I85PREP
⌘ K
Phius Certified Passive House Consultant (CPHC) study materials
Phius Certified Passive House Consultant (CPHC) study resources

Phius Certified Passive House Consultant (CPHC) practice questions

One question at a time. Build your Phius Certified Passive House Consultant (CPHC) understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Passive Building Principles

In passive building design, what does the term 'thermal bridge' describe?

  1. A continuous layer of insulation that wraps the entire building without interruption
  2. A localized path where heat flows more readily through the envelope than through adjacent insulated areas Correct answer.
  3. A gap in the air barrier that allows bulk water to enter the wall assembly
  4. A mechanical duct that carries conditioned air between floors

Explanation

A thermal bridge is a localized region of the envelope with higher thermal conductance than its surroundings, so heat bypasses the intended insulation layer. Common examples are slab edges, balcony penetrations, and framing that interrupts insulation. Designers reduce them by keeping insulation continuous and minimizing structural penetrations.

Question 2Passive Building Principles

Which metric expresses the rate of air leakage through a building envelope normalized to the envelope area?

  1. Specific heat capacity
  2. U-value
  3. Solar heat gain coefficient
  4. Air changes per hour at a reference pressure (ACH) Correct answer.

Explanation

Air leakage is quantified by measuring airflow at a reference pressure difference, typically 50 Pa, and normalizing it either to volume (air changes per hour) or to envelope area. This lets designers compare envelope airtightness across different building sizes. U-value, specific heat, and SHGC describe other physical properties.

Question 3Passive Building Principles

Why do passive building standards place strong emphasis on a continuous, well-defined air barrier?

  1. It replaces the need for thermal insulation in cold climates
  2. It eliminates the need for any mechanical ventilation system
  3. It reduces both infiltration heat loss and moisture transport into assemblies Correct answer.
  4. It raises the solar heat gain coefficient of the glazing

Explanation

An effective air barrier limits uncontrolled air movement, which carries both sensible heat and moisture. Reducing infiltration lowers heating and cooling loads and helps prevent condensation within assemblies. It does not remove the need for ventilation or insulation, nor does it change glazing properties.

Question 4Passive Building Principles

What is the primary function of a heat recovery ventilator (HRV) in a passive building?

  1. To heat domestic hot water using exhaust air
  2. To transfer sensible heat between exhaust and supply airstreams while providing controlled ventilation Correct answer.
  3. To recirculate interior air to reduce heating demand
  4. To dehumidify outdoor air before it enters the space

Explanation

An HRV provides continuous balanced ventilation and transfers sensible heat from the outgoing exhaust air to the incoming fresh air. This keeps fresh-air supply comfortable while limiting ventilation heat loss. Moisture transfer is the role of an energy recovery ventilator, not a basic HRV.

Question 5Passive Building Principles

In passive building terminology, what does 'form factor' refer to?

  1. The ratio of internal gains to solar gains
  2. The ratio of glazed area to opaque wall area
  3. The ratio of north-facing to south-facing windows
  4. The ratio of envelope surface area to treated floor area Correct answer.

Explanation

Form factor compares the heat-loss surface of the envelope to the conditioned floor area it serves. Compact shapes with low form factors generally lose less heat per unit of floor area. This is why compact massing is favored in passive design.

Question 6Passive Building Principles

Which statement best describes the passive building principle of 'free cooling' via ventilation?

  1. Using mechanical chillers to precool supply air during peak hours
  2. Using cooler outdoor air or night flush to remove internal heat without a vapor-compression system Correct answer.
  3. Cooling the slab with refrigerant circulated through embedded pipes
  4. Relying on window openings alone in every climate

Explanation

Free cooling uses favorable outdoor conditions, such as cool night air, to purge internal heat without running chillers. It depends on climate, control strategy, and adequate airflow paths. Mechanical precooling and refrigerant-based slab cooling are active systems, not free cooling.

Question 7Passive Building Principles

What does the solar heat gain coefficient (SHGC) of a window quantify?

  1. The amount of ultraviolet radiation the glazing blocks
  2. The visible light transmittance of the glazing
  3. The fraction of incident solar radiation admitted as heat gain to the interior Correct answer.
  4. The conductive heat loss per unit area per degree of temperature difference

Explanation

SHGC expresses the share of incident solar radiation that becomes heat inside the building, including directly transmitted and absorbed-then-released components. Lower values reduce cooling loads and solar overheating; higher values can be beneficial for passive solar heating. It is distinct from U-value and visible transmittance.

Question 8Passive Building Principles

Which of the following is a characteristic feature of a passive building envelope in a cold climate?

  1. Thin walls with high-performance glazing only
  2. Reliance on internal gains alone for heating
  3. Large unshaded west-facing glazing to capture afternoon sun
  4. A highly insulated, airtight envelope with minimized thermal bridges Correct answer.

Explanation

Cold-climate passive envelopes combine high insulation levels, excellent airtightness, and careful detailing to avoid thermal bridges. These measures reduce transmission and infiltration losses so that remaining demand can be met with minimal heating. Glazing area and orientation are also optimized rather than maximized indiscriminately.

Question 9Passive Building Principles

A designer is evaluating a wall assembly and wants to know the steady-state heat flow through it per unit area for a given temperature difference. Which property should be used?

  1. The material density
  2. The vapor permeance
  3. The assembly U-value Correct answer.
  4. The assembly R-value only

Explanation

The U-value is the overall heat transfer coefficient of an assembly, directly giving heat flow per unit area per degree of temperature difference. It is the reciprocal of the total R-value. Density and permeance describe mass and moisture behavior, not steady-state heat flow.

Question 10Passive Building Principles

In a passive building, why is a compact building shape generally preferred over a sprawling one with the same floor area?

  1. It eliminates the need for mechanical ventilation
  2. It increases the available roof area for solar panels
  3. It improves the solar heat gain coefficient of the windows
  4. It reduces envelope area per unit of floor area, lowering transmission losses Correct answer.

Explanation

A compact form has less exposed envelope relative to conditioned floor area, so heat loss per square meter of floor area is lower. This reduces the heating and cooling demand that the envelope must offset. Glazing properties and ventilation requirements are unaffected by compactness itself.

Question 11Passive Building Principles

A wall in a cold climate has continuous exterior insulation but steel shelf angles penetrate it at each floor. What is the most appropriate design response?

  1. Increase interior insulation thickness to compensate
  2. Add a thermal break at each penetration and minimize the number and size of penetrations Correct answer.
  3. Seal the penetrations with vapor-impermeable tape
  4. Remove the exterior insulation behind the angles

Explanation

Steel penetrations create localized conductive bridges that can dominate heat loss and cause cold interior surfaces. The effective remedy is to interrupt the conductive path with a thermal break and to reduce penetration count and size. Simply adding interior insulation does not eliminate the bridge and can worsen condensation risk.

Question 12Passive Building Principles

During a blower-door test, a building measures 0.6 air changes per hour at 50 Pa. What does this result most directly indicate?

  1. The moisture content of the wall assemblies
  2. The building's ventilation rate during normal occupancy
  3. The heating demand of the building
  4. The envelope airtightness under a standardized pressure difference Correct answer.

Explanation

The ACH50 value is a standardized measure of envelope leakage at a 50 Pa pressure difference. It allows comparison between buildings and verification against airtightness targets. It is not the normal operating ventilation rate, nor does it directly quantify heating demand or moisture content.

Question 13Passive Building Principles

A designer places a vapor-impermeable interior membrane in a cold-climate wall that also has exterior insulation. What is the primary risk of this configuration?

  1. Increased air infiltration through the membrane
  2. Loss of thermal mass benefits
  3. Trapping moisture at the cold side and creating condensation risk within the assembly Correct answer.
  4. Reduced solar heat gain through the wall

Explanation

In cold climates the vapor retarder should generally be on the warm side, and the assembly should be able to dry. A vapor-impermeable interior membrane can trap moisture that migrates outward and condenses at cold surfaces. Designers assess vapor profiles to keep assemblies dryable and avoid trapped moisture.

Question 14Passive Building Principles

Why is a balanced ventilation system with heat recovery preferred over exhaust-only ventilation in a tight passive building?

  1. It avoids depressurization that could draw soil gases or moisture into the building Correct answer.
  2. It eliminates the need for filtration
  3. It allows windows to remain open in winter
  4. It increases the building's air leakage rate

Explanation

Exhaust-only systems depressurize the building, which can pull in outdoor air through unintended paths, including soil gases and moisture-laden air. Balanced systems supply and exhaust equal airflow, maintaining pressure control and enabling heat recovery. Filtration and window operation are separate considerations.

Question 15Passive Building Principles

A project team wants to reduce summer overheating in a passive building with large south-facing glazing. Which combination of measures is most consistent with passive design principles?

  1. Remove the air barrier to allow natural cooling
  2. Add exterior shading and select glazing with a lower SHGC Correct answer.
  3. Rely on increased mechanical cooling capacity
  4. Increase glazing area and reduce insulation

Explanation

Exterior shading blocks solar radiation before it enters the glazing, and lower-SHGC glazing limits the solar heat that does enter. Together they reduce cooling loads while preserving daylight. Increasing glazing or removing the air barrier would worsen performance.

Question 16Passive Building Principles

In passive building load analysis, what is meant by 'specific space heating demand'?

  1. The peak heating power of the boiler
  2. The heating capacity of the ventilation system
  3. The annual heating energy required per unit of treated floor area Correct answer.
  4. The total heating energy used by the building over its lifetime

Explanation

Specific space heating demand normalizes annual heating energy to treated floor area, allowing comparison of buildings of different sizes. Passive building targets are commonly expressed in these area-normalized units. It is distinct from peak load and from total lifetime energy.

Question 17Passive Building Principles

A building has excellent insulation and airtightness but still shows high heating demand in winter. Which factor is most likely to be overlooked?

  1. The visible light transmittance of the glazing
  2. The number of occupants in summer
  3. Uninsulated slab edges and balcony penetrations acting as thermal bridges Correct answer.
  4. The color of the interior paint

Explanation

Even well-insulated envelopes can lose substantial heat through structural penetrations such as slab edges and balconies. These localized bridges bypass the insulation and can dominate transmission losses. Paint color, summer occupancy, and visible transmittance do not explain winter heating demand.

Question 18Passive Building Principles

Which strategy best supports passive cooling in a hot-dry climate?

  1. Sealing the building completely and relying on internal gains
  2. Using shading, thermal mass, and night ventilation to flush stored heat Correct answer.
  3. Increasing internal moisture sources to raise humidity
  4. Maximizing unshaded east glazing for morning light

Explanation

In hot-dry climates, shading blocks direct solar gains, thermal mass absorbs daytime heat, and night ventilation purges stored heat when outdoor air is cooler. This combination reduces cooling loads without active systems. Unshaded glazing and added moisture would worsen comfort.

Question 19Passive Building Principles

An energy model shows a passive building meeting its heating demand target but exceeding its primary energy target. Which measure is most likely to address the gap?

  1. Adding more insulation to the walls
  2. Lowering the airtightness target
  3. Reducing plug and appliance loads and improving ventilation fan efficiency Correct answer.
  4. Increasing the glazing area on the south facade

Explanation

Primary energy includes all end uses, so appliances, lighting, and fans can dominate even when heating demand is low. Reducing plug loads and improving fan efficiency directly lowers primary energy. Additional insulation or glazing changes affect heating demand, not the broader end-use picture.

Question 20Passive Building Principles

Why does passive building design emphasize minimizing the conditioned volume, for example by locating unconditioned spaces outside the thermal envelope?

  1. It increases the building's solar heat gain coefficient
  2. It reduces the envelope area and volume that must be heated or cooled Correct answer.
  3. It allows the use of single-glazed windows
  4. It removes the need for an air barrier

Explanation

Keeping unconditioned spaces such as garages or storage outside the thermal envelope reduces the volume and surface area that must be conditioned. This lowers heat loss and simplifies envelope detailing. It does not change glazing properties or eliminate air-barrier requirements.

Question 21Passive Building Principles

A design team is comparing two glazing options for a cold climate: one with a low U-value and moderate SHGC, another with a higher U-value and very high SHGC. Which consideration is most relevant to the choice?

  1. The balance between reducing conductive losses and capturing useful solar gains Correct answer.
  2. The visible light transmittance alone determines performance
  3. The glazing frame color is the deciding factor
  4. Only the SHGC matters in cold climates

Explanation

In cold climates, glazing selection involves balancing low U-values to limit heat loss against sufficient SHGC to capture beneficial solar gains. The optimal balance depends on orientation, climate, and internal gains. Visible transmittance and frame color are secondary considerations.

Question 22Passive Building Principles

What is the purpose of a 'thermal envelope' in passive building design?

  1. To identify the location of plumbing fixtures
  2. To describe the exterior cladding material
  3. To define the boundary between conditioned and unconditioned space Correct answer.
  4. To specify the color of the roof

Explanation

The thermal envelope is the continuous boundary that separates conditioned interior space from unconditioned or exterior space. It encompasses insulation, air barrier, and glazing, and must be continuous to perform well. Cladding, plumbing, and roof color are unrelated to its definition.

Question 23Passive Building Principles

A project team is selecting insulation for a wall where the exterior sheathing is cold in winter. Which property most directly determines the risk of moisture accumulation at the sheathing?

  1. The fire rating of the insulation
  2. The vapor permeance and temperature profile of the assembly Correct answer.
  3. The insulation's compressive strength
  4. The insulation's recycled content

Explanation

Moisture accumulation depends on how much vapor reaches the cold sheathing and whether the assembly can dry. Vapor permeance and the temperature profile determine whether condensation occurs and whether drying is possible. Compressive strength, recycled content, and fire rating do not govern this moisture risk.

Question 24Passive Building Principles

In a passive building, why can a very low form factor still fail to achieve low heating demand if the glazing is poorly distributed?

  1. Compact forms always overheat in winter
  2. Glazing distribution affects only daylight, not energy
  3. Form factor and glazing have no interaction
  4. Poor orientation and distribution can cause excessive losses or unwanted gains that offset the benefit of compactness Correct answer.

Explanation

Form factor reduces envelope area, but glazing orientation and area determine solar gains and losses. Poorly distributed glazing can create overheating on one facade and excessive losses on another, offsetting compactness benefits. Glazing also affects daylight, but its energy role is significant.

Question 25Passive Building Principles

A blower-door test reveals a leakage path behind a kitchen cabinet on an exterior wall. Why is this location particularly problematic in a cold climate?

  1. It can allow moist interior air to enter the assembly and condense on cold surfaces Correct answer.
  2. It increases the solar heat gain coefficient of the wall
  3. It improves the effectiveness of the ventilation system
  4. It reduces the thermal mass of the wall

Explanation

Air leakage carries moisture-laden interior air into the assembly, where it can condense on cold surfaces and cause deterioration. This hidden path is hard to detect and can persist undetected. It does not change SHGC, thermal mass, or ventilation effectiveness in a beneficial way.

Question 26Passive Building Principles

In passive building design, what does the term 'thermal bridge' refer to?

  1. A gap in the airtightness layer that allows outdoor air infiltration
  2. A localized path of increased heat flow through the envelope that bypasses the main insulation layer Correct answer.
  3. A window frame detail that increases solar heat gain in winter
  4. A section of wall where insulation thickness exceeds the design value

Explanation

A thermal bridge is a localized area of the building envelope where heat conduction is higher than in adjacent assemblies, usually because a material with high conductivity penetrates the insulation. These paths raise total heat loss and can create cold interior surfaces prone to condensation.

Question 27Passive Building Principles

Which metric expresses the airtightness of a passive building envelope as measured by a blower-door test?

  1. Specific heat capacity in kilojoules per kilogram-kelvin
  2. U-value in watts per square meter-kelvin
  3. Solar heat gain coefficient of the glazing
  4. Air changes per hour at 50 pascals of pressure difference Correct answer.

Explanation

Airtightness is normally reported as n50, the number of whole-building air changes per hour at a 50 Pa pressure difference. The passive building airtightness limit is usually stated in this unit, so designers and verifiers compare test results against it directly.

Question 28Passive Building Principles

What does the heating load of a passive building represent, as distinct from its heating demand?

  1. The peak rate of heat that the heating system must deliver to maintain comfort on the design day Correct answer.
  2. The total amount of heat energy delivered over an entire heating season
  3. The rate at which solar radiation enters through the glazing
  4. The share of total energy use attributable to domestic hot water

Explanation

Heating load is a power quantity, expressed in watts or watts per square meter, describing the peak output the system must supply at design conditions. Heating demand is an energy quantity accumulated over the season, so the two are related but not interchangeable.

Question 29Passive Building Principles

Why does passive building design treat internal heat gains from occupants and appliances as an important input?

  1. They offset part of the heating need in cold weather but can contribute to overheating in warm weather Correct answer.
  2. They reduce ventilation requirements by replacing fresh outdoor air
  3. They have no effect on the energy balance because they are too small to model
  4. They increase the heating demand by raising the indoor temperature setpoint

Explanation

Internal gains are a double-edged input: in winter they reduce the heat the building must supply, while in summer or shoulder seasons they can push a well-insulated building toward overheating. Good passive design accounts for both effects when sizing glazing, shading and ventilation.

Question 30Passive Building Principles

What is the primary function of a heat recovery ventilation unit in a passive building?

  1. To provide supplementary space heating through a hydronic coil
  2. To dehumidify the incoming air to a fixed absolute humidity
  3. To transfer heat from exhaust air to incoming fresh air while maintaining balanced supply and exhaust flows Correct answer.
  4. To recirculate filtered indoor air without introducing outdoor air

Explanation

A heat recovery ventilator brings in fresh outdoor air and exhausts stale indoor air in balanced quantities, transferring heat between the two streams. This keeps ventilation losses low in a tight, well-insulated envelope while ensuring continuous fresh air supply.

Question 31Passive Building Principles

Which climate condition most strongly justifies specifying glazing with a high solar heat gain coefficient in a passive building?

  1. A cold, sunny heating-dominated climate with substantial winter solar availability Correct answer.
  2. A mild coastal climate with frequent summer fog and low solar exposure
  3. A hot, arid climate with intense summer sun and high cooling loads
  4. A hot, humid climate with high year-round cooling demand

Explanation

In heating-dominated climates where winter sun is available, high solar heat gain allows free solar energy to reduce the heating demand. Cooling-dominated climates instead favor lower solar gain to limit overheating and cooling energy.

Question 32Passive Building Principles

Why is a compact building form generally beneficial in passive building design?

  1. It guarantees that the building will meet the airtightness limit
  2. It reduces the envelope area available for heat loss relative to the conditioned floor area Correct answer.
  3. It increases the internal volume so that heat is distributed more evenly
  4. It eliminates the need for mechanical ventilation

Explanation

A compact form has a lower surface-area-to-volume ratio, so each square meter of conditioned floor is served by less exposed envelope. With less envelope area, transmission losses and thermal bridge exposure are reduced for the same floor area.

Question 33Passive Building Principles

What does the U-value of a building assembly describe?

  1. The ability of a material to store thermal energy per unit volume
  2. The rate of steady-state heat transfer through a unit area per unit temperature difference Correct answer.
  3. The amount of moisture vapor that diffuses through the assembly
  4. The resistance of a surface to radiant heat exchange

Explanation

The U-value, expressed in watts per square meter-kelvin, is the overall thermal transmittance of an assembly and is the reciprocal of its total thermal resistance. Lower U-values mean better insulating performance, which is why passive buildings target very low values.

Question 34Passive Building Principles

A designer specifies continuous exterior insulation on a cold-climate wall. What is the main thermal benefit compared with locating the same insulation between studs?

  1. It reduces heat flow through the framing members by keeping them on the warm side of the insulation Correct answer.
  2. It removes the need for an interior air barrier
  3. It increases the thermal mass exposed to the interior
  4. It raises the solar heat gain of the opaque wall

Explanation

Continuous exterior insulation covers the framing, reducing the thermal bridging that occurs when insulation sits only between studs. It also keeps the structural framing warmer, which lowers condensation risk within the assembly.

Question 35Passive Building Principles

A design team wants to place the vapor control layer correctly in a cold-climate wall with thick exterior insulation. Which principle should guide the decision?

  1. The vapor control layer should be located where it stays warm enough to avoid condensing conditions at the condensing plane Correct answer.
  2. The vapor control layer should be placed on both faces of the wall regardless of climate
  3. The vapor control layer should be omitted whenever exterior insulation is used
  4. The vapor control layer should always be placed on the coldest possible surface

Explanation

Vapor control strategy depends on where the dew point or condensing plane falls within the assembly. With substantial exterior insulation the framing stays warmer, allowing a less restrictive or differently placed vapor control layer, but the layer must still be positioned to avoid trapping moisture at a cold surface.

Question 36Passive Building Principles

An energy model shows a passive building meeting its heating demand target but exceeding its primary energy target. Which measure is most directly aimed at closing that gap?

  1. Increasing the ventilation airflow rate to improve indoor air quality
  2. Increasing the insulation thickness in the exterior wall
  3. Replacing a fossil-fuel heating source with a high-efficiency electric heat pump and reducing appliance loads Correct answer.
  4. Adding more south-facing glazing to increase winter solar gains

Explanation

Primary energy accounts for source conversion factors, so switching to an efficient electric heat pump and lowering plug loads reduces primary energy without necessarily changing the heating demand. Envelope improvements affect demand, but the gap here is in the source-energy metric.

Question 37Passive Building Principles

Why does passive building practice favor locating unconditioned spaces such as garages, storerooms or mechanical rooms outside the thermal envelope?

  1. Doing so increases the internal heat gains available to the conditioned space
  2. Doing so removes the need for a continuous air barrier at those boundaries
  3. Doing so reduces the conditioned volume that must be heated, cooled and ventilated Correct answer.
  4. Doing so allows the ventilation system to be downsized to zero

Explanation

Every cubic meter inside the thermal envelope must be conditioned, so excluding buffer spaces lowers the energy needed to maintain comfort. It also simplifies the envelope by concentrating airtightness and insulation on a smaller, more continuous boundary.

Question 38Passive Building Principles

A cold-climate project compares two windows: one with a very low U-value and low solar heat gain, another with a slightly higher U-value and high solar heat gain. Which consideration is decisive for net heating performance?

  1. The number of panes, since more panes always improve net performance
  2. The frame color, since it affects the surface temperature of the glass
  3. The visible light transmittance alone, since it determines daylight availability
  4. The balance between reduced transmission losses and increased useful winter solar gains over the heating season Correct answer.

Explanation

Window performance in a heating climate depends on the trade-off between conductive losses, driven by U-value, and useful solar gains, driven by solar heat gain coefficient and orientation. A slightly higher U-value can be justified if the additional winter solar gain more than offsets the extra losses.

Question 39Passive Building Principles

A wall assembly has high thermal resistance but the interior surface above a shelf angle shows condensation in winter. Which explanation is most consistent with this observation?

  1. The insulation has too high a thermal resistance for the climate
  2. A localized thermal bridge at the penetration creates a cold interior surface below the dew point Correct answer.
  3. The interior relative humidity is necessarily too low
  4. The vapor control layer is too far toward the exterior

Explanation

Condensation on an interior surface indicates that the surface temperature has fallen below the dew point of the indoor air. A structural penetration that interrupts the insulation creates exactly this localized cold spot even when the rest of the wall performs well.

Question 40Passive Building Principles

What is the purpose of a shading strategy such as exterior overhangs on south-facing glazing in a passive building?

  1. To reduce winter solar gains so that heating demand falls
  2. To block high-angle summer sun while admitting lower-angle winter sun Correct answer.
  3. To eliminate the need for mechanical cooling entirely
  4. To increase the U-value of the glazing assembly

Explanation

Properly sized overhangs exploit the seasonal change in solar altitude, blocking summer sun that would cause overheating while allowing winter sun to contribute useful heat. The geometry must be tuned to the latitude and window height.

Question 41Passive Building Principles

A project has excellent insulation and airtightness but still shows an unexpectedly high heating demand in winter. Which factor is most likely to explain the gap?

  1. An overly high internal heat gain from occupants
  2. A building form factor that is lower than assumed
  3. A high ventilation rate combined with poor heat recovery effectiveness Correct answer.
  4. An overly low window U-value

Explanation

In a very tight, well-insulated building, ventilation losses become a dominant share of the remaining heating demand. If the ventilation rate is high or the heat recovery effectiveness is poor, the model will show a heating demand that insulation alone cannot fix.

Question 42Passive Building Principles

Why is a balanced ventilation system with heat recovery generally preferred over exhaust-only ventilation in a tight passive building?

  1. It supplies and exhausts air in equal measure while recovering heat, avoiding uncontrolled infiltration to make up the exhaust Correct answer.
  2. It removes the requirement to commission the ventilation system
  3. It allows the building to be operated without an airtightness layer
  4. It eliminates the need for any filtration of outdoor air

Explanation

Exhaust-only systems depressurize the building and draw makeup air through envelope leakage, which brings in unfiltered air and can drive moisture into assemblies. A balanced system with heat recovery maintains pressure neutrality and captures heat from the exhaust stream.

Question 43Passive Building Principles

In passive cooling strategy for a hot-dry climate, which combination is most appropriate?

  1. Sealed building with no ventilation and reliance on thermal mass alone
  2. Large unshaded west glazing and high internal gains
  3. External shading, night flushing with cool dry air, and controlled internal gains Correct answer.
  4. High solar heat gain glazing on all orientations and minimal insulation

Explanation

In hot-dry climates, blocking solar gain before it enters, using cool night air to flush stored heat, and limiting internal gains all reduce cooling needs. Thermal mass can support night flushing when it is coupled to the interior and ventilated effectively.

Question 44Passive Building Principles

What is meant by 'specific space heating demand' in passive building verification?

  1. Total heating energy for the whole building per year
  2. Peak heating power per unit of glazed area
  3. Heating energy per occupant per year
  4. Annual heating energy per unit of treated floor area Correct answer.

Explanation

Specific space heating demand normalizes annual heating energy by treated floor area, allowing buildings of different sizes to be compared against a single criterion. It is an energy quantity per area, not a peak power or a per-occupant figure.

Question 45Passive Building Principles

A compact building with excellent envelope performance still shows high summer overheating. Which explanation is most plausible?

  1. An airtightness result that is better than the target
  2. A form factor that is too low for the climate
  3. An insulation level that exceeds the minimum requirement
  4. Large unshaded glazing combined with limited ventilation capacity to remove gains Correct answer.

Explanation

Overheating in a well-insulated, airtight building usually comes from solar and internal gains that cannot escape. Unshaded glazing admits solar gain, and if ventilation or shading cannot remove it, temperatures rise even though the envelope performs well.

Question 46Passive Building Principles

Which property most directly governs whether a material can act as a vapor retarder in a wall assembly?

  1. Its thermal conductivity, describing heat flow through it
  2. Its vapor permeance, describing the rate at which water vapor diffuses through it Correct answer.
  3. Its density, describing mass per unit volume
  4. Its compressive strength, describing structural capacity

Explanation

Vapor retarder performance is defined by permeance, which quantifies how readily water vapor diffuses through a material under a vapor pressure difference. Low-permeance materials restrict vapor flow and must be placed thoughtfully within the assembly.

Question 47Passive Building Principles

A blower-door test identifies a leakage path behind a kitchen cabinet mounted on an exterior wall. Why is this location particularly problematic?

  1. Concealed leakage can drive moist indoor air into the assembly, where it may condense on cold surfaces and cannot be seen or easily repaired Correct answer.
  2. Leakage behind cabinets always improves ventilation effectiveness
  3. Cabinets increase the thermal resistance of the wall so that heat loss is underestimated
  4. The cabinet blocks solar gain, which raises the heating demand

Explanation

Leakage paths hidden behind cabinets are hard to find and repair, and they can carry warm moist indoor air into a cold part of the assembly. That raises the risk of concealed condensation and moisture damage that may go unnoticed for years.

Question 48Passive Building Principles

A design team is weighing whether to add exterior insulation versus upgrading glazing to meet a heating demand target. Which reasoning best reflects passive building priorities?

  1. Upgrade glazing first because windows always dominate envelope heat loss in passive buildings
  2. Add insulation only after all glazing has been upgraded to triple glazing
  3. Treat opaque and glazed areas as independent so that neither affects the other
  4. Reduce transmission losses through the opaque envelope and thermal bridges first, then optimize glazing for the solar and U-value balance Correct answer.

Explanation

Opaque envelope and thermal bridge improvements reduce losses without adding solar gains that could cause overheating, making them a reliable first step. Glazing then needs to be optimized for the balance between U-value, solar gain and orientation rather than upgraded reflexively.

Question 49Passive Building Principles

A project team proposes a very low form factor but specifies poorly insulated, highly glazed walls on the north facade. What is the likely outcome?

  1. The north glazing will offset its losses with strong winter solar gains
  2. The low form factor guarantees compliance regardless of the facade design
  3. Compactness reduces the U-value of the glazing automatically
  4. The compactness benefit is offset because the north glazing adds conduction losses with little useful solar gain Correct answer.

Explanation

Form factor only describes how much envelope area exists relative to floor area; it says nothing about the quality of that envelope. North glazing in a heating climate receives little useful solar gain, so its conduction losses can erase the benefit of compactness.

Question 50Passive Building Principles

Why does passive building design emphasize a continuous airtightness layer aligned with the insulation layer?

  1. Alignment removes the need for mechanical ventilation
  2. Alignment increases the thermal conductivity of the insulation
  3. Alignment allows the vapor control layer to be omitted
  4. Alignment keeps the air barrier warm and dry, reducing condensation risk while preventing air movement through the insulation Correct answer.

Explanation

When the air barrier coincides with the insulated plane, the barrier stays near interior temperature and is less likely to reach the dew point. This also prevents air from bypassing the insulation, which would otherwise degrade its effective performance through wind washing and convective loops.