Aarushhh/wikipedia-simple-splitted huggingface dataset:
Other examples include:
 Data Processing Centers
 Textile Factories
 Physical Testing Facilities
 Plants and Farm Growing Areas
 Nuclear Facilities
 Mines
 Industrial Environments
 Food Cooking and Processing Areas

In both comfort and process applications, the objective is not only to control temperature; (although in some comfort applications, this is all that is controlled) but also factors like humidity, air movement, and air quality.)

 Air conditioning system basics and theories 
 Refrigeration cycle 

In the refrigeration cycle, a pump transfers heat from a lower temperature source into a higher temperature heat sink. Heat will naturally flow in the opposite direction. This is the most common type of air conditioning.  A refrigerated air conditioning system works in much the same way, pumping heat out of the room in which it stands.
The most common refrigeration cycle uses an electric motor to drive a compressor. In an automobile, the compressor is driven by a pulley on the engine's crankshaft, with both using electric motors for air circulation. Since evaporation occurs when heat is absorbed, and condensation occurs when heat is released, air conditioners are designed to use a compressor to cause pressure changes between two compartments, and actively pump a coolant around an enclosed system. They do this in a Condenser and a Evaporator The cooling liquid, or refrigerant is pumped into the cooled compartment (the evaporator coil). Low pressure then causes the refrigerant to evaporate taking the heat with it. In the other compartment (the condenser), the refrigerant vapor is compressed and forced through another heat exchange coil, condensed into a liquid which then rejects the heat previously absorbed from the cooled space.

Health implications
Air conditioning has as much influence on human health as any generic heating system. Poorly maintained air-conditioning systems (especially large, centralized systems) can occasionally promote the growth and spread of microorganisms such as Legionella pneumophila,'' the infectious agent responsible for Legionnaire's disease.  Air conditioning can have a positive effect on sufferers of allergies and asthma.

In serious heat waves, air conditioning can save the lives of the elderly. Some local authorities have even set up public cooling centers for the benefit of those without air conditioning at home.

References

Related pages
 Energy
 Heat pump
 Renewable energy

Other websites
How Air Conditioners Work .
History of Automotive Air Conditioning  on NYC.net
Energy Efficiency
 Consumer Guide to Home Energy Savings - Central Air Conditioners  from the American Council for an Energy Efficient Economy (ACEEE)
 Energy Efficiency Program Database  from the ACEEE
 Space heating and cooling from the U.S. Department of Energy's Energy Efficiency and Renewable Energy
UK Enhanced Capital Allowance Scheme (ECA), a UK Government scheme to provide tax rebates for companies who use products which are ECA approved.
International Energy Agency - Energy Conservation In Buildings And Community Systems
AHAM website on Room-air Conditioners 
Top-Rated Energy-Efficient Central Air Conditioners 
Energy Star Central Air Conditioners 

Engineering
HVAC
Home appliances
A branch is a part of a tree.

Branch or branching could also mean:

Computing
 Branch (computer science), a point in a computer program where program-flow may change depending on a condition.
Branch predictor, the part of a processor that determines whether a conditional branch in the instruction flow of a program is likely to be taken or not.
Branch table, a term used to describe an efficient method of transferring program control (branching) to another part of a program using a table of branch instructions.
 Indirect branch, a type of program control instruction.
 Branching (software), a way of duplicating an object under revision control.

Geography
 Branch, Arkansas, United States
 Branch, Newfoundland and Labrador, Canada

Mathematics
 Branch (graph theory), a concept in mathematical logic
 Branch point, a point at which a multiple-valued function changes values
 Principal branch, a function which selects one branch of a multi-valued function
Religion
 Branch (Christ), the Branch Davidian new name of Christ
 Branch (Latter Day Saints), the Latter Day Saints equivalent of a congregation

Other
 Arthur Branch, a fictional character on the TV crime drama Law & Order
 Branch (academia), an academic sub-discipline
 Branch (banking), a retail location.
 Branch (business), a franchise location.
 Branch (bridle), a crooked piece of iron in a bit shank
 Branch line, a relatively minor railway line
 Branching (chemistry), a concept in polymer chemistry
 Branching (linguistics), the general tendency towards a given order of words within sentences and smaller grammatical units within sentences
 Cadet branch, a family line of nobility not descending from the first born son
 Earthly Branches, one Chinese system for reckoning time
 Executive branch, the branch of government responsible for the day-to-day management of the state
 Olive branch, a gesture of peace
 Post office branch, a type of postal facility that is not a main post office
People named Branch
 Branch, Christopher (circa 1600-1682), early American colonist
 Branch, Cliff (1948–2019), retired American football player
 Branch, David (born 1948), Commissioner of the Ontario Hockey League
 Branch, Emmett Forrest (1874-1932), governor of the U.S. state of Indiana
 Branch, Frank (born 1944), Canadian politician 
 Branch, John, Jr. (1782–1863), U.S. Senator, Secretary of the Navy, governor of North Carolina, and  territorial governor of Florida
 Branch, Lawrence O'Bryan (1820-1862), Confederate General and Representative from North Carolina
 Branch, Michael (born 1978), English professional footballer
 Branch, Michelle (born 1983), American singer, songwriter and guitarist
 Branch, Vanessa (born 1973), British actress and model
 McCracken, Branch (1908–1970), college men's basketball coach

Related pages
 Branch County
 Branch Township
 East Branch
 Fort Branch
 Long Branch
 North Branch
 South Branch
 West Branch
 USS Branch
The first law of thermodynamics is that energy can neither be created nor destroyed; it can change only from one form to another. The law forms the basis of the principle of conservation of energy. This means that anything that uses energy is changing the energy from one kind of energy to another. For example, exercising changes energy from food into kinetic (motion) energy.  Another example:  In the Sun (or any star), nuclear fusion changes mass into heat and light (electromagnetic radiation), which travels to Earth and is used by plants to create food (chemical energy) via photosynthesis, which can be eaten by animals allowing them to move (kinetic energy).  Energy only ever changes its form; it is neither created nor destroyed. This is why perpetual motion machines do not exist and could never exist; it would break a fundamental law of physics.
People can use the changes to do work that is useful. Examples of forms of energy in classical mechanics include heat, light, kinetic (movement) or potential energy. However, in modern physics it is considered that there are only two types of energy - mass and kinetic energy, although this may not be helpful to those not familiar with more complex physics.

The law means that the total energy of the universe (or any Closed system) is a constant. However, energy can be transferred from one part of the universe to another.

The most common wording of the first law of thermodynamics used by scientists is:

History
James Prescott Joule was the first person who found out by experiments that heat and work are convertible.

The first explicit statement of the first law of thermodynamics was given by Rudolf Clausius in 1850: "There is a state function E, called 'energy', whose differential equals the work exchanged with the surroundings during an adiabatic process."
Thermodynamics and Engineering 
In thermodynamics and engineering, it is natural to think of the system as a heat engine which does work on the surroundings, and to state that the total energy added by heating is equal to the sum of the increase in internal energy plus the work done by the system. Hence  is the amount of energy lost by the system due to work done by the system on its surroundings. During the portion of the thermodynamic cycle where the engine is doing work,  is positive, but there will always be a portion of the cycle where  is negative, e.g., when the working gas is being compressed. When  represents the work done by the system, the first law is written:

People disagree whether energy is a positive or a negative number. So that  is the flow of heat out of the system, and  is the work into the system:

Because of this ambiguity, it is very important in any discussion involving the first law to explicitly establish the sign convention in use.

dU = the change in internal energy

Q = heat
Q = heat

W = work

Related pages
 Second law of thermodynamics

References

 Goldstein, Martin, and Inge F., 1993. The Refrigerator and the Universe. Harvard Univ. Press. A gentle introduction.

Thermodynamics
Laws of physics
This article refers to the law of conservation of energy in physics. For energy resources sustainably, see: Energy conservation.

In physics, the conservation of energy is that energy can not be created or destroyed, it can only be changed from one form to another, such as when electrical energy is changed into heat energy. Formally, it says that the total amount of energy in an isolated system remains constant, although it may change forms, e.g. friction turns kinetic energy into thermal energy.  In thermodynamics, the first law of thermodynamics is a statement of the conservation of energy for thermodynamic systems.

From a mathematical point of view, the energy conservation law is a consequence of the shift symmetry of time; energy conservation is a result of the empirical fact that the laws of physics do not change with time itself. Philosophically, this can be stated as "nothing depends on time per se (time itself)".
Historical information 
Ancient philosophers as far back as Thales of Miletus had the idea that there is some underlying substance of which everything is made. But that is not the same as our concept of "mass-energy" today (for example, Thales thought the underlying substance was water).
In 1638, Galileo published his analysis of several situations. This included the famous "interrupted pendulum". This can be described (in modernized language) as conservatively converting potential energy to kinetic energy and back again. However, Galileo did not explain the process in modern terms and had not understood the modern concept either. The German Gottfried Wilhelm Leibniz during 1676-1689 attempted a mathematical formulation of the kind of energy which is connected with motion (kinetic energy). Leibniz noticed that in many mechanical systems (of several masses, mi  each with velocity vi ),
was conserved so long as the masses did not interact. He called this quantity the vis viva or living force of the system. The principle represents an accurate statement of the approximate conservation of kinetic energy in situations where there is no friction. 

Meanwhile, in 1843 James Prescott Joule independently discovered the mechanical equivalent in a series of experiments. In the most famous, now called the "Joule apparatus", a descending weight attached to a string caused a paddle immersed in water to rotate.  He showed that the gravitational potential energy lost by the weight in descending was approximately equal to the thermal energy (heat) gained by the water by friction with the paddle.

Over the period 1840-1843, similar work was carried out by engineer Ludwig A. Colding though it was little-known outside his native Denmark.

Proof
It is easy to see that

which is also

Assuming that  and that , then

(Since )

Therefore, energy does not vary with time.
Related pages
 Conservation law
 Energy
 Thermodynamics

Sources

Modern accounts 
Goldstein, Martin, and Inge F., 1993. The Refrigerator and the Universe. Harvard Univ. Press. A gentle introduction.
  
 
 
 
  
Stenger, Victor J. (2000). Timeless Reality. Prometheus Books. Especially chpt. 12. Nontechnical.
  ISBN  0-534-40842-7

Classic accounts
 
 
 ,  Chapter 8, "Energy and Thermo-dynamics"

Other websites 
 MISN-0-158 The First Law of Thermodynamics  (PDF file) by Jerzy Borysowicz for Project PHYSNET.

Thermodynamics
Laws of physics
The Lepidoptera are the butterflies and moths. However, though the butterflies are a natural monophyletic group, moths are not. Butterflies are often put in the suborder  Rhopalocera, which includes Papilionoidea (true butterflies), the Hesperiidae (skippers), and the Hedylidae (butterfly moths). 

In Linnaean taxonomy, moths are usually put in the suborder Heterocera. This tends to cover up the fact that they are not a true natural monophyletic group. However, moths do look and behave rather different from butterflies, which explains why people came to call them by a different name.

Other taxonomic schemes have been proposed, but none of them is perfect. Both taxonomists and amateurs make use of the obvious differences between butterflies and moths.

Morphological differences
Shape and structure of antennae
The most obvious difference is in the feelers, or antennae. Most butterflies have thin slender filamentous antennae which are club shaped at the end. Moths, on the other hand, often have comb-like or feathery antennae, or filamentous and unclubbed. This distinction is the basis for the earliest taxonomic divisions in the Lepidoptera  the Rhopalocera ("clubbed horn", the butterflies) and the Heterocera ("varied horn", the moths).

There are, however, exceptions to this rule and a few moths (the family Castniidae) have clubbed antennae. Some butterflies, like Pseudopontia paradoxa from the forests of central Africa, lack the clubbed ends. The Hesperiids often have an angle to the tip of the antenna.
Wing coupling mechanisms
Many moths have a frenulum or wing coupling physically attaching upper and lower parts of their wings together. The frenulum can be seen only when a specimen is in hand. There are various types. It may be a filament from the hindwing coupling with barbs on the forewing. Butterflies usually lack these structures. Their wing coupling is usually done by simple overlap of wing edges.

Pupae 
Most moth caterpillars spin a cocoon made of silk when they go into the pupal stage. Most butterflies on the other hand form an exposed pupa called a chrysalis.
There are many exceptions to this rule. Hawk moths form an exposed chrysalis which is underground. Spongy moths sometimes form butterfly-style pupae, hanging on twigs or tree bark, although usually they create flimsy cocoons out of silk strands and a few leaves, partially exposing the chrysalis. A few Skipper butterfly larvae also make crude cocoons in which they pupate, exposing the pupa a bit. The Parnassius butterfly larvae make a flimsy cocoon for pupation and they pupate near the ground surface between debris.

Colour of the wings 
Most butterflies have bright colours on their wings. Nocturnal moths on the other hand are usually plain brown, grey, white or black and often with obscuring patterns of zigzags or swirls which help camouflage them as they rest during the day. However many day-flying moths are brightly coloured, particularly if they are toxic. A few butterflies are quite plain, like the cabbage white butterfly.
Structure of the body
Moths tend to have stout and hairy or furry-looking bodies. Butterflies on the other hand have slender and smoother abdomens. Moths have larger scales on their wings. These make them look more dense and fluffy. Butterflies on the other hand have fine scales.  This difference is possibly due to the need for moths to conserve heat during the cooler nights whereas butterflies are able to absorb sunlight.

Behavioural differences

Time of activity
Most moths are nocturnal or crepuscular (active at night) while most butterflies are diurnal (active at daytime). There are however exceptions, including the diurnal spongy moth and the spectacular "Uraniidae" or Sunset moths.
Resting posture
Moths usually rest with their wings spread out to their sides. Butterflies frequently fold their wings above their backs when they are perched although they will occasionally "bask" with their wings spread for short periods. However some butterflies, like the skippers, may hold their wings either flat or folded or even in-between (the so-called "jet plane" position) when perched. Most moths also occasionally fold their wings above their backs when they are in a certain spot (like when there is no room to fully spread their wings).  A sometimes confusing family can be the "Geometridae" (such as the winter moth) because the adults often rest with their wings folded vertically.  These moths have thin bodies and large wings like many butterflies but may be distinguished easily by structural differences in their antennae (e.g. bipectinate).

Lepidoptera
Monophyly means common descent from a single ancestor.
Biologists have introduced  a kind of taxonomy called cladistics. The aim of this is to make biological classification fit what we know about the way organisms evolved.

If there is a group made of a common ancestor, and all its descendants, that group is monophyletic.  (Greek: "of one race").

A group which contains organisms, without their common ancestor, is called polyphyletic. Convergent evolution is a usual cause of such groups. If a group contains the common ancestor, but leaves out some of its descendants, it is called paraphyletic. All living things on this planet are thought, on the basis of DNA analysis, to be monophyletic, that is, to have one origin, not many.

Example: all species in the genus Homo have come from the same ancestral form in the family Hominidae, and no other descendants are known. Thus the genus Homo is monophyletic.
If, on the other hand, it were discovered that Homo habilis had developed from a different ancestor from Homo sapiens, and this ancestor were not included in the genus, then the genus would be polyphyletic. Since biologists by and large tend to prefer monophyletic groups, in this case, they would likely either split the genus or broaden it to include the additional forms.

Example of polyphyletic group: Sea slugs.

Polyploidy 
Sometimes taxonomists are frustrated fitting plant species into a monophyletic group because of polyploidy. There is clear evidence that some polyploid plant species are of multiple origins (the species has arisen more than once). For example, Salsify, the hybrid goat's-beard, (Tragopogon miscellus) has formed as many as 20 times in eastern Washington.
Also, it can happen that hybrids between two close plant species undergo polyploidy, and the polyploids continue as a new and distinct species. Situations like this are outside the normal rules of descent, and are dealt with by special decisions, guided by the International Commission of Botanical Nomenclature (ICBN).

References

Cladistics
The order Lepidoptera is the second biggest order of  insects. It includes the moths and butterflies including the  skippers. There is no common word for the group: ordinary people talk of "butterflies and moths". 

The order has more than 180,000 species in 128 families and 47 superfamilies. They are 10% of all the described species of living organisms. The Coleoptera (the beetles) is the only order that has more species.

The name, Lepidoptera, comes from the Ancient Greek words λεπίδος (scale) and πτερόν (wing).

The earliest discovered fossils date to 200 mya or earlier. This early origin was long before flowering plants evolved. Earlier butterflies must have been adapted to a habitat of cycads and conifers, something which had not previously been suspected.
Characteristics of Lepidoptera 
Lepidopterans go through complete metamorphosis. This means that they have a four parts to their lives. The first part is the egg. The second part is the caterpillar or larva. The third part is the pupa. The last part is the adult or imago.

Larva 
The larvae have a tough head and a soft body. They have mouths that are made to chew. Some larvae are covered with hairs, or other body extensions. The larvae have three pairs of small legs on the thorax. These legs are called true legs. There are up to five pairs of bigger legs on the abdomen. These legs are called prolegs. Lepidopteran larvae can be confused with the larvae of sawflies. The difference between Lepidopteran larvae and sawfly larvae is that Lepidopteran larvae have tiny hooks on their prolegs. These hooks are called crochets. Most larvae are herbivores, but a few are carnivores and detritivores.
Adult 
Adults have two pairs of wings. They are covered by small scales. In some species, the adults have very small wings or no wings at all. This is more common in females. Adults have antennae. Some moths have antennae that look like feathers. These feather-like antennae are larger in males than females. Adults have a mouthpart called a proboscis. It  sucks nectar from flowers. Some adults do not have mouths and cannot feed. Others have different mouths that are made to pierce and suck blood or fruit juices.

Images

Related pages
 Differences between butterflies and moths
 Lepidopteran diversity

References

Other websites 

 Forum Lepidoptera
 Lepidopterology.com
 Lepidoptera  in online insect museum 
 Historic Moth illustrations
Animals that are active during the day are called diurnal. They hunt or feed during the day and sleep during the night. Nocturnal animals do it the other way round.

Scientists sometimes use the word crepuscular to describe nocturnal  animals that are not active when it is very dark at night; they are mostly active near dawn, dusk, and sometimes when the moon makes a lot of light.

Zoology
The skippers are a family of butterflies, the Hesperiidae. They are named after their quick, darting flight. 

Skippers used to be classified in their own superfamily, Hesperioidea, because they have their antennae clubs hooked backward like a crochet while the other butterflies have club-like tips to their antennae. Skippers also have generally stockier bodies than regular butterflies, with stronger wing muscles.

Subfamilies 
There are about 3500 species of skippers.  They are usually classified in the following subfamilies:
 Coeliadinae: awls, awlets and policeman (butterfly) (about 75 species)
 Hesperiinae: grass skippers (over 2000 species)
 Heteropterinae: skipperlings (about 150 species)
 Megathyminae: giant skippers (about 100 species)
 Pyrginae: spread-winged skippers (about 1000 species)
 Pyrrhopyginae: firetips (about 150 species)
 Trapezitinae: Australian skippers (about 60 species)
Many species of skippers look frustratingly alike. For example, some species in the genera Erynnis, Hesperia, and Amblyscirtes cannot currently be distinguished in the field even by experts. The only reliable method of telling them apart involving dissection and examination of the genitalia.

Examples
Examples include:
Aaron's skipper - Poanes aaroni
Chequered skipper - Carterocephalus palaemon
Small skipper - Thymelicus sylvestris
Essex skipper - Thymelicus lineola
Lulworth skipper - Thymelicus acteon
Silver-spotted skipper - Hesperia comma
Large skipper - Ochlodes venata
Dingy skipper - Erynnis tages
Grizzled skipper - Pyrgus malvae
Dakota skipper - Hesperia dacotae

References

Other websites
Skippers of North America: Large format diagnostic photographs Cirrus Digital Imaging
 Tree of Life Hesperiidae
Energy conservation is reducing the amount of energy used for different purposes. This may result in an increase of financial capital, environmental value, national and personal security, and human comfort.

Individuals and organizations that consume energy may conserve energy to reduce costs and promote economic, political and environmental sustainability.  Industrial and commercial users may want to increase efficiency and thus maximize profit.

On a larger scale, energy conservation is an energy policy.  In general, energy conservation  reduces the energy consumption and energy demand per capita.  This reduces the rise in energy costs, and can reduce the need for new power plants, and energy imports.  The reduced energy demand can provide more flexibility in choosing the methods of energy production.
By reducing emissions, energy conservation helps to prevent climate change.  Energy conservation makes it easier to replace non-renewable resources with renewable energy.  Energy conservation is often the most economical solution to energy shortages.

Energy efficiency trends in the United States
The U.S. is the largest consumer of energy, although at current levels of growth, China may become the leading energy consumer. The U.S. Department of Energy categorizes national energy use in four broad sectors: transportation, residential, commercial, and industrial.

Energy usage in the transportation and residential sectors (about half of U.S. energy consumption) is largely controlled by individual domestic consumers.  Commercial and industrial energy usage are controlled by businesses.  National energy policy has a significant effect on energy usage across all four sectors.
Transportation sector
The transportation sector includes all vehicles used for personal or freight transportation. Of the energy used in this sector, about 65% is used by gasoline-powered vehicles, mostly personally owned. Diesel-powered transport (trains, merchant ships, heavy trucks, etc.) consumes about 20%, and air traffic consumes most of the remaining 15%.

The oil supply crises of the 1970s spurred the creation, in 1975, of the federal Corporate Average Fuel Economy (CAFE) program, which required auto manufacturers to meet progressively higher fleet fuel economy targets.  The next decade saw dramatic improvements in fuel economy, mostly the result of reductions in vehicle size and weight. These gains eroded somewhat after 1990 due to the growing popularity of sport utility vehicles, pickup trucks and minivans, which fall under the more lenient "light truck" CAFE standard.
In addition to the CAFE program, the U.S. government has tried to encourage better vehicle efficiency through tax policy.  Since 2002, taxpayers have been eligible for income tax credits for gas/electric hybrid vehicles. A "gas-guzzler" tax has been assessed on manufacturers since 1978 for cars with exceptionally poor fuel economy.  While this tax remains in effect, it currently generates very little revenue as overall fuel economy has improved.

Another focus in gasoline conservation is reducing the number of miles driven. An estimated 40% of American automobile use is associated with daily commuting. Many urban areas offer subsidized public transportation to reduce commuting traffic, and encourage carpooling by providing designated high-occupancy vehicle lanes and lower tolls for cars with multiple riders. In recent years telecommuting has also become a viable alternative to commuting for some jobs.
A vehicle's gas mileage normally decreases rapidly at speeds above 55 miles per hour.  A car or truck moving at 55 miles an hour can get about 15 percent better fuel economy than the same car going 65 mph. According to the U.S. Department of Energy (DOE), as a rule of thumb, each 5 mph you drive over 60 mph is similar to paying an additional $1.20 per gallon for gas (at $3.10 per gallon).

Residential sector
The residential sector refers to all private residences, including single-family homes, apartments, manufactured homes and dormitories.  Energy use in this sector varies significantly across the country, due to regional climate differences and different regulation.  On average, about half of the energy used in the U.S. homes is expended on space conditioning (i.e. heating and cooling).
The efficiency of furnaces and air conditioners has increased steadily since the energy crises of the 1970s. The 1987 National Appliance Energy Conservation Act authorized the Department of Energy to set minimum efficiency standards for space conditioning equipment and other appliances each year, based on what is "technologically feasible and economically justified".

Despite technological improvements, many American lifestyle changes have put higher demands on heating and cooling resources.  The average size of homes built in the United States has increased significantly, from 1500 ft² in 1970 to 2300 ft² in 2005.  The single-person household has become more common, as has central air conditioning: 23% of households had central air conditioning in 1978, that figure rose to 55% by 2001.
As a cheaper alternative to the purchase of a new furnace or air conditioner, most public utilities encourage smaller changes the consumer can make.  Consumers have also been asked to adopt a wider indoor temperature range (e.g. 65 °F in the winter, 80 °F in the summer).

Home energy consumption averages:

 space conditioning (includes both heating and air conditioning) 44%
 water heating, 13%
 lighting, 12%
 refrigeration, 8%
 home electronics, 6%
 laundry appliances, 5%
 kitchen appliances, 4%
 other uses, 8%

Energy usage in some homes may vary widely from these averages. In most residences no single appliance dominates, and any conservation efforts must be directed to numerous areas in order to achieve substantial energy savings.  However, ground source heat pump systems are the more energy efficient, environmentally clean, and cost-effective space conditioning systems available (Environmental Protection Agency). They can achieve reductions in energy consumptions of up to 70%.

Best building practices
Current best practices in building design and construction result in homes that are much more energy conserving than average new homes.  See Passive house, Superinsulation, Self-sufficient homes, Zero energy building, Earthship, Straw-bale construction, MIT Design Advisor, Energy Conservation Code for Indian Commercial Buildings.

Smart ways to construct homes such that minimal resources are used to cooling and heating the house in summer and winter respectively can significantly reduce energy costs!
Commercial sector
The commercial sector consists of retail stores, offices (business and government), restaurants, schools and other workplaces.  Energy in this sector has the same basic end uses as the residential sector, in slightly different proportions. Space conditioning is again the single biggest consumption area, but it represents only about 30% of the energy use of commercial buildings.  Lighting, at 25%, plays a much larger role than it does in the residential sector.  Lighting is also generally the most wasteful component of commercial use.  A number of case studies indicate that more efficient lighting and elimination of over-illumination can reduce lighting energy by approximately fifty percent in many commercial buildings.
Commercial buildings can greatly increase energy efficiency by thoughtful design, with today's building stock being very poor examples of the potential of systematic (not expensive) energy efficient design (Steffy, 1997).  Commercial buildings often have professional management, allowing centralized control and coordination of energy conservation efforts.

Solar heat loading through standard window designs usually leads to high demand for air conditioning in summer months.  An example of building design overcoming this excessive heat loading is the Dakin Building in Brisbane, California, where fenestration was designed to achieve an angle with respect to sun incidence to allow maximum reflection of solar heat; this design also assisted in reducing interior over-illumination to enhance worker efficiency and comfort.
Industrial sector
The industrial sector represents all production and processing of goods, including manufacturing, construction, farming, water management and mining.  Increasing costs have forced energy-intensive industries to make substantial efficiency improvements in the past 30 years.  For example, the energy used to produce steel and paper products has been cut 40% in that time frame, while petroleum/aluminum refining and cement production have reduced their usage by about 25%.  These reductions are largely the result of recycling waste material and the use of cogeneration equipment for electricity and heating.

The energy required for delivery and treatment of fresh water often constitutes a significant percentage of a region's electricity and natural gas usage (an estimated 20% of California's total energy use is water-related.)  In light of this, some local governments have worked toward a more integrated approach to energy and water conservation efforts.
Unlike the other sectors, total energy use in the industrial sector has declined in the last decade.  While this is partly due to conservation efforts, it's also a reflection of the growing trend for U.S. companies to move manufacturing operations offshore.

The usage of telecommuting by major corporations is a significant opportunity to conserve energy, as many Americans now work in service jobs that enable them to work from home instead of commuting to work each day.

Related pages
 Energy efficiency
 Light pollution
 List of renewable energy topics

References
References

 
 Bain, A.,  “The Hindenburg Disaster: A Compelling Theory of Probable Cause and Effect,” Procs. NatL Hydr. Assn. 8th Ann. Hydrogen Meeting, Alexandria, Va., March 11-13, pp 125–128 (1997)
 Gary Steffy, Architectural Lighting Design,  John Wiley and Sons (2001) 
 Lumina Technologies, Analysis of energy consumption in a San Francisco Bay Area research office complex, for (confidential) owner, Santa Rosa, Ca. May 17, 1996
 GSA paves way for IT-based buildings

Other websites
Resources for homes
 Conserving energy with plants 
 Energy Savings Tips for Your Home 
 Energy conservation tips for apartments
 Energy Saving Resources for the Home 

Government and international websites
 U.S. Energy Information Administration
 Buildings Energy Data Book  - commercial/residential building consumption patterns
UNEP- Energy Branch. 
IEA Energy Conservation in Buildings and Community Systems Programme.

 
Engineering
Cogeneration (also combined heat and power, CHP) is the use of a heat engine or a power station to make both electricity and useful heat at the same time.

Conventional power plants emit the heat created as a byproduct of electricity generation into the environment through cooling towers, as flue gas, or by other means. Combined heat and power captures the byproduct heat for domestic or industrial heating purposes, either very close to the plant, or - especially in Scandinavia and eastern Europe - for distribution through pipes to heat local housing. 

Byproduct heat at moderate temperatures (100 to 180°C) can also be used in absorption chillers for cooling. A plant producing electricity, heat and cold is sometimes called regeneration or more generally: polygene ration plant. 

Cogeneration is a thermodynamically efficient use of fuel. In separate production of electricity some energy is lost as waste heat, but in cogeneration this energy performs useful work (see energy).

Overview
Overview

Thermal power plants (including those that use fissile elements or burn coal, petroleum, or natural gas), and heat engines in general, do not convert all of their available energy into electricity.  In most heat engines, a bit more than half is wasted as excess heat (see: Second law of thermodynamics). By capturing the excess heat, CHP uses heat that would be wasted in a conventional power plant, potentially reaching an efficiency of up to 70%, compared with at most 40% for the conventional plants. This means that less fuel needs to be consumed to produce the same amount of useful energy.  Also, less pollution is produced for a given economic benefit.

An exact match between the heat and electricity needs rarely exists. A CHP plant can either meet the need for heat (heat driven operation) or be run as a power plant with some use of its waste heat.
CHP is most efficient when the heat can be used on site or very close to it.  Overall efficiency is reduced when the heat must be transported over longer distances.  This requires heavily insulated pipes, which are expensive and inefficient; whereas electricity can be transmitted along a comparatively simple wire, and over much longer distances for the same energy loss.

A car motor becomes a CHP plant in winter, when the reject heat is useful for warming the interior of the vehicle. This example scores the point that deployment of CHP depends on heat uses in the neighbourhood of the heat engine.

Cogeneration plants are commonly found in district heating systems of big towns, hospitals, prisons, oil refineries, paper mills, wastewater treatment plants, thermal enhanced oil recovery wells and industrial plants with large heating needs.
Other websites 
 Energy Policy Act of 2005 - sec. 1817 "Study of Cogeneration"
 www.mccree.com  - Air Products and Chemicals Cogeneration Plant (Orlando, Florida)
 www.co-generationsystems.com - Industrial Co-generation Equipment Provider
Sequoien - Non-profit CHP 
  CHP in Finland:
 High cogeneration performance by innovative steam turbine for biomass-fired CHP plant in Iisalmi, Finland  (URL accessed on 30 March 2006)
 UK micro CHP schemes:
 www.defra.gov.uk, CHP 
 BBC News: Power from the people
 Powergen WhisperGen
 M.I.T. algae reactor 
 Stirling/ Oven 
 Associations:
 U.S. Combined Heat and Power Association
 CHP Association
 COGEN Europe The European Association for the Promotion of Cogeneration
 The World Alliance for Decentralized Energy

Electricity
Quakenbrück is a small town in Lower Saxony. It has about 13,000 inhabitants.

References

Other websites
The dew point is the temperature where water vapor condenses into liquid water.

All air holds different amounts of water vapor. The dew point shows the amount of moisture in the air. The higher the dew point is, the higher the level of moisture in the air at a given temperature. The dew point of humid air will be higher than the dew point of dry air.

Condensation of water vapor starts when the temperature of air is lowered to its dew point and beyond. The dew point, like other measures of humidity, can be found from measurement taken by a hygrometer.

Related pages
 Relative humidity

Other websites 
 What is the dew point? 
 NOAA Dew point
 dew point formula 
 Windows program for Heat Index, Dew Point, etc 
 Dew point evaporates on KPRC newscast ("The dew point is absolutely worthless information")
 Often Needed Answers about Temp, Humidity & Dew Point from the sci.geo.meteorology Usenet newsgroup

Weather
Weather measurements
Podgorica () is the capital of Montenegro. In 2011, the population was 185,937.

References 

Cities in Montenegro
Municipalities of Montenegro
National capitals in Europe
The Región Autónoma del Atlántico Sur is an independent part of Nicaragua. It is often simply known as RAAS. Its capital is Bluefields. It was made when new regions were formed in Nicaragua in 1989. The old region was turned into Atlántico Sur and Atlántico Norte. The capital of Atlántico Norte is Puerto Cabezas. There is also a popular tourist place called Corn Island, which is about 45 km from the capital Bluefields

Geography of Nicaragua
Región Autónoma del Atlántico Norte is an autonomous region of Nicaragua. It was created in 1989. Its capital is Puerto Cabezas. Often the name is shotened to RAAN.

Geography of Nicaragua
Compressor could mean:
Gas compressor, a mechanical device that compresses a gas e.g. air
Compressor (software), a video and audio compression and encoding application made for use with Final Cut
A device used to apply audio level compression to an audio signal
KOMPRESSOR, an electronic musician

Related pages 
Compression
Compaction
Decompression
Expansion
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. Compression of a gas naturally increases its temperature. When the gas is air, the machine is called an air compressor.

Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible, so the main action of a pump is to transport liquids.

Types of compressors 
There are many different types of gas compressors. The two primary categories are:
 Positive displacement compressors with two sub-categories:
 Reciprocating
 Rotary
 Dynamic compressors also with two sub-categories:
 Centrifugal
 Axial

The more important types in each of the four sub-categories are discussed below.

Centrifugal compressors
Centrifugal compressors use a vaned rotating disk or impeller in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser (divergent duct) section converts the velocity energy to pressure energy. They are primarily used for continuous, stationary service in industries such as oil refineries, chemical and petrochemical plants and natural gas processing plants. Their application can be from 100 hp (75 kW) to thousands of horsepower. With multiple staging, they can achieve extremely high output pressures greater than 10,000 psi (69 MPa).

Many large snow-making operations (like a ski resort) use this type of compressor. They are also used in internal combustion engines as superchargers and turbochargers. Centrifugal compressors are used in small gas turbine engines or as the final compression stage of medium-sized gas turbines.
Diagonal or mixed-flow compressors 
Diagonal or mixed-flow compressors are similar to centrifugal compressors, but have a radial and axial velocity component at the exit from the rotor. The diffuser is often used to turn diagonal flow to the axial direction. The diagonal compressor has a lower diameter diffuser than the equivalent centrifugal compressor.

Axial-flow compressors 

Axial-flow compressors use a series of fan-like rotating rotor blades to progressively compress the gasflow. Stationary stator vanes, located downstream of each rotor, redirect the flow onto the next set of rotor blades. The area of the gas passage diminishes through the compressor to maintain a roughly constant axial Mach number. Axial-flow compressors are normally used in high flow applications, such as medium to large gas turbine engines. They are almost always multi-staged. Beyond about 4:1 design pressure ratio, variable geometry is often used to improve operation.
Reciprocating compressors 
Reciprocating compressors use pistons driven by a crankshaft. They can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. Small reciprocating compressors from 5 to 30 horsepower (hp) are commonly seen in automotive applications and are typically for intermittent duty. Larger reciprocating compressors up to 1000 hp are still commonly found in large industrial applications, but their numbers are declining as they are replaced by various other types of compressors. Discharge pressures can range from low pressure to very high pressure (>5000 psi or 35 MPa). In certain applications, such as air compression, multi-stage double-acting compressors are said to be the most efficient compressors available, and are typically larger, noisier, and more costly than comparable rotary units.
Rotary screw compressors 
Rotary screw compressors use two meshed rotating positive-displacement helical screws to force the gas into a smaller space. These are usually used for continuous operation in commercial and industrial applications and may be either stationary or portable. Their application can be from 3 hp (2.24 kW) to over 500 hp (375 kW) and from low pressure to very high pressure (>1200 psi or 8.3 MPa). They are commonly seen with roadside repair crews powering air-tools. This type is also used for many automobile engine superchargers because it is easily matched to the induction capacity of a piston engine. It's a type of positive displacement gas compression.

Scroll compressors
A scroll compressor, also known as scroll pump and scroll vacuum pump, uses two interleaved spiral-like vanes to pump or compress fluids such as liquids and gases. The vane geometry may be involute, archimedean spiral, or hybrid curves. They operate more smoothly, quietly, and reliably than other types of compressors.

Often, one of the scrolls is fixed, while the other orbits eccentrically without rotating, thereby trapping and pumping or compressing pockets of fluid between the scrolls.

Diaphragm compressors 
A diaphragm compressor (also known as a membrane compressor) is a variant of the conventional reciprocating compressor. The compression of gas occurs by the movement of a flexible membrane, instead of an intake element. The back and forth movement of the membrane is driven by a rod and a crankshaft mechanism. Only the membrane and the compressor box come in touch with the gas being compressed.
Diaphragm compressors are used for hydrogen and compressed natural gas (CNG) as well as in a number of other applications.

Miscellany 
Air compressors sold to and used by the general public are often attached on top of a tank for holding the pressurized air. Oil-lubricated and oil-free compressors are available. Oil-free compressors are desirable because without a properly designed separator, oil can make its way into the air stream. For some purposes, for example as a diving air compressor, even a little oil in the air stream may be unacceptable.
Temperature 
Charles's law says "when a gas is compressed, temperature is raised". There are three possible relationships between temperature and pressure in a volume of gas undergoing compression:
 Isothermal - gas remains at constant temperature throughout the process. In this cycle, internal energy is removed from the system as heat at the same rate that it is added by the mechanical work of compression. Isothermal compression or expansion is favored by a large heat exchanging surface, a small gas volume, or a long time scale (i.e., a small power level). With practical devices, isothermal compression is usually not attainable. For example, even a bicycle tire-pump gets hot during use.
Adiabatic - In this process there is no heat transfer to or from the system, and all supplied work is added to the internal energy of the gas, resulting in increases of temperature and pressure. Theoretical temperature rise is T2 = T1·Rc((k-1)/k)), with T1 and T2 in degrees Rankine or kelvins, and k = ratio of specific heats (approximately 1.4 for air). The rise in air and temperature ratio means compression does not follow a simple pressure to volume ratio. This is less efficient, but quick. Adiabatic compression or expansion is favored by good insulation, a large gas volume, or a short time scale (i.e., a high power level). In practice there will always be a certain amount of heat flow, as to make a perfect adiabatic system would require perfect heat insulation of all parts of a machine.
Polytropic - This assumes that heat may enter or leave the system, and that input shaft work can appear as both increased pressure (usually useful work) and increased temperature above adiabatic (usually losses due to cycle efficiency). Cycle efficiency is then the ratio of temperature rise at theoretical 100 percent (adiabatic) vs. actual (polytropic).
Staged compression 
Since compression generates heat, the compressed gas is to be cooled between stages making the compression less adiabatic and more isothermal. The inter-stage coolers cause condensation meaning water separators with drain valves are present. The compressor flywheel may drive a cooling fan.

For instance in a typical diving compressor, the air is compressed in three stages. If each stage has a compression ratio of 7 to 1, the compressor can output 343 times atmospheric pressure (7 x 7 x 7 = 343 Atmospheres).