ARCH 215 Midterm Study Guide: Thermal and Atmospheric Environment Flashcards

Vocabulary flashcards covering core terms, concepts, metrics, and thermal formulas for ARCH 215.

Building as an Environmental Filter

An architectural model where the building sits between outdoor climate and the human body, modifying heat, air, sunlight, and moisture before environmental conditions reach occupants.

Lechner's Three-Tier Approach

A sequential environmental design framework prioritizing basic building design and architecture first (Tier 1), passive systems second (Tier 2), and mechanical systems third (Tier 3).

Operational Energy

Energy consumed during the ongoing active use of a building for heating, cooling, ventilation, lighting, power, water heating, and appliances.

Embodied Energy

The cumulative energy required to extract, process, manufacture, transport, install, maintain, and dispose of or recycle building materials.

Life-Cycle Assessment (LCA)

A methodological framework for evaluating environmental impacts over the entire lifespan of a material, product, or whole building.

Passive Survivability

The ability of a building to maintain habitable, safe indoor thermal conditions during power grid or fuel outages without relying on mechanical equipment.

Power

The instantaneous rate of energy transfer or conversion, measured in Watts ($1\,\text{W} = 1\,\text{J/s}$) or kilowatts ($1\,\text{kW} = 1000\,\text{W}$).

Energy

The total quantity of work done or power consumed over time, calculated as power multiplied by time (such as kilowatt-hours, where $1\,\text{kWh} = 1\,\text{kW} \times 1\,\text{hour}$).

British Thermal Unit (Btu)

The heat energy required to raise the temperature of one pound of water by $1^\circ\text{F}$, where $1\,\text{Btu} \approx 0.293\,\text{Wh}$ and $1\,\text{MMBtu} \approx 293.1\,\text{kWh}$.

Energy Use Intensity (EUI)

A building metric normalizing annual energy consumption by gross floor area, calculated as $\text{EUI} = \frac{\text{Annual Energy Use}}{\text{Gross Floor Area}}$ (typically expressed in $\text{kBtu/ft}^2 \cdot \text{year}$).

Benchmark

A standard reference value representing actual historical or existing energy performance across comparable buildings.

Target

A planned energy performance goal or specific metric established during design for a building to achieve.

Site Energy

The amount of energy directly consumed at the building site as measured by utility meters.

Source Energy

The total raw fuel energy consumed off-site to extract, generate, and transmit energy to the building, including generation and delivery losses.

Zero Net Energy (ZNE)

A building metric achieved when annual on-site renewable energy generation is equal to or greater than annual site energy consumption.

Bioclimatic Design

An architectural approach that utilizes local climate and natural systems to fulfill human comfort requirements while minimizing mechanical equipment dependence.

Macroclimate

The general regional atmospheric climate conditions characteristic of a large geographical area.

Microclimate

The localized environmental and climatic conditions existing in the immediate proximity of a specific site or building.

Cold-Air Pooling

A nocturnal microclimatic effect where heavy, cool air drains downhill into low-lying land areas or valleys.

Dry-Bulb Temperature

The ambient air temperature measured by a standard thermometer shielded from radiation and moisture evaporation.

Relative Humidity (RH)

The percentage ratio of actual water vapor contained in the air to the maximum amount of water vapor the air can hold at that specific dry-bulb temperature.

Humidity Ratio

The absolute mass of water vapor present per unit mass of dry air, plotted vertically on a psychrometric chart.

Dew-Point Temperature

The temperature at which air becomes fully saturated ($100\%$ relative humidity) and water vapor begins condensing into liquid.

Wet-Bulb Temperature

The lowest air temperature achievable strictly through adiabatic water evaporation from a wetted surface in moving air.

Typical Meteorological Year (TMY)

A representative annual weather dataset assembled from multi-year historical climate observations for building energy simulation.

EnergyPlus Weather (EPW)

A standard digital weather file containing 8,760 hourly data entries for environmental parameters used in energy calculations.

Wind Rose

A circular diagram depicting the frequency, speed, and directional distribution of prevailing winds coming toward a site.

Psychrometry

The thermodynamic branch of physical science studying moist air properties and thermodynamic process interactions.

Building Balance Point Temperature

The outdoor temperature where internal heat gains equal envelope and air leakage heat losses, calculated as $T_{bp} = T_{therm} - \frac{Q_i}{UA}$.

Heating Degree Days (HDD)

A quantified indicator of heating demand over time when outdoor mean temperature drops below the balance point, expressed daily as $\text{HDD} = \max(0, T_{bp} - T_{mean})$.

Cooling Degree Days (CDD)

A quantified indicator of cooling demand over time when outdoor mean temperature rises above the balance point, expressed daily as $\text{CDD} = \max(0, T_{mean} - T_{bp})$.

Heating Load

The rate of heat thermal energy that must be supplied to an indoor space to maintain thermostat setpoints during cold conditions.

Cooling Load

The rate of thermal energy that must be removed from an indoor space to maintain thermostat setpoints during warm conditions.

Peak Load

The maximum instantaneous rate of heating or cooling demand experienced by a building, governing mechanical HVAC equipment sizing.

Thermal Zone

A individual space or grouping of spaces within a building sharing similar environmental exposures, occupant loads, and thermal control parameters.

Perimeter Zone

The peripheral zone of a building floor plan (typically within 15 to 20 feet of exterior walls) directly affected by weather, solar gain, and envelope conduction.

Interior Zone

The core interior area of a building isolated from exterior walls that experiences heat gains primarily driven by people, lighting, and equipment.

Vasodilation

A physiological human heating response expanding peripheral blood vessels near skin surfaces to accelerate heat loss.

Vasoconstriction

A physiological human cooling protection response narrowing blood vessels near skin surfaces to reduce heat loss to the cold environment.

Conduction

Direct thermal energy transfer occurring across physical contact between adjacent solid bodies or materials.

Convection

Heat transfer occurring between a solid body surface and a moving fluid or surrounding air stream.

Thermal Radiation

Electromagnetic energy exchange occurring between separated surfaces across open space.

Evaporation

A latent heat absorption phase change process converting liquid water into vapor, removing energy from the skin or surrounding air.

Thermal Comfort

As defined by ASHRAE, a condition of mind expressing satisfaction with the surrounding thermal environment.

Mean Radiant Temperature (MRT)

The uniform surface temperature of an imaginary enclosure radiating the same net heat quantity to an occupant as the actual surrounding non-uniform surfaces.

Operative Temperature

An integrated thermal metric combining air temperature and mean radiant temperature into a single value, approximated as $T_{operative} \approx \frac{T_{air} + \text{MRT}}{2}$.

Metabolic Rate

The biological energy generation rate at which the human body converts food energy into heat and work during metabolic activity.

Clo Unit

A standardized thermal insulation unit quantifying the thermal resistance provided by clothing ensembles.

Predicted Mean Vote (PMV)

A thermal comfort index forecasting the mean thermal sensation vote of a group on a 7-point scale from -3 (cold) to +3 (hot).

Static Comfort Model

A comfort framework assuming occupants require fixed, narrow, mechanically maintained indoor climate conditions year-round.

Adaptive Comfort Model

A comfort model establishing that acceptable indoor comfort ranges shift dynamically with outdoor climate variations and occupant behavioral adaptation.

Thermal Autonomy

The percentage of annual occupied hours during which an indoor zone achieves acceptable thermal comfort strictly through passive architectural means.

Thermal Delight

Sensory pleasure derived from localized, dynamic, or non-neutral thermal sensations and microclimates.

Solar Declination

The geometric angle formed between direct sunlight rays and Earth's equatorial plane ($\delta \approx +23.44^\circ$ at summer solstice, $0^\circ$ at equinox, $\approx -23.44^\circ$ at winter solstice).

Solar Altitude

The vertical solar angle measured upward in degrees from the horizontal ground plane to the sun.

Solar Azimuth

The horizontal angle specifying the sun's compass direction along the horizon plane.

Irradiance

The instantaneous rate of incident solar power delivered per unit area, measured in $\text{W/m}^2$ or $\text{kW/m}^2$.

Irradiation

The accumulated solar radiant energy striking a unit area over a specified time duration, measured in $\text{Wh/m}^2$ or $\text{kWh/m}^2$.

Direct Solar Radiation

Unscattered solar radiation traveling in direct straight beam lines from the solar disk to strike a surface.

Diffuse Solar Radiation

Solar radiation scattered by clouds, water vapor, dust, and atmosphere that reaches surfaces multi-directionally from the sky dome.

Global Horizontal Radiation

The combined direct solar beam and diffuse sky radiation striking a flat horizontal exterior surface.

Solar Heat Gain Coefficient (SHGC)

A dimensionless fraction between 0 and 1 indicating how much incident solar thermal radiation passes through glazing or is absorbed and re-radiated indoors.

Visible Transmittance (VT)

A dimensionless optical ratio between 0 and 1 indicating the fraction of visible light spectrum transmitted through glazing.

Spectrally Selective Glazing

An engineered glazing technology designed to transmit high levels of visible daylight while reflecting invisible heat-carrying solar near-infrared wavelengths.

Window-to-Wall Ratio (WWR)

The ratio of total window glazing area relative to total exterior vertical wall area, calculated as $\text{WWR} = \frac{\text{Window Area}}{\text{Exterior Wall Area}}$.

Cosine Effect

The geometric reduction of direct-beam solar irradiance striking a surface as the beam angle of incidence grows oblique, described by $I_{surface} = I_{normal} \cos(\theta)$.

Thermal Mass

High heat capacity material (such as concrete, stone, or brick) that absorbs, stores, and slowly releases heat energy to damp indoor temperature swings.

Night-Purge Ventilation

A cooling process that flushes cool nighttime outdoor air through a space to purge heat accumulated in exposed indoor thermal mass.

Comfort Ventilation

The strategy of directing moving air across human skin to increase convective and evaporative heat loss without necessarily lowering ambient air temperature.

Stack Effect

Buoyancy-driven air movement caused by thermal air density differentials, where warm interior air rises and exits through upper openings while drawing cool air in through lower openings.