Environmental Systems Core Concepts

Vocabulary flashcards covering the fundamentals of environmental systems, psychrometrics, ventilation, acoustics, HVAC, and building codes based on lecture notes.

Thermal Comfort

Condition determined by air temp, mean radiant temp, humidity, air speed, clothing, and metabolic rate.

Sensible heat

The heat associated with a temperature change.

Latent heat

The heat associated with a phase change ($\text{evaporation/condensation}$) and humidity rather than temperature.

Mean Radiant Temperature (MRT)

The average radiant temperature of surrounding surfaces, which often affects comfort more than air temperature.

Psychrometric Chart: Horizontal Axis

Represents the Dry bulb temp.

Psychrometric Chart: Vertical Axis

Represents the Humidity ratio.

Dew point

The temperature at the left boundary of a psychrometric chart where condensation occurs if the surface temp is lower.

Humidification

A psychrometric process represented by a vertical up movement on the chart.

Evaporative cooling

A process that adds moisture while lowering temperature, moving diagonal up-left along constant wet-bulb on a chart.

Stack effect

A ventilation driver where warm air rises to create vertical airflow, which is stronger in tall buildings.

Bernoulli principle

The principle stating that faster wind results in lower pressure.

Trombe walls

A passive heating strategy involving high thermal mass to store heat.

Illuminance

Measured in $\text{lux}$ or $\text{footcandles}$.

Luminance

The perceived brightness of a surface.

Glare

Discomfort caused by excessive contrast, not by brightness alone.

CRI

Abbreviation for Color Rendering Index used in electric lighting.

Sound Pressure Level

Measured in $dB$.

Reverberation Time (RT60)

The time required for sound to decay by $60\,dB$, depending on room volume and absorption.

Absorption coefficient

A value ranging from $0$ to $1$ that indicates how much sound a material absorbs.

VAV (Variable Air Volume)

An all-air HVAC system that saves energy by reducing airflow instead of temperature.

Heat pumps

Systems that move heat rather than generate it, working best in moderate climates like Hawai‘i.

Greywater

Wastewater that is not potable but is distinct from blackwater.

Electric Power Formula

$\text{Power (W)} = \text{Voltage (V)} \times \text{Current (A)}$.

Circuit breakers

Electrical components designed to protect wiring rather than the connected appliances.

LEED Categories

Includes Energy & Atmosphere, Water Efficiency, Materials, Indoor Environmental Quality, and Site & Transportation.

ASHRAE 55

The standard code governing thermal comfort.

ASHRAE 62.1

The standard code governing ventilation.

IECC

The code governing energy benchmarks.