ARCH 2151 Lecture Notes - Lecture 4: Heat Transfer, Absorptance, Thermal Bridge
2.1 Heat and Air
Heat in buildings:
Cold is the absence of heat, not a “thing.”
Heat is energy in motion.
- Seeks equilibrium
- Cannot be created or destroyed
Methods of Heat Transfer (radiation, conduction, etc.)
Supply and return
- Better in cooling
Heat loss and gain
Building response:
- Site selection and orientation
- Material choices
- Window openings, sizing and locating them
- Interior configuration
- Building system response
- Active systems
Passive systems
Material response to heat
- Reflectance
- Absorptance
- Material composition and color, mass
- Emittance
- Value equal to absorptance
*Chart with different materials and their emittance and reflective responses
Heat transfer within buildings
- If you’re next to the fireplace you can feel it more intensely up close
- Heat emitted from stove
- Ducted warm air
- Hydronic heating- steam radiators; located near windows
- Radiant floor heating/in-slab heating
1. Natural behavior of heat to rise and dissipate
2. Thermal capacity examples
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Document Summary
Cold is the absence of heat, not a thing. *chart with different materials and their emittance and reflective responses. If you"re next to the fireplace you can feel it more intensely up close. Hydronic heating- steam radiators; located near windows. R-value, designates how resistant materials are to heat flow. Thermal bridge: material or building elements that moves from outside to inside the building ex. Thermal break: solution to a thermal bridge. Thermal resistance; assembly response: things to keep in mind/avoid: condensation, dew point, vapor retarder, toward the warm side of the wall assembly in colder climates, breathable exterior membrane. Passive ventilation- wind: promote health, there is a code for minimum number of air changes, increase comfort, stack effect, stack ventilation, cross ventilation, solar chimneys, air changes, remove heat. Used as a way of adding to comfort: hvac, use energy to function, usually needed to effectively maintain comfort in all situations, factors, cost- initial, performance, maintenance.
