Amber Book - Thermal Flashcards
What are some common building materials R-Values?
What is a skin-load dominated building?
Buildings where energy consumption is primarily dictated by the influence of the exterior climate on a building’s envelope, or “skin.”
What is an internal-load dominated building?
Buildings that consume the majority of their energy to provide interior lighting and to provide cooling to counteract the heat given off by people, plug-loads (such as computers), fixtures, and other internal sources.
Usually have a higher mass to surface area ratio. Usually need to be shedding heat year round (hospitals, skyscraper, factories, etc.)
What is Solar Heat Gain Coefficient (CHGC) ?
The fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward.
0 < (SHGC) < 1
High SHGC means lots of solar heat gets through. (0.7-0.9)
Low SHGC means less heat gets through
What is a British Thermal Unit (BTU)?
The heat required to raise one LB of water one degree Farenheit.
People are emitting ~500 BTU’s an hour (250 latent, 250 sensible)
What is a Balance Point Temperature?
The temperature of a building interior relative to the outside temperature.
If a building produces a lot of heat internally, it will take a very low outdoor temperature to require heating, therefore it has a LOW balance point temp.
What is a Degree Day?
a unit of measurement equal to a difference of one degree between the mean outdoor temperature and a reference temperature (65°F). Degree Days are used in estimating the energy needs for heating or cooling a building.
What is Conductivity (k)?
The rate at which heat passes through a specific material.
Conductors have high k
Insulators have high resistivity and low k
*Inverse of Resistivity 1/k=r and 1/r=k
What is the U-Value?
The measure of the overall ability of a series of conductive and convective barriers to transfer heat.
The inversion of all the R-values added together
U = 1/(R1+R2+R3)
What are the important elements of a passively heated building?
- Windows to allow solar radiation
- Well insulated and well-sealed envelope
- Thermal mass to hold heat
