RESNET HERS National Rater Test — Questions and Answers

Question 1: A HERS rater finds duct leakage to outside of 8% of system airflow. Under RESNET standards, how is this reported?

Reported as Total Duct Leakage only
Fail — must be below 6% for all homes
Pass — within the 10% default allowance (Correct answer)
Reported as QII verified leakage requiring correction

Correct answer: Pass — within the 10% default allowance

RESNET allows a 10% duct leakage to outside default, so 8% passes the verified leakage threshold.

Question 2: When sizing combustion air openings for appliances in a confined space, the upper opening should be located:

At mid-wall height to balance supply and exhaust
At floor level to supply dense cold air
Within 12 inches of the ceiling to exhaust heat (Correct answer)
Directly behind the appliance burner intake

Correct answer: Within 12 inches of the ceiling to exhaust heat

The upper combustion air opening is placed within 12 inches of the ceiling per code, allowing hot flue gases to escape and drawing fresh air in through the lower opening.

Question 3: What is the primary purpose of a vapor retarder in a wall assembly from a HERS building science perspective?

To reflect radiant heat away from the framing
To serve as the primary air barrier
To control moisture diffusion and prevent condensation within the assembly (Correct answer)
To increase the wall's R-value

Correct answer: To control moisture diffusion and prevent condensation within the assembly

A vapor retarder controls the diffusion of water vapor through the wall assembly to prevent condensation and moisture damage within the building envelope.

Question 4: A rater finds that CFM25 out (duct leakage to outside) exceeds the RESNET threshold for the home size. What is the most appropriate next step?

Report the result and recommend duct sealing, then retest (Correct answer)
Increase fan speed and retest immediately
Replace all ductwork before filing the HERS rating
Seal the blower door and cancel the test

Correct answer: Report the result and recommend duct sealing, then retest

When duct leakage exceeds thresholds, the rater reports the finding, recommends corrective duct sealing by the contractor, and then conducts a retest to verify compliance.

Question 5: Why is third-party verification important in HERS ratings?

Reduces time needed for inspections
Ensures accurate and unbiased results (Correct answer)
Allows flexible standards
Limits contractor responsibility

Correct answer: Ensures accurate and unbiased results

Third-party verification ensures objectivity and accuracy in energy rating assessments and compliance.

Question 6: Which climate-related factor most influences whether a HERS rater recommends a vented or unvented attic assembly?

Annual heating degree days only
The age of the existing HVAC equipment in the attic
The local wind speed and prevailing wind direction
The climate zone, humidity levels, and roof geometry (Correct answer)

Correct answer: The climate zone, humidity levels, and roof geometry

Climate zone moisture conditions and roof geometry determine whether vented attics will introduce harmful humidity or whether unvented conditioned attics are more appropriate.

Question 7: Which of the following is a common source of air leakage that a rater should pre-seal before a blower door test to avoid skewing results toward envelope leakage?

Attic hatch with no weatherstripping
Electrical outlets on interior walls
Mechanical exhaust fans without dampers (Correct answer)
Recessed lights on interior ceilings

Correct answer: Mechanical exhaust fans without dampers

Mechanical exhaust fans without self-closing dampers are intentional openings that should be temporarily sealed before the test so they don't inflate envelope leakage readings.

Question 8: A HERS rater verifies continuous rigid foam insulation on the exterior of a wall assembly. What thermal performance benefit does this provide beyond cavity insulation alone?

Higher combustion safety margin
Elimination of thermal bridging through framing members (Correct answer)
Reduced blower door test time
Increased vapor permeance

Correct answer: Elimination of thermal bridging through framing members

Continuous exterior insulation eliminates thermal bridging through studs, dramatically improving whole-wall R-value.

Question 9: What is the RESNET-recognized default infiltration rate used for the Reference Home in HERS Index calculations?

0.35 ACHn
5 ACH50
3 ACH50
7 ACH50 (Correct answer)

Correct answer: 7 ACH50

RESNET uses 7 ACH50 as the default infiltration rate for the Reference Home when no blower door test is performed.

Question 10: A homeowner wants to improve their HERS rating from 72 to 55. Which measure is most likely to produce the largest single improvement?

Adding a programmable thermostat
Installing low-flow showerheads
Replacing incandescent bulbs with LEDs throughout the home
Air sealing the building envelope to reduce infiltration from 8 ACH50 to 3 ACH50 (Correct answer)

Correct answer: Air sealing the building envelope to reduce infiltration from 8 ACH50 to 3 ACH50

Significantly reducing air infiltration through envelope air sealing typically yields large energy savings and a meaningful drop in the HERS Index.

Question 11: In HERS energy modeling, how is incoming cold water (mains) temperature typically determined?

A fixed 55°F is used regardless of location
Always equal to the outdoor design dry-bulb temperature
Location-dependent values based on ground temperature data (Correct answer)
A fixed 65°F is applied for all US climate zones

Correct answer: Location-dependent values based on ground temperature data

RESNET/ANSI 301 uses location-specific mains water temperatures based on geographic ground temperature data, as cold water temperatures vary significantly across US climate zones.

Question 12: Which of the following best describes the hazard of a cracked heat exchanger in a forced-air gas furnace?

Increased gas consumption without a safety hazard
Refrigerant leakage into the air stream
Combustion gases including CO can mix with and be distributed through supply air throughout the home (Correct answer)
Reduced heating efficiency only

Correct answer: Combustion gases including CO can mix with and be distributed through supply air throughout the home

A cracked heat exchanger allows combustion gases to cross into the supply airstream, distributing CO and other combustion byproducts to every room served by the duct system.

Question 13: What is 'duct leakage to outside' (Qto) and why is it modeled differently from total duct leakage in energy software?

Qto measures duct leakage at 25 Pa while total leakage is measured at 50 Pa
Qto applies only to multi-family buildings with shared duct chases
Qto is leakage into the return plenum only; supply leakage is modeled separately
Qto is leakage to unconditioned space that causes a net energy penalty, whereas leakage within conditioned space recirculates and has less energy impact (Correct answer)

Correct answer: Qto is leakage to unconditioned space that causes a net energy penalty, whereas leakage within conditioned space recirculates and has less energy impact

Duct leakage to unconditioned space (outside) is a true energy loss, while leakage within conditioned space partially recirculates, so models apply different penalty factors to each.

Question 14: What is the purpose of measuring CO in the undiluted flue gas stream rather than in ambient air during a combustion safety test?

To evaluate combustion quality and detect problems at the source before dilution obscures them (Correct answer)
To determine the heating efficiency of the appliance
To measure the oxygen content of indoor air
To identify refrigerant leaks in split systems

Correct answer: To evaluate combustion quality and detect problems at the source before dilution obscures them

Measuring undiluted flue CO directly evaluates the combustion process quality; ambient readings can be very low even when the appliance is producing dangerous CO concentrations.

Question 15: When performing a draft test on a natural draft furnace, the primary purpose is to verify that:

A stable, negative pressure is established to continuously move combustion byproducts up the flue. (Correct answer)
The heat exchanger has reached its steady-state efficiency.
The flue gas temperature is within the manufacturer's specified range.
The ambient air in the CAZ has sufficient oxygen for complete combustion.

Correct answer: A stable, negative pressure is established to continuously move combustion byproducts up the flue.

The purpose of a draft test is to confirm that the venting system is creating a sufficient and sustained negative pressure (draft) to pull the flue gases out of the appliance and exhaust them safely to the outdoors. An inadequate or unstable draft can lead to spillage of combustion byproducts into the home. While related to temperature and efficiency, the direct purpose of the draft measurement itself is to verify this negative pressure.

Question 16: Which RESNET standard establishes requirements for rating software to calculate the HERS Index?

RESNET Publication 001 - Mortgage Industry Standards
RESNET Chapter 7 - Quality Assurance
RESNET Standard 55-2017
ANSI/RESNET/ICC Standard 301 (Correct answer)

Correct answer: ANSI/RESNET/ICC Standard 301

ANSI/RESNET/ICC Standard 301 establishes the calculation methodology that approved rating software must use to determine the HERS Index score.

Question 17: Which metric is used to quantify the airtightness of a building in a blower door test?

CFM50 or ACH50 (Correct answer)
Net free area per square foot
MERV rating
Latent heat ratio

Correct answer: CFM50 or ACH50

Blower door results are reported as CFM50 (cubic feet per minute at 50 Pa) or ACH50 (air changes per hour at 50 Pa depressurization.

Question 18: What is 'interstitial condensation' in a building assembly?

Condensation on exterior foundation walls below grade
Condensation forming within the layers of a wall, roof, or floor assembly (Correct answer)
Condensation in ductwork caused by oversized cooling equipment
Condensation on interior glass surfaces

Correct answer: Condensation forming within the layers of a wall, roof, or floor assembly

Interstitial condensation occurs inside the building assembly layers when vapor migrates to a surface that is at or below the dew point.

Question 19: When inspecting wall insulation in a home under construction, a rater notices kraft-faced batts have been installed with the vapor retarder facing away from the conditioned space (facing the exterior sheathing). In a cold climate, why is this a problem?

The vapor retarder in the wrong position can trap moisture within the wall assembly (Correct answer)
Fire codes require the facing to be exposed to the interior for fire suppression access
Kraft facing reduces the R-value of the batt when installed in reverse
The batting will compress over time if installed facing outward

Correct answer: The vapor retarder in the wrong position can trap moisture within the wall assembly

In cold climates, the vapor retarder should face the warm interior side; installing it facing the cold exterior side traps moisture from indoor air within the wall cavity, risking condensation and rot.

Question 20: Which of the following scenarios describes a 'Total Duct Leakage' test?

A test that measures all the air leaking from the duct system, regardless of whether it leaks into conditioned or unconditioned space. (Correct answer)
A test where the duct system is pressurized to 50 Pa and compared against the building's CFM50 value.
A test using both a blower door and a duct tester to measure leaks to the attic and crawlspace.
A test performed at the rough-in stage before drywall is installed.

Correct answer: A test that measures all the air leaking from the duct system, regardless of whether it leaks into conditioned or unconditioned space.

A 'Total Duct Leakage' test measures all the air escaping from the duct system, including leaks to the inside of the conditioned space and leaks to the outside (e.g., attics, crawlspaces). This is distinct from a 'Leakage to Outside' test, which isolates only the leaks to unconditioned areas.

Question 21: Which measurement is commonly recorded during a blower door test?

CFM50 air leakage (Correct answer)
Voltage flow
BTU usage
R-value rating

Correct answer: CFM50 air leakage

CFM50 (cubic feet per minute at 50 Pascals) is the standard measurement used to evaluate air leakage.

Question 22: During a pressure diagnostics test, a rater measures -3 Pascals in a bedroom with the door closed and the HVAC system running. This indicates:

Return air is located in the bedroom
Excessive supply airflow to the bedroom relative to return air capacity (Correct answer)
Adequate air balancing in the bedroom
The bedroom window is leaking

Correct answer: Excessive supply airflow to the bedroom relative to return air capacity

A negative pressure in a bedroom with the door closed indicates more supply air is being delivered than can return, causing the room to be pressurized relative to... actually -3 Pa means the room is slightly negative, indicating insufficient supply or excessive return bypass — but typically a negative room with door closed means the return is pulling more than the supply delivers, suggesting the system is pulling from that room.

Question 23: What is the term for the phenomenon where combustion appliance exhaust is pulled back into the living space through the flue?

Flue recirculation
Short-cycling
Stack effect reversal
Backdrafting (Correct answer)

Correct answer: Backdrafting

Backdrafting occurs when negative house pressure or adverse weather conditions reverse the intended upward flow of combustion gases through the flue.

Question 24: A rater is performing total duct leakage testing on a home where all registers cannot be sealed. Which method should be used instead of the standard total leakage test?

Visual inspection only
Pressure pan testing
Blower door subtraction method
Duct leakage to outside test (Correct answer)

Correct answer: Duct leakage to outside test

When registers cannot all be sealed, the duct leakage to outside (sometimes called duct leakage outside conditioned space) method is used to isolate leakage from the exterior.

Question 25: A rater is preparing to conduct a worst-case depressurization test in a Combustion Appliance Zone (CAZ) containing a natural draft water heater and a furnace. Which of the following is a critical first step in the standard procedure?

Pressurize the house to +50 Pa with a blower door to identify any pre-existing backdrafting.
Immediately fire the largest combustion appliance to warm the flue.
Establish and record the baseline pressure of the CAZ with reference to the outdoors before turning on any fans or appliances. (Correct answer)
Turn on all exhaust fans and the furnace air handler simultaneously.

Correct answer: Establish and record the baseline pressure of the CAZ with reference to the outdoors before turning on any fans or appliances.

Before inducing depressurization by turning on exhaust fans and air handlers, it is essential to measure the baseline pressure difference between the CAZ and the outdoors. This baseline reading is the starting point from which the 'worst-case' depressurization level is calculated after all air-moving equipment is activated. Without this baseline, the net effect of the exhaust appliances cannot be accurately determined.

Question 26: Which insulation material is classified as an air barrier when installed properly at the correct thickness?

Closed-cell spray polyurethane foam (ccSPF) (Correct answer)
Fiberglass batt
Mineral wool batt
Cellulose dense-pack

Correct answer: Closed-cell spray polyurethane foam (ccSPF)

Closed-cell spray foam is both an insulator and a Class II vapor retarder and air barrier when applied at sufficient thickness (typically 2 inches or more).

Question 27: When testing a newly constructed home using RESNET protocols, at what project stage should the 'rough-in' duct leakage test occur?

After all insulation and drywall are installed and finished
After landscaping is complete
Only after the certificate of occupancy is issued
Before drywall installation so duct connections are still accessible (Correct answer)

Correct answer: Before drywall installation so duct connections are still accessible

The rough-in duct leakage test is performed before drywall installation so that any failing connections are still accessible for repair by the HVAC contractor.

Question 28: Which aspect of a home's window specifications is directly input into HERS rating software to calculate energy performance?

Frame color and glazing tint only
U-factor and Solar Heat Gain Coefficient (SHGC) (Correct answer)
Window age and installation date
Window brand and model number only

Correct answer: U-factor and Solar Heat Gain Coefficient (SHGC)

HERS rating software requires window U-factor (thermal conductance) and SHGC (solar gain) values to calculate heating, cooling, and lighting loads.

Question 29: A HERS Rater is preparing a home for a blower door test according to RESNET standards. Which of the following should be done to prepare the house?

Seal all HVAC supply and return registers with tape.
Turn off the water heater and seal its flue vent.
Close all interior doors to isolate each room.
Close and latch exterior windows and doors, but do not apply extra sealing. (Correct answer)

Correct answer: Close and latch exterior windows and doors, but do not apply extra sealing.

Per ANSI/RESNET/ICC 380, exterior windows and doors should be closed and latched as they would be normally, without extra sealing beyond the standard weatherstripping. Interior doors must be opened, HVAC systems turned off, and dampers must be closed but not sealed.

Question 30: A HERS Rater is performing a blower door test on a 2,500 sq ft house with 8-foot ceilings. The final reading on the manometer is 1,800 CFM50. What is the approximate Air Changes per Hour at 50 Pascals (ACH50)?

4.82 ACH50
7.20 ACH50
5.40 ACH50 (Correct answer)
6.00 ACH50

Correct answer: 5.40 ACH50

To calculate ACH50, use the formula: (CFM50 * 60) / Conditioned Volume. First, find the volume: 2,500 sq ft * 8 ft = 20,000 cubic feet. Then, apply the formula: (1,800 CFM50 * 60) / 20,000 cu ft = 108,000 / 20,000 = 5.4 ACH50.

Question 31: A rater enters a furnace with AFUE of 0.96 into HERS software. What does the remaining 4% represent?

Duct distribution losses
Standby pilot light consumption
Energy lost to flue gases and jacket losses (Correct answer)
Energy used by the blower motor

Correct answer: Energy lost to flue gases and jacket losses

AFUE measures seasonal efficiency, and the 4% not converted to useful heat is lost through combustion exhaust and jacket radiation.

Question 32: What is 'exfiltration' in the context of building air leakage?

The movement of radon gas from the soil into the building
Conditioned air leaking out of the building through gaps in the envelope (Correct answer)
Air transfer between floors through penetrations
Outdoor air leaking into the conditioned space

Correct answer: Conditioned air leaking out of the building through gaps in the envelope

Exfiltration is conditioned interior air escaping outward through the building envelope, the opposite of infiltration.

Question 33: Which of the following window characteristics must a HERS rater verify in the field against the plans and specifications?

U-factor and Solar Heat Gain Coefficient (SHGC) (Correct answer)
Window manufacturer and country of origin
Glass color and frame material only
Operability type (casement vs. double-hung)

Correct answer: U-factor and Solar Heat Gain Coefficient (SHGC)

U-factor and SHGC are the thermal performance metrics used in the HERS energy model and must be field-verified against the rated values listed on the NFRC label or documentation.

Question 34: Which condition would most likely cause a natural-draft appliance to backdraft even without house depressurization?

A flue that is too short or has an obstruction (Correct answer)
An oversized gas orifice
A flue that is too long
A clogged condensate drain

Correct answer: A flue that is too short or has an obstruction

A blocked or undersized flue creates resistance that prevents adequate draft, causing combustion gases to spill back into the space even when the house is at neutral pressure.

Question 35: During HERS verification, a rater checks that window U-factors meet IECC requirements. What does a lower U-factor indicate?

Lower thermal resistance (worse insulation)
Greater solar heat gain
Higher thermal resistance (better insulation) (Correct answer)
Higher visible light transmittance

Correct answer: Higher thermal resistance (better insulation)

U-factor is the rate of heat transfer; a lower value means less heat flows through the window, indicating better insulating performance.

Question 36: A rater finds that a home has recessed can lights (IC-rated) installed in an insulated ceiling. What field verification is required for proper air sealing?

Verify fixtures have built-in LED lamps to reduce heat output
Confirm the insulation is pulled back 3 inches from each fixture
Verify the fixtures are airtight (AT-rated) and gasketed or sealed at the ceiling plane (Correct answer)
Confirm the fixture wattage does not exceed the rated maximum

Correct answer: Verify the fixtures are airtight (AT-rated) and gasketed or sealed at the ceiling plane

Even IC-rated recessed fixtures are major air leakage points unless they are also airtight (AT)-rated and properly sealed at the ceiling plane to prevent conditioned air from escaping into the attic.

Question 37: Which condition best describes a 'negative pressure' house?

Pressure is equal on all sides of the envelope
Interior air pressure is higher than exterior pressure
The HVAC system is over-sized for the heating load
Interior air pressure is lower than exterior pressure (Correct answer)

Correct answer: Interior air pressure is lower than exterior pressure

A negative pressure building has interior pressure below outdoor pressure, causing outdoor air to be drawn inward through any gaps.

Question 38: A HERS rater documents that the home uses a variable-speed air handler. What efficiency advantage does this provide compared to a single-speed unit?

Lower electricity consumption during part-load operation (Correct answer)
Reduced refrigerant charge requirements
Higher AFUE rating for heating
Elimination of duct leakage losses

Correct answer: Lower electricity consumption during part-load operation

Variable-speed air handlers consume significantly less electricity during part-load conditions, which represents the majority of operating hours.

Question 39: During a HERS pre-drywall inspection, a rater identifies missing insulation in a rim joist cavity. Why is this location particularly important?

Rim joists directly affect duct leakage test results
Rim joists are required to be spray-foamed by code
RESNET requires rim joist R-value to match wall R-value exactly
Rim joists are a significant thermal bridge and air leakage point at the foundation-to-wall junction (Correct answer)

Correct answer: Rim joists are a significant thermal bridge and air leakage point at the foundation-to-wall junction

Rim joists are a major source of both heat loss and air infiltration at the critical junction between the foundation and above-grade framing.

Question 40: Which entity accredits HERS raters and Rating Quality Assurance Providers in the United States?

ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers)
RESNET (Residential Energy Services Network) (Correct answer)
ICC (International Code Council)
The U.S. Department of Energy (DOE)

Correct answer: RESNET (Residential Energy Services Network)

RESNET is the national standards body that accredits HERS raters, training providers, and Quality Assurance Providers in the US.

Question 41: A home's HERS modeling shows that switching from natural gas heating to an electric heat pump reduces the HERS Index significantly. What is the primary reason?

Heat pumps have a COP above 1.0, while gas furnaces are limited to below 100% combustion efficiency (Correct answer)
Heat pumps do not consume any on-site energy
Electric systems are always more efficient regardless of fuel source
Natural gas is excluded from HERS calculations, inflating gas-heated home scores

Correct answer: Heat pumps have a COP above 1.0, while gas furnaces are limited to below 100% combustion efficiency

Heat pumps achieve COPs of 2–4 (200–400% efficiency), far exceeding even the highest-efficiency gas furnaces, dramatically reducing modeled energy use.

Question 42: When testing a home's air barrier continuity during a blower door test, a rater uses smoke or a thermal camera. What does a significant temperature differential at an electrical outlet on an exterior wall indicate?

The insulation behind the outlet has higher than expected R-value
The HVAC system is pressurizing the wall cavity
The outlet is correctly sealed with an insulating foam gasket
Air is leaking through the outlet from the exterior or wall cavity (Correct answer)

Correct answer: Air is leaking through the outlet from the exterior or wall cavity

A temperature differential at an exterior outlet during a blower door test indicates air infiltration through the outlet box from the unconditioned wall cavity or exterior.

Question 43: What role does ventilation play in building science?

Reduces foundation cost
Improves structural load capacity
Controls indoor air quality (Correct answer)
Increases wall insulation

Correct answer: Controls indoor air quality

Ventilation controls indoor air quality by exchanging stale air with fresh air, reducing pollutants and humidity.

Question 44: A gas water heater located in a garage must have its burner and pilot elevated at least how high above the floor?

12 inches
6 inches
18 inches (Correct answer)
24 inches

Correct answer: 18 inches

Garage-installed water heaters must have ignition sources elevated at least 18 inches above the floor to avoid igniting gasoline vapors that pool at floor level.

Question 45: What credit does a solar water heating system receive in a HERS rating?

A flat 10-point reduction in the HERS Index regardless of system size
No credit; solar thermal is not recognized in HERS ratings
Automatic HERS Index of zero for the entire water heating end use
Credit based on the calculated solar fraction and system efficiency per RESNET standards (Correct answer)

Correct answer: Credit based on the calculated solar fraction and system efficiency per RESNET standards

Solar water heating systems receive HERS credit based on the calculated solar fraction and system efficiency as specified in RESNET/ANSI 301 standards.

Question 46: A home tests at 1,850 CFM50 and has a volume of 12,000 cubic feet. What is the ACH50 value?

6.5 ACH50
9.25 ACH50 (Correct answer)
15.4 ACH50
0.15 ACH50

Correct answer: 9.25 ACH50

ACH50 = (CFM50 × 60) / volume = (1,850 × 60) / 12,000 = 111,000 / 12,000 = 9.25 ACH50.

Question 47: Which of the following best describes a 'compact' hot water distribution system as recognized in HERS ratings?

Any system that uses a recirculation pump and timer
A system where all pipe runs are insulated with R-3 or greater insulation
A system limited to homes under 1,500 square feet
A system where total pipe volume from water heater to all fixtures is minimized using small-diameter pipes and short runs (Correct answer)

Correct answer: A system where total pipe volume from water heater to all fixtures is minimized using small-diameter pipes and short runs

Compact distribution systems minimize the pipe volume between the water heater and fixtures, reducing the amount of cooled water that must be purged before hot water arrives.

Question 48: What is the primary function of RESNET's National Registry of HERS Ratings?

To collect federal tax incentive applications for rated homes
To track and store completed HERS ratings for public and industry access (Correct answer)
To market energy-efficient homes to prospective buyers
To assign HERS Index scores to homes without rater involvement

Correct answer: To track and store completed HERS ratings for public and industry access

RESNET's National Registry serves as the official repository for completed HERS ratings, allowing lenders, appraisers, and homeowners to verify and access rating information.

Question 49: Which of the following hot water distribution improvements would most directly earn a HERS distribution efficiency credit?

Increasing water heater tank size from 40 to 80 gallons
Increasing the water heater setpoint from 120°F to 140°F
Installing a structured plumbing system with a central manifold and small-diameter individual home runs (Correct answer)
Adding a second water heater in a remote bathroom addition

Correct answer: Installing a structured plumbing system with a central manifold and small-diameter individual home runs

Structured plumbing (central manifold with individual small-diameter home runs) minimizes pipe volume and water wasted awaiting hot water, earning recognized HERS distribution efficiency credits.

Question 50: According to the RESNET/ANSI 301 Standard, which of the following attributes of the HERS Reference Home is set to be identical to the Rated Home to create a basis for comparison?

Air leakage rate (ACH50)
HVAC system efficiency (AFUE/SEER)
Building geometry, size, and orientation (Correct answer)
Window efficiency (U-factor and SHGC)

Correct answer: Building geometry, size, and orientation

The HERS Reference Home is a computer-generated model with the same geometry, size, and orientation as the Rated Home. Its energy efficiency features (like insulation, window performance, air tightness, and system efficiencies) are set to levels consistent with a baseline energy code (historically the 2006 IECC), creating the benchmark against which the Rated Home is compared to generate the HERS Index of 100.

Question 51: Which instrument is specifically used to measure the airflow of individual supply registers during HVAC diagnostics?

Blower door
Duct blaster
Flow hood (balancing hood) (Correct answer)
Anemometer

Correct answer: Flow hood (balancing hood)

A flow hood, or balancing hood, is placed directly over a supply or return register to measure the airflow in CFM at that specific outlet.

Question 52: In HERS energy modeling, what is the thermal performance metric used to describe the insulating value of a wall assembly including all components?

R-value
C-value
U-factor
Assembly R-value (whole-wall R-value) (Correct answer)

Correct answer: Assembly R-value (whole-wall R-value)

Whole-wall or assembly R-value accounts for all components including framing, insulation, sheathing, and cladding for an accurate thermal performance measure.

Question 53: A HERS rater evaluating a home with a water heater located in an unconditioned garage should ensure what is accurately modeled?

Only that the fuel type matches the energy model
That the ambient garage temperature is accounted for, as it affects standby heat losses from the tank (Correct answer)
That the water heater has been pressure-tested prior to the rating
That the water heater is located within 20 feet of the main living area

Correct answer: That the ambient garage temperature is accounted for, as it affects standby heat losses from the tank

Ambient temperature affects standby heat losses from the water heater tank; a colder unconditioned garage results in greater standby losses than conditioned space installation.

Question 54: A newly constructed home receives a confirmed HERS Index of 65. How should the rater explain this result to the homeowner in terms of energy efficiency?

The home is 35% more energy efficient than a standard new home built to the HERS Reference Home specifications. (Correct answer)
The home uses 65% of the energy that a standard new home uses.
The home is 65% less efficient than a Net Zero Energy Home.
The home's energy efficiency is 35% below the current energy code requirements.

Correct answer: The home is 35% more energy efficient than a standard new home built to the HERS Reference Home specifications.

Each point below 100 on the HERS Index represents a 1% improvement in energy efficiency compared to the HERS Reference Home. Therefore, a score of 65 (100 - 65 = 35) means the home is 35% more energy efficient than the Reference Home.

Question 55: What is the benefit of using dense-pack cellulose in existing wall cavities during an energy retrofit verified by a HERS rater?

It provides a Class I vapor barrier
It fills voids and gaps that batts cannot reach, improving both insulation and air sealing (Correct answer)
It eliminates the need for a blower door test
It qualifies as a Grade I installation in new construction only

Correct answer: It fills voids and gaps that batts cannot reach, improving both insulation and air sealing

Dense-pack cellulose fills irregular cavities and small gaps that batt insulation cannot access, improving both thermal and air barrier performance.

Question 56: According to RESNET/ANSI 301, the HERS reference design water heater efficiency is based on what?

A heat pump water heater regardless of fuel type
The average efficiency of water heaters sold in the US
The most efficient water heater available on the market
Federal minimum efficiency standards for the installed fuel type (Correct answer)

Correct answer: Federal minimum efficiency standards for the installed fuel type

The HERS reference design uses federal minimum efficiency standards for water heaters matching the rated home's installed fuel type.

Question 57: Which RESNET standard governs combustion safety testing procedures for HERS raters?

RESNET/ICC 380 (Correct answer)
RESNET 55
RESNET/ICC 301
RESNET/ACCA 310

Correct answer: RESNET/ICC 380

RESNET/ICC 380 establishes standard test methods for building enclosures, including combustion safety diagnostics performed by HERS raters.

Question 58: A sealed-combustion furnace draws combustion air directly from outside. How does this affect CAZ depressurization concerns?

It only reduces risk if the flue is also sealed
It eliminates CAZ depressurization risk for that appliance since it does not use zone air (Correct answer)
It has no effect on CAZ depressurization
It increases CAZ depressurization risk because more air is consumed

Correct answer: It eliminates CAZ depressurization risk for that appliance since it does not use zone air

Sealed-combustion (direct-vent) appliances draw combustion air from outside and exhaust directly outside, so they are unaffected by CAZ pressure and do not contribute to backdrafting concerns.

Question 59: What does a HERS score of 0 indicate?

Below code compliance
Net-zero energy usage (Correct answer)
The house is not rated
Minimal energy efficiency

Correct answer: Net-zero energy usage

A HERS score of 0 indicates a net-zero energy home, which produces as much energy as it consumes.

RESNET HERS National Rater Test

The RESNET HERS National Rater Test certifies candidates as Home Energy Rating System (HERS) Raters, evaluating knowledge of building science, energy systems, air leakage, insulation, and RESNET rating procedures required to perform residential energy audits and ratings.

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120 min

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73%

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