SHGC
Solar Heat Gain Coefficient
Solar Heat Gain Coefficient
Solar Heat Gain Coefficient (SHGC) measures the fraction of solar radiation (heat) admitted through a window, door, or skylight, ranging from 0 to 1. A lower SHGC (e.g., < 0.30) reduces heat gain, ideal for warm climates to lower cooling costs. Higher values are better for cold climates to allow passive solar heating.
Skin Loaded Building
A skin-load dominated building is a structure whose energy consumption—specifically heating and cooling—is primarily driven by external weather conditions interacting with its envelope (walls, roof, windows) rather than internal heat sources like people or equipment.
Internal Loaded Building
An internal-load dominated building is a structure where heat generated inside by occupants, lighting, and equipment is the primary factor driving energy consumption, rather than exterior weather conditions. Common examples include schools, hospitals, offices, and theaters. These buildings often require cooling year-round, even in winter, because of high internal heat gains.
Low E Glass
Allows less heat to move through.
Low-E (low-emissivity) glass is a type of energy-efficient window glass coated with a microscopically thin, transparent layer of metal or metal oxide. This coating reflects infrared and ultraviolet light while allowing visible light to pass through, keeping interiors cooler in summer, warmer in winter, and reducing energy bills.
BTU
British Thermal Unit
1 Degree of water per pound of water.
A BTU (British Thermal Unit) is a standard measure of energy, representing the amount of heat needed to raise one pound of water by one degree Fahrenheit.
Evaporation
the process of turning from liquid into vapor.
When things evaporate, they make what’s around them cold.
Evaporation in architecture, often called evaporative cooling or adiabatic cooling, is a sustainable, passive, or active technique that uses the natural, heat-absorbing process of water changing from liquid to vapor to cool buildings. It reduces air temperatures by passing hot, dry air through water-saturated materials (pads, walls, or fountains), making it highly effective in arid climates for energy-efficient cooling.
Air Temp
air temperature defines the thermal intensity of the air within or surrounding a structure, serving as a primary, though incomplete, indicator of occupant comfort and a key factor in calculating HVAC energy loads. It measures how hot or cold the air is at specific locations, usually recorded at 1.5 meters above ground level.
Humidity
the management of water vapor in the air and materials to ensure occupant comfort, health, and structural integrity, ideally maintained at 40–55% relative humidity (RH). It affects building performance through condensation, material decay, and energy consumption, requiring design strategies like proper insulation, ventilation, and HVAC control.
Conduction
Conduction in architecture is the transfer of heat directly through solid building materials—such as walls, roofs, and windows—from warmer areas to cooler ones. It is a primary driver of heat gain and loss in buildings, necessitating the use of insulation to resist this flow, measured by R-value.
Convection
the transfer of heat through the movement of fluids—primarily air—within building spaces or assemblies, where warmer, less dense air rises and cooler, denser air sinks. It is a critical component of building energy performance, affecting occupant comfort through drafts, heating, and ventilation, as well as moisture management.
Radiation
A form of heating that follows the line of sight. (The sun, fire, etc.) Radiation does not turn a corner.
…an energy-efficient, comfortable system that warms people and objects directly via infrared radiation from surfaces like floors, walls, or ceilings. Unlike forced-air, it minimizes air circulation, reducing dust movement and providing uniform, quiet, and efficient heat. Commonly installed as hydronic (liquid-based) or electric systems, it works by heating surfaces to a higher temperature than the room, enhancing thermal comfort without duct losses.
Delta T
Delta T ((\Delta T)) in architecture and HVAC engineering represents the temperature difference between two points in a system, typically the supply and return air or water. It is a critical metric for measuring energy efficiency, heat transfer capacity, and system performance, often calculated as
Delta T = Return Temperature - Supply Temperature
Elements of a Passive Thermal Building
- South facing glass
- shading
- good insulation
- thermal mass
Thermal Mass
Holds heat
Thermal Resistance
Resists heat passing through
SIP
Structurally Insulated Panel
Benefit: Thermal Break
In an HVAC system, a PUMP = ?
Compressor
Closed Loop System (in HVAC)
a sealed piping network that recirculates a fixed volume of water, glycol, or refrigerant to transfer heat without exposing the fluid to the atmosphere. These systems minimize water loss, contamination, and maintenance by keeping the medium contained, often using heat exchangers to release heat into the ground or air.
HVAC zones are determined by…?
Exposure, Air Quality, Schedule, Occupancy
Grille (HVAC)
Air Goes In
Register (HVAC)
Air Goes Out
Diffuser (HVAC)
Spreads Air Out
Why do we not want buildings to have Negative Pressure?
It would suck moisture into the building
