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Lecture 4 Heat Exchange Process & U-value - Coggle Diagram
Lecture 4
Heat Exchange Process
& U-value
Thermal comfort
What is that?
the ability to release a desired amount of heat to make building users thermally comfortable
Heat movement in and out of building
Solar heat gained from windows
Heat transferred via see through building material
Heat exchange via air movement
Convection of heat via indoor and outdoor space
Conduction of heat via building envelope
Heat conducted via building wall material
Internal heat gain
Heat generated from inside the building
activities inside creates heat
Many people breathing inside creates more heat
Mechanical Control
Some indoor need heating
eg. Sauna room
Passive design
Not using mechanical means to cool the building to thermal comfort level
use architecture design strategies to implement this
Lots of benefiting existing wind ventilation on site and incorporate into design
U value
What is that?
How good is the building material at letting heat pass through
High value = heat loss high
heat transfer quite fast
Need high energy to maintain thermal comfort
Indicator of its insulation ability
a.k.a. heat transfer coefficient
Thermal transmittance
What factors influence this?
Material thickness (W/m2K)
Thermal conductivity (W/mK)
The time needed to heat transfer
High conductivity = good heat transfer
poor conductivity = good insulator
The material properties to conduct heat
Thermal resistance (m2 K/W)
The thermal resistance of the material
Thermal resistivity (mK/W)
time needed for heat to pass through material's surface area & thickness