AIRAH Professional Engineer Register (APER) Overview
These study notes are designed to prepare candidates for the AIRAH Professional Engineer Register (APER) examination. The exam assesses competency in HVAC&R engineering, building energy performance, ventilation, refrigeration safety, fire and smoke control, and hydronic systems. The notes are based on official sources including ASHRAE Handbooks, Australian Standards (AS 1668, AS/NZS 5149, AS/NZS 3666), NCC Section J, and relevant codes. Candidates should verify specific eligibility, pass marks, and regulatory details with AIRAH and the relevant state engineering board (e.g., BPEQ for RPEQ).
For Technical Conquer practice planning, this module is tracked as 100 questions over about 180 minutes with a listed pass mark of 70%. Treat those numbers as practice baselines and verify the current official format before scheduling.
How This Guide Is Organized
The sections below turn the syllabus into studyable subject blocks. Read a subject first, explain the must-know ideas without notes, then use questions, flashcards, and mind maps to test whether the knowledge holds under field-style pressure.
- HVAC&R Thermodynamics and Psychrometric Analysis
- Building Energy Performance and NCC Section J Compliance
- Mechanical Ventilation and Indoor Air Quality (AS 1668)
- Refrigeration Systems, Safety, and AS/NZS 5149
- Fire and Smoke Control Systems (AS 1668.1)
- Hydronic Systems and Microbial Control (AS/NZS 3666)
Exam Snapshot and Readiness Target
Format: 100 multiple-choice questions, 180 minutes, pass mark 70% (practice baseline; verify with AIRAH)
Candidate level: Professional engineer seeking registration on the AIRAH Professional Engineer Register (APER)
Readiness target: Demonstrate competency in HVAC&R thermodynamics, psychrometrics, energy compliance, ventilation, refrigeration safety, fire/smoke control, and hydronic systems.
Most candidates should budget at least 42+ focused study hours, then adjust upward for unfamiliar equipment, code, regulatory, commissioning, controls, or calculation-heavy content.
HVAC&R Thermodynamics and Psychrometric Analysis
Syllabus Focus
- Thermodynamic cycles (vapor-compression, absorption)
- Psychrometric processes (heating, cooling, humidification, dehumidification)
- Property relationships (temperature, pressure, enthalpy, entropy)
- Refrigerant properties and phase changes
- Energy balance and system efficiency
Key Notes
- The vapor-compression cycle consists of compression, condensation, expansion, and evaporation. Key parameters: evaporator and condenser pressures, superheat, subcooling.
- Psychrometric chart: dry-bulb, wet-bulb, dew-point temperatures; humidity ratio; relative humidity; enthalpy; specific volume. Use for analyzing air conditioning processes.
- Sensible heat factor (SHF) = sensible heat / total heat. Used to determine slope of process line on psychrometric chart.
- Coefficient of performance (COP) = cooling/heating effect / work input. For heat pumps, COP_heating = COP_cooling + 1.
- Refrigerant selection criteria: ODP, GWP, safety classification (ASHRAE 34), thermodynamic performance, and compatibility with system materials.
Must Know
- Calculate cooling/heating loads using psychrometric analysis (e.g., mixed air conditions, coil bypass factor).
- Determine system COP and EER (Energy Efficiency Ratio) from measured temperatures and power input.
- Identify and correct common psychrometric process errors (e.g., over-humidification, inadequate dehumidification).
- Apply thermodynamic principles to diagnose system performance issues (e.g., high discharge temperature, low superheat).
Field and Exam Application
- Field troubleshooting: measure suction and discharge pressures, calculate superheat and subcooling to diagnose refrigerant charge issues.
- Design review: verify that selected equipment meets design conditions using psychrometric analysis (e.g., cooling coil selection).
- Energy audit: calculate system COP from logged data and compare to manufacturer specifications to identify degradation.
High-Yield Distinctions
- Difference between saturated and superheated vapor: saturated vapor exists at boiling point for given pressure; superheated vapor has temperature above saturation.
- Sensible vs. latent heat: sensible heat changes temperature without phase change; latent heat changes phase at constant temperature.
- Adiabatic vs. diabatic processes: adiabatic has no heat transfer (e.g., compression); diabatic involves heat transfer (e.g., condenser).
Common Pitfalls
- Confusing wet-bulb with dew-point temperature: wet-bulb is affected by evaporation; dew-point is temperature at which condensation begins.
- Neglecting altitude correction for psychrometric properties: standard chart is for sea level; adjust for altitude.
- Assuming constant specific heat for air: use actual values from psychrometric chart or tables for accuracy.
Review Tasks
- Plot a cooling and dehumidification process on a psychrometric chart and calculate required coil capacity.
- Calculate COP of a vapor-compression system given evaporator and condenser temperatures and compressor power.
- Compare R-134a and R-410A properties: identify differences in pressure, temperature glide, and safety classification.
Building Energy Performance and NCC Section J Compliance
Syllabus Focus
- NCC Section J (Energy Efficiency) requirements
- Building envelope thermal performance (insulation, glazing, air leakage)
- HVAC system efficiency (minimum COP, fan power limits)
- Lighting and power provisions
- Energy modeling and verification methods
Key Notes
- NCC Section J sets minimum energy efficiency requirements for commercial buildings. Key parts: J1 (building fabric), J2 (glazing), J3 (building sealing), J5 (HVAC), J6 (lighting), J7 (power).
- Building envelope: total R-value (insulation + air films) must meet or exceed minimums. Thermal bridging must be minimized.
- HVAC system efficiency: minimum COP for chillers (e.g., >6.0 for water-cooled centrifugal), minimum efficiency for heat pumps, fan power limits (e.g., <2.5 W/(L/s)).
- Air leakage: building sealing requirements to limit infiltration. Testing per AS/NZS ISO 9972.
- Energy modeling: use accredited software (e.g., EnergyPlus, IES VE) to demonstrate compliance via performance-based pathway.
Must Know
- Determine required insulation levels for different climate zones (NCC climate zones 1-8).
- Calculate U-value for a wall assembly including insulation, framing, and air films.
- Verify HVAC system efficiency meets Section J minimums using manufacturer data.
- Identify acceptable verification methods: deemed-to-satisfy (DTS) vs. performance-based (energy modeling).
Field and Exam Application
- Site inspection: check insulation installation for gaps, compression, and continuity; verify glazing type and shading.
- Commissioning: measure air leakage rate using blower door test and compare to Section J limits.
- Energy audit: compare actual HVAC energy use to modeled baseline to identify performance gaps.
High-Yield Distinctions
- Deemed-to-satisfy (DTS) vs. performance-based: DTS uses prescriptive requirements; performance-based allows trade-offs via energy modeling.
- Total R-value vs. effective R-value: total includes air films; effective accounts for thermal bridging.
- Climate zone differences: zone 1 (high humidity) vs. zone 8 (alpine) have different insulation and glazing requirements.
Common Pitfalls
- Ignoring thermal bridging in steel-framed walls: use continuous insulation or calculate effective R-value.
- Assuming all glazing is equal: Section J requires specific U-value and SHGC depending on orientation and climate.
- Overlooking air leakage in existing buildings: sealing requirements apply to new work and major renovations.
Review Tasks
- Calculate U-value for a wall with R2.0 insulation in a steel frame (thermal bridging factor 0.8).
- Determine minimum chiller COP for a water-cooled system in climate zone 5 per NCC 2022.
- Compare DTS and performance-based pathways for a mixed-use building: list pros and cons.
Mechanical Ventilation and Indoor Air Quality (AS 1668)
Syllabus Focus
- AS 1668.2 (ventilation for acceptable indoor air quality)
- Minimum outdoor air rates (per person, per area)
- Air filtration requirements
- Exhaust systems for contaminants
- Demand-controlled ventilation (DCV)
Key Notes
- AS 1668.2 specifies minimum outdoor air supply rates: e.g., 10 L/s per person for offices, 7.5 L/s per person for retail. Also area-based rates (e.g., 0.5 L/s per m²).
- Filtration: minimum MERV 8 (or equivalent) for supply air; higher for special areas (e.g., healthcare).
- Exhaust systems: required for toilets, kitchens, carpark, and areas with contaminants. Minimum exhaust rates specified.
- Demand-controlled ventilation (DCV): use CO2 sensors to modulate outdoor air based on occupancy. Must maintain minimum rates.
- Indoor air quality (IAQ) parameters: CO2 < 1000 ppm (typical), temperature, humidity, particulate matter.
Must Know
- Calculate required outdoor air flow for a zone using both per-person and per-area methods (take the larger).
- Select appropriate filter class (e.g., MERV 8, MERV 13) based on application and AS 1668.2 requirements.
- Design exhaust system for a commercial kitchen: capture hood type, exhaust rate (e.g., 0.5 m/s face velocity), make-up air.
- Implement DCV: sensor placement (return air or zone), setpoint (e.g., 800 ppm CO2), minimum ventilation override.
Field and Exam Application
- IAQ investigation: measure CO2, temperature, humidity, and particulate levels; compare to AS 1668.2 and ASHRAE 62.1.
- Commissioning: verify outdoor air flow rates using flow hood or traverse measurements; check damper positions.
- Retrofit: upgrade filtration to MERV 13 for improved IAQ; ensure fan static pressure can handle increased resistance.
High-Yield Distinctions
- Per-person vs. per-area method: per-person accounts for occupancy; per-area accounts for building-related sources (e.g., off-gassing).
- Minimum outdoor air vs. total supply air: outdoor air is a fraction of total supply; recirculated air is filtered.
- CO2 as a proxy for occupancy: CO2 generation rate depends on activity level; use 0.005 L/s per person (typical).
Common Pitfalls
- Using only per-person rate in high-density spaces (e.g., conference rooms): must also meet per-area rate.
- Placing CO2 sensors in dead zones or near doors: ensure representative sampling.
- Neglecting filter pressure drop in fan selection: high-efficiency filters require higher fan static pressure.
Review Tasks
- Calculate outdoor air flow for a 100 m² office with 20 occupants using AS 1668.2 rates.
- Design a DCV system for a meeting room: specify sensor type, setpoint, and minimum ventilation rate.
- List three common IAQ problems and their likely causes (e.g., high CO2 = insufficient ventilation).
Refrigeration Systems, Safety, and AS/NZS 5149
Syllabus Focus
- Refrigeration system components (compressor, condenser, evaporator, expansion device)
- Refrigerant safety classifications (ASHRAE 34)
- AS/NZS 5149 (refrigerant safety)
- Leak detection and system integrity
- Pressure vessel and piping safety
Key Notes
- AS/NZS 5149 series (parts 1-4) covers safety requirements for refrigeration systems: classification, design, installation, and maintenance.
- Refrigerant safety groups: A1 (non-toxic, non-flammable), A2L (lower flammability), A3 (highly flammable), B1 (toxic, non-flammable), etc.
- System charge limits based on refrigerant safety group and occupancy category (e.g., A1: no limit; A2L: limited in occupied spaces).
- Leak detection: required for systems with charge > specified thresholds (e.g., 50 kg for A1). Use fixed or portable detectors.
- Pressure vessels: must comply with AS 1210 or equivalent; relief devices required (pressure relief valve, rupture disc).
Must Know
- Determine refrigerant safety group from ASHRAE 34 (e.g., R-410A is A1, R-32 is A2L).
- Calculate maximum allowable charge for a given space per AS/NZS 5149.1 (based on room volume and refrigerant LFL).
- Identify required safety devices: high-pressure cutout, low-pressure cutout, oil pressure switch, relief valve.
- Perform leak test: use nitrogen with trace refrigerant or electronic leak detector; hold pressure per AS/NZS 5149.3.
Field and Exam Application
- Installation: verify piping supports, insulation, and protection from mechanical damage; check relief valve discharge location.
- Maintenance: log refrigerant usage, leak test results, and system pressures; comply with ARCtick record-keeping.
- Retrofit: when changing refrigerant (e.g., R-22 to R-407C), ensure compatibility with materials and safety requirements.
High-Yield Distinctions
- A2L vs. A3: A2L has lower burning velocity and higher ignition energy; A3 is highly flammable (e.g., R-290).
- Direct vs. indirect systems: direct expansion has refrigerant in occupied space; indirect uses secondary coolant (e.g., water, glycol).
- High-pressure vs. low-pressure cutout: high-pressure protects against overpressure; low-pressure protects against loss of charge or freeze-up.
Common Pitfalls
- Assuming all refrigerants are A1: check safety group before installation, especially for new low-GWP refrigerants.
- Ignoring relief valve discharge location: must vent to safe area, not into occupied space or near ignition sources.
- Overlooking pressure vessel inspection requirements: periodic inspection per AS/NZS 5149.4 or local regulations.
Review Tasks
- Classify R-32, R-290, R-1234yf, and R-134a by ASHRAE 34 safety group.
- Calculate maximum charge of R-32 in a 50 m² room with 2.5 m ceiling per AS/NZS 5149.1 (LFL = 0.307 kg/m³).
- List three safety devices required on a large ammonia system (B2L refrigerant).
Fire and Smoke Control Systems (AS 1668.1)
Syllabus Focus
- AS 1668.1 (fire and smoke control in buildings)
- Smoke management systems (pressurization, exhaust, stairwell pressurization)
- Fire dampers and smoke dampers
- Interface with fire alarm and HVAC controls
- Commissioning and testing requirements
Key Notes
- AS 1668.1 specifies requirements for smoke control systems to maintain tenable conditions during fire. Key systems: stairwell pressurization, zone smoke exhaust, and air-handling unit shutdown.
- Stairwell pressurization: maintain positive pressure (e.g., 50 Pa) relative to adjacent spaces to prevent smoke ingress. Fan capacity based on leakage area.
- Smoke exhaust: exhaust rate typically 6 air changes per hour for fire zone; make-up air provided.
- Fire dampers: installed in ductwork penetrating fire-rated barriers; fusible link or actuator closes on fire signal.
- Smoke dampers: close on smoke detection; may be combined with fire dampers (combination fire/smoke damper).
Must Know
- Design stairwell pressurization system: calculate required airflow to maintain pressure differential using leakage area method (e.g., 0.01 m² per floor).
- Specify fire damper location and type: required at fire-rated wall penetrations; dynamic vs. static rating.
- Program HVAC controls for fire mode: shutdown AHU, open smoke exhaust dampers, start pressurization fans.
- Commission smoke control system: test pressure differentials, damper operation, and fan start/stop sequences.
Field and Exam Application
- Inspection: verify fire damper installation (access door, proper orientation, fusible link on upstream side).
- Testing: conduct smoke control mode test: simulate fire alarm, observe damper positions, measure pressure differentials.
- Troubleshooting: if stairwell pressure is low, check for open doors, duct leakage, or fan performance.
High-Yield Distinctions
- Fire damper vs. smoke damper: fire damper closes on heat (fusible link); smoke damper closes on smoke detection (actuator).
- Static vs. dynamic fire damper: static rated for ducts that shut down; dynamic rated for ducts that remain operational during fire.
- Stairwell pressurization vs. zone smoke exhaust: pressurization prevents smoke entry; exhaust removes smoke from fire zone.
Common Pitfalls
- Placing fire damper in wrong orientation: fusible link must be on the side exposed to fire (upstream).
- Neglecting make-up air for smoke exhaust: without make-up, exhaust is ineffective; provide via natural or mechanical means.
- Assuming all dampers are combination fire/smoke: verify damper listing and application.
Review Tasks
- Design a stairwell pressurization system for a 10-story building: calculate airflow per floor (leakage area 0.02 m² per floor, pressure differential 50 Pa).
- List the sequence of operations for a smoke control system upon fire alarm activation.
- Identify three common commissioning failures in smoke control systems and their remedies.
Hydronic Systems and Microbial Control (AS/NZS 3666)
Syllabus Focus
- Hydronic system components (chillers, boilers, pumps, pipes, valves)
- Water treatment and microbial control (Legionella)
- AS/NZS 3666 (air-handling and water systems)
- Cooling tower operation and maintenance
- Expansion tanks and pressure maintenance
Key Notes
- AS/NZS 3666 series covers microbial control in air-handling and water systems. Part 1: design and installation; Part 2: operation and maintenance; Part 3: cooling towers.
- Legionella control: maintain water temperature <20°C or >60°C; biocide treatment; regular testing and cleaning.
- Cooling towers: drift eliminators, bleed-off, chemical treatment (e.g., chlorine, bromine). Risk of Legionella if stagnant or warm.
- Hydronic system balancing: use balancing valves (e.g., circuit setters, pressure-independent valves) to achieve design flow rates.
- Expansion tank: pre-charge pressure set to system static pressure; tank size based on system volume and temperature range.
Must Know
- Design water treatment program: select biocides, corrosion inhibitors, and scale inhibitors based on water quality and system materials.
- Calculate expansion tank size: use formula V_t = (V_s * (v2/v1 - 1)) / (1 - P1/P2), where v1, v2 are specific volumes at fill and max temp.
- Implement cooling tower maintenance schedule: weekly biocide dosing, monthly cleaning, quarterly Legionella testing.
- Balance hydronic system: measure flow at each terminal, adjust balancing valves to achieve design flow ±10%.
Field and Exam Application
- Water sampling: collect from cooling tower basin and representative points; test for Legionella, total bacteria, pH, conductivity.
- System flushing: after installation or repair, flush with clean water and chemical cleaner to remove debris and biofilm.
- Troubleshooting: if differential pressure across chiller is low, check for air in system, closed valves, or pump cavitation.
High-Yield Distinctions
- Open vs. closed loop: open loop (cooling tower) exposed to atmosphere; closed loop (chilled water) sealed, requires less treatment.
- Chemical vs. non-chemical treatment: chemical uses biocides; non-chemical uses UV, ozone, or copper-silver ionization.
- Bleed-off vs. blowdown: bleed-off continuous to control dissolved solids; blowdown periodic to remove sludge.
Common Pitfalls
- Ignoring Legionella risk in domestic hot water systems: maintain temperature >60°C at heater, >50°C at outlets.
- Oversizing expansion tank: leads to water logging; undersizing causes relief valve discharge.
- Neglecting water treatment in closed loops: corrosion and scale still occur; use inhibitor and monitor pH.
Review Tasks
- Calculate expansion tank volume for a system with 1000 L water, fill temp 20°C, max temp 80°C, static pressure 200 kPa, pre-charge 150 kPa.
- List three control measures for Legionella in cooling towers per AS/NZS 3666.3.
- Describe the procedure for balancing a hydronic system with pressure-independent control valves.
How To Use These Notes With Practice Questions
Do not jump straight from reading to a full mock. Work by subject first: review the key notes, make a short recall sheet from memory, then answer a focused question set. After each miss, decide whether the problem was missing theory, weak code/source recall, poor measurement setup, calculation error, or a field sequence you did not visualize.
Technical Conquer's question bank, flashcards, mind maps, and spaced review tools are most useful after this instruction layer because they reveal which parts of the notes are not yet retrievable.
Final Review Checklist
- Review all six subject areas focusing on key standards: AS 1668.1, AS 1668.2, AS/NZS 5149, AS/NZS 3666, NCC Section J, and ASHRAE Handbooks.
- Practice psychrometric chart reading and thermodynamic cycle calculations.
- Understand the differences between deemed-to-satisfy and performance-based compliance pathways.
- Memorize refrigerant safety groups and charge limits per AS/NZS 5149.
- Know the sequence of operations for fire and smoke control systems.
- Be familiar with water treatment principles and Legionella control strategies.
- Verify all regulatory details (pass mark, eligibility, fees) with AIRAH and relevant state engineering board (e.g., BPEQ for RPEQ).
Official Sources and Further Reading
Use these sources as the final authority for format, eligibility, rules, regulatory limits, and exam updates. Study notes are a preparation layer, not a replacement for official candidate guidance.