1. Energy In Buildings
Heating systems
Cooling Systems
By Mina Greas

2. Heating systems

3. Furnaces
Furnaces heat air and distribute the heated air through a building using ducts.
Furnaces are the most common heating systems used in homes in the United States.
They can be all electric, gas-fired (including propane or natural gas), or oil-fired.

4. Boilers
Boilers consist of a vessel or tank where heat produced from the combustion of such fuels as natural gas, fuel oil, or coal is used to generate hot water or steam.
Most medium-to-large facilities use boilers to generate hot water or steam for space heating, domestic water heating, food preparation, and industrial processes.
In homes with boilers, steam is distributed via pipes to steam radiators.
Steam boilers operate at a higher temperature than hot water boilers, and are inherently less efficient, but high-efficiency versions of all types of furnaces and boilers are currently available.

5. Wood and Pellet Heating
Wood-burning and pellet fuel appliances use biomass or waste resources to heat homes or buildings.
Types of Wood- and Pellet-Burning Appliances
The following is a brief overview of the different types of wood and pellet fuel appliances available:
High-Efficiency Fireplaces and Fireplace Inserts
Wood Stoves and Wood-Burning Boilers
Masonry Heaters
Pellet Fuel Appliances

6. High-Efficiency Fireplaces and Fireplace Inserts
Effective in increasing the heating efficiency of older fireplaces.

7. Wood Stoves and Wood-Burning Boilers
Wood stoves are the most common appliance for burning wood. New catalytic stoves and inserts have advertised efficiencies of 70%-80%.

8. Masonry Heaters
Masonry heaters are also known as "Russian," "Siberian," and "Finnish" fireplaces. They produce more heat and less pollution than any other wood- or pellet-burning appliance.

9. Pellet Fuel Appliances
Pellet fuel appliances burn small, 3/8-1 inch pellets that look like rabbit feed. Pellets are made from compacted sawdust, wood chips, bark, agricultural crop waste, waste paper, and other organic materials.

10. Electric Resistance Heating
Electric resistance heat can be supplied by centralized forced-air electric furnaces or by heaters in each room. Electric resistance heating converts nearly all of the energy in the electricity to heat.
Types of Electric Resistance Heaters

11.  Electric Furnaces
With electric furnaces, heated air is delivered throughout the home through supply ducts and returned to the furnace through return ducts.

12. Electric Baseboard Heaters
Electric baseboard heaters are zonal heaters controlled by thermostats located within each room.
Run the length of the baseboard or cabinet.
As air within the heater is warmed, it rises into the room, and cooler air is drawn into the bottom of the heater.

13. Electric Wall Heaters
Electric wall heaters consist of an electric element (with a reflector behind it to reflect heat into the room) and usually a fan to move air through the heater

14. Electric Thermal Storage
The most common type of electric thermal storage heater is a resistance heater with elements encased in heat-storing ceramic

15. Control Systems
All types of electric resistance heating are controlled through some type of thermostat:
This turns the system on and off and controls the temperature settings.

16. Radiant Heating
Radiant heating systems involve supplying heat directly to the floor or to panels in the walls or ceiling of a house.
The systems depend largely on radiant heat transfer: the delivery of heat directly from the hot surface to the people and objects in the room via the radiation of heat, which is also called infrared radiation.
Radiant heating is the effect you feel when you can feel the warmth of a hot stovetop element from across the room.
Types of Radiant Floor Heating Systems
There are three types of radiant floor heating systems.

17. Radiant Air Floors
Radiant air floor systems use a conventional furnace to pump the air through the floor. Because air cannot hold large amounts of heat, however, radiant air floors are seldom installed in residential applications.

18. Electric Radiant Floors
Electric radiant floors typically consist of electric cables built into the floor. Systems that feature mats of electrically conductive plastic are also available, and are mounted onto the subfloor below a floor covering such as tile.

19. Hot Water (Hydronic) Radiant Floors
Pump heated water from a boiler through tubing laid underneath the floor. In some systems, the temperature in each room is controlled by regulating the flow of hot water through each tubing loop.

20. Small Space Heaters
Small space heaters, also called portable heaters, are typically used when the main heating system is inadequate or when central heating is too costly to install or operate.
Although most space heaters rely on convection (the circulation of air in a room), some rely on radiant heating.

21. Combustion Space Heaters
Space heaters are classified as vented and unvented, or "vent free."
Unvented combustion units are not recommended for inside use, as they introduce unwanted combustion products into the living space, including nitrogen oxides, carbon monoxide, and water vapor. The units also deplete the air in the space where they are located.
Vented units are designed to be permanently located next to an outside wall, so that the flue gas vent can be installed through a ceiling or directly through the wall to the outside.

22. Passive Solar Design
The difference between a passive solar home and a conventional home is design.
Passive solar homes and other buildings are designed to take advantage of the local climate.
Involves using a building's windows, walls, and floors to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer.

23. Direct Gain
Direct gain is the process by which sunlight directly enters a building through the windows and is absorbed and temporarily stored in massive floors or walls.

24. Indirect Gain
Indirect gain is the process by which the sun warms a heat storage element—such as a Trombe wall—and the heat is later distributed to the interior space by convection, conduction, and radiation.

25. Isolated Gain
Isolated gain involves the collection of heat in one area—such as a sunspace on the south side of a house—and used in another.

26. Roof Overhangs
Roof overhangs are used to shade windows, walls, and doors from direct solar radiation.

27. Daylighting
This video explains how homeowners and businesses can use highly efficient, strategically placed windows to save money.

28. Cooling Systems

29. Ventilation
Ventilation allows air to move into and out of homes and buildings either by natural or mechanical means.
Ventilation Systems
Too little ventilation = poor indoor air quality,
Too much ventilation = higher heating and cooling loads.

30. Natural Ventilation
Natural ventilation occurs when outdoor air is drawn inside through open windows or doors.
Natural ventilation is created by the differences in the distribution of air pressures around a building.
Air moves from areas of high pressure to areas of low pressure.
The value of good design has to do with placement and control of doors and windows which alter natural ventilation patterns.

31. Mechanical Ventilation
Mechanical ventilation is when outside air is brought indoors with fans that draw air from outside and force it through ducts to the interior spaces. .

32. Principles of Heating and Cooling
Understanding how heat is transferred from the outdoors into a building and from the building to your body is important for understanding the challenge of keeping homes and buildings cool.
Understanding the processes that help keep your body cool is important in understanding cooling strategies for homes and buildings.

33. Principles of Heat Transfer
Heat is transferred to and from objects via three processes: conduction, radiation, and convection.
Conduction is heat traveling through a solid material.
On hot days, heat is conducted into a building through the roof, walls, and windows.
Heat-reflecting roofs, insulation, and energy efficient windows will help to reduce that heat conduction.

34. Principles of Heat Transfer
Radiation is heat traveling in the form of visible and non-visible light.
Sunlight is an obvious source of heat for buildings. In addition, low-wavelength, non-visible infrared radiation can carry heat directly from warm objects to cooler objects.
Infrared radiation is why you can feel the heat of a hot burner element on a stovetop, even from across the room.
Older windows will allow infrared radiation coming from warm objects outside to radiate into a home or building; shades can help to block this radiation.
Newer windows have low-e coatings that block infrared radiation.

35. Principles of Heat Transfer
Convection is another means for the heat from the walls and ceiling to reach you.
Hot air naturally rises, carrying heat away from the walls and causing it to circulate throughout a building. As the hot air circulates past your skin (and you breathe it in), it warms you.

36. Cooling Your Body
Your body can cool down through three processes: convection, radiation, and perspiration.
Ventilation enhances all these processes. You can also cool your body via conduction some car seats now feature cooling elements, for instance Convection occurs when heat is carried away from your body via moving air.
If the surrounding air is cooler than your skin, the air will absorb your heat and rise.
As the warmed air rises around you, cooler air moves in to take its place and absorb more of your warmth. The faster this convecting air moves, the cooler you feel.

37. Cooling Your Body
Radiation occurs when heat radiates across the space between you and the objects in a building. If objects are warmer than you are, heat will travel toward you.
Removing heat through ventilation reduces the temperature of the ceiling, walls, and furnishings. The cooler your surroundings, the more you will radiate heat to the objects, rather than the other way around.
Perspiration can be uncomfortable, and many people would prefer to stay cool without it. Perspiration is the body's powerful cooling mechanism. As moisture leaves your skin pores, it carries a lot of heat with it, cooling your body. If a breeze (ventilation) passes over your skin, that moisture will evaporate more quickly, and you'll be even cooler.

38. Evaporative Cooling
In dry climates, evaporative cooling or "swamp cooling" provides an experience like air conditioning, but with much lower energy use.
An evaporative cooler uses the outside air's heat to evaporate water inside the
cooler. The heat is drawn
out of the air and the cooled
air is Blown into the space by
The cooler's fan.
Evaporative cooling uses
evaporated water to naturally
and energy-efficiently cool.

39. How Evaporative Coolers Work
There are two types of evaporative coolers:
Direct evaporative coolers, also called swamp coolers, work by cooling outdoor air by passing it over water-saturated pads, causing the water to evaporate into it. Cooler air is then directed into the home or building and pushes warmer air out through windows.
Indirect evaporative coolers have a heat exchanger that prevents humidity from entering the building. Efficiency tends to be lower than that of direct evaporative coolers.
Evaporative coolers require more frequent maintenance than refrigerated air conditioners and are suitable only for areas with low humidity.

40.  Air Conditioning
Air conditioning is one of the most common ways to cool homes and buildings.
How Air Conditioners Work
Air conditioners employ the same operating principles and basic components as refrigerators.
Refrigerators use energy (usually electricity) to transfer heat from the cool interior of the refrigerator to the relatively warm surroundings; likewise, an air conditioner uses energy to transfer heat from the interior space to the relatively warm outside environment.

41. Types of Air Conditioners
Room air conditioners cool just one room or small space, rather than an entire building.

42. Types of Air Conditioners
Central air conditioners circulate cool air through a system of supply and return ducts that carry cool air from the air conditioner to the building.

43. Types of Air Conditioners
Ductless, mini-split systems are similar to central air conditioners in that they have an outdoor compressor or condenser and an indoor air-handling unit. However, because they are "ductless," they are often used in buildings with non-ducted systems.

44. Absorption Cooling
Absorption coolers use heat rather than electricity as their energy source. Because natural gas is the most common heat source for absorption cooling, it is also referred to as gas-fired cooling. Other potential heat sources include propane, solar-heated water, or geothermal-heated water.
Although mainly
used in industrial or
commercial settings,
absorption coolers
are commercially
available for large
residential homes.

45. How Absorption Cooling Works
An absorption cooling cycle relies on three basic principles:
When a liquid is heated it boils (vaporizes) and when a gas is cooled it condenses Lowering the pressure above a liquid reduces its boiling point Heat flows from warmer to cooler surfaces.

46. Absorption Cooling in Commercial Buildings
Absorption cooling is most frequently used to air condition large commercial buildings. Absorption chillers can be teamed with electric chillers in "hybrid" central plants to provide cooling at the lowest energy costs.
In this case, the absorption chillers are used during the summer to avoid high electric demand charges, and the electric chillers are used during the winter when they are more economical. Because absorption chillers can make use of waste heat, they can essentially provide free cooling in certain facilities.