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While moving heat via machinery to provide air conditioning is a relatively modern invention, the cooling of buildings is not. Wealthy ancient Romans circulated aqueduct water through walls to cool their luxurious houses.
The 2nd century Chinese inventor Ding Huan (fl. 180) of the Han Dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (10 ft) in diameter and manually powered In 747, Emperor Xuanzong (r. 712-762) of the Tang Dynasty (618-907) had the Cool Hall (Liang Tian) built in the imperial palace, which the Tang Yulin describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains. During the subsequent Song Dynasty (960-1279), written sources mentioned the air conditioning rotary fan as even more widely used.
Medieval Persia had buildings that used cisterns and wind towers to cool buildings during the hot season: cisterns (large open pools in central courtyards, not underground tanks) collected rain water; wind towers had windows that could catch wind and internal vanes to direct the airflow down into the building, usually over the cistern and out through a downwind cooling tower. Cistern water evaporated, cooling the air in the building.
Ventilators were invented in medieval Egypt and were widely used in many houses throughout Cairo during the middle Ages. These ventilators were later described in detail by Abdu al-Latif al-Baghdadi in 1200, who reported that almost every house in Cairo has a ventilator, and that they cost anywhere from 1 to 500 dinars depending on their sizes and shapes. Most ventilators in the city were oriented towards the Qibla, as was the city in general.
The invention of 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 introduced by companies and inventors all over the world. The three central functions of heating, ventilating, and air-conditioning are interrelated, providing thermal comfort, acceptable indoor air quality, within reasonable installation, operation, and maintenance costs. HVAC systems can provide ventilation, reduce air infiltration, and maintain pressure relationships between spaces. How air is delivered to, and removed from spaces 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 "size" and select HVAC systems and equipment. For larger buildings, building services designers and engineers, such as mechanical, architectural, or building services engineers analyze, design, and specify the HVAC systems, and specialty mechanical contractors build and commission them. Building permits and code-compliance inspections of the installations are normally required for all sizes of buildings.
The HVAC industry is a worldwide enterprise, with career opportunities including operation and maintenance, system design and construction, equipment manufacturing and sales, and in education and research. The HVAC industry had been historically regulated by the manufacturers of HVAC equipment, but Regulating and Standards organizations such as HARDI, ASHRAE, SMACNA, ACCA, Uniform Mechanical Code, International Mechanical Code, and AMCA have been established to support the industry and encourage high standards and achievement
AIR CONDITIONING. Mechanical air conditioning made its first appearance at the turn of the twentieth century. Defined as the control of temperature, humidity, cleanliness, and distribution of air, it largely grew out of successful efforts to control humidity levels indoors. Systems were custom designed for each installation and were used to either add moisture to the air or remove the excess depending upon the application. Two basic types of air conditioning were marketed: comfort air conditioning for establishing the optimum conditions for human comfort, and process air conditioning for setting the most favorable atmospheric conditions for industrial processing.
One of the first comfort air conditioning systems was designed by Alfred Wolff for the trading room of the New York Stock Exchange in 1902, while Willis Carrier installed a process air conditioning system in the Sacketts-Wilhems Printing Company the same year. Carrier has long been air conditioning's most famous engineer due in part to his pioneering status and in part to the visibility of his company, which established a dominant place in the industry first through its engineering expertise and then through its strong patent position
Air conditioning applications.
Air conditioning engineers broadly divide air conditioning applications into comfort and process.
Comfort applications aim to provide a building indoor environment that remains relatively constant in a range preferred by humans despite changes in external weather conditions or in internal heat loads.
Air conditioning makes deep plan buildings feasible, for otherwise they'd have to be built narrower or with light wells so that inner spaces receive sufficient outdoor air via natural ventilation. Air conditioning also allows buildings to be taller since wind speed increases significantly with altitude making natural ventilation impractical for very tall buildings. Comfort applications for various building types are quite different and may be categorized as
Low-Rise Residential buildings, including single family houses, duplexes, and small apartment buildings
High-Rise Residential buildings, such as tall dormitories and apartment blocks
Commercial buildings, which are built for commerce, including offices, malls, shopping centers, restaurants, etc.
Institutional buildings, which includes hospitals, governmental, academic, and so on.
Industrial spaces where thermal comfort of workers is desired
1) Efficiency of the human beings increases: It has been found by research that in the comfort conditions the working capacity of the human beings increases. If the room temperature is very high, not all the heat from the body is released and the person feels uncomfortable from deep within that causes irritation of mind and lack of concentration. The person also tends to get tired fast in hot temperatures. At the comfort conditions created by the AC, the person feels peaceful from deep inside and is able to work more. The clean air further helps human beings perform more work.
2) Better health: The air conditioner helps circulate filtered air inside the room or office. This air is free from dust and dirt particles, smoke, microorganisms, bacteria etc. Due to this healthy environment is created inside the room and the health of person is improved.
3) Less noise: The windows of the air conditioned rooms and offices are closed, due to this less outside sound enters the rooms. Even the noise from the air-conditioners is very low. Due to this there is quietness inside the rooms, which gives soothing sleep at night and also maintains peace inside the hospitals and theaters. The noise inside the air conditioned room can be further reduced by soundproofing the room.
4) Fresh air: The fresh air can be taken inside the air-conditioned room at any time merely by opening the door or windows. Fresh can also be taken in by the blower of the air-conditioner.
Due to above so many advantages the use of the air conditioners has become so much rampant today. In the earlier days air-conditioner was considered to be the item of luxury, now it has become the item of necessity without which one just can't live in the extreme summer conditions.
Air conditioning, benefits and disadvantages .
Over a hundred years ago the first installation of air conditioning was produced in the United States. Certainly nobody could anticipate the magnitude that such equipment has reached today. Both summer and winter, the demand for air conditioning devices are increasing. Of course their benefits are recognized, but can they become our enemies?
The human body normally has a stable internal temperature of 37 degrees Celsius which is held by a natural mechanism which helps us to permanently remove excess heat produced by the body.
The air conditioning units are helping our body to ensure that the rate of excess heat removal, which is valid for summer and also for winter. They keep the air temperature and humidity in certain limits.
The first air conditioning products were those with two units, one outside the room and one inside. However, most of them are not properly installed. They were designed for small rooms, one for each room, estimating a number of two people living inside. But these devices are frequently installed in larger rooms, crowded and requiring mechanical ventilation. Thus, the air conditioners with 2 units are installed in discotheques, restaurants, theaters, kitchens.
It is no recommended to place these units in such places because they are not producing fresh air. They are only recycling the existing air in the room and they cool it. On the other hand, cold air is introduced as a jet, and this creates a feeling of discomfort for those who are forced to stay close to the device. Is the current sensation, more unbearable in small rooms?
Split has a small thermal power, is therefore you need more devices in a larger room. Their filters are designed relatively clean rooms, without too much dust and no pollutants.
The air conditioning gives us the opportunity to set the thermostat to desired temperature. For those who work in the office, for example, and are dressed accordingly to the season, internal comfort temperature varies during the summer, between 24 degrees Celsius and +26.5 degrees Celsius with relative humidity between 30-70%. Usually, in a room there are people with different metabolic characteristics, therefore it is recommended to choose a temperature that is comfortable for all.
Direct contact with the jet of air can be avoided by mounting the air conditioning units so that it does not work directly to the cephalic extremity (neck, eyes, ears) and spinal column. As the air flows a greater distance and changes direction several times, is even better. Those who spend too much time in rooms where air conditioning cannot be adapted to summer temperatures could face the common cold and influenza .
An improved room air conditioner of the type assembled from a first subassembly, which includes a base pan having an indoor region proximate the front of the base pan and an outdoor region proximate the back of the base pan. A compressor, a condenser coil, an evaporator coil, and a refrigeration flow circuit are all included in the first subassembly. A second subassembly includes a vertically extending partition having an indoor side, an outdoor side and an opening therein extending from the indoor side to the outdoor side. The partition is configured to cooperate with the base pan to separate the indoor region from the outdoor region. The second subassembly includes an electric motor mounted on the partition, which is adapted to drive an indoor fan and an outdoor fan. The first and second subassemblies are configured such that they may be assembled separate from one another and may be assembled to one another by the positioning of the second subassembly in a position vertically spaced above the subassembly and lowering the second subassembly into a predetermined alignment with the first subassembly with the partition engaging the base pan. The partition is provided with a vertically extending lower portion defining a lower edge. The base pan defines a lower wall having formed therein an upstanding structural wall,
Configured to receive the lower portion of the partition in confronting relation therewith with the lower edge of the partition in contact with the lower wall .
To be exempt development, the development:
(a) Must meet the relevant deemed-to-satisfy provisions of the Building Code of Australia, or if those provisions do not apply, must be structurally adequate, and
(b) Must not, if it relates to an existing building, cause the building to contravene the Building Code of Australia, and
(c) Must not be designated development, and
(d) Must not be carried out on land that comprises, or on which there is, an item that is listed on the State Heritage Register under the Heritage Act 1977 or that is subject to an interim heritage order under the Heritage Act 1977.
(2) Development that relates to an existing building that is classified under the Building Code of Australia as class 1b or class 2-9 is exempt development only if:
(a) The building has a current fire safety certificate or fire safety statement, or
(b) No fire safety measures are currently implemented, required or proposed for the building.
(3) To be exempt development, the development must:
(a) Be installed in accordance with the manufacturer's specifications, if applicable .
(b) Must not involve the removal or pruning of a tree or other vegetation that requires a permit or development consent for removal or pruning, unless that removal or pruning is undertaken in accordance with a permit or development consent.
Air conditioning and thermal comfort in Australian Public Service offices.
This information booklet has been developed jointly by the Department of Industrial Relations and The Community and Public Sector Union (CPSU) with assistance from Mr. Paul Spry of Australian Construction Services (a division of the Department of Administrative Services) and Compares Australia.
The purpose of this information booklet is to provide workplace Health and Safety Representatives (HSRs) in Australian Public Service (APS) employment with an increased understanding and awareness of air-conditioning, indoor air quality and thermal comfort.
This booklet does not purport to provide instant answers to workplace problems which may be associated with office air conditioning. It does, however, attempt to raise awareness, provide steps to follow and issues to consider when discussing air-conditioning issues in the workplace.
It is envisaged that HSR's, the designated work groups they represent, union representatives, employers and supervisors will, in a co-operative spirit, consider and apply this material where possible to resolve problems that might arise in relation to air-conditioning.
Installing a central air conditioning take at least a few hours and will require some help from an electrician, unless you are one yourself. If you need pipes or ducts, it will take much longer. You might want to consult a contractor for additional help. If you are used to similar installations, you might be able to do the process yourself. Just make sure your main power supply supports the system before starting.