Comfortable and Healthy Indoor Climate EEN-E4001

Transcription

1 Comfortable and Healthy Indoor Climate EEN-E4001 Lecture 3: Indoor Air Quality Risto Kosonen Aalto University, Espoo, Finland

2 Presentation outline Factors affecting indoor air quality Indoor air pollutants Meaning of ventilation

3 The Right to Healthy Indoor Air (2000) The World Health Organization (WHO) report states: Indoor air quality is an important determinant of population s health and wellbeing. Exposure to hazardous airborne agents present in many indoor spaces causes adverse effects such as respiratory disease, allergy and irritation of the respiratory tract. That is why our responsibility is to provide healthy indoor environment for occupants.

4 INDOOR AIR QUALITY IAQ = an indicator of the types and amounts of pollutants in the air that might cause discomfort or risk of adverse effects on human or animal health, or damage to vegetation. (ISIAQ) Acceptable IAQ = air in which there are no harmful concentrations of contaminants as determined by cognizant authorities and with which 80% or more the exposed occupants do not express dissatisfaction (ASHRAE) 4

5 Indoor Air Quality Indoor Air Quality (IAQ) is considered to be healthy when the air does not contain contaminants in harmful concentrations and is acceptable when the majority of people feel satisfied. Exposure to hazardous airborne agents present in many indoor spaces causes adverse effects such as respiratory and cardiovascular diseases, allergy, irritation of the respiratory tract and possibly lead to cancer. That is why our responsibility is to provide healthy indoor environment for occupants. We breathe about 12,000 litres of air every day and it is vital for our health to make sure that the air we breathe is clean. Source: ISHRAE 5 Position Paper on IEQ

6 Three different sources of pollutant Biological pollutants Vapors, gas and TVOC Particle matters

7 Air Pollution The Clean Air Act (enacted since 1990) requires The United States Environmental Protection Agency (EPA) to set national ambient air quality standards for criteria pollutants that are: Sulphur dioxide, Ozone, Lead, Carbon monoxide, Nitrogen oxides, Particulate matter. The EPA has listed nearly 200 other hazardous air pollutants including Formaldehyde, Benzene, Toluene, Perchlorethlyene and Methylene Chloride. According the International Agency for Research on Cancer (larc), e.g. Outdoor Air Pollution, Particulate Matter, Asbestos, Benzene, Formaldehyde, Radon and Tobacco Smoke belongs to Group 1 "Carcinogenic to humans substances. More than 200 microbial VOC (MVOC) including alcohols, aldehydes, ketones, terpenes, esters, amines, and aromatic compounds, as well as sulphurcontaining and nitrogen-containing compounds, have been associated with the growth of different fungi. Man-made Vitreous Fibres (MMVF) in indoor air can also be a reason for reduced air quality and health symptoms.

8 Air Pollution and Health Risk Humans have a relatively good immunity against microbiological contamination (infectious or allergenic substances like bacteria, yeast, mould, fungi, virus and pollen or their toxins and by-products). There is no immunity against particulates that we breathe in. Ultra-fine particulates (less than 2.5 µm) travel deep into alveoli and stays there starting to reduce the active surface area of lungs. Larger particles are of less concern, although they irritate eyes, nose & throat. More particulates we breath in, higher is the risk of reduced lung capacity, asthma, cardiovascular disease and cancer. 8

9 Sick Building Syndrome (SBS) Definition - Residents of a building experience acute health problems and / or discomfort clearly associated with time spent on the building, while no specific illness or cause of these results can be determined Users of buildings complain of symptoms such as lethargy, headaches, loss of concentration, runny/stuffy nose, sore throat and eye and skin irritation These symptoms often disappear quickly when users leave the building Factors that determine the appearance of SBS - Ventilation system - Internal contaminants - External contaminants - Biological contaminants 9

10 Symptomatology for Sick Building" Its characteristics are nonspecific symptoms that occur to users of a building and not caused by a specific disease Vary from building to building, depending on the different causal factors that are active in each case Symptoms of eye irritation, respiratory tract, headache and drowsiness are usually present in all cases of the syndrome 10

11 Indoor Air Quality Outdoor air is the most significant indoor air pollution source - if air is not properly filtered and purified before taken indoors; Other indoor air pollution sources are: Tobacco smoking; Copy machines and printers; Cleaning products; Moisture damages and mould growth; Paints, solvents and other construction materials; New furniture; Scents (perfumes, temple sticks, etc.); Other people. 11

12 Airborne Particulate Pollution Airborne particulate matter consists of both solid particles and liquid droplets of different sizes, compositions, and origins. They can range from small molecules less than μm to pollens and spores ranging from 2 to 50 μm, and very large visible dust particles in the range of 100 μm and bigger. 12

13 Global View of PM 2.5 Pollution by NASA 13

14 Loss of Statistical Life Expectancy in the EU in 2000 Source: Impact assesment of the thematic strategy on air polution (PM 2,5) and the directive on ambient air quality and cleaner air for Europe, EN Summary paper, 2005

15 Particulate Pollution has Become More Harmful Residual Oil Fly Ash (ROFA) and Diesel Exhaust Particles (DEP) represent two important types of environmental pollutants generated from traffic, power generation plants and ships. There are several studies that support the notion that adsorbed chemical substances (including metals) often found on environmental particles can increase allergy-related immune responses. According to a study in Hong Kong, nearly 20 per cent of PM 2.5 particle samples collected in the city carried metals such as copper, magnesium, lithium, nickel, cobalt, arsenic, selenium and zinc - hazardous elements for humans. 15

16 Volatile Organic Compounds The main sources of Volatile Organic Compound (VOC) in buildings are furniture, construction materials, paints and cleaning products. Sometimes also human activities and office equipment increases the VOC level. Although this standard gives a guideline for TVOC, there is no precise value currently for a healthy level of TVOC in indoor air. The other prevalent VOC in indoor air are Benzene, Toluene, Ethylbenzene, O-xylene, and Halogenated Hydrocarbons. However, there are hundreds of other VOC that may reduce the indoor air quality. In case the TVOC level is high, more detailed analysis are required to find out which specific VOC concentrations are high. The target levels of WHO and EPA shall be followed when analysing individual VOC parameters.

17 Formaldehyde Formaldehyde (HCHO) is colourless, poisonous, highly water-soluble gas with an obnoxious odour. It is used in the manufacture of disinfectants, preservatives, and hundreds of construction products such as adhesives, carpeting, decorative panelling, foam insulation, fiber and particle boards.

18 Total Fungal and Bacteria Count There are always fungal spores and bacteria in the indoor air. The aim of IAQ management is not to remove all of them. Sterilization of air also kills the healthy bacteria and negatively impacts on people s immunity. However, pathogenic and toxigenic fungi are unacceptable in indoor air. When there is dampness and mould in a building, airborne culturable fungal and bacteria concentrations of indoor air are often (but not always) higher than the ambient air concentrations at the same time. For fungal spores and bacteria, the seasonal variation is considerable. Therefore measurements taken in different seasons or weather conditions can not be compared. There are no established health-based guidelines or standards for fungal or bacteria concentrations in the indoor air because different types of fungi or bacteria may have different health effects.

19 Humidity Humidity in the occupied spaces affects: the comfort of the occupants, corrosion of the building materials, electrostatic discharge, mould and mildew, bacteria and virus. Although human beings can tolerate a wide range of humidity conditions without the feeling of discomfort, very low humidity conditions cause dryness of skin and mucous membranes in the nose, throat and eyes while extreme humidity results in sweating and discomfort particularly at higher temperatures. 19

20 Moisture and Mould Moisture is the universal requirement for fungal growth; keeping it under control is critical to inhibit mildew and mould. Mildew grows on damp organic materials such as paper. Moulds can damage property and can spoil food. Certain moulds can be very pathogenic and cause disease. The health consequences are particularly significant in hospitals, but can impact users in all types of buildings. 20

21 Air Quality Target Values Finnish IEQ classification (class 1 / 2 / 3) WHO CO 2 Max ppm 750/900/ Indian AQI ASHRAE WELL NABER Good / 62.1 / 55 standard S Satisfactory ambient OSHA EPA Health AFSSET Effects (France) OEHHA Noteboo k Health Canada Malaysi Singapore a Taiwan 800 < PM h µg/m 3-25 / / PM h µg/m 3 20/40/50 50 / / CO 8 h ppm / 2 9 (max) 9 (max) 9 (max) SO 2 24 h µg/m 3-20 / / NO 2 24 h µg/m (1h) 40 / O 3 8 h µg/m 3 20/50/ / NH 3 24 h µg/m 3 30/30/ / TVOC µg/m 3 200/300/ no exact ppm (8h) 3 ppm value (8h) HCHO 24h µg/m 3 30/50/ (24h) 94 (1 h), 123 (1h) 100 ( no value 10 (longtermtermterm) 3 (long- 50 (long- min) 120 (8h) Benzene µg/m 3 - no safe level Toluene µg/m no value 300 (LCI) 300 Pb 24 h µg/m (annual) 0.5 / Total Bacteria Count Total Fungal Count CFU/m 3 - CFU/m (total) 50 (single species) 500 (total) 50 (single species) IEQ User Survey yes yes yes 500 (total) 50 (single species) 500 (total) 50 (single species) 0.56 ppm (1h)

22 Poor indoor air quality Poor air distribution Bad filtration Pressure difference between spaces Supply air is dirty Too high room air temperature Impurity sources in the space Cleaning of the space

23 Different Methods to Evaluate IEQ Design phase Operation phase Building Performance simulations (thermal comfort, IAQ, lighting) Measurements on building (thermal comfort, IAQ, lighting, acoustic) User Survey Questionnaire (perceived thermal comfort, IAQ, lighting, acoustic) User s Health Questionnaire and Health Statistics (building related health symptoms) Satisfaction of an average person with standardized clothing and metabolism Satisfaction of actual personnel

24 IAQ assessment in field Measurements Subjective votes

25 Analysis Method of Indoor Air Quality:Indoor air quality specialist Settled surface dust sample (wipe sampling) - Contaminants in settled surface dust like mineral wool fibres, mould spores, soot, pollen from outdoor air, pet scurf, and asbestos Indoor air /material emission sampling (TENAX) - Chemical contaminants (VOCs) in indoor air, Material VOC emissions (FLEC), Others, like PAH, ammonia, and formaldehyde, via another adsorbent Volumetric air sampling (Andersen sampler) - Culturable fungal spores present in the air Surface and material sampling (bulk) - Moulds actually growing on the surface sampled

26 Analysis Method of Indoor Air Quality: building physics specialist Surface moisture measurement - Locating wet areas of floors, roofs, and walls made of homogeneous material Structural humidity measurement - The water content of concrete at measured depths Thermal infrared imaging - Air and thermal leakage in structures such as windows and external walls, temperature differences in the structure

27 Analysis Method of Indoor Air Quality: HVAC specialist Measurement of room conditions - Room air and operative temperature, relative humidity, and CO 2 level at the measurement point Air flow balance measurements - Pressure difference over the envelope - Supply and exhaust air flow rate measurements Air flow visualisation using smoke - Air diffusion in the space - Air flows between spaces - Pressure difference between spaces

28 Perceived indoor air quality There is large difference between individuals percentage of dissatisfied 28

29 Perceived indoor air quality Panels of subject judging Individual judgement Immediately upon exposure 15 subjects and unadapted vote Continuous acceptability scale 29

30 Factors affecting percieved indoor air quality Olfactory sense Humidity and temperature Duration of exposure (adaptation to odours, no adaptaion to irritants) Odour index = ratio of the concentration of a compound to its odour threshold >= 1 odour can be detected by humans < 1 odour will not be probably detected by humans 30

31 Generalized comfort model Gc - Strenght of pollution souces: Olf unit 1 olf = sensory pollution a standard person,average adult working in a office in thermal comfort, 0,7 bath/day = ventilation efficiency 31

32 Perceived indoor air quality Pol unit - perceived air quality in a space with a sensory load of 1 olf ventilated by 1 L/s 32

33 Why ventilate? To provide fresh air to occupants Heating and Air-Conditioning Why Why Ventilation? Air Quality To distribute heating or cooling To provide natural passive cooling To dilute and remove pollutants 33

34 Evaluation of required ventilation rate for office spaces... for residential buildings... 1 cfm/person= l/s, person Ventilation Rates (cfm/person) Brief Ventilation Rate History History And Background of Ventilation Rates, Kansas City Seminar 4 June 29, 2003; Fred Kohloss Consulting Engineer, Honolulu, Hawaii 34

35 AIR QUALITY COMFORT HEALTH STUFFY ODOUR TOXIC 35 Required: SICK BUILDING HOT COLD DRAUGHTY Ventilation and Air Quality LOSS OF CONDITIONED AIR FAN ENERGY A Solution: VENTILATION CAN REMOVE POLLUTANTS CAN REMOVE HEAT A Problem: ENERGY

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38 Efficiency of different air distribution methods Air Change Efficiency = shortest possible air change time = actual air change time

39 Contaminant removal efficiency e c = c e c 39

40 Room mean Age of air n q v = V t t n t = t n 2 t n t 2 < t < n t n t n t n t =t n t >t n 40

41 Perceived indoor air quality Classification into IAQ categories: EN CR 1752:1998 A, B, C, D EN 15251: 2007 I, II, III, IV Categ. Categ. Explanation I A High level of expectation and is recommended for spaces occupied by very sensitive and fragile persons II B Normal level of expectations III C An acceptable moderate level of expectations IV D Values outside the criteria for the above categories 41

42 Classification of indoor air quality (IDA) (EN13779:2004). Category IDA 1 IDA 2 IDA 3 IDA 4 Description High indoor air quality Medium indoor air quality Moderate indoor air quality Low indoor air quality

43 Classification of indoor air quality (IDA) (EN13779:2004): CO 2 levels Category CO 2 -level above level of outdoor air in ppm (parts per million) typical range default value IDA IDA IDA IDA 4 > The outdoor CO 2 -level is about 400 ppm

44 Perceived indoor air quality and the concentration of CO 2 44

45 Classification of indoor air quality (IDA) (EN13779:2004): air flow rates Category Unit Rate of outdoor air per person non-smoking area smoking area typical range IDA 1 m 3 h -1 person -1 > 54 Ls -1 person -1 > 15 default value typical range > 108 > 30 default value IDA 2 m 3 h -1 person Ls -1 person IDA 3 m 3 h -1 person -1 Ls -1 person IDA 4 m 3 h -1 person -1 Ls -1 person -1 < 22 < < 43 <

46 Calculation of air flow rate Indoor air pollution is generated by occupants (bio effluents) and emission from building materials. q = n q + tot p A R q B where q tot = total ventilation rate for the breathing zone, m 3 /s n = design value for the number of the persons in the room, q p = ventilation rate for occupancy per person, m 3 /s, pers A R = room floor area, m 2 q B = ventilation rate for emissions from building, m 3 /s,m 2

47 Indoor Air Quality and Ventilation Rate ASHRAE 62.1 and EN specifies the ventilation rate for office building Standards Occupancy ASHRAE 62.1 EN Category I Category II Category III Minimum ventilation for occupants (l/s person) Additional ventilation for building (l/s-m 2 ) 2, A B C A B C A B C 0,3 0, ,35 0,7 1,4 0,3 0,4 0,8 A Very Low Pollution B Low Pollution C Not Low Pollution ASHRAE: ( *7)/7 = 0.7 l/s,m 2 LEED (ASHRAE+30%): 0.7 l/s,m 2 * 1.3 = 0.9 l/s,m 2 EN Category II, low polluting: ( *7)/7 = 1.7 l/s,m 2

48 Percentage dissatisfied with air quality as a function of ventilation rate Perceived Air Quality, % of Dissatisfied D C B A Q is the flow rate -0,25 PD(%) = 395 x exp [-1,83 (Q/3,6) ] Fresh air flow rate, m³/(h.person)

49 Thank you