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96-412: Ventilation is the intentional introduction of outdoor air into a space. Ventilation is mainly used to control indoor air quality by diluting and displacing indoor pollutants ; it can also be used to control indoor temperature, humidity, and air motion to benefit thermal comfort , satisfaction with other aspects of the indoor environment, or other objectives. The intentional introduction of outdoor air

192-468: A Thanksgiving dinner can produce very high concentrations of particulate matter, exceeding 300 μg/m . Particulates can penetrate deep into the lungs and brain from blood streams, causing health problems such as heart disease , lung disease , cancer and preterm birth . Other small particles include airborne microplastics , for example in the form of microplastic dust produced during renovation , building, bridge and road reconstruction projects and

288-414: A compressibility factor "Z" is introduced to allow for non-ideality. To introduce the compressibility factor to the equation divide ACF by "Z". Cubic feet per minute (CFM) is an often confusing term because it has no single definition that applies to all instances. Gases are compressible , which means that a figure in cubic feet per minute cannot necessarily be compared with another figure when it comes

384-418: A fireplace , gas heater , candle , oil lamp , etc.) consumes oxygen while producing carbon dioxide and other unhealthy gases and smoke , requiring ventilation air. An open chimney promotes infiltration (i.e. natural ventilation) because of the negative pressure change induced by the buoyant , warmer air leaving through the chimney. The warm air is typically replaced by heavier, cold air. Ventilation in

480-568: A gaseous and a particulate materials which, with particular hazards arising from levels of carbon monoxide and very small particulates (fine particulate matter, especially PM2.5 and PM10 ) which get into the bronchioles and alveoles in the lung. Inhaling secondhand smoke on multiple occasions can cause asthma , pneumonia , lung cancer , and sudden infant death syndrome , among other conditions. Thirdhand smoke (THS) refers to chemicals that settle on objects and bodies indoors after smoking. Exposure to thirdhand smoke can happen even after

576-506: A more diverse thermal environment that can improve thermal satisfaction for most occupants. Local exhaust ventilation addresses the issue of avoiding the contamination of indoor air by specific high-emission sources by capturing airborne contaminants before they are spread into the environment. This can include water vapor control, lavatory effluent control, solvent vapors from industrial processes, and dust from wood- and metal-working machinery. Air can be exhausted through pressurized hoods or

672-427: A much greater risk of developing asthma and allergic rhinitis . More than half of adult workers in moldy or humid buildings suffer from nasal or sinus symptoms due to mold exposure. Some varieties of mold contain toxic compounds ( mycotoxins ). However, exposure to hazardous levels of mycotoxin via inhalation is not possible in most cases, as toxins are produced by the fungal body and are not at significant levels in

768-610: A non-smoking environment. The amount of ventilation in an ETS area is equal to the amount of an ETS-free area plus the amount V, where: V = DSD × VA × A/60E Primitive ventilation systems were found at the Pločnik archeological site (belonging to the Vinča culture ) in Serbia and were built into early copper smelting furnaces. The furnace, built on the outside of the workshop, featured earthen pipe-like air vents with hundreds of tiny holes in them and

864-648: A prototype chimney to ensure air goes into the furnace to feed the fire and smoke comes out safely. Passive ventilation and passive cooling systems were widely written about around the Mediterranean by Classical times. Both sources of heat and sources of cooling (such as fountains and subterranean heat reservoirs) were used to drive air circulation, and buildings were designed to encourage or exclude drafts, according to climate and function. Public bathhouses were often particularly sophisticated in their heating and cooling. Icehouses are some millennia old, and were part of

960-424: A relative humidity of indoor air below 60%, in agreement with the guidelines for thermal comfort that recommend a relative humidity between 40 and 60 %. Moisture buildup in buildings may arise from water penetrating areas of the building envelope or fabric, from plumbing leaks, rainwater or groundwater penetration, or from condensation due to improper ventilation, insufficient heating or poor thermal quality of

1056-538: A resurgence in commercial buildings both globally and throughout the US. The benefits of natural ventilation include: Techniques and architectural features used to ventilate buildings and structures naturally include, but are not limited to: Natural ventilation is a key factor in reducing the spread of airborne illnesses such as tuberculosis, the common cold, influenza, meningitis or COVID-19. Opening doors and windows are good ways to maximize natural ventilation, which would make

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1152-771: A robust research effort in 1919. By 1935, ASHVE-funded research conducted by Lemberg, Brandt, and Morse – again using human subjects in test chambers – suggested the primary component of "bad air" was an odor, perceived by the human olfactory nerves. Human response to odor was found to be logarithmic to contaminant concentrations, and related to temperature. At lower, more comfortable temperatures, lower ventilation rates were satisfactory. A 1936 human test chamber study by Yaglou, Riley, and Coggins culminated much of this effort, considering odor, room volume, occupant age, cooling equipment effects, and recirculated air implications, which guided ventilation rates. The Yaglou research has been validated, and adopted into industry standards, beginning with

1248-499: A signal when systems need maintenance or repair. Being responsive to occupancy means that a smart ventilation system can adjust ventilation depending on demand such as reducing ventilation if the building is unoccupied. Smart ventilation can time-shift ventilation to periods when a) indoor-outdoor temperature differences are smaller (and away from peak outdoor temperatures and humidity), b) when indoor-outdoor temperatures are appropriate for ventilative cooling, or c) when outdoor air quality

1344-449: A significantly higher hazard as they are more likely to release fibers to the air. Indoors ozone (O 3 ) is produced by certain high-voltage electric devices (such as air ionizers ), and as a by-product of other types of pollution. It appears in lower concentrations indoors than outdoors, usually at 0.2-0.7 of the outdoor concentration. Typically, most ozone is lost to surface reactions indoors, rather than to reactions in air, due to

1440-497: A space with fresh air aims to avoid "bad air". The study of what constitutes bad air dates back to the 1600s when the scientist Mayow studied asphyxia of animals in confined bottles. The poisonous component of air was later identified as carbon dioxide (CO 2 ), by Lavoisier in the very late 1700s, starting a debate as to the nature of "bad air" which humans perceive to be stuffy or unpleasant. Early hypotheses included excess concentrations of CO 2 and oxygen depletion . However, by

1536-422: A structure is also needed for removing water vapor produced by respiration , burning, and cooking , and for removing odors. If water vapor is permitted to accumulate, it may damage the structure, insulation , or finishes. When operating, an air conditioner usually removes excess moisture from the air. A dehumidifier may also be appropriate for removing airborne moisture. Ventilation guidelines are based on

1632-520: A well-developed ice industry by classical times. The development of forced ventilation was spurred by the common belief in the late 18th and early 19th century in the miasma theory of disease , where stagnant 'airs' were thought to spread illness. An early method of ventilation was the use of a ventilating fire near an air vent which would forcibly cause the air in the building to circulate. English engineer John Theophilus Desaguliers provided an early example of this when he installed ventilating fires in

1728-506: Is 4 mg/m . Acute exposure should not exceed 10 mg/m in 8 hours, 35 mg/m in one hour and 100 mg/m in 15 minutes. Secondhand smoke is tobacco smoke which affects people other than the 'active' smoker. It is made up of the exhaled smoke (15%) and mostly of smoke coming from the burning end of the cigarette, known as sidestream smoke (85%). Secondhand smoke contains more than 7000 chemicals, of which hundreds are harmful to health. Secondhand tobacco smoke includes both

1824-447: Is 455 SCFM when defined at 32 °F (0 °C) but 481 SCFM when defined at 60 °F (16 °C). Due to the variability of the definition and the consequences of ambiguity, it is best engineering practice to state what standard conditions are used when communicating a "standard" flow value. In countries using the SI metric system of units, the term " normal cubic metre " (Nm )

1920-438: Is 60 μg/m for long-term exposure and 100 μg/m as the maximum average over an 8-hour period. The EPA standard for ozone concentration is 0.07 ppm average over an 8-hour period. Occupants in buildings can be exposed to fungal spores, cell fragments, or mycotoxins which can arise from a host of means, but there are two common classes: (a) excess moisture induced growth of mold colonies and (b) natural substances released into

2016-601: Is a parasite of protozoans such as amoeba , and thus requires conditions suitable for both organisms. The bacterium forms a biofilm which is resistant to chemical and antimicrobial treatments, including chlorine. Remediation for Legionella outbreaks in commercial buildings vary, but often include very hot water flushes (160 °F (71 °C)), sterilisation of standing water in evaporative cooling basins, replacement of shower heads, and, in some cases, flushes of heavy metal salts. Preventive measures include adjusting normal hot water levels to allow for 120 °F (49 °C) at

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2112-447: Is a particular concern in low and middle-income countries where such practices are common. Cooking using natural gas (also called fossil gas, methane gas or simply gas) is associated with poorer indoor air quality. Combustion of gas produces nitrogen dioxide and carbon monixide, and can lead to increased concentrations of nitrogen dioxide throughout the home environment which is linked to respiratory issues and diseases . One of

2208-468: Is acceptable. Being responsive to electricity grid needs means providing flexibility to electricity demand (including direct signals from utilities) and integration with electric grid control strategies. Smart ventilation systems can have sensors to detect airflow, systems pressures, or fan energy use in such a way that systems failures can be detected and repaired, as well as when system components need maintenance, such as filter replacement. Combustion (in

2304-473: Is an integral component of maintaining good indoor air quality, it may not be satisfactory alone. A clear understanding of both indoor and outdoor air quality parameters is needed to improve the performance of ventilation in terms of occupant health and energy. In scenarios where outdoor pollution would deteriorate indoor air quality, other treatment devices such as filtration may also be necessary. In kitchen ventilation systems, or for laboratory fume hoods ,

2400-425: Is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion. Natural ventilation requires little maintenance and is inexpensive. Natural ventilation is not practical in much of the infrastructure because of climate. This means that the facilities need to have effective mechanical ventilation systems and or use Ceiling Level UV or FAR UV ventilation systems. Ventilation

2496-409: Is identified to significantly increase the localized moldy smell in specific places of the room including room corners. There are three types of natural ventilation occurring in buildings: wind-driven ventilation , pressure-driven flows, and stack ventilation . The pressures generated by 'the stack effect ' rely upon the buoyancy of heated or rising air. Wind-driven ventilation relies upon the force of

2592-651: Is measured in terms of air changes per hour (ACH). As of 2023, the CDC recommends that all spaces have a minimum of 5 ACH. For hospital rooms with airborne contagions the CDC recommends a minimum of 12 ACH. Challenges in facility ventilation are public unawareness, ineffective government oversight, poor building codes that are based on comfort levels, poor system operations, poor maintenance, and lack of transparency. Pressure, both political and economic, to improve energy conservation has led to decreased ventilation rates. Heating, ventilation, and air conditioning rates have dropped since

2688-467: Is not the case as the most important change between these two definitions is the pressure. To move a gas, a positive pressure or a vacuum must be created. When positive pressure is applied to a standard cubic foot of gas, it is compressed. When a vacuum is applied to a standard cubic foot of gas, it expands. The volume of gas after it is pressurized or rarefied is referred to as its "actual" volume. SCF and ACF for an ideal gas are related in accordance with

2784-452: Is part of indoor environmental quality (IEQ), along with other factors that exert an influence on physical and psychological aspects of life indoors (e.g., lighting, visual quality, acoustics, and thermal comfort). Indoor air pollution is a major health hazard in developing countries and is commonly referred to as " household air pollution " in that context. It is mostly relating to cooking and heating methods by burning biomass fuel , in

2880-822: Is preferable to minimize ventilation with outdoor air to conserve energy, cost, or filtration. This critique (e.g. Tiller) led ASHRAE to reduce outdoor ventilation rates in 1981, particularly in non-smoking areas. However subsequent research by Fanger, W. Cain, and Janssen validated the Yaglou model. The reduced ventilation rates were found to be a contributing factor to sick building syndrome . The 1989 ASHRAE standard (Standard 62–89) states that appropriate ventilation guidelines are 20 CFM (9.2 L/s) per person in an office building, and 15 CFM (7.1 L/s) per person for schools, while 2004 Standard 62.1-2004 has lower recommendations again (see tables below). ANSI/ASHRAE (Standard 62–89) speculated that "comfort (odor) criteria are likely to be satisfied if

2976-538: Is significant for human health as humans spend a large proportion of their time in indoor environments. Americans and Europeans on average spend approximately 90% of their time indoors. The World Health Organization (WHO) estimates that 3.2 million people die prematurely every year from illnesses attributed to indoor air pollution caused by indoor cooking, with over 237 thousand of these being children under 5. These include around an eighth of all global ischaemic heart disease , stroke , and lung cancer deaths. Overall

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3072-650: Is the air quality within buildings and structures . Poor indoor air quality due to indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to sick building syndrome , respiratory issues, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: secondhand tobacco smoke , air pollutants from indoor combustion , radon , molds and other allergens , carbon monoxide , volatile organic compounds , legionella and other bacteria, asbestos fibers , carbon dioxide , ozone and particulates . Source control, filtration, and

3168-414: Is the preferred unit for volumetric flow rate in the SI system of units). The ventilation rate can also be expressed on a per person or per unit floor area basis, such as CFM/p or CFM/ft², or as air changes per hour (ACH). For residential buildings, which mostly rely on infiltration for meeting their ventilation needs, a common ventilation rate measure is the air change rate (or air changes per hour):

3264-416: Is used in the home. Benzene is emitted from fuel stored in attached garages. Human activities such as cooking and cleaning can also emit VOCs. Cooking can release long-chain aldehydes and alkanes when oil is heated and terpenes can be released when spices are prepared and/or cooked. Leaks of natural gas from cooking appliances have been linked to elevated levels of VOCs including benzene in homes in

3360-423: Is usually categorized as either mechanical ventilation, natural ventilation , or mixed-mode ventilation . Ventilation is typically described as separate from infiltration. The design of buildings that promote occupant health and well-being requires a clear understanding of the ways that ventilation airflow interacts with, dilutes, displaces, or introduces pollutants within the occupied space. Although ventilation

3456-431: Is very often used to denote gas volumes at some normalized or standard condition. Again, as noted above, there is no universally accepted set of normalized or standard conditions. Actual cubic foot per minute (ACFM) is the volume of gas flowing anywhere in a system, taking into account its temperature and pressure. If the system were moving a gas at exactly the "standard" condition, then ACFM would equal SCFM. This usually

3552-569: The United States , the EPA defines standard conditions for volume and volumetric flow as a temperature of 293 K (68 °F) and a pressure of 101.3 kilopascals (29.92 in. Hg), although various industry users may use definitions from 60 °F to 78 °F. A variation in standard temperature can result in a significant volumetric variation for the same mass flow rate. For example, a mass flow rate of 1,000 kg/h of air at 1 atmosphere of absolute pressure

3648-460: The combined gas law : Defining standard conditions by the subscript 1 and actual conditions by the subscript 2, then: where P {\displaystyle P} is in absolute pressure units and T {\displaystyle T} is in absolute temperature units (i.e., either kelvins or degrees Rankine ). This is only valid when at a pressure and temperature close to standard conditions. For non-ideal gasses (most gasses)

3744-403: The energy crisis in the 1970s and the banning of cigarette smoke in the 1980s and 1990s. Mechanical ventilation of buildings and structures can be achieved by the use of the following techniques: Demand-controlled ventilation ( DCV , also known as Demand Control Ventilation) makes it possible to maintain air quality while conserving energy. ASHRAE has determined that "It is consistent with

3840-629: The ASA code in 1946. From this research base, ASHRAE (having replaced ASHVE) developed space-by-space recommendations, and published them as ASHRAE Standard 62-1975: Ventilation for acceptable indoor air quality. As more architecture incorporated mechanical ventilation, the cost of outdoor air ventilation came under some scrutiny. In 1973, in response to the 1973 oil crisis and conservation concerns, ASHRAE Standards 62-73 and 62–81) reduced required ventilation from 10 CFM (4.76 L/s) per person to 5 CFM (2.37 L/s) per person. In cold, warm, humid, or dusty climates, it

3936-881: The American Society of Heating, Refrigerating and Air-Conditioning Engineers ( ASHRAE ) Standards 62.1 and 62.2, the International Residential Code, the International Mechanical Code , and the United Kingdom Building Regulations Part F . Other standards that focus on energy conservation also impact the design and operation of ventilation systems, including ASHRAE Standard 90.1, and the International Energy Conservation Code . When indoor and outdoor conditions are favorable, increasing ventilation beyond

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4032-466: The LEV systems are performing adequately. All parts of the system must be visually inspected and thoroughly tested and where any parts are found to be defective, the inspector must issue a red label to identify the defective part and the issue. The owner of the LEV system must then have the defective parts repaired or replaced before the system can be used. Smart ventilation is a process of continually adjusting

4128-855: The US. Due to these initiatives an increasing number of low-emitting products became available to purchase. At least 18 microbial VOCs (MVOCs) have been characterised including 1-octen-3-ol (mushroom alcohol), 3-Methylfuran , 2-pentanol , 2-hexanone , 2-heptanone , 3-octanone , 3-octanol , 2-octen-1-ol , 1-octene , 2-pentanone , 2-nonanone , borneol , geosmin , 1-butanol , 3-methyl-1-butanol , 3-methyl-2-butanol , and thujopsene . The last four are products of Stachybotrys chartarum , which has been linked with sick building syndrome . Many common building materials used before 1975 contain asbestos , such as some floor tiles, ceiling tiles, shingles, fireproofing, heating systems, pipe wrap, taping muds, mastics, and other insulation materials. Normally, significant releases of asbestos fiber do not occur unless

4224-858: The USA. Cleaning products contain a range of VOCs, including monoterpenes , sesquiterpenes , alcohols and esters . Once released into the air, VOCs can undergo reactions with ozone and hydroxyl radicals to produce other VOCs, such as formaldehyde. Health effects include eye, nose, and throat irritation ; headaches , loss of coordination, nausea ; and damage to the liver , kidney, and central nervous system . Testing emissions from building materials used indoors has become increasingly common for floor coverings, paints, and many other important indoor building materials and finishes. Indoor materials such as gypsum boards or carpet act as VOC 'sinks', by trapping VOC vapors for extended periods of time, and releasing them by outgassing . The VOCs can also undergo transformation at

4320-568: The WHO estimated that poor indoor air quality resulted in the loss of 86 million healthy life years in 2019. Studies in the UK and Europe show exposure to indoor air pollutants, chemicals and biological contamination can irritate the upper airway system, trigger or exacerbate asthma and other respiratory or cardiovascular conditions, and may even have carcinogenic effects. Poor indoor air quality can cause sick building syndrome . Symptoms include burning of

4416-556: The actual cigarette smoke is not present anymore and affect those entering the indoor environment much later. Toxic substances of THS can react with other chemicals in the air and produce new toxic chemicals that are otherwise not present in cigarettes. The only certain method to improve indoor air quality as regards secondhand smoke is to eliminate smoking indoors. Indoor e-cigarette use also increases home particulate matter concentrations. Atmospheric particulate matter, also known as particulates , can be found indoors and can affect

4512-440: The air can be circulated in the room using vortexes which can be initiated in various ways: The ventilation rate, for commercial, industrial, and institutional (CII) buildings, is normally expressed by the volumetric flow rate of outdoor air, introduced to the building. The typical units used are cubic feet per minute (CFM) in the imperial system, or liters per second (L/s) in the metric system (even though cubic meter per second

4608-948: The air such as animal dander and plant pollen. While mold growth is associated with high moisture levels, it is likely to grow when a combination of favorable conditions arises. As well as high moisture levels, these conditions include suitable temperatures, pH and nutrient sources. Mold grows primarily on surfaces, and it reproduces by releasing spores, which can travel and settle in different locations. When these spores experience appropriate conditions, they can germinate and lead to mycelium growth. Different mold species favor different environmental conditions to germinate and grow, some being more hydrophilic (growing at higher levels of relative humidity) and other more xerophilic (growing at levels of relative humidity as low as 75–80%). Mold growth can be inhibited by keeping surfaces at conditions that are further from condensation, with relative humidity levels below 75%. This usually translates to

4704-541: The air tubes on the roof of the House of Commons . Starting with the Covent Garden Theatre , gas burning chandeliers on the ceiling were often specially designed to perform a ventilating role. A more sophisticated system involving the use of mechanical equipment to circulate the air was developed in the mid-19th century. A basic system of bellows was put in place to ventilate Newgate Prison and outlying buildings, by

4800-465: The air. Inhalation of asbestos fibers over long exposure times is associated with increased incidence of lung cancer , mesothelioma , and asbestosis . The risk of lung cancer from inhaling asbestos fibers is significantly greater for smokers. The symptoms of disease do not usually appear until about 20 to 30 years after the first exposure to asbestos. Although all asbestos is hazardous, products that are friable, e.g. sprayed coatings and insulation, pose

4896-535: The backdraft of combustion products from "naturally vented" appliances into the occupied space. This issue is of greater importance for buildings with more air-tight envelopes. To avoid the hazard, many modern combustion appliances utilize "direct venting" which draws combustion air directly from outdoors, instead of from the indoor environment. The air in a room can be supplied and removed in several ways, for example via ceiling ventilation, cross ventilation , floor ventilation or displacement ventilation . Furthermore,

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4992-624: The bathroom floor drains, exacerbated by the draw of bathroom exhaust fans, resulting in the rapid spread of SARS in Amoy Gardens in Hong Kong . Elsewhere in Hong Kong, SARS CoV RNA was found on the carpet and in the air intake vents of the Metropole Hotel, which showed that secondary environmental contamination could generate infectious aerosols and resulted in superspreading events. Humans are

5088-719: The brain of oxygen, acute exposure to carbon monoxide may have effects on the neurological system (headache, nausea, dizziness, alteration in consciousness and subjective weakness), the cardiovascular and respiratory systems ( myocardial infarction , shortness of breath, or rapid breathing, respiratory failure ). Acute exposure can also lead to long-term neurological effects such as cognitive and behavioural changes. Severe CO poisoning may lead to unconsciousness, coma and death. Chronic exposure to low concentrations of carbon monoxide may lead to lethargy, headaches, nausea, flu-like symptoms and neuropsychological and cardiovascular issues. The WHO recommended levels of indoor CO exposure in 24 hours

5184-474: The breathing zone with far less air volume. Beyond improved air quality benefits, the strategy can also improve occupants' thermal comfort, perceived air quality, and overall satisfaction with the indoor environment. Individuals' preferences for temperature and air movement are not equal, and so traditional approaches to homogeneous environmental control have failed to achieve high occupant satisfaction. Techniques such as personalized ventilation facilitate control of

5280-443: The building envelope. Even something as simple as drying clothes indoors on radiators can increase the risk of mold growth, if the humidity produced is not able to escape the building via ventilation. Mold predominantly affects the airways and lungs. Known effects of mold on health include asthma development and exacerbation, with children and elderly at greater risk of more severe health impacts. Infants in homes with mold have

5376-433: The building materials are disturbed, such as by cutting, sanding, drilling, or building remodelling. Removal of asbestos-containing materials is not always optimal because the fibers can be spread into the air during the removal process. A management program for intact asbestos-containing materials is often recommended instead. When asbestos-containing material is damaged or disintegrates, microscopic fibers are dispersed into

5472-452: The ceiling of St George's Hospital in Liverpool , so that the pressure produced by the fans would force the incoming air upward and through vents in the ceiling. Reid's pioneering work provides the basis for ventilation systems to this day. He was remembered as "Dr. Reid the ventilator" in the twenty-first century in discussions of energy efficiency , by Lord Wade of Chorlton . Ventilating

5568-609: The chamber through thousands of small holes drilled into the floor, and would be extracted through the ceiling by a special ventilation fire within a great stack. Reid's reputation was made by his work in Westminster. He was commissioned for an air quality survey in 1837 by the Leeds and Selby Railway in their tunnel. The steam vessels built for the Niger expedition of 1841 were fitted with ventilation systems based on Reid's Westminster model. Air

5664-514: The construction of the replacement for the Houses of Parliament. The post was in the capacity of ventilation engineer, in effect; and with its creation there began a long series of quarrels between Reid and Charles Barry , the architect. Reid advocated the installation of a very advanced ventilation system in the new House. His design had air being drawn into an underground chamber, where it would undergo either heating or cooling. It would then ascend into

5760-425: The design of effective effluent capture can be more important than the bulk amount of ventilation in a space. More generally, the way that an air distribution system causes ventilation to flow into and out of a space impacts the ability of a particular ventilation rate to remove internally generated pollutants. The ability of a system to reduce pollution in space is described as its "ventilation effectiveness". However,

5856-420: The engineer Stephen Hales in the mid-1700s. The problem with these early devices was that they required constant human labor to operate. David Boswell Reid was called to testify before a Parliamentary committee on proposed architectural designs for the new House of Commons , after the old one burned down in a fire in 1834. In January 1840 Reid was appointed by the committee for the House of Lords dealing with

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5952-656: The eyes, scratchy throat, blocked nose, and headaches. Indoor combustion, such as for cooking or heating, is a major cause of indoor air pollution and causes significant health harms and premature deaths. Hydrocarbon fires cause air pollution. Pollution is caused by both biomass and fossil fuels of various types, but some forms of fuels are more harmful than others. Indoor fire can produce black carbon particles, nitrogen oxides , sulfur oxides , and mercury compounds , among other emissions. Around 3 billion people cook over open fires or on rudimentary cook stoves. Cooking fuels are coal, wood, animal dung, and crop residues. IAQ

6048-452: The form of wood , charcoal , dung , and crop residue , in indoor environments that lack proper ventilation. Millions of people, primarily women and children, face serious health risks. In total, about three billion people in developing countries are affected by this problem. The World Health Organization (WHO) estimates that cooking-related indoor air pollution causes 3.8 million annual deaths. The Global Burden of Disease study estimated

6144-623: The gas-phase, or on surfaces. VOCs presenting health hazards include benzene , formaldehyde , tetrachloroethylene and trichloroethylene . VOCs are emitted by thousands of indoor products. Examples include: paints, varnishes, waxes and lacquers, paint strippers, cleaning and personal care products, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper , graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions. Chlorinated drinking water releases chloroform when hot water

6240-455: The health effects of CO 2 at lower concentrations is conflicting and it is difficult to link CO 2 to health impacts at exposures below 5000 ppm – reported health outcomes may be due to the presence of human bioeffluents, and other indoor air pollutants related to inadequate ventilation. Standard cubic feet per minute#Cubic feet per minute In Europe , the standard temperature is most commonly defined as 0 °C, but not always. In

6336-603: The health of occupants. Indoor particulate matter can come from different indoor sources or be created as secondary aerosols through indoor gas-to-particle reactions. They can also be outdoor particles that enter indoors. These indoor particles vary widely in size, ranging from nanomet (nanoparticles/ultrafine particles emitted from combustion sources) to micromet (resuspensed dust). Particulate matter can also be produced through cooking activities. Frying produces higher concentrations than boiling or grilling and cooking meat produces higher concentrations than cooking vegetables. Preparing

6432-424: The hourly ventilation rate divided by the volume of the space ( I or ACH ; units of 1/h). During the winter, ACH may range from 0.50 to 0.41 in a tightly air-sealed house to 1.11 to 1.47 in a loosely air-sealed house. ASHRAE now recommends ventilation rates dependent upon floor area, as a revision to the 62-2001 standard, in which the minimum ACH was 0.35, but no less than 15 CFM/person (7.1 L/s/person). As of 2003,

6528-513: The indoor air. Air pollutants can enter a building in many ways, including through open doors or windows. Poorly maintained air conditioners/ventilation systems can harbor mold, bacteria, and other contaminants, which are then circulated throughout indoor spaces, contributing to respiratory problems and allergies. There have been many debates among indoor air quality specialists about the proper definition of indoor air quality and specifically what constitutes "acceptable" indoor air quality. IAQ

6624-620: The large surface to volume ratios found indoors. Outdoor air used for ventilation may have sufficient ozone to react with common indoor pollutants as well as skin oils and other common indoor air chemicals or surfaces. Particular concern is warranted when using "green" cleaning products based on citrus or terpene extracts, because these chemicals react very quickly with ozone to form toxic and irritating chemicals as well as fine and ultrafine particles . Ventilation with outdoor air containing elevated ozone concentrations may complicate remediation attempts. The WHO standard for ozone concentration

6720-651: The late 1800s, scientists thought biological contamination, not oxygen or CO 2 , was the primary component of unacceptable indoor air. However, it was noted as early as 1872 that CO 2 concentration closely correlates to perceived air quality. The first estimate of minimum ventilation rates was developed by Tredgold in 1836. This was followed by subsequent studies on the topic by Billings in 1886 and Flugge in 1905. The recommendations of Billings and Flugge were incorporated into numerous building codes from 1900–the 1920s and published as an industry standard by ASHVE (the predecessor to ASHRAE ) in 1914. The study continued into

6816-563: The main indoor source of carbon dioxide (CO 2 ) in most buildings. Indoor CO 2 levels are an indicator of the adequacy of outdoor air ventilation relative to indoor occupant density and metabolic activity. Indoor CO 2 levels above 500 ppm can lead to higher blood pressure and heart rate, and increased peripheral blood circulation. With CO 2 concentrations above 1000 ppm cognitive performance might be affected, especially when doing complex tasks, making decision making and problem solving slower but not less accurate. However, evidence on

6912-519: The main sources of indoor CO emission come from cooking and heating devices that burn fossil fuels and are faulty, incorrectly installed or poorly maintained. Appliance malfunction may be due to faulty installation or lack of maintenance and proper use. In low- and middle-income countries the most common sources of CO in homes are burning biomass fuels and cigarette smoke. Health effects of CO poisoning may be acute or chronic and can occur unintentionally or intentionally ( self-harm ). By depriving

7008-413: The mass of the gas. To further confuse the issue, a centrifugal fan is a constant CFM device or a constant volume device. This means that, provided the fan speed remains constant, a centrifugal fan will pump a constant volume of air. This is not the same as pumping a constant mass of air. Again, the fan will pump the same volume, though not mass, at any other air density. This means that the air velocity in

7104-869: The minimum required for indoor air quality can significantly improve both indoor air quality and thermal comfort through ventilative cooling , which also helps reduce the energy demand of buildings. During these times, higher ventilation rates, achieved through passive or mechanical means ( air-side economizer , ventilative pre-cooling), can be particularly beneficial for enhancing people's physical health. Conversely, when conditions are less favorable, maintaining or improving indoor air quality through ventilation may require increased use of mechanical heating or cooling, leading to higher energy consumption. Ventilation should be considered for its relationship to "venting" for appliances and combustion equipment such as water heaters , furnaces, boilers , and wood stoves. Most importantly, building ventilation design must be careful to avoid

7200-497: The minimum ventilation rate required to maintain acceptable levels of effluents. Carbon dioxide is used as a reference point, as it is the gas of highest emission at a relatively constant value of 0.005 L/s. The mass balance equation is: Q = G/(C i − C a ) ASHRAE standard 62 states that air removed from an area with environmental tobacco smoke shall not be recirculated into ETS-free air. A space with ETS requires more ventilation to achieve similar perceived air quality to that of

7296-435: The most acutely toxic indoor air contaminants is carbon monoxide (CO), a colourless and odourless gas that is a by-product of incomplete combustion . Carbon monoxide may be emitted from tobacco smoke and generated from malfunctioning fuel burning stoves (wood, kerosene, natural gas, propane) and fuel burning heating systems (wood, oil, natural gas) and from blocked flues connected to these appliances. In developed countries

7392-592: The most commonly reported cases of Legionellosis. More than one case has involved outdoor fountains at public attractions. The presence of Legionella in commercial building water supplies is highly under-reported, as healthy people require heavy exposure to acquire infection. Legionella testing typically involves collecting water samples and surface swabs from evaporative cooling basins, shower heads, faucets/taps, and other locations where warm water collects. The samples are then cultured and colony forming units (cfu) of Legionella are quantified as cfu/liter. Legionella

7488-734: The number of deaths in 2017 at 1.6 million. For health reasons it is crucial to breathe clean air, free from chemicals and toxicants as much as possible. It is estimated that humans spend approximately 90% of their lifetime indoors and that indoor air pollution in some places can be much worse than that of the ambient air. Various factors contribute to high concentrations of pollutants indoors, ranging from influx of pollutants from external sources, off-gassing by furniture, furnishings including carpets, indoor activities (cooking, cleaning, painting, smoking, etc. in homes to using office equipment in offices), thermal comfort parameters such as temperature, humidity, airflow and physio-chemical properties of

7584-452: The overall impacts of ventilation on indoor air quality can depend on more complex factors such as the sources of pollution, and the ways that activities and airflow interact to affect occupant exposure. An array of factors related to the design and operation of ventilation systems are regulated by various codes and standards. Standards dealing with the design and operation of ventilation systems to achieve acceptable indoor air quality include

7680-660: The prevailing wind to pull and push air through the enclosed space as well as through breaches in the building's envelope. Almost all historic buildings were ventilated naturally. The technique was generally abandoned in larger US buildings during the late 20th century as the use of air conditioning became more widespread. However, with the advent of advanced Building Performance Simulation (BPS) software, improved Building Automation Systems (BAS), Leadership in Energy and Environmental Design (LEED) design requirements, and improved window manufacturing techniques; natural ventilation has made

7776-603: The released spores. Legionnaires' disease is caused by a waterborne bacterium Legionella that grows best in slow-moving or still, warm water. The primary route of exposure is through the creation of an aerosol effect, most commonly from evaporative cooling towers or showerheads. A common source of Legionella in commercial buildings is from poorly placed or maintained evaporative cooling towers, which often release water in an aerosol which may enter nearby ventilation intakes. Outbreaks in medical facilities and nursing homes, where patients are immuno-suppressed and immuno-weak, are

7872-411: The results. A large fraction of the bacteria found in indoor air and dust are shed from humans. Among the most important bacteria known to occur in indoor air are Mycobacterium tuberculosis , Staphylococcus aureus , Streptococcus pneumoniae . Viruses can also be a concern for indoor air quality. During the 2002–2004 SARS outbreak , virus-laden aerosols were found to have seeped into bathrooms from

7968-449: The risk of airborne contagion much lower than with costly and maintenance-requiring mechanical systems. Old-fashioned clinical areas with high ceilings and large windows provide the greatest protection. Natural ventilation costs little and is maintenance-free, and is particularly suited to limited-resource settings and tropical climates, where the burden of TB and institutional TB transmission is highest. In settings where respiratory isolation

8064-637: The specification of acceptable concentrations of certain contaminants in indoor air but does not prescribe ventilation rates or air treatment methods. This addresses both quantitative and subjective evaluations and is based on the Ventilation Rate Procedure. It also accounts for potential contaminants that may have no measured limits, or for which no limits are not set (such as formaldehyde off-gassing from carpet and furniture). Natural ventilation harnesses naturally available forces to supply and remove air in an enclosed space. Poor ventilation in rooms

8160-465: The standard has been changed to 3 CFM/100 sq. ft. (15 L/s/100 sq. m.) plus 7.5 CFM/person (3.5 L/s/person). Ventilation Rate Procedure is rate based on standard and prescribes the rate at which ventilation air must be delivered to space and various means to the condition that air. Air quality is assessed (through CO 2 measurement) and ventilation rates are mathematically derived using constants. Indoor Air Quality Procedure uses one or more guidelines for

8256-672: The surface through interaction with ozone. In both cases, these delayed emissions can result in chronic and low-level exposures to VOCs. Several initiatives aim to reduce indoor air contamination by limiting VOC emissions from products. There are regulations in France and in Germany, and numerous voluntary ecolabels and rating systems containing low VOC emissions criteria such as EMICODE, M1, Blue Angel and Indoor Air Comfort in Europe, as well as California Standard CDPH Section 01350 and several others in

8352-576: The system reduces ventilation to conserves energy. DCV is a well-established practice, and is required in high occupancy spaces by building energy standards such as ASHRAE 90.1 . Personalized ventilation is an air distribution strategy that allows individuals to control the amount of ventilation received. The approach delivers fresh air more directly to the breathing zone and aims to improve the air quality of inhaled air. Personalized ventilation provides much higher ventilation effectiveness than conventional mixing ventilation systems by displacing pollution from

8448-479: The tap, evaluating facility design layout, removing faucet aerators, and periodic testing in suspect areas. There are many bacteria of health significance found in indoor air and on indoor surfaces. The role of microbes in the indoor environment is increasingly studied using modern gene-based analysis of environmental samples. Currently, efforts are under way to link microbial ecologists and indoor air scientists to forge new methods for analysis and to better interpret

8544-439: The use of power tools . Volatile organic compounds (VOCs) include a variety of chemicals, some of which may have short- and long-term adverse health effects. There are numerous sources of VOCs indoors, which means that their concentrations are consistently higher indoors (up to ten times higher) than outdoors. Some VOCs are emitted directly indoors, and some are formed through the subsequent chemical reactions that can occur in

8640-554: The use of ventilation to dilute contaminants are the primary methods for improving indoor air quality. Although ventilation is an integral component of maintaining good indoor air quality, it may not be satisfactory alone. In scenarios where outdoor pollution would deteriorate indoor air quality, other treatment devices such as filtration may also be necessary. IAQ is evaluated through collection of air samples, monitoring human exposure to pollutants, analysis of building surfaces, and computer modeling of air flow inside buildings. IAQ

8736-536: The use of fans and pressurizing a specific area. A local exhaust system is composed of five basic parts: In the UK, the use of LEV systems has regulations set out by the Health and Safety Executive (HSE) which are referred to as the Control of Substances Hazardous to Health ( CoSHH ). Under CoSHH, legislation is set to protect users of LEV systems by ensuring that all equipment is tested at least every fourteen months to ensure

8832-502: The varied effects of thermal comfort , oxygen, carbon dioxide, and biological contaminants. The research was conducted with human subjects in controlled test chambers. Two studies, published between 1909 and 1911, showed that carbon dioxide was not the offending component. Subjects remained satisfied in chambers with high levels of CO 2 , so long as the chamber remained cool. (Subsequently, it has been determined that CO 2 is, in fact, harmful at concentrations over 50,000ppm) ASHVE began

8928-462: The ventilation rate is set so that 1,000 ppm CO 2 is not exceeded" while OSHA has set a limit of 5000 ppm over 8 hours. ASHRAE continues to publish space-by-space ventilation rate recommendations, which are decided by a consensus committee of industry experts. The modern descendants of ASHRAE standard 62-1975 are ASHRAE Standard 62.1, for non-residential spaces, and ASHRAE 62.2 for residences. Indoor air quality Indoor air quality ( IAQ )

9024-442: The ventilation rate procedure that demand control be permitted for use to reduce the total outdoor air supply during periods of less occupancy." In a DCV system, CO 2 sensors control the amount of ventilation. During peak occupancy, CO 2 levels rise, and the system adjusts to deliver the same amount of outdoor air as would be used by the ventilation-rate procedure. However, when spaces are less occupied, CO 2 levels reduce, and

9120-692: The ventilation system in time, and optionally by location, to provide the desired IAQ benefits while minimizing energy consumption, utility bills, and other non-IAQ costs (such as thermal discomfort or noise). A smart ventilation system adjusts ventilation rates in time or by location in a building to be responsive to one or more of the following: occupancy, outdoor thermal and air quality conditions, electricity grid needs, direct sensing of contaminants, operation of other air moving and air cleaning systems. In addition, smart ventilation systems can provide information to building owners, occupants, and managers on operational energy consumption and indoor air quality as well as

9216-471: Was dried, filtered and passed over charcoal. Reid's ventilation method was also applied more fully to St. George's Hall, Liverpool , where the architect, Harvey Lonsdale Elmes , requested that Reid should be involved in ventilation design. Reid considered this the only building in which his system was completely carried out. With the advent of practical steam power , ceiling fans could finally be used for ventilation. Reid installed four steam-powered fans in

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