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67-500: The heat plant has an installed thermal capacity of 512 MW. It has one 300-metre (980 ft) high flue gas stack , which is one of Poland's tallest free standing structures. This article about a power station is a stub . You can help Misplaced Pages by expanding it . This article about a building or structure in Warsaw is a stub . You can help Misplaced Pages by expanding it . Flue gas stack A flue-gas stack , also known as

134-422: A smoke stack , chimney stack or simply as a stack , is a type of chimney , a vertical pipe, channel or similar structure through which combustion product gases called flue gases are exhausted to the outside air. Flue gases are produced when coal, oil, natural gas, wood or any other fuel is combusted in an industrial furnace, a power plant's steam-generating boiler, or other large combustion device. Flue gas

201-443: A wind tunnel which has thousands of changes per hour. The highest air change rates are for crowded spaces, bars, night clubs, commercial kitchens at around 30 to 50 air changes per hour. Room pressure can be either positive or negative with respect to outside the room. Positive pressure occurs when there is more air being supplied than exhausted, and is common to reduce the infiltration of outside contaminants. Natural ventilation

268-487: A building in a high dust environment, or a home with furry pets, will need to have the filters changed more often than buildings without these dirt loads. Failure to replace these filters as needed will contribute to a lower heat exchange rate, resulting in wasted energy, shortened equipment life, and higher energy bills; low air flow can result in iced-over evaporator coils, which can completely stop airflow. Additionally, very dirty or plugged filters can cause overheating during

335-729: A building that was not designed to receive it) because of the bulky air ducts required. (Minisplit ductless systems are used in these situations.) Outside of North America, packaged systems are only used in limited applications involving large indoor space such as stadiums, theatres or exhibition halls. An alternative to packaged systems is the use of separate indoor and outdoor coils in split systems . Split systems are preferred and widely used worldwide except in North America. In North America, split systems are most often seen in residential applications, but they are gaining popularity in small commercial buildings. Split systems are used where ductwork

402-481: A central location such as a furnace room in a home, or a mechanical room in a large building. The heat can be transferred by convection , conduction, or radiation . Space heaters are used to heat single rooms and only consist of a single unit. Heaters exist for various types of fuel, including solid fuels , liquids , and gases . Another type of heat source is electricity , normally heating ribbons composed of high resistance wire (see Nichrome ). This principle

469-549: A circulator, which is a pump, to move hot water through the distribution system (as opposed to older gravity-fed systems ). The heat can be transferred to the surrounding air using radiators , hot water coils (hydro-air), or other heat exchangers. The radiators may be mounted on walls or installed within the floor to produce floor heat. The use of water as the heat transfer medium is known as hydronics . The heated water can also supply an auxiliary heat exchanger to supply hot water for bathing and washing. Warm air systems distribute

536-527: A facility to be heated and cooled by a single piece of equipment by the same means, and with the same hardware. Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, using free cooling early in

603-410: A feature of many industrial chimneys from the 1860s, with over-sailing caps and patterned brickwork. The invention of fan-assisted forced draft in the early 20th century removed the industrial chimney's original function, that of drawing air into the steam-generating boilers or other furnaces. With the replacement of the steam engine as a prime mover, first by diesel engines and then by electric motors,

670-489: A furnace by increasing the draft of air into the combustion zone. As such, they played an important part in the development of reverberatory furnaces and a coal-based metallurgical industry, one of the key sectors of the early Industrial Revolution . Most 18th-century industrial chimneys (now commonly referred to as flue gas stacks ) were built into the walls of the furnace, much like a domestic chimney. The first freestanding industrial chimneys were probably those erected at

737-410: A heat pump system in which a compressor is used to drive thermodynamic refrigeration cycle , or in a free cooling system that uses pumps to circulate a cool refrigerant (typically water or a glycol mix). It is imperative that the air conditioning horsepower is sufficient for the area being cooled. Underpowered air conditioning systems will lead to power wastage and inefficient usage. Adequate horsepower

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804-416: A heating cycle, which can result in damage to the system or even fire. Because an air conditioner moves heat between the indoor coil and the outdoor coil, both must be kept clean. This means that, in addition to replacing the air filter at the evaporator coil, it is also necessary to regularly clean the condenser coil. Failure to keep the condenser clean will eventually result in harm to the compressor because

871-455: A huge difference for the environment and help expand the knowledge of using different methods. HVAC is based on inventions and discoveries made by Nikolay Lvov , Michael Faraday , Rolla C. Carpenter , Willis Carrier , Edwin Ruud , Reuben Trane , James Joule , William Rankine , Sadi Carnot , Alice Parker and many others. Multiple inventions within this time frame preceded the beginnings of

938-475: A larger district heating (DH) or district cooling (DC) network, or a combined DHC network. In such cases, the operating and maintenance aspects are simplified and metering becomes necessary to bill for the energy that is consumed, and in some cases energy that is returned to the larger system. For example, at a given time one building may be utilizing chilled water for air conditioning and the warm water it returns may be used in another building for heating, or for

1005-494: A room for the purpose of reducing the perceived temperature by increasing evaporation of perspiration on the skin of the occupants. Because hot air rises, ceiling fans may be used to keep a room warmer in the winter by circulating the warm stratified air from the ceiling to the floor. Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and

1072-403: 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 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

1139-410: Is air change rate or air changes per hour : the hourly rate of ventilation divided by the volume of the space. For example, six air changes per hour means an amount of new air, equal to the volume of the space, is added every ten minutes. For human comfort, a minimum of four air changes per hour is typical, though warehouses might have only two. Too high of an air change rate may be uncomfortable, akin to

1206-515: Is also used for baseboard heaters and portable heaters . Electrical heaters are often used as backup or supplemental heat for heat pump systems. The heat pump gained popularity in the 1950s in Japan and the United States. Heat pumps can extract heat from various sources , such as environmental air, exhaust air from a building, or from the ground. Heat pumps transfer heat from outside the structure into

1273-410: Is an approximation because it assumes that the molar mass of the flue gas and the outside air are equal and that the pressure drop through the flue gas stack is quite small. Both assumptions are fairly good but not exactly accurate. As a "first guess" approximation, the following equation can be used to estimate the flue-gas flow-rate induced by the draft of a flue-gas stack. The equation assumes that

1340-877: Is channeled through the space to enhance cooling and ventilation. Cross ventilation is most effective when there are clear, unobstructed paths for airflow within the building. In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside ( stack effect ), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate. An important component of natural ventilation

1407-675: Is dropped, as in HACR (as in the designation of HACR-rated circuit breakers ). HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels, and senior living facilities; medium to large industrial and office buildings such as skyscrapers and hospitals; vehicles such as cars, trains, airplanes, ships and submarines; and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors. Ventilating or ventilation (the "V" in HVAC)

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1474-478: 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 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

1541-499: Is known as room air distribution . In modern buildings, the design, installation, and control systems of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally estimate the capacity and type of system needed and then design the system, selecting the appropriate refrigerant and various components needed. For larger buildings, building service designers, mechanical engineers, or building services engineers analyze, design, and specify

1608-581: Is needed to improve the performance of ventilation in terms of ... In scenarios where outdoor pollution would deteriorate indoor air quality, other treatment devices such as filtration may also be necessary. Methods for ventilating a building may be divided into mechanical/forced and natural types. Mechanical, or forced, ventilation is provided by an air handler (AHU) and used to control indoor air quality. Excess humidity , odors, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates more energy

1675-450: Is not feasible or where the space conditioning efficiency is of prime concern. The benefits of ductless air conditioning systems include easy installation, no ductwork, greater zonal control, flexibility of control, and quiet operation. In space conditioning, the duct losses can account for 30% of energy consumption. The use of minisplits can result in energy savings in space conditioning as there are no losses associated with ducting. With

1742-639: Is possible to use a cooling tower as a flue gas stack. Examples can be seen in Germany at the Power Station Staudinger Grosskrotzenburg and at the Rostock Power Station . Power plants without flue gas purification would experience serious corrosion in such stacks. In the United States and a number of other countries, atmospheric dispersion modeling studies are required to determine the flue gas stack height needed to comply with

1809-436: Is required for any air conditioner installed. The refrigeration cycle uses four essential elements to cool, which are compressor, condenser, metering device, and evaporator. In variable climates, the system may include a reversing valve that switches from heating in winter to cooling in summer. By reversing the flow of refrigerant, the heat pump refrigeration cycle is changed from cooling to heating or vice versa. This allows

1876-458: Is required to remove excess moisture from ventilation air. Kitchens and bathrooms typically have mechanical exhausts to control odors and sometimes humidity. Factors in the design of such systems include the flow rate (which is a function of the fan speed and exhaust vent size) and noise level. Direct drive fans are available for many applications and can reduce maintenance needs. In summer, ceiling fans and table/floor fans circulate air within

1943-497: Is the process of changing or replacing air in any space to control the temperature or remove any combination of moisture, odors, smoke, heat, dust, airborne bacteria, or carbon dioxide, and to replenish oxygen. It plays a critical role in maintaining a healthy indoor environment by preventing the buildup of harmful pollutants and ensuring the circulation of fresh air. Different methods, such as natural ventilation through windows and mechanical ventilation systems , can be used depending on

2010-408: Is the process of exchanging or replacing air in any space to provide high indoor air quality which involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide, and other gases. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of

2077-460: Is the use of various technologies to control the temperature , humidity , and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality . HVAC system design is a subdiscipline of mechanical engineering , based on the principles of thermodynamics , fluid mechanics , and heat transfer . " Refrigeration " is sometimes added to the field's abbreviation as HVAC&R or HVACR , or "ventilation"

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2144-432: Is usually composed of carbon dioxide (CO 2 ) and water vapor, as well as nitrogen and excess oxygen remaining from the intake combustion air. It also contains a small percentage of pollutants such as particulate matter , carbon monoxide , nitrogen oxides and sulfur oxides . The flue gas stacks are often quite tall, up to 420 metres (1,380 ft), to increase the stack effect and dispersion of pollutants. When

2211-568: The dew point , moisture in the air condenses on the evaporator coil tubes. This moisture is collected at the bottom of the evaporator in a pan and removed by piping to a central drain or onto the ground outside. A dehumidifier is an air-conditioner-like device that controls the humidity of a room or building. It is often employed in basements that have a higher relative humidity because of their lower temperature (and propensity for damp floors and walls). In food retailing establishments, large open chiller cabinets are highly effective at dehumidifying

2278-411: The early industrial chimneys began to disappear from the industrial landscape. Building materials changed from stone and brick to steel and later reinforced concrete, and the height of the industrial chimney was determined by the need to disperse combustion flue gases to comply with governmental air pollution control regulations. The combustion flue gases inside the flue gas stacks are much hotter than

2345-421: The CDC recommends a minimum of 12 ACH. The 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. UVC or Ultraviolet Germicidal Irradiation is a function used in modern air conditioners which reduces airborne viruses , bacteria , and fungi , through

2412-458: The HVAC systems. Specialty mechanical contractors and suppliers then fabricate, install and commission the systems. Building permits and code-compliance inspections of the installations are normally required for all sizes of buildings Although HVAC is executed in individual buildings or other enclosed spaces (like NORAD's underground headquarters), the equipment involved is in some cases an extension of

2479-433: The air inside. Initially, heat pump HVAC systems were only used in moderate climates, but with improvements in low temperature operation and reduced loads due to more efficient homes, they are increasing in popularity in cooler climates. They can also operate in reverse to cool an interior. In the case of heated water or steam, piping is used to transport the heat to the rooms. Most modern hot water boiler heating systems have

2546-399: The ambient outside air and therefore less dense than the ambient air. That causes the bottom of the vertical column of hot flue gas to have a lower pressure than the pressure at the bottom of a corresponding column of outside air. That higher pressure outside the chimney is the driving force that moves the required combustion air into the combustion zone and also moves the flue gas up and out of

2613-484: The architecture permits. ASHRAE defined Natural ventilation as the flow of air through open windows, doors, grilles, and other planned building envelope penetrations , and as being driven by natural and/or artificially produced pressure differentials. Natural ventilation strategies also include cross ventilation , which relies on wind pressure differences on opposite sides of a building. By strategically placing openings, such as windows or vents, on opposing walls, air

2680-483: The blood, forming carboxyhemoglobin, reducing the blood's ability to transport oxygen. The primary health concerns associated with carbon monoxide exposure are its cardiovascular and neurobehavioral effects. Carbon monoxide can cause atherosclerosis (the hardening of arteries) and can also trigger heart attacks. Neurologically, carbon monoxide exposure reduces hand to eye coordination, vigilance, and continuous performance. It can also affect time discrimination. Ventilation

2747-440: The building design and air quality needs. Ventilation often refers to the intentional delivery of the outside air to the building indoor space. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Although ventilation 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

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2814-404: The chimney. That movement or flow of combustion air and flue gas is called "natural draft", "natural ventilation" , "chimney effect", or " stack effect ". The taller the stack, the more draft is created. The equation below provides an approximation of the pressure difference, Δ P , (between the bottom and the top of the flue gas stack) that is created by the draft: where: The above equation

2881-511: The components of HVAC systems went hand-in-hand with the Industrial Revolution , and new methods of modernization, higher efficiency, and system control are constantly being introduced by companies and inventors worldwide. Heaters are appliances whose purpose is to generate heat (i.e. warmth) for the building. This can be done via central heating . Such a system contains a boiler , furnace , or heat pump to heat water, steam, or air in

2948-413: The condenser coil is responsible for discharging both the indoor heat (as picked up by the evaporator) and the heat generated by the electric motor driving the compressor. HVAC is significantly responsible for promoting energy efficiency of buildings as the building sector consumes the largest percentage of global energy. Since the 1980s, manufacturers of HVAC equipment have been making an effort to make

3015-446: The control system will open (fully or partially) the outside air damper and close (fully or partially) the return air damper. This will cause fresh, outside air to be supplied to the system. When the outside air is cooler than the demanded cool air, this will allow the demand to be met without using the mechanical supply of cooling (typically chilled water or a direct expansion "DX" unit), thus saving energy. The control system can compare

3082-415: The cooling season, and later employing a heat pump to chill the circulation coming from the storage. The heat pump is added-in because the storage acts as a heat sink when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season. Some systems include an "economizer mode", which is sometimes called a "free-cooling mode". When economizing,

3149-559: The design of chimneys and stacks (notably, the ASME codes). The design of large stacks poses considerable engineering challenges. Vortex shedding in high winds can cause dangerous oscillations in the stack, and may lead to its collapse. The use of helical strake is common to prevent this process occurring at or close to the resonant frequency of the stack. Some fuel-burning industrial equipment does not rely upon natural draft. Many such equipment items use large fans or blowers to accomplish

3216-646: The emission of carbon monoxide , nitrogen oxides , formaldehyde , volatile organic compounds , and other combustion byproducts. Incomplete combustion occurs when there is insufficient oxygen; the inputs are fuels containing various contaminants and the outputs are harmful byproducts, most dangerously carbon monoxide, which is a tasteless and odorless gas with serious adverse health effects. Without proper ventilation, carbon monoxide can be lethal at concentrations of 1000 ppm (0.1%). However, at several hundred ppm, carbon monoxide exposure induces headaches, fatigue, nausea, and vomiting. Carbon monoxide binds with hemoglobin in

3283-410: The end of the long condensing flues associated with smelting lead . The powerful association between industrial chimneys and the characteristic smoke-filled landscapes of the industrial revolution was due to the universal application of the steam engine for most manufacturing processes. The chimney is part of a steam-generating boiler, and its evolution is closely linked to increases in the power of

3350-587: The first comfort air conditioning system, which was designed in 1902 by Alfred Wolff (Cooper, 2003) for the New York Stock Exchange, while Willis Carrier equipped the Sacketts-Wilhems Printing Company with the process AC unit the same year. Coyne College was the first school to offer HVAC training in 1899. The first residential AC was installed by 1914, and by the 1950s there was "widespread adoption of residential AC". The invention of

3417-410: The flue gases are exhausted from stoves, ovens, fireplaces, heating furnaces and boilers, or other small sources within residential abodes, restaurants, hotels, or other public buildings and small commercial enterprises, their flue gas stacks are referred to as chimneys. The first industrial chimneys were built in the mid-17th century, when it was first understood how they could improve the combustion of

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3484-433: 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 is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion. Natural ventilation requires little maintenance and

3551-417: The heated air through ductwork systems of supply and return air through metal or fiberglass ducts. Many systems use the same ducts to distribute air cooled by an evaporator coil for air conditioning. The air supply is normally filtered through air filters to remove dust and pollen particles. The use of furnaces, space heaters, and boilers as a method of indoor heating could result in incomplete combustion and

3618-568: The interior air. Methods for ventilating a building are divided into mechanical/forced and natural types. The three major functions of heating, ventilation, and air conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can be used in both domestic and commercial environments. HVAC systems can provide ventilation, and maintain pressure relationships between spaces. The means of air delivery and removal from spaces

3685-494: The internal air. Conversely, a humidifier increases the humidity of a building. The HVAC components that dehumidify the ventilation air deserve careful attention because outdoor air constitutes most of the annual humidity load for nearly all buildings. All modern air conditioning systems, even small window package units, are equipped with internal air filters. These are generally of a lightweight gauze-like material, and must be replaced or washed as conditions warrant. For example,

3752-522: The local air pollution regulations. The United States also limits the maximum height of a flue gas stack to what is known as the "Good Engineering Practice" (GEP) stack height. In the case of existing flue gas stacks that exceed the GEP stack height, any air pollution dispersion modelling studies for such stacks must use the GEP stack height rather than the actual stack height. HVAC#Natural ventilation Heating, ventilation, and air conditioning ( HVAC )

3819-401: The molar mass of the flue gas and the outside air are equal and that the frictional resistance and heat losses are negligible:. where: Also, this equation is only valid when the resistance to the draft flow is caused by a single orifice characterized by the discharge coefficient C. In many, if not most situations, the resistance is primarily imposed by the flue stack itself. In these cases,

3886-400: The opening of this vent. Typical fresh air intake is about 10% of the total supply air. Air conditioning and refrigeration are provided through the removal of heat. Heat can be removed through radiation , convection, or conduction . The heat transfer medium is a refrigeration system, such as water, air, ice, and chemicals are referred to as refrigerants . A refrigerant is employed either in

3953-569: The overall heating-portion of the DHC network (likely with energy added to boost the temperature). Basing HVAC on a larger network helps provide an economy of scale that is often not possible for individual buildings, for utilizing renewable energy sources such as solar heat, winter's cold, the cooling potential in some places of lakes or seawater for free cooling , and the enabling function of seasonal thermal energy storage . By utilizing natural sources that can be used for HVAC systems it can make

4020-574: The resistance is proportional to the stack height H. This causes a cancellation of the H in the above equation predicting Q to be invariant with respect to the flue height. Designing chimneys and stacks to provide the correct amount of natural draft involves a great many factors such as: The calculation of many of the above design factors requires trial-and-error reiterative methods. Government agencies in most countries have specific codes which govern how such design calculations must be performed. Many non-governmental organizations also have codes governing

4087-406: The rooms. Split systems are more efficient and the footprint is typically smaller than the package systems. On the other hand, package systems tend to have a slightly lower indoor noise level compared to split systems since the fan motor is located outside. Dehumidification (air drying) in an air conditioning system is provided by the evaporator. Since the evaporator operates at a temperature below

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4154-483: The same objectives, namely: the flow of combustion air into the combustion chamber and the flow of the hot flue gas out of the chimney or stack. A great many power plants are equipped with facilities for the removal of sulfur dioxide (i.e., flue-gas desulfurization ), nitrogen oxides (i.e., selective catalytic reduction , exhaust gas recirculation , thermal deNOx, or low NOx burners) and particulate matter (i.e., electrostatic precipitators ). At such power plants, it

4221-438: The split system, the evaporator coil is connected to a remote condenser unit using refrigerant piping between an indoor and outdoor unit instead of ducting air directly from the outdoor unit. Indoor units with directional vents mount onto walls, suspended from ceilings, or fit into the ceiling. Other indoor units mount inside the ceiling cavity so that short lengths of duct handle air from the indoor unit to vents or diffusers around

4288-460: The steam engine. The chimneys of Thomas Newcomen ’s steam engine were incorporated into the walls of the engine house. The taller, freestanding industrial chimneys that appeared in the early 19th century were related to the changes in boiler design associated with James Watt ’s "double-powered" engines, and they continued to grow in stature throughout the Victorian period. Decorative embellishments are

4355-447: The system intended to maintain constant indoor air conditions. Outside, fresh air is generally drawn into the system by a vent into a mix air chamber for mixing with the space return air. Then the mixture air enters an indoor or outdoor heat exchanger section where the air is to be cooled down, then be guided to the space creating positive air pressure. The percentage of return air made up of fresh air can usually be manipulated by adjusting

4422-581: The temperature of the outside air vs. return air, or it can compare the enthalpy of the air, as is frequently done in climates where humidity is more of an issue. In both cases, the outside air must be less energetic than the return air for the system to enter the economizer mode. Central, "all-air" air-conditioning systems (or package systems) with a combined outdoor condenser/evaporator unit are often installed in North American residences, offices, and public buildings, but are difficult to retrofit (install in

4489-521: The use of a built-in LED UV light that emits a gentle glow across the evaporator. As the cross-flow fan circulates the room air, any viruses are guided through the sterilization module’s irradiation range, rendering them instantly inactive. An air conditioning system, or a standalone air conditioner, provides cooling and/or humidity control for all or part of a building. Air conditioned buildings often have sealed windows, because open windows would work against

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