Mechanical and Electrical Equipment for Buildings - Key Terms

Vocabulary flashcards covering key building design, thermal comfort, indoor air quality, and daylighting terms based on Mechanical and Electrical Equipment for Buildings, 13th Edition by Walter T. Grondzik and Alison G. Kwok.

Ambient

Surrounding environmental conditions, particularly the conditions of the air around a building, person, or object, including air temperature, humidity, and other environmental factors.

Dew Point Temperature

The temperature at which air becomes saturated with moisture and water vapor begins to condense into liquid water.

Passive Solar Design

A design approach that uses the sun, building orientation, windows, thermal mass, shading, and other architectural features to provide heating, cooling, and lighting with minimal reliance on mechanical systems.

Clerestory

A high-level window or opening located above the main wall openings of a building designed to bring daylight and ventilation into a building.

Dry-Bulb Temperature (DB)

The ambient air temperature measured with a standard thermometer, thermocouple, or resistance temperature device.

Potable Water

Water of sufficient quality to be used for drinking and other uses requiring safe water, controlled closely by building codes.

Comfort Zone

The range of environmental conditions in which most building occupants experience thermal comfort, influenced by air temperature, radiant temperature, air speed, relative humidity, clothing, and metabolic activity.

Emissivity

A dimensionless measure of how effectively a surface emits thermal radiation compared with an ideal emitter, represented by $\text{ε}$ (epsilon).

Psychrometric Chart

A graphical tool used to represent the physical properties of moist air and the thermodynamic processes that affect it, combining dry-bulb temperature, wet-bulb temperature, relative humidity, humidity ratio, specific volume, and enthalpy.

Conductivity

A material's ability to conduct heat, where high thermal conductivity allows heat to move through readily and low conductivity resists heat flow.

Enthalpy

The total heat content of an air-moisture mixture, including both sensible and latent heat, relative to a reference condition, expressed in $\text{Btu/lb}$ or $\text{kJ/kg}$ of dry air.

Relative Humidity (RH)

The amount of moisture present in air compared with the maximum amount of moisture the air could hold at that temperature, expressed as a percentage.

Convection

Heat transfer caused by the movement of air or another fluid, such as warm air rising and cool air sinking.

Globe Thermometer

An instrument that measures the temperature of a blackened globe to account for the effects of radiant heat and air movement.

Sustainability

Creating buildings and systems that reduce environmental impacts, conserve resources, minimize environmental degradation, and consider long-term environmental performance.

Daylighting

The intentional use of natural daylight to illuminate building interiors, using strategies such as sidelighting, toplighting, light shelves, and solar shading.

Mean Radiant Temperature (MRT)

The combined effect of the temperatures of surrounding surfaces (walls, windows, ceilings, floors) on a person.

Wet-Bulb Temperature (WB)

Temperature measured using a thermometer with a wetted bulb exposed to moving air, where evaporation lowers the thermometer reading.

Wet-Bulb Depression

The difference between dry-bulb temperature and wet-bulb temperature; a larger difference generally indicates lower relative humidity.

ASHRAE

American Society of Heating, Refrigerating and Air-Conditioning Engineers; develops standards and guidelines related to thermal comfort (such as Standard 55), HVAC systems, energy efficiency, and indoor air quality (such as Standards 62.1 and 62.2).

LEED

Leadership in Energy and Environmental Design; a green building rating and certification system developed by the U.S. Green Building Council (USGBC).

SBS

Sick Building Syndrome; situations where building occupants experience health or comfort complaints associated with spending time in a building, without a single specific illness or cause being identified.

VOC

Volatile Organic Compound; chemical compounds that can evaporate into the air and potentially contribute to indoor air pollution.

Outgassing

The process by which building materials release Volatile Organic Compounds (VOCs) into the air.