Greenhouses
Jason Sander
Grade 11 D
2013
EGD PAT
Table of Contents
Design Brief
Free Hand Sketches
Two Point Perspective
Isometric
Blue Prints
Conclusion
Research
Introduction
A greenhouse (also called a glasshouse) is a building in which plants are grown. These structures range in size from small sheds to industrial-sized buildings. A miniature greenhouse is known as a cold frame.
A greenhouse is a structural building with different types of covering materials, such as a glass or plastic roof and frequently glass or plastic walls; it heats up because incoming visible solar radiation (for which the glass is transparent) from the sun is absorbed by plants,soil, and other things inside the building. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall. In addition, the warmed structures and plants inside the greenhouse re-radiate some of their thermal energy in the infrared spectrum, to which glass is partly opaque, so some of this energy is also trapped inside the glasshouse. However, this latter process is a minor player compared with the former (convective) process. Thus, the primary heating mechanism of a greenhouse is convection. This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature drops considerably. This principle is the basis of the autovent automatic cooling system. Thus, the glass used for a greenhouse works as a barrier to air flow, and its effect is to trap energy within the greenhouse. The air that is warmed near the ground is prevented from rising indefinitely and flowing away.
Although heat loss due to thermal conduction through the glass and other building materials occurs, net energy (and therefore temperature) increases inside the greenhouse.
Types
Greenhouses can be divided into glass greenhouses and plastic greenhouses. Plastics mostly used are polyethylene film and multiwall sheets of polycarbonate material, or PMMA acrylic glass.
Grade 11 D
2013
EGD PAT
Table of Contents
Design Brief
Free Hand Sketches
Two Point Perspective
Isometric
Blue Prints
Conclusion
Research
Introduction
A greenhouse (also called a glasshouse) is a building in which plants are grown. These structures range in size from small sheds to industrial-sized buildings. A miniature greenhouse is known as a cold frame.
A greenhouse is a structural building with different types of covering materials, such as a glass or plastic roof and frequently glass or plastic walls; it heats up because incoming visible solar radiation (for which the glass is transparent) from the sun is absorbed by plants,soil, and other things inside the building. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall. In addition, the warmed structures and plants inside the greenhouse re-radiate some of their thermal energy in the infrared spectrum, to which glass is partly opaque, so some of this energy is also trapped inside the glasshouse. However, this latter process is a minor player compared with the former (convective) process. Thus, the primary heating mechanism of a greenhouse is convection. This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature drops considerably. This principle is the basis of the autovent automatic cooling system. Thus, the glass used for a greenhouse works as a barrier to air flow, and its effect is to trap energy within the greenhouse. The air that is warmed near the ground is prevented from rising indefinitely and flowing away.
Although heat loss due to thermal conduction through the glass and other building materials occurs, net energy (and therefore temperature) increases inside the greenhouse.
Types
Greenhouses can be divided into glass greenhouses and plastic greenhouses. Plastics mostly used are polyethylene film and multiwall sheets of polycarbonate material, or PMMA acrylic glass.
Bibliography: * Cunningham, Anne S. (2000). Crystal palaces : garden conservatories of the United States. Princeton Architectural Press, New York, ISBN 1-56898-242-9 * Lemmon, Kenneth (1963). The covered garden. Dufour, Philadelphia * Muijzenberg, Erwin W B van den (1980) A history of greenhouses. Institute for Agricultural Engineering, Wageningen, Netherlands; * Vleeschouwer, Olivier de (2001). Greenhouses and conservatories. Flammarion, Paris, ISBN 2-08-010585-X * Woods, May (1988). Glass houses: history of greenhouses, orangeries and conservatories. Aurum Press, London, ISBN 0-906053-85-4