All Divisions Flashcards
Sensible Heat
Sensible heat is heat exchanged by a body or thermodynamic system in which the exchange of heat changes the temperature of the body or system, and some macroscopic variables of the body or system, but leaves unchanged certain other macroscopic variables of the body or system, such as volume or pressure.
Latent Heat
the heat required to convert a solid into a liquid or vapor, or a liquid into a vapor, without change of temperature.
Enthalpy
a thermodynamic quantity equivalent to the total heat content of a system. It is equal to the internal energy of the system plus the product of pressure and volume.
Adiabatic Shift
Thermal Mass
Thermal Resistance
Low-E Glass
Solar Heat Gain Coefficient (SHGC)
Solar gain is the increase in thermal energy of a space, object or structure as it absorbs incident solar radiation. The amount of solar gain a space experiences is a function of the total incident solar irradiance and of the ability of any intervening material to transmit or resist the radiation.
RANGE: 0 to 1
GOOD: 0.25 or less
AVERAGE: 0.35-0.60
HIGH: 0.60 or higher
Degree Days (DD)
a unit used to determine the heating requirements of buildings, representing a fall of one degree below a specified average outdoor temperature (usually 18°C or 65°F) for one day.
Heating Degree Days (HDD)
Heating degree day is a measurement designed to quantify the demand for energy needed to heat a building. HDD is derived from measurements of outside air temperature. The heating requirements for a given building at a specific location are considered to be directly proportional to the number of HDD at that location.
WINTER
Cooling Degree Days (CDD)
Degree days are the difference between the daily temperature mean, (high temperature plus low temperature divided by two) and 65°F. If the temperature mean is above 65°F, we subtract 65 from the mean and the result is Cooling Degree Days.
SUMMER
Balance Point Temperature
The building balance point temperature is the outdoor air temperature when the heat gains of the building are equal to the heat losses.
Internal Load Dominated Building
Skin Load Dominated Building
Thermal Conductivity (k)
Is the rate at which heat passes through 1 sq ft of a 1 in thickness of the material when the temperature differential is 1°F.
Resistivity (r)
Conduction
We touch other surfaces and heat is transferred
Convection
Air molecules contacts our body absorbing heat
Radiation
When our skin surface is hotter than other surfaces “seen” not touched, heat is radiated to these cooler surfaces and vice versa when other surfaces are hotter than our skin.
Evaporation
A liquid can evaporate only by removing large quantities of heat from the surface it is leaving.
Thermal Conductance (C)
Is the same property as Thermal Conductivity (k) when the material is a thickness other than 1 in.
R-value (Thermal Resistance)
In the context of construction, the R-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat.
FORMULA: R = r X d (resistivity X dimension)
GOOD: high = good insulation
BAD: low = poor insulation
U-Value (Thermal Transmittance)
Thermal transmittance, also known as U-value, is the rate of transfer of heat through a structure (which can be a single material or a composite), divided by the difference in temperature across that structure. The units of measurement are W/m²K. The better-insulated a structure is, the lower the U-value will be.
A U-value is a sum of the thermal resistances of the layers that make up an entire building element – for example, a roof, wall or floor. It also includes adjustments for any fixings or air gaps.
FORMULA: 1/R1 + R2 + …
RANGE: 0 to 1
GOOD: low = good insulation
BAD: high = poor insulation
Outdoor Design Temperature
Ventilation
Infiltration
Permeation of a liquid into something by filtration
Exfiltration
Windward side
Leeward side
The Different Climates
Saturation Point
The stage at which no more of a substance can be absorbed into a vapor or dissolve into a solution.
Dew Point
The atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense and dew can form.
Relative Humidity
The amount of water vapor present in air expressed as a percentage of the amount needed for saturation at the same temperature.
Thermal Bridging
Jack Studs
Structural Insulated Panel (SIP)
Indoor Air Quality (IAQ)
Absorptance
Emittance / Emissivity
Mean Radiant Temperature (MRT)
The radiant temperature of surrounding surfaces influence human comfort.
The concept of mean radiant temperature is used to quantify the exchange of radiant heat between a human and their surrounding environment, with a view to understanding the influence of surface temperatures on personal comfort.