
• In a particular room or zone, or may be widespread throughout the building.
What is Sick Building Syndrome (SBS)?
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• Headache; dry / itchy skin; cough; dizziness and nausea; fatigue.
• No clinically defined disease or specific chemical or biological contaminant
• Relief soon after leaving the building.
SBS Indicators:
Sick Buildings
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Contributing Factors of SBS:
Chemical contaminants from outdoor sources:Vehicle exhausts, building exhausts, etc.
Chemical contaminants from indoor sources:
Adhesives, upholstery, carpeting, copy machines, manufactured wood products, cleaning agents, pesticides, VOCs,tobacco smoke and combustion products,etc.
Biological contaminants: Pollen, bacteria, viruses and molds, etc.
Inadequate ventilation:Inadequate in design stage, shut down of ventilation facilities etc.
Sick Buildings
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What is BRI?
Symptoms of diagnosable illness are identified and can be attributed directly to airborne building contaminants such as :
Legionnaire Disease, and
Humidifier Fever, etc.
Building Related Illness (BRI)
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Legionnaire Disease:
The first known outbreak was in Philadelphia of USA in 1976. A total of 221 people contacted the disease and 34 died (15.4%).
Building Related Illness (BRI)
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The bacteria reproduce to high numbers in warm, stagnant water (32 °C – 40.5 °C):
Plumbing systems;
Water tanks;
Cooling towers;
Evaporative condensers; and
Whirlpool spas.
Sources of aerosols with Legionella bacteria:
Building Related Illness (BRI)
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Humidifier Fever:
Uncertain etiology.
Exposure to amoebae, bacteria, and fungi found in humidifier reserviors, air conditioners, and aquaria.
Symptoms:
Flu-like illness with symptoms:
Hypersensitivity pneumonitis and marked fever, headache, chills, myalgia, and malaise but without prominent pulmonary symptoms.
Subsides within 24 hours without residual effects.
Building Related Illness (BRI)
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Indoor Air Quality
Thermal Comfort & Ventilation
Lighting
Noise & Acoustics
Indoor Environmental Quality
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• Distinguish between discomfort vs health hazard
Discomfort (examples) Health Hazard
Thermal Warm / cool sensation Heat stress, Cold stress
IAQ Odour Inhalation of toxic gases
Visual Glare, Eye strains Retina damages due to blue-light hazard: Excessive illumination with blue light or UV radiation
Aural Noise annoyance Hearing damages
Normally, IEQ problem in built environment would not lead to hazardous level, although sick symptoms may be reported.
Discomfort Vs Health Hazard
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• Carbon Monoxide (CO)• Oxides of Nitrogen (NOX)
• Respirable Suspended Particulate (RSP)
• Volatile organic compounds (VOCs)• Carbon dioxide (CO2)• Biological contaminants• Radon (Rn) • Formaldehyde (HCHO)• Ozone (O3)• Environmental tobacco smoke
Indoor Air Quality
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Carbon Monoxide (CO) from vehicle exhaust at road surface & car parks
Oxides of Nitrogen (NOX) from vehicle exhaustions & incomplete combustion in industry
Respirable Suspended Particulate (RSP) from vehicular exhaust, construction activities, power plants etc.
Outdoor Sources for Indoor Air Pollutants
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• Carbon dioxide (CO2) and biological contaminants from people, pets & plants
• Radon (Rn) from building materials
• Volatile organic compounds (VOCs) from consumer products such as cosmetics, pesticide, cleaning agent, etc.
• Formaldehyde (HCHO) from pressed wood products such as MDF furnitures
• Ozone (O3) from printing machines
• Environmental tobacco smoke from smoking
Indoor Sources for Indoor Air Pollutants
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• Effective filtration systems• Avoidance of short circuiting• Accessible HVAC ducts • Control air pollutant generation at
source eg. water based paints for VOCs & materials finishes for Radon
• Fresh air to dilute pollutants as last resort (energy inefficient) & could be linked to air pollutant sensors
• Regular monitoring
IAQ Management
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1997 – consultancy study to characterize & quantify IAQ in offices (40) and public places (33) in Hong Kong
70’s – study to prevent occupational diseases at workplace for persons with long exposure.
Aug 2003 – IAQ Management Programme for Offices & Public Places with 2 level objectives (IAQ-O) :
– (Excellent class) : standard for high-class and comfortable buildings
– (Good class): provide protection for all population
IAQ Development
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IAQ Certification Scheme
Source: http://www.iaq.gov.hk/images/IAQ_Cert_excellent.jpg Source: http://www.iaq.gov.hk/images/IAQ_Cert_Good.jpg
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Indoor Air Pollutants Unit Excellent Good
CO2 ppm <800 <1000
CO µg/m3 <2000 <10000
RSP µg/m3 <20 <180
NO2 µg/m3 <40 <150
O3 µg/m3 <50 <120
Formaldehyde µg/m3 <30 <100
TVOC µg/m3 <200 <600
Radon Bq/m3 <150 <200
Air-borne Bacteria cfu/m3 <500 <1000
Room Temperature ºC 20 – 25.5 <25.5
Humidity % 40 – 70 <70
Air Movement m/s <0.2 <0.3
IAQ Objectives
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IAQ Certificate Issuing Body
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Thermal comfort depends on Physical & (personal) factors :
• Air temperature Summer : 23 °C and 26 °C Winter : 20 °C to 24 °C
• Relative humidity (RH) Indoor RH between 40% to 70% High RH prevents growth of micro-
organisms
• Air Speed and Distribution Air speed between 0.1 to 0.25 m/s. Dir distribution depends on design –
allocation of diffuser location & type of diffusers.
Thermal Comfort
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Efficient ventilation & proper maintenance of ventilation systems :
• provide a comfortable environment • avoid various invisible health hazards in buildings.
Functions of ventilation :
• Supply fresh air
• Remove airborne contaminants
• Maintain temperature and humidity
Ventilation
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• Natural and mechanical ventilations
• Different building types adopt different ventilation rate and air change
• Provision of adequate fresh air to meet stipulated requirement
• Fresh air intake locations away from exhaust & pollutant points
• Exhaust points at high level and not directed to neighbouring buildings.
• Independent exhaust for pollutant generating areas
Ventilation Considerations
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• Visibility
• Security
• Social & Communication
Individual Well-being
• Mood & Comfort
• Health & Safety
• Aesthetic judgment.
Architecture• Forms
• Composition
• Style
• Codes & Standards
Economics• Installations
• Maintenance
• Operation
• Energy
Interior Lighting
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Light Output Levels (Lux level)
e.g. 500 lux for Office
Light Output Quality
Colour Rendering Index (Ra > 80)
Glare Index (GI < 19)
Lighting Performance
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• Eyestrain
• eye irritation
• blurred vision
• dry burning eye
• headaches
Adverse Effects of Poor Lighting
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Utilize Natural Daylight
Combine natural and artificial lighting with photo-sensor and dimmer to improve lighting at workplace;
Optimum and Energy Efficient
Keep optimum illuminance, e.g. 200 lux for general offices and 300 to 500 lux for normal desktop; and
Use of T5 fluorescent or LED tubes
Management of Lighting at Work
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Avoid Poor Contrast
Reposition, avoiding use of polished surfaces and reducing the contrast between work station and surrounding
Avoid Shadow Effect
Change light source’s direction to avoid shadowing effect
Tackle Poor Lighting Arrangement
Relocation of light sources to provide comfortable and uniform illumination and suits actual office layout
Management of Lighting at Work
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Control Light flicker
Set up lamp replacement schedule and remove cause of flicker;
Adoption of high frequency electronic ballast to reduce flickering; and
Avoid Discomfort Glare
Reposition of workstation to prevent too bright light sources.
Management of Lighting at Work
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• Healthy light • Renewable energy source• Reduces air pollution - use less fossil fuels• Fixed electricity cost at daytime• Less maintenance and chemical waste disposal• Increases comfort – less eyestrain and glare • Improves visual acuity • Reduces lighting heat gain
Benefits of Natural Day Lighting
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• Unwanted/Annoying Sound• Annoyance depends on loudness, quality of sound &
personal attitudes• More annoying at night - sleep interference• Measured in dB / dB(A)• Sound pressures vary from 20µPa (threshold of
hearing) to 100 Pa (threshold of pain)
What is Noise?
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Physiological Effects• Short Term - muscular response, etc. • Long Term - heart attack.
Hearing Impairment (Nerve cell damage)• Temporary threshold shift • Permanent threshold shift
Noise – Effects on Humans
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• Threshold of hearing at 0 dB
• SPL of domestic environments below 60 dB
• Construction equipment eg. pneumatic chippers can generate 100 dB
• Jet Engine at 25 m emits 140 dB, threshold of pain
Typical SPLs in the Audible Range
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Building Services Systems :
• Chillers
• Extraction Fans
• Air Handling Units
• Fan Coil Units (FCU) / Variable Air Volume Units (VAV)
• Vertical Transportation systems (lift motors, etc)
Indoor Noise Pollution Sources – Commercial Building
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Could be based on maximum intrusive level for building design – British Standard :
• Below 45 Leq, dB(A) for privates offices and conference rooms
• Below 50 Leq, dB(A) for open plan offices
Acceptable Indoor Noise Levels for Office
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• Time for the sound to decay 60 dB below its original level.
• RT in a room determined from surface area & absorption coefficient of materials
• RT for office = 0.6s or below• RT shorter for lecture room & longer for
theater
Reverberation Time (RT)
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Noise Mitigation Measures – Sitting of Noisy Equipment
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• Spring isolator (vibration)
• Flexible connector (vibration)
• Silencer (~20 dB) (sound absorption)
• Acoustic Enclosure (~ 20 dB)
Noise Mitigation Measures for Noisy Equipment
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• Acoustic wall panel (~ 20 dB)
• Floating floor (~ 30 dB)
• Isolation ceiling (~ 20 dB)
Noise Mitigation Measures
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Seal up any gaps around doors, window and partition walls
An office environment (Cross talk noise)
Suspendedceiling
Wall
a good (bad) sound path is present above aperforated false ceiling => reduction ininsulation of the wall of 10 dB or more.
Noise Mitigation Measures for Office
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• Porous Finishing Material on Wall or Ceiling
• Acoustic Door
• Cross Talk Silencer
• Furniture, Carpet
Noise Mitigation Measures for Office (RT)
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