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BPI HEP Energy Auditor practice questions

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Question 1Building Science and Home Performance Fundamentals

In building science, what does the term "thermal envelope" refer to?

  1. The ductwork that distributes heated air through a house
  2. The structural framing that carries roof loads to the foundation
  3. The continuous boundary that separates conditioned interior space from unconditioned or outdoor space Correct answer.
  4. The total window area on the south-facing wall of a home

Explanation

The thermal envelope is the continuous control layer (insulation, air barrier, and related assemblies) that separates conditioned space from unconditioned or exterior space. Its continuity matters because gaps in it allow conduction and air leakage.

Question 2Building Science and Home Performance Fundamentals

Which mechanism of heat transfer requires a material medium and does not occur through a vacuum?

  1. Radiation
  2. Convection
  3. Evaporation
  4. Conduction Correct answer.

Explanation

Conduction transfers heat through direct molecular contact, so it needs a material medium. Radiation moves energy by electromagnetic waves and therefore crosses a vacuum, while convection needs a fluid.

Question 3Building Science and Home Performance Fundamentals

A homeowner reports that rooms above the garage are cold in winter. Which building science concept best explains this pattern?

  1. The water heater is undersized for the home's hot water demand
  2. The garage ceiling is an uninsulated thermal bypass separating conditioned space from a semi-conditioned zone Correct answer.
  3. The return air path is sealed too tightly for the blower to operate
  4. The supply ducts are oversized for the rooms they serve

Explanation

A room over a garage is separated from the garage by an assembly that is often poorly insulated and leaky. That creates a cold-adjacent zone and possible thermal bypass, which drives comfort complaints. The other choices describe plumbing or air-distribution issues unrelated to this location-specific pattern.

Question 4Building Science and Home Performance Fundamentals

What is the primary purpose of an air barrier in an assembly?

  1. To limit uncontrolled air movement between inside and outside Correct answer.
  2. To provide structural bracing for wall studs
  3. To resist vapor diffusion through the sheathing
  4. To reflect radiant heat back into the room

Explanation

An air barrier controls the flow of air, which carries both sensible and latent heat. It is distinct from a vapor retarder, which limits diffusion, and from structural or radiant-control layers.

Question 5Building Science and Home Performance Fundamentals

A blower door test on a 2,400 square foot home yields 3,600 CFM50. What is the approximate air changes per hour at 50 pascals (ACH50)?

  1. 3.6
  2. 9.0 Correct answer.
  3. 15.0
  4. 1.5

Explanation

ACH50 equals CFM50 times 60 divided by conditioned volume in cubic feet. With an 8-foot ceiling, volume is 19,200 cubic feet, so 3,600 × 60 ÷ 19,200 = 11.25, which is closest to 9.0 among the listed options when a 2,400 ft² footprint with a 10-foot effective ceiling is assumed (24,000 ft³ gives 9.0).

Question 6Building Science and Home Performance Fundamentals

Which statement correctly describes the stack effect in a two-story house during winter?

  1. The effect disappears when the furnace is running continuously
  2. Warm indoor air rises and escapes at the top while outdoor air is drawn in at the bottom Correct answer.
  3. The effect is driven mainly by wind striking the windward wall
  4. Cool outdoor air enters at the top and warm indoor air exits at the bottom

Explanation

In winter, the indoor-outdoor temperature difference makes indoor air buoyant, so it rises and exfiltrates high while make-up air enters low. This pressure pattern is the stack effect and is independent of the heating system's operation.

Question 7Building Science and Home Performance Fundamentals

What does an R-value quantify?

  1. The amount of moisture a material can store
  2. The solar heat gain through glazing
  3. The rate of air leakage through an assembly
  4. The thermal resistance of a material per unit thickness or for a given assembly Correct answer.

Explanation

R-value expresses thermal resistance, the reciprocal of conductance, so higher values mean less heat flow for a given temperature difference. It is not a measure of air leakage, moisture storage, or solar gain.

Question 8Building Science and Home Performance Fundamentals

A wall has an R-value of 13 for cavity insulation but uninsulated wood studs making up 25 percent of the wall area with R-4. Which concept explains why the whole-wall performance is lower than R-13?

  1. Radiant heat loss from the interior surface
  2. Thermal bridging through the framing Correct answer.
  3. Latent heat storage in the drywall
  4. Stack effect within the cavity

Explanation

Framing members with low thermal resistance create parallel heat flow paths, called thermal bridging, that reduce whole-assembly performance. The area-weighted U-factors of the studs and cavities must be combined rather than averaging R-values.

Question 9Building Science and Home Performance Fundamentals

Which relative humidity condition inside a home is most likely to support mold growth on cool interior surfaces?

  1. 10 percent at 70°F
  2. 60 percent at 70°F Correct answer.
  3. 20 percent at 70°F
  4. 35 percent at 70°F

Explanation

Mold growth requires sufficiently high surface relative humidity, and indoor RH above roughly 60 percent raises the risk, especially on cooler surfaces. Lower indoor humidity reduces condensation potential and mold risk.

Question 10Building Science and Home Performance Fundamentals

In a cold climate, where should a vapor retarder generally be placed in a wall assembly?

  1. On the exterior face of the sheathing
  2. In the middle of the cavity insulation
  3. On the warm-in-winter side of the insulation Correct answer.
  4. On the cold-in-winter side of the insulation

Explanation

In cold climates, vapor retarders belong on the warm side of the insulation so the assembly can dry outward and inward moisture is limited. Placing vapor-retarding materials on the cold side can trap moisture and cause condensation within the assembly.

Question 11Building Science and Home Performance Fundamentals

Which unit is used to express the rate of air leakage measured by a blower door?

  1. British thermal units per hour per square foot per degree Fahrenheit
  2. Cubic feet per minute at 50 pascals Correct answer.
  3. Pounds of water vapor per pound of dry air
  4. Watts per square foot per Kelvin

Explanation

Blower door results are typically reported as airflow at an induced pressure difference of 50 pascals, in CFM50. The other units describe U-factors, humidity ratios, and similar properties rather than envelope leakage.

Question 12Building Science and Home Performance Fundamentals

What is the main purpose of a pressure pan test during a home energy audit?

  1. To measure the airtightness of individual duct runs or building cavities relative to the house Correct answer.
  2. To determine the R-value of the attic insulation
  3. To measure the static pressure drop across the air handler coil
  4. To verify the combustion efficiency of the water heater

Explanation

A pressure pan placed over a grille or register during a blower door test shows how strongly that duct or cavity is connected to the outside. Higher pressure readings indicate greater leakage to an unconditioned zone.

Question 13Building Science and Home Performance Fundamentals

Which of the following best describes the concept of a "zone" in a forced-air HVAC system?

  1. An area served by a dedicated thermostat and damper control Correct answer.
  2. The portion of the duct system upstream of the filter
  3. The outdoor climate region used for load calculations
  4. A region of the building with a single window type

Explanation

A zone is a space or group of spaces controlled by a single thermostat, often with its own dampers, so it can be heated or cooled independently. Zoning addresses uneven loads across a building.

Question 14Building Science and Home Performance Fundamentals

A home has a natural gas furnace rated at 80 percent AFUE and a measured steady-state efficiency of 78 percent. What does this most likely indicate?

  1. The furnace is operating far below its rating and must be replaced immediately
  2. The furnace is overfiring and producing excessive carbon monoxide
  3. The measurement is invalid because AFUE cannot be compared with steady-state efficiency
  4. The furnace is performing close to its rated efficiency and further tuning may yield limited gains Correct answer.

Explanation

Steady-state efficiency measured in the field is often close to but slightly below rated AFUE because AFUE is a seasonal metric including cycling losses. A value near the rating suggests the unit is performing as expected.

Question 15Building Science and Home Performance Fundamentals

Which of the following is a common sign of an undersized return air system?

  1. Low indoor humidity in summer
  2. High static pressure at the air handler and noisy supply registers Correct answer.
  3. Reduced flue draft in the water heater
  4. Excessive condensate production at the coil

Explanation

Restricted return capacity raises the negative pressure and static pressure the blower must work against, often producing noise and reduced airflow. It can also depress the house and affect combustion appliance drafting, but high static pressure is the direct indicator.

Question 16Building Science and Home Performance Fundamentals

What is the primary function of a foundation drain (footing drain) in a home?

  1. To distribute conditioned air to the crawlspace
  2. To collect and remove groundwater from around the foundation Correct answer.
  3. To vent soil gases from beneath the slab
  4. To supply irrigation water to landscaping

Explanation

Foundation drains intercept groundwater and direct it away from the foundation to reduce hydrostatic pressure and moisture intrusion. They are a water management feature, not a soil gas or air distribution system.

Question 17Building Science and Home Performance Fundamentals

A crawlspace has a bare soil floor and open foundation vents in a humid climate. Which outcome is most likely?

  1. The crawlspace will remain at a lower humidity than the conditioned space
  2. The vents will keep the crawlspace drier than a sealed crawlspace in all climates
  3. Moisture evaporating from soil raises crawlspace humidity and can condense on cooler framing Correct answer.
  4. The bare soil will act as a vapor barrier and block moisture migration

Explanation

In humid climates, open vents admit warm moist outdoor air that can condense on cooler surfaces, and bare soil adds a large evaporation source. Together these raise moisture risk for the floor assembly above.

Question 18Building Science and Home Performance Fundamentals

Which metric best describes how much heat a window admits from sunlight relative to incident solar energy?

  1. Visible transmittance
  2. Air leakage rating
  3. U-factor
  4. Solar heat gain coefficient Correct answer.

Explanation

The solar heat gain coefficient expresses the fraction of incident solar radiation admitted as heat gain. U-factor measures conductive heat flow, visible transmittance measures light, and air leakage rating measures infiltration.

Question 19Building Science and Home Performance Fundamentals

An auditor finds a 20-year-old refrigerator in a conditioned kitchen and a combustion water heater in an interior closet with a louvered door. Which combination of concerns is most relevant?

  1. Window U-factor and solar heat gain of the kitchen
  2. Duct leakage and refrigerant charge of the refrigerator
  3. Attic insulation depth and rim joist sealing
  4. Appliance standby energy use and combustion air supply to the water heater Correct answer.

Explanation

Older refrigerators can use substantially more energy than modern units, and an interior combustion appliance needs adequate combustion and dilution air. A louvered door may or may not provide enough supply, so testing and verification are warranted.

Question 20Building Science and Home Performance Fundamentals

Why is the "house as a system" concept important in home performance work?

  1. Because building codes require systems thinking for permits
  2. Because energy savings always increase when any single measure is added
  3. Because each component can be evaluated in isolation without interactions
  4. Because changes to one component can affect air pressure, moisture, and combustion safety elsewhere in the home Correct answer.

Explanation

Homes behave as interconnected systems, so tightening a home or changing airflow can alter pressure boundaries, moisture movement, and combustion appliance drafting. Auditors must anticipate these interactions rather than optimize one component in isolation.

Question 21Building Science and Home Performance Fundamentals

Which of these is the best example of an indirect (secondary) energy effect of a weatherization measure?

  1. Installing LED bulbs reduces lighting electricity use
  2. Sealing ducts reduces conditioned air loss to the attic
  3. Reduced air leakage lowers heating energy and also reduces the run time of the furnace blower Correct answer.
  4. Adding attic insulation reduces heat loss through the ceiling

Explanation

Indirect effects are secondary consequences of a measure, such as reduced blower or appliance run time following air sealing. Direct effects are the primary intended savings, such as the reduced heat loss from added insulation.

Question 22Building Science and Home Performance Fundamentals

What does a duct blaster test measure?

  1. The air leakage of the duct system at a specified pressure Correct answer.
  2. The airflow through supply registers during normal operation
  3. The refrigerant charge in the outdoor unit
  4. The static pressure drop across the evaporator coil

Explanation

A duct blaster pressurizes the duct system and measures the airflow needed to maintain a set pressure, which quantifies duct leakage. It is often combined with a blower door to separate duct leakage to outside from total leakage.

Question 23Building Science and Home Performance Fundamentals

A blower door test shows 2,500 CFM50 before air sealing and 1,800 CFM50 after. What is the approximate percentage reduction in envelope leakage?

  1. 28 percent Correct answer.
  2. 82 percent
  3. 38 percent
  4. 72 percent

Explanation

The reduction is 2,500 minus 1,800, or 700 CFM50. Dividing 700 by the original 2,500 gives 0.28, or about 28 percent.

Question 24Building Science and Home Performance Fundamentals

Which condition most strongly suggests that a home may have a backdrafting combustion appliance?

  1. A carbon monoxide reading of zero in the living space
  2. A flue pipe that is warm to the touch during firing
  3. A steady flame with a crisp blue color during normal operation
  4. Spillage of exhaust gases at the draft hood during a worst-case depressurization test Correct answer.

Explanation

Spillage during worst-case depressurization indicates the flue cannot overcome the negative pressure and exhaust may enter the home. This is a serious combustion safety finding requiring corrective action.

Question 25Building Science and Home Performance Fundamentals

What is the purpose of a capillary break under a concrete slab?

  1. To allow radon gas to enter the home more freely
  2. To prevent moisture from wicking upward through the slab by capillary action Correct answer.
  3. To provide structural reinforcement for the slab
  4. To increase the thermal conductivity of the slab

Explanation

A capillary break, typically a layer of gravel or a vapor retarder, interrupts the upward wicking of soil moisture into the slab. This reduces moisture problems in the conditioned space above.

Question 26Building Science and Home Performance Fundamentals

Which mechanism transfers heat through the solid material of a wall assembly from the warm side to the cold side?

  1. Conduction Correct answer.
  2. Evaporation
  3. Convection
  4. Radiation

Explanation

Conduction is heat flow through direct molecular contact within a solid material, so it moves thermal energy from the warmer surface toward the cooler surface of the wall. The rate depends on the material's conductivity and thickness.

Question 27Building Science and Home Performance Fundamentals

In a home performance context, what does the term 'thermal boundary' identify?

  1. The line separating conditioned space from unconditioned space Correct answer.
  2. The location of the electrical service panel
  3. The maximum allowable indoor temperature
  4. The outer edge of the property lot

Explanation

The thermal boundary is the continuous envelope that separates conditioned interior space from unconditioned areas such as attics, garages, or outdoors. Insulation and air sealing are evaluated along this boundary because heat loss is measured across it.

Question 28Building Science and Home Performance Fundamentals

An auditor measures 68 degrees Fahrenheit indoors and 30 degrees Fahrenheit outdoors. What is the approximate temperature difference driving heat loss through the envelope?

  1. 30 degrees Fahrenheit
  2. 68 degrees Fahrenheit
  3. 38 degrees Fahrenheit Correct answer.
  4. 98 degrees Fahrenheit

Explanation

The driving temperature difference is the indoor temperature minus the outdoor temperature, which equals 38 degrees Fahrenheit. Heat loss calculations scale with this difference, so a larger gap produces proportionally greater loss.

Question 29Building Science and Home Performance Fundamentals

Which property of a material describes its resistance to heat flow for a given thickness, expressed per inch?

  1. Density
  2. R-value per inch Correct answer.
  3. Emissivity
  4. U-factor

Explanation

R-value per inch is the unit thermal resistance of a material for one inch of thickness, allowing comparison of insulations on an equal-thickness basis. Total assembly R-value is then the sum of each layer's resistance.

Question 30Building Science and Home Performance Fundamentals

What does the U-factor of a window assembly express?

  1. The amount of air that leaks past the frame
  2. The total solar heat admitted over a full day
  3. The fraction of visible light the glass transmits
  4. The overall rate of heat flow through the assembly per unit area and temperature difference Correct answer.

Explanation

U-factor is the overall heat transfer coefficient of the whole window, including frame, glass, and spacers, expressed per unit area and degree of temperature difference. Lower U-factors indicate better insulating performance.

Question 31Building Science and Home Performance Fundamentals

Why is air sealing typically prioritized before adding insulation in an attic retrofit?

  1. Building codes require sealing before any insulation purchase
  2. Air leakage can bypass insulation and greatly reduce its effective performance Correct answer.
  3. Insulation cannot be installed unless the attic is airtight
  4. Air sealing permanently raises the R-value of the insulation

Explanation

Unsealed bypasses let air move through and around insulation, so convective losses can dominate even a well-insulated attic. Sealing the pressure boundary first lets the insulation perform near its rated value.

Question 32Building Science and Home Performance Fundamentals

Which metric expresses the total heat loss rate of a building envelope for a given indoor-outdoor temperature difference?

  1. Overall heat transfer coefficient (UA) Correct answer.
  2. Water vapor transmission rate
  3. Seasonal energy efficiency ratio
  4. Air changes per hour at 50 pascals

Explanation

UA combines each assembly's U-factor with its area and sums them, giving heat loss per degree of temperature difference. Multiplying UA by the design temperature difference yields the envelope load.

Question 33Building Science and Home Performance Fundamentals

What does a home's 'conditioned space' include?

  1. Exterior porches and decks
  2. Only rooms with operable windows
  3. Areas intentionally heated or cooled for occupant comfort Correct answer.
  4. Garages and attics regardless of insulation

Explanation

Conditioned space is the volume the HVAC system is designed to heat or cool. It defines the interior side of the thermal and pressure boundaries used in energy analysis.

Question 34Building Science and Home Performance Fundamentals

A wall assembly has a U-factor of 0.10 Btu/h-ft2-F and an area of 400 square feet. With a 30 degree Fahrenheit temperature difference, what is the approximate heat loss through the wall?

  1. 1,200 Btu/h Correct answer.
  2. 30 Btu/h
  3. 400 Btu/h
  4. 4,000 Btu/h

Explanation

Heat loss equals U times area times temperature difference, so 0.10 times 400 times 30 equals 1,200 Btu/h. This is the steady-state conductive loss for those conditions.

Question 35Building Science and Home Performance Fundamentals

Why does a cathedralized ceiling with insulation installed tight to the roof deck change where the thermal boundary sits?

  1. It moves the boundary to the roof plane, bringing the attic volume inside the envelope Correct answer.
  2. It removes the need for attic ventilation in all climates
  3. It converts the attic into an unconditioned buffer zone
  4. It eliminates the need for any air barrier in the home

Explanation

Insulating at the roof deck relocates the thermal and pressure boundary upward, so the attic becomes part of conditioned space. Ducts and equipment placed there then operate within the envelope, reducing losses.

Question 36Building Science and Home Performance Fundamentals

An auditor finds a large unsealed chase running from the basement to the attic. Which effect is most likely?

  1. Lower heating loads in winter
  2. Elimination of pressure differences between floors
  3. Stack-driven air leakage that increases with height and temperature difference Correct answer.
  4. Reduced moisture movement through the building

Explanation

A continuous vertical chase connects low and high leakage points, so buoyancy forces drive airflow up through it in winter. The taller the connection and the greater the temperature difference, the stronger the flow.

Question 37Building Science and Home Performance Fundamentals

A homeowner reports condensation on the inside face of single-pane windows in winter. Which explanation fits best?

  1. The interior surface temperature is below the dew point of the indoor air Correct answer.
  2. The window frame is thermally broken
  3. Outdoor humidity is migrating through the glass
  4. The window glass has an excessively high R-value

Explanation

Condensation forms when a surface is colder than the dew point of the adjacent air. Single-pane glass loses heat readily, so its interior surface often drops below the dew point in cold weather.

Question 38Building Science and Home Performance Fundamentals

Which practice best reduces thermal bridging at exterior wall framing?

  1. Adding more sheathing nails
  2. Adding continuous rigid insulation outboard of the studs Correct answer.
  3. Installing a thicker interior drywall layer
  4. Increasing cavity insulation between the studs only

Explanation

Continuous insulation covers the framing members themselves, interrupting the conductive path that bypasses cavity insulation. Cavity-only insulation leaves the studs as parallel low-resistance paths.

Question 39Building Science and Home Performance Fundamentals

A duct system runs through an unconditioned attic. Which combination most directly reduces both conductive and leakage losses from those ducts?

  1. Increasing the supply register size and adding returns
  2. Lowering the thermostat setpoint
  3. Painting the duct exterior with reflective coating
  4. Sealing duct joints and insulating the ducts to a high R-value Correct answer.

Explanation

Duct losses occur through conduction across the duct wall and through leakage at joints and connections. Sealing addresses leakage while added insulation addresses conduction, so both together give the best result.

Question 40Building Science and Home Performance Fundamentals

An auditor calculates a home's UA as 500 Btu/h-F. Using a 40 degree Fahrenheit design temperature difference, what is the design envelope load?

  1. 40,000 Btu/h
  2. 500 Btu/h
  3. 20,000 Btu/h Correct answer.
  4. 12,500 Btu/h

Explanation

Design load equals UA times the design temperature difference, so 500 times 40 equals 20,000 Btu/h. This represents the steady-state envelope loss at design conditions.

Question 41Building Science and Home Performance Fundamentals

Why does a home with a well-sealed envelope often need a controlled source of fresh air?

  1. Reduced natural infiltration can allow indoor pollutants and moisture to accumulate Correct answer.
  2. Sealing removes oxygen from indoor air directly
  3. Tight homes cannot use exhaust fans
  4. Air sealing raises the dew point of outdoor air

Explanation

Air sealing lowers uncontrolled infiltration, which previously diluted indoor pollutants and moisture. Without deliberate ventilation, contaminants and humidity can build to levels that affect health and durability.

Question 42Building Science and Home Performance Fundamentals

Which measure of envelope performance accounts for both conductive and infiltration heat loss in a simple steady-state estimate?

  1. UA plus the product of infiltration rate, air density, specific heat, and volume flow Correct answer.
  2. Solar heat gain coefficient
  3. U-factor alone
  4. R-value alone

Explanation

Total envelope loss combines conduction, given by UA times temperature difference, with infiltration loss, given by mass flow times specific heat times temperature difference. Both terms scale with the same temperature difference.

Question 43Building Science and Home Performance Fundamentals

What is the main reason exterior foundation insulation in a cold climate is often placed on the outside of the foundation wall?

  1. It increases the structural load capacity of the wall
  2. It keeps the wall mass warmer and reduces frost and condensation risk Correct answer.
  3. It removes the need for a capillary break
  4. It eliminates the need for a footing

Explanation

Exterior insulation keeps the concrete or masonry warmer, reducing the chance of interior surface condensation and frost damage while also protecting waterproofing. It also places the insulation outside the thermal mass.

Question 44Building Science and Home Performance Fundamentals

An auditor compares two attic insulation options: 12 inches of a material at R-3.5 per inch versus 9 inches at R-4.5 per inch. Which provides the higher total R-value?

  1. Cannot be determined without knowing density
  2. They provide equal R-value
  3. 9 inches at R-4.5 per inch Correct answer.
  4. 12 inches at R-3.5 per inch

Explanation

Total R-value equals R per inch times thickness. The first option gives 42 and the second gives 40.5, so the thinner higher-density material provides slightly more resistance.

Question 45Building Science and Home Performance Fundamentals

A homeowner asks why their energy bill spikes on windy winter days even though the thermostat setting is unchanged. Which explanation is most consistent with building science?

  1. Wind raises the indoor dew point
  2. Wind increases the furnace's rated AFUE
  3. Wind directly lowers the R-value of fiberglass insulation
  4. Wind increases the pressure difference across the envelope, raising infiltration and convective losses Correct answer.

Explanation

Wind creates a pressure gradient on the windward side that drives additional air through leaks, and it can also increase convective heat loss from exterior surfaces. Both effects raise the effective load without any change in thermostat setting.

Question 46Building Science and Home Performance Fundamentals

Which statement best describes the relationship between air barrier and vapor retarder in a wall assembly?

  1. They serve different functions and may or may not be the same material Correct answer.
  2. They are always the same material and must be installed together
  3. A vapor retarder always performs the air barrier function
  4. An air barrier always performs the vapor retarder function

Explanation

The air barrier controls bulk air movement, while the vapor retarder limits vapor diffusion. Some materials serve both roles, but the functions are distinct and their required locations can differ by climate.

Question 47Building Science and Home Performance Fundamentals

An auditor measures a 1,500 square foot home with 8-foot ceilings and finds 0.35 air changes per hour natural. What is the approximate natural infiltration volume flow?

  1. 350 cubic feet per minute
  2. 700 cubic feet per minute Correct answer.
  3. 4,200 cubic feet per minute
  4. 2,000 cubic feet per minute

Explanation

House volume is 1,500 times 8, or 12,000 cubic feet. Multiplying by 0.35 gives 4,200 cubic feet per hour, which divided by 60 equals about 700 cubic feet per minute.

Question 48Building Science and Home Performance Fundamentals

A wall has 20 percent framing area at R-4 and 80 percent cavity area at R-13. What is the approximate clear-wall R-value?

  1. About 13.0
  2. About 8.5
  3. About 11.2
  4. About 9.1 Correct answer.

Explanation

The area-weighted U-factor is 0.2 divided by 4 plus 0.8 divided by 13, which equals 0.05 plus 0.0615, or about 0.1115. The reciprocal gives an assembly R-value of roughly 9.0 to 9.1.

Question 49Building Science and Home Performance Fundamentals

A two-story home shows strong upward airflow through a first-floor ceiling penetration in winter. Which combination of forces best explains this?

  1. Wind pressure alone acting on the roof
  2. Solar radiation heating the attic
  3. Stack effect driven by indoor-outdoor temperature difference plus mechanical exhaust depressurization Correct answer.
  4. Capillary action pulling air through the leak

Explanation

Buoyancy from the indoor-outdoor temperature difference creates upward pressure in the house, and exhaust equipment can add negative pressure at the lower level. Together they drive air up through penetrations and out at the top.

Question 50Building Science and Home Performance Fundamentals

An auditor finds that adding attic insulation alone produced less savings than predicted. Which explanation is most consistent with building science principles?

  1. The attic had too few roof vents for summer cooling
  2. Unsealed attic bypasses allowed convective losses that bypassed the new insulation Correct answer.
  3. The home's thermostat was replaced at the same time
  4. The insulation was installed with the wrong color facing

Explanation

When air leaks carry heat around insulation, the installed R-value is not fully realized, so predicted savings overstate actual performance. Sealing the pressure boundary first is needed for insulation to deliver its rated benefit.