1.Residential environment.Criteria for healthful housing.Housing standards. Methodsfor hygienic assessment ofheating, lighting andventilation

2. A building and skybridge in Munich,Germany. 3. Example of a religious building : the Great Mosque ofKairouan (also called the Mosque of Uqba), founded in670, dates in its present state principally from the 9thcentury. The Great Mosque of Kairouan is located in thecity of Kairouan, Tunisia. 4. Rivers Towers building underconstruction. Ccuta, Colombia. 5. Anyhuman-made structure used or intended for supporting or sheltering any use or continuous occupancy, orAn act of construction (i.e. the activity of building, see also builder) 6. Buildings come in a wide amount ofshapes and functions, and have beenadapted throughout history for a widenumber of factors, from buildingmaterials available, to weatherconditions, to land prices, groundconditions, specific uses and aestheticreasons. 7. Buildings serve several needs of society primarily as shelter from weather andas general living space, to provideprivacy, to store belongings and tocomfortably live and work. A building asa shelter represents a physical division ofthe human habitat (a place of comfortand safety) and the outside (a place thatat times may be harsh and harmful). 8. Ever since the first cave paintings,buildings have also become objects orcanvasess of artistic expression. In recentyears, interest in sustainable planningand building practices has also becomepart of the design process of many newbuildings. 9. As a Civil Engineering structures such as ahouse,worship centre,Factories etc. that has afoundation,wall,roof etc. that protect humanbeing and their properties from direct harsheffect of weather like rain,wind,sun etc. The act of constructing, erecting, or establishing. The art of constructing edifices, or the practice ofcivil architecture. That which is built; a fabric or edificeconstructed, as a house, a church, castle, arena/stadium, etc 10. The act of constructing or building something;"during the construction we had to take adetour"; "his hobby was the building of boats" The commercial activity involved in constructingbuildings; "their main business is homeconstruction"; "workers in the building trades" A structure that has a roof and walls and standsmore or less permanently in one place; "therewas a three-storey building on the corner"; "itwas an imposing edifice" The occupants of a building; "the entire buildingcomplained about the noise" 11. To differentiate buildings in the usage of this articlefrom other buildings and other structures that arenot intended for continuous human occupancy, thelatter are called non-building structures or simplystructures. Structural height in technical usage is the height tothe highest architectural detail on building fromstreet-level. Depending on how they are classified,spires and masts may or may not be included in thisheight. Spires and masts used as antennas are notgenerally included. The definition of a low-rise vs. a high-rise building isa matter of debate, but generally three storeys or lessis considered low-rise. 12. The first shelter on Earthconstructed by a relatively closeancestor to humans is believed tobe built 500,000 years ago by anearly ancestor of humans, Homoerectus. 13. A timber framing house in Marburg,Germany. 14. Residential buildings are calledhouses/homes, though buildingscontaining large numbers ofseparate dwelling units are oftencalled apartment buildings orapartment blocks to differentiatethem from the more individualhouse. 15. Building types may range from one-roomwood-framed, masonry, or adobedwellings to multi-million dollar high-rise buildings able to house thousands ofpeople. Increasing settlement density inbuildings (and closer distances betweenbuildings) is usually a response to highground prices resulting from manypeople wanting to live close to work orsimilar attractors. 16. Some of Denvers multi-storey buildings. 17. Amulti-storey building is a building thathas multiple floors above ground in thebuilding. Multi-storey buildings aim to increasethe area of the building withoutincreasing the area of the land thebuilding is built on, hence saving landand, in most cases, money (depending onmaterial used and land prices in thearea). 18. The practice of designing,constructing, and operatingbuildings is most usually a collectiveeffort of different groups ofprofessionals and trades. Dependingon the size, complexity, and purposeof a particular building project, theproject team may include: 19. A real estate developer who secures funding forthe project; One or more financial institutions or otherinvestors that provide the funding Local planning and code authorities A Surveyor who performs an ALTA/ACSM andconstruction surveys throughout the project; Construction managers who coordinate the effortof different groups of project participants; Licensed architects and engineers who providebuilding design and prepare constructiondocuments; 20. Landscape architects; Interior designers; Other consultants; Contractors who provideconstructionservices and install building systems such asclimate control, electrical, plumbing,Decoration, fire protection, security andtelecommunications; Marketing or leasing agents; Facility managers who are responsible foroperating the building. 21. Regardless oftheir size or intended use,all buildings in the US must comply withzoning ordinances, building codes andother regulations such as fire codes, lifesafety codes and related standards. Vehiclessuch as trailers, caravans,ships and passenger aircraftare treatedas "buildings" for life safety purposes. 22. Any building requires a certain amount ofinternal infrastructure to function, whichincludes such elements like heating /cooling, power and telecommunications,water and wastewater etc. Especially incommercial buildings (such as offices orfactories), these can be extremely intricatesystems taking up large amounts of space(sometimes located in separate areas ordouble floors / false ceilings) and constitutea big part of the regular maintenancerequired. 23. Systems for transport of people withinbuildings: Elevator Escalator Moving sidewalk (horizontal andinclined) Systems for transport of people betweeninterconnected buildings: Skyway Underground city 24. A building in Massueville, Quebec,Canada engulfed by fire. 25. Buildings may be damaged duringthe construction of the building orduring maintenance. There areseveral other reasons behindbuilding damage like accident.Buildings also may suffer from firedamage and flooding in specialcircumstances. 26. International guidance on "healthyhousing" should be developed to helpprevent a wide range of diseases andunintentional injuries that can beeffectively addressed through betterhousing. This was a key messageemerging from an internationalconsultation of 40 experts from 18countries hosted by WHO in Geneva 13-15 October, 2010. 27. "Housing improvements are acceleratingfor many reasons to conserve energy inthe face of climate change, address needsof a rapidly urbanizing global population,prevention of homelessness and slumgrowth, and other factors," theparticipants said in a closing statement. 28. "There is a clear need and opportunity forgovernments and others to promote healthin the course of making investments inhousing. International guidance on healthyhousing targeting construction experts,architects and engineers as well as housingagencies and local authorities wouldenable action that is scientifically-based,and protects and advances public health. 29. Examples of key housing-related healthrisks include: respiratory andcardiovascular diseases from indoor airpollution; illness and deaths fromtemperature extremes; communicablediseases spread because of poor livingconditions, and risks of home injuries. WHOestimates that nearly 2 million people indeveloping countries die from indoor airpollution caused by the burning of biomassand coal in leaky and inefficient householdstoves. 30. Inadequate ventilation is also associatedwith a higher risk of airborne infectiousdisease transmission, includingtuberculosis, as well as the accumulation ofindoor pollutants and dampness, which arefactors in the development of allergies andasthma. Poor housing quality and designalso can exacerbate the health impacts fromexposure to temperature extremes, whichare occurring more frequently due toclimate change. 31. "Most of the worlds population growthover the next 20 years will occur in lowand middle income cities; nearly 40percent of urban growth today is inunhealthy slum housing. Additionally,many countries have initiatedprogrammes to modify their existinghousing stock to make homes moreenergy efficient and more resilient in theface of climate change." 32. Ventilation 33. An air handling unit is used for theheating and cooling of air in a centrallocation 34. Ventilating (the V in HVAC) is the process of"changing" or replacing air in any space toprovide high indoor air quality (i.e. tocontrol temperature, replenish oxygen, orremove moisture, odors, smoke, heat, dust,airborne bacteria, and carbon dioxide).Ventilation is used to remove unpleasantsmells and excessive moisture, introduceoutside air, to keep interior building aircirculating, and to prevent stagnation of theinterior air. 35. Ventilation includes both the exchangeof air to the outside as well ascirculation of air within the building. Itis one of the most important factors formaintaining acceptable indoor airquality in buildings. Methods forventilating a building may be dividedinto mechanical/forced and naturaltypes. 36. is used to control indoor air quality.Excess humidity, odors, andcontaminants can often be controlledvia dilution or replacement withoutside air. However, in humid climatesmuch energy is required to removeexcess moisture from ventilation air. 37. Kitchens and bathrooms typically have mechanicalexhaust to control odors and sometimes humidity.Kitchens have additional problems to deal withsuch as smoke and grease (see kitchen ventilation).Factors in the design of such systems include theflow rate (which is a function of the fan speed andexhaust vent size) and noise level. If ducting for thefans traverse unheated space (e.g., an attic), theducting should be insulated as well to preventcondensation on the ducting. Direct drive fans areavailable for many applications, and can reducemaintenance needs. 38. Ceiling fans and table/floor fans circulateair within a room for the purpose ofreducing the perceived temperaturebecause of evaporation of perspiration onthe skin of the occupants. Because hot airrises, ceiling fans may be used to keep aroom warmer in the winter by circulatingthe warm stratified air from the ceiling tothe floor. Ceiling fans do not provideventilation as defined as the introduction ofoutside air. 39. is the ventilation of a building with outsideair without the use of a fan or othermechanical system. It can be achieved withopenable windows or trickle vents when thespaces to ventilate are small and thearchitecture permits. In more complexsystems warm air in the building can beallowed to rise and flow out upper openingsto the outside (stack effect) thus forcingcool outside air to be drawn into thebuilding naturally through openings in thelower areas. 40. These systems use very little energy but caremust be taken to ensure the occupantscomfort. In warm or humid months, in manyclimates, maintaining thermal comfort solelyvia natural ventilation may not be possible soconventional air conditioning systems areused as backups. Air-side economizersperform the same function as naturalventilation, but use mechanical systems fans,ducts, dampers, and control systems tointroduce and distribute cool outdoor airwhen appropriate. 41. Ventilation is the intentional movement of air fromoutside a building to the inside. Ventilation air, asdefined in ASHRAE Standard 62.1 and the ASHRAEHandbook, is that air used for providing acceptableindoor air quality. It mustnt be confused with ventsor flues; which mean the exhausts of clothes dryersand combustion equipment such as water heaters,boilers, fireplaces, and wood stoves. The vents orflues carry the products of combustion which have tobe expelled from the building in a way which doesnot cause harm to the occupants of the building.Movement of air between indoor spaces, and not theoutside, is called transfer air. 42. In commercial, industrial, and institutional (CII)buildings, and modern jet aircraft, return air isoften recirculated to the air handling unit. Aportion of the supply air is normally exfiltratedthrough the building envelope or exhausted fromthe building (e.g., bathroom or kitchen exhaust)and is replaced by outside air introduced into thereturn air stream. The rate of ventilation airrequired, most often provided by thismechanically-induced outside air, is oftendetermined from ASHRAE Standard 62.1 for CIIbuildings, or 62.2 for low-rise residential buildings,or similar standards. 43. When people or animals are present in buildings,ventilation air is necessary to dilute odors and limit theconcentration of carbon dioxide and airbornepollutants such as dust, smoke and volatile organiccompounds (VOCs). Ventilation air is often delivered tospaces by mechanical systems which may also heat,cool, humidify and dehumidify the space. Airmovement into buildings can occur due to uncontrolledinfiltration of outside air through the building fabric(see stack effect) or the use of deliberate naturalventilation strategies. Advanced air filtration andtreatment processes such as scrubbing, can provideventilation air by cleaning and recirculating aproportion of the air inside a building. 44. Mechanical or forced ventilation:through an air handling unit ordirect injection to a space by afan. A local exhaust fan canenhance infiltration or naturalventilation, thus increasing theventilation air flow rate. 45. Natural ventilation occurs when the air in aspace is changed with outdoor air withoutthe use of mechanical systems, such as a fan.Most often natural ventilation is assuredthrough operable windows but it can also beachieved through temperature and pressuredifferences between spaces. Open windowsor vents are not a good choice forventilating a basement or other belowground structure. Allowing outside air into acooler below ground space will causeproblems with humidity and condensation. 46. Mixed Mode Ventilation or Hybrid ventilation: utilisesboth mechanical and natural ventilation processes. Themechanical and natural components may be used inconjunction with each other or separately at differenttimes of day. The natural component, sometimessubject to unpredictable external weather conditionsmay not always be adequate to ventilate the desiredspace. The mechanical component is then used toincrease the overall ventilation rate so that the desiredinternal conditions are met. Alternatively themechanical component may be used as a controlmeasure to regulate the natural ventilation process, forexample, to restrict the air change rate during periodsof high wind speeds. 47. Infiltration is separate from ventilation, but is often used to provide ventilation air. 48. The ventilation rate, for CII buildings, isnormally expressed by the volumetricflowrate of outside air being introducedto the building. The typical units usedare cubic feet per minute (CFM) or litersper second (L/s). The ventilation ratecan also be expressed on a per personor per unit floor area basis, such asCFM/p or CFM/ft, or as air changes perhour. 49. For residential buildings, which mostly relyon infiltration for meeting their ventilationneeds, the common ventilation ratemeasure is the number of times the wholeinterior volume of air is replaced per hour,and is called air changes per hour (I or ACH;units of 1/h). During the winter, ACH mayrange from 0.50 to 0.41 in a tightly insulatedhouse to 1.11 to 1.47 in a loosely insulatedhouse. 50. In 1973, in response to the 1973 oil crisis andconservation concerns, ASHRAE Standards 62-73and 62-81) reduced required ventilation from 10CFM (4.76 L/S) per person to 5 CFM (2.37 L/S)per person. This was found to be a primary causeof sick building syndrome. Current ASHRAE standards (Standard 62-89)states that appropriate ventilation guidelines are20 CFM (9.2 L/s) per person in an office building,and 15 CFM (7.1 L/s) per person for schools. Incommercial environments with tobacco smoke,the ventilation rate may range from 25 CFM to125 CFM. 51. FumehoodBiological safety cabinetDilution ventilationRoom air distributionHeat recovery ventilation 52. Natural ventilation involvesharnessing naturally available forcesto supply and removing air throughan enclosed space. There are threetypes of natural ventilationoccurring in buildings: wind drivenventilation, pressure-driven flows,and stack ventilation. 53. DCV makes it possible to maintainproper ventilation and improve airquality while saving energy. ASHRAE hasdetermined that: "It is consistent withthe Ventilation rate procedure thatDemand Control be permitted for use toreduce the total outdoor air supplyduring periods of less occupancy." CO2sensors will control the amount ofventilation for the actual number ofoccupants. 54. Local exhaust ventilation addresses the issue ofavoiding the contamination of indoor air byspecific high-emission sources by capturingairborne contaminants before they are spreadinto the environment. This can include watervapor control, lavatory bioeffluent control,solvent vapors from industrial processes, anddust from wood- and metal-working machinery.Air can be exhausted through pressurizedhoods or through the use of fans andpressurizing a specific area. 55. A local exhaust system is composed of 5basic parts A hood that captures the contaminant at itssource Ducts for transporting the air An air-cleaning device thatremoves/minimizes the contaminant A fan that moves the air through the system An exhaust stack through which thecontaminated air is discharged 56. Combustion (e.g., fireplace, gas heater,candle, oil lamp, etc.) consumes oxygenwhile producing carbon dioxide and otherunhealthy gases and smoke, requiringventilation air. An open chimney promotesinfiltration (i.e. natural ventilation) becauseof the negative pressure change induced bythe buoyant, warmer air leaving through thechimney. The warm air is typically replacedby heavier, cold air. 57. ASHRAE standard 62 states that airremoved from an area withenvironmental tobacco smoke shallnot be recirculated into ETS-free air.A space with ETS requires moreventilation to achieve similarperceived air quality to that of a non-smoking environment. 58. In hot, humid climates,unconditioned ventilation air willdeliver approximately one pound ofwater each day for each cfm ofoutdoor air per day, annual average.This is a great deal of moisture, andit can create serious indoor moistureand mold problems. 59. Ventilation efficiency is determined by designand layout, and is dependent upon placementand proximity of diffusers and return airoutlets. If they are located closely together,supply air may mix with stale air, decreasingefficiency of the HVAC system, and creating airquality problems. System imbalances occur when components ofthe HVAC system are improperly adjusted orinstalled, and can create pressure differences(too much circulating air creating a draft or toolittle circulating air creating stagnancy). 60. Cross-contaminationoccurs when pressuredifferences arise, forcing potentiallycontaminated air from one zone to anuncontaminated zone. This often involvesundesired odors or VOCs. Re-entry of exhaust air occurs when exhaustoutlets and fresh air intakes are either tooclose, or prevailing winds change exhaustpatterns, or by infiltration between intakeand exhaust air flows. 61. Entrainment of contaminated outside airthrough intake flows will result in indoorair contamination. There are a variety ofcontaminated air sources, ranging fromindustrial effluent to VOCs put off bynearby construction work. 62. Ventilation Rate Procedure is rate basedon standard, and prescribes the rate atwhich ventilation air must be deliveredto a space and various means tocondition that air. Air quality isassessed (through CO2 measurement)and ventilation rates aremathematically derived using constants. 63. Indoor Air Quality Procedure uses one ormore guidelines for the specification ofacceptable concentrations of certaincontaminants in indoor air but does notprescribe ventilation rates or air treatmentmethods. This addresses both quantitativeand subjective evaluation, and is based onthe Ventilation Rate Procedure. It alsoaccounts for potential contaminants thatmay have no measured limits, or limits arenot set (such as formaldehyde offgassingfrom carpet and furniture). 64. HVAC systems use ventilation air ductsinstalled throughout a building thatsupply conditioned air to a room throughrectangular or round outlet vents, calleddiffusers; and ducts that remove airthrough return-air grilles 65. HVAC (heating, ventilation, and airconditioning) refers to technology of indoorand automotive environmental comfort.HVAC system design is a major subdisciplineof mechanical engineering, based on theprinciples of thermodynamics, fluidmechanics, and heat transfer. Refrigerationis sometimes added to the fieldsabbreviation as HVAC&R or HVACR, orventilating is dropped as in HACR (such asthe designation of HACR-rated circuitbreakers). 66. HVAC is important in the design ofmedium to large industrial and officebuildings such as skyscrapers and inmarine environments such asaquariums, where safe and healthybuilding conditions are regulated withrespect to temperature and humidity,using fresh air from outdoors. 67. Central heating system 68. Central heating is often used in cold climates to heatprivate houses and public buildings. Such a systemcontains a boiler, furnace, or heat pump to heatwater, steam, or air in a central location such as afurnace room in a home or a mechanical room in alarge building. The use of water as the heat transfermedium is known as hydronics. These systems alsocontain either ductwork for forced air systems orpiping to distribute a heated fluid and radiators totransfer this heat to the air. The term radiator in thiscontext is misleading since most heat transfer fromthe heat exchanger is by convection, not radiation.The radiators may be mounted on walls or buried inthe floor to give under-floor heat. 69. All but the simplest boiler-fed or radiantheating systems have a pump to circulatethe water and ensure an equal supply ofheat to all the radiators. The heatedwater can also be fed through another(secondary) heat exchanger inside astorage cylinder to provide hot runningwater. 70. Forcedair systems send heated air throughductwork. During warm weather the sameductwork can be used for air conditioning.The forced air can also be filtered or passedthrough air cleaners. Heat can also be provided electrically byresistive heating, in which conductivefilaments are heated by the passage ofelectricity. This is used in baseboardheaters, portable heaters, and as backup orsupplemental heating for heat pump (orreverse heating) systems. 71. The heat pump is a form of heating thatgained popularity in the 1950s. Heatpumps can extract heat from the air orsuck heat from the ground. Heat pumpswork well in moderate climates, wheresummers are long and winters are mild.However, they tend to be more expensivethan conventional heating systems andalthough more energy efficient, a groundextraction system is more costly. 72. The heating elements (radiators or vents) should belocated in the coldest part of the room, typically nextto the windows, to minimize condensation and offsetthe convective air current formed in the room due tothe air next to the window becoming negativelybuoyant due to the cold glass. Devices that directvents away from windows to prevent "wasted" heatdefeat this design intent. Cold air drafts cancontribute significantly to subjectively feeling colderthan the average room temperature, and for thisreason it is important to control air leaks fromoutside in addition to properly designing the heatingsystem 73. The invention of central heating is often credited tothe ancient Romans, who installed systems of airducts called hypocausts in the walls and floors ofpublic baths and private villas. The use of furnaces, space heaters and boilers asmeans of indoor heating may result in incompletecombustion and the emission of carbon monoxide,NOx, formaldehyde, VOCs and other combustion by-products. Incomplete combustion occurs when thereis insufficient oxygen; the inputs are fuels containingvarious contaminants and the outputs are theharmful by-products, most dangerously carbonmonoxide which is a tasteless and odorless gas thathas serious adverse health effects when inhaled. 74. Without proper ventilation, carbon monoxide can beextremely dangerous and can vary from a small, limitedamount to a lethal amount. Carbon monoxide can be lethal athigh concentration, usually less than 1000 ppmv. However, atseveral hundred ppmv, carbon monoxide exposure can induceheadaches, fatigue, nausea and vomiting. Carbon monoxidebinds with hemoglobin in the blood, formingcarboxyhemoglobin, reducing the bloods ability to transportoxygen. The primary health concerns associated with carbonmonoxide exposure are its cardiovascular and neurobehavioraleffects. Carbon monoxide can cause atherosclerosis; thehardening of arteries, and can also trigger heart attacks.Neurologically, carbon monoxide exposure reduces hand to eyecoordination, vigilance and continuous performance. It canalso affect your time discrimination. 75. Lighting 76. Low-intensity lighting and haze in aconcert hall allows laser effects to bevisible 77. Daylight used at the train station Gare delEst Paris 78. Illuminated Cherry blossoms, light fromthe shop windows, and Japanese lanternat night in Ise, Mie, Japan 79. Indoor lighting is usuallyaccomplished using lightfixtures, and is a key part ofinterior design. Lighting can alsobe an intrinsic component oflandscape projects. 80. Forms of lighting include alcove lighting,which like most other uplighting is indirect.This is often done with fluorescent lighting(first available at the 1939 Worlds Fair) orrope light, or occasionally with neonlighting. It is a form of backlighting. Soffit or close to wall lighting can be generalor a decorative wall-wash, sometimes usedto bring out texture (like stucco or plaster)on a wall, though this may also show itsdefects as well. The effect depends heavilyon the exact type of lighting source used. 81. Recessed lighting (often called "pot lights" inCanada, "can lights" or high hats" in the US) ispopular, with fixtures mounted into the ceilingstructure so as to appear flush with it. Thesedownlights can use narrow beam spotlights, orwider-angle floodlights, both of which are bulbshaving their own reflectors. There are alsodownlights with internal reflectors designed toaccept common A lamps (light bulbs) which aregenerally less costly than reflector lamps.Downlights can be incandescent, fluorescent, HID(high intensity discharge) or LED. 82. Track lighting, invented by Lightolier, was popular at onepoint because it was much easier to install than recessedlighting, and individual fixtures are decorative and can beeasily aimed at a wall. It has regained some popularityrecently in low-voltage tracks, which often look nothing liketheir predecessors because they do not have the safetyissues that line-voltage systems have, and are therefore lessbulky and more ornamental in themselves. A mastertransformer feeds all of the fixtures on the track or rod with12 or 24 volts, instead of each light fixture having its ownline-to-low voltage transformer. There are traditional spotsand floods, as well as other small hanging fixtures. Amodified version of this is cable lighting, where lights arehung from or clipped to bare metal cables under tension. 83. Theportable or table lamp is probably themost common fixture, found in many homesand offices. The standard lamp and shadethat sits on a table is general lighting, whilethe desk lamp is considered task lighting.Magnifier lampA sconce is a wall-mountedfixture, particularly one that shines up andsometimes down as well. A torchiere is anuplight intended for ambient lighting. It istypically a floor lamp but may be wall-mounted like a sconce. s are also task lighting. 84. Animated fountain in Moscows Square of Europe, lit at night. 85. The illuminated ceiling was once popular in the 1960s and1970s but fell out of favor after the 1980s. This uses diffuserpanels hung like a suspended ceiling below fluorescentlights, and is considered general lighting. Other formsinclude neon, which is not usually intended to illuminateanything else, but to actually be an artwork in itself. Thiswould probably fall under accent lighting, though in a darknightclub it could be considered general lighting. In a movie theater each step in the aisles is usually markedwith a row of small lights, for convenience and safety whenthe film has started, hence the other lights are off.Traditionally made up of small low wattage, low voltagelamps in a track or translucent tube, these are rapidly beingreplaced with LED based versions. 86. Vehicles typically includeheadlamps and tail lights. 87. Commonly called light bulbs, lamps are theremovable and replaceable part of a light fixture,which converts electrical energy intoelectromagnetic radiation. While lamps havetraditionally been rated and marketed primarilyin terms of their power consumption, expressedin watts, proliferation of lighting technologybeyond the incandescent light bulb haseliminated the correspondence of wattage to theamount of light produced. For example, a 60 Wincandescent light bulb produces about the sameamount of light as a 13 W compact fluorescentlamp. 88. Ballast: A ballast is an auxiliary piece ofequipment designed to start and properlycontrol the flow of power to discharge lightsources such as fluorescent and high intensitydischarge (HID) lamps. Some lamps require theballast to have thermal protection. fluorescent light: A tube coated with phosphorcontaining low pressure mercury vapor thatproduces white light. Halogen: High pressure incandescent lampscontaining halogen gases such as iodine orbromine, increasing the efficacy of the lampversus a plain incandescent lamp. 89. Neon:A low pressure gas contained within aglass tube; the color emitted depends on thegas. Light emitting diodes: Light emitting diodes(LED) are solid state devices that emit lightby dint of the movement of electrons in asemiconductor material. Compact fluorescent lamps: CFLs aredesigned to replace incandescent lamps inexisting and new installations.