Building Science Fundamentals Flashcards
7 cards from real HERS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Building Science Fundamentals flashcards as text
In a mixed-humid climate, what is the primary moisture concern during summer months?
Answer: Warm humid outdoor air infiltrating and condensing on air-conditioned surfaces
In mixed-humid climates, warm humid outdoor air infiltrating a cooled building can condense on surfaces below the dew point, causing moisture damage.
Which term describes the total heat flow through a building assembly per unit area per unit temperature difference?
Answer: U-factor
U-factor (thermal transmittance) measures heat flow rate through an assembly per square foot per degree Fahrenheit of temperature difference.
What is 'stack effect' in a building context?
Answer: Pressure-driven airflow caused by buoyancy differences between indoor and outdoor air
Stack effect occurs when indoor-outdoor temperature differences create buoyancy-driven pressure differences that drive air infiltration and exfiltration.
A home in Climate Zone 5 has a cathedral ceiling. Which insulation approach best controls both thermal performance and moisture?
Answer: Unventilated assembly with sufficient vapor-impermeable insulation above the roof deck
An unventilated cathedral ceiling in CZ5 requires enough rigid foam above the deck to keep the sheathing above the dew point, preventing condensation.
What does the term 'thermal bridging' refer to in wall assemblies?
Answer: Conductive heat loss through high-conductivity elements that bypass insulation
Thermal bridging occurs when conductive materials like steel or wood studs create a path for heat to bypass the insulation in a wall cavity.
According to building science principles, where should the air barrier be located relative to the insulation layer?
Answer: At or near the insulation layer but its exact position depends on climate
The optimal air barrier location depends on climate — it should be positioned to prevent moisture-laden air from reaching surfaces where condensation could occur.
Which mechanism is responsible for the majority of heat transfer through a well-sealed, well-insulated attic floor on a cold winter night?
Answer: Conduction through the insulation material
Conduction through the insulation material is the dominant heat transfer mechanism in a properly sealed and installed fibrous insulation layer.