ASHRAE Building Energy Modeling Professional (BEMP) Overview
These study notes are designed to prepare candidates for the ASHRAE BEMP certification exam. The BEMP credential validates expertise in building energy modeling, including simulation physics, HVAC system performance, envelope characterization, internal loads, compliance with ASHRAE Standard 90.1, and quality assurance. The notes are anchored to official ASHRAE resources and related codes. Candidates should verify exam details (format, pass mark, eligibility) with ASHRAE.
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.
- Modeling Process and Quality Assurance
- Building Envelope and Site Characterization
- HVAC System Selection and Performance
- Internal Loads and Operational Schedules
- ASHRAE Standard 90.1 Compliance Modeling
- Simulation Physics and Data Interpretation
Exam Snapshot and Readiness Target
Format: 100 questions, 180 minutes (practice baseline; verify with ASHRAE)
Candidate level: Professional engineer or architect with experience in energy modeling
Readiness target: Demonstrate proficiency in building energy modeling processes, simulation tools, and standards compliance
Most candidates should budget at least 42+ focused study hours, then adjust upward for unfamiliar equipment, code, regulatory, commissioning, controls, or calculation-heavy content.
Modeling Process and Quality Assurance
Syllabus Focus
- Model development workflow
- Quality assurance and quality control (QA/QC)
- Calibration and validation
- Documentation and reporting
Key Notes
- The modeling process typically follows: define scope, gather data, develop model, simulate, calibrate, and report.
- QA/QC includes checking inputs, outputs, and assumptions against design documents and standards.
- Calibration involves adjusting model parameters to match measured energy use (e.g., utility bills) within acceptable tolerances (e.g., NMBE ≤ 5%, CVRMSE ≤ 15% per ASHRAE Guideline 14).
- Documentation should include all assumptions, sources of data, and version control for reproducibility.
- Sensitivity analysis helps identify key parameters affecting model results.
- Use of automated tools for error checking (e.g., missing zones, unconnected HVAC) improves quality.
Must Know
- ASHRAE Guideline 14 for measurement and verification (M&V) and calibration criteria.
- IPMVP (International Performance Measurement and Verification Protocol) options.
- Common modeling software: EnergyPlus, DOE-2, eQUEST, OpenStudio, IES VE, TRNSYS.
- Importance of weather data selection (TMY3, actual year) and its impact on results.
Field and Exam Application
- Calibrating a model to within 5% NMBE for a LEED energy performance credit.
- Using sensitivity analysis to prioritize envelope upgrades in a retrofit project.
- Documenting model assumptions for a utility incentive program application.
High-Yield Distinctions
- Calibration vs. validation: calibration adjusts to measured data; validation checks against independent data.
- TMY vs. AMY weather data: TMY for typical year analysis, AMY for actual performance comparison.
- Steady-state vs. dynamic simulation: steady-state for peak load, dynamic for annual energy.
Common Pitfalls
- Over-calibrating by adjusting too many parameters without physical basis.
- Using default software assumptions without verifying appropriateness.
- Neglecting to document changes between model versions.
Review Tasks
- Practice calibrating a simple model to monthly utility data.
- Review ASHRAE Guideline 14 calibration criteria.
- Create a QA/QC checklist for a typical office building model.
Building Envelope and Site Characterization
Syllabus Focus
- Opaque envelope assemblies
- Fenestration and daylighting
- Site conditions and shading
- Thermal bridging and infiltration
Key Notes
- Envelope U-factors and R-values must be modeled per ASHRAE 90.1 or actual construction.
- Fenestration includes windows, skylights, and curtain walls; SHGC and U-value are critical.
- Site characterization includes orientation, shading from adjacent buildings/landscaping, and ground reflectance.
- Infiltration rates depend on construction quality and pressurization; use ASHRAE 90.1 default or blower door data.
- Thermal bridging (e.g., steel studs, slab edges) reduces effective R-value; model with parallel path or 3D analysis.
- Daylighting controls can reduce lighting energy; model with photosensor response and dimming curves.
Must Know
- ASHRAE 90.1 prescriptive envelope requirements (climate zone specific).
- U-factor calculation methods (series/parallel path, isothermal planes).
- Solar heat gain coefficient (SHGC) and visible transmittance (VT) for fenestration.
- Effect of thermal mass on peak loads and energy use.
Field and Exam Application
- Modeling a high-performance curtain wall with low-e coating and argon fill.
- Evaluating the impact of exterior shading fins on cooling energy.
- Assessing infiltration reduction from air sealing measures in a retrofit.
High-Yield Distinctions
- U-factor vs. R-value: U = 1/R; lower U is better insulation.
- SHGC vs. SC: SHGC is the fraction of solar heat admitted; SC is shading coefficient (SHGC/0.87).
- Visible transmittance (VT) vs. SHGC: VT affects daylight, SHGC affects heat gain.
Common Pitfalls
- Using nominal R-values without accounting for framing factors or installation quality.
- Ignoring thermal bridging in steel-framed walls.
- Assuming constant infiltration rate regardless of wind or stack effect.
Review Tasks
- Calculate overall U-factor for a wall assembly with insulation and framing.
- Model a simple box with windows and compare cooling loads with and without shading.
- Review climate zone map and typical envelope requirements for your region.
HVAC System Selection and Performance
Syllabus Focus
- System types and configurations
- Equipment performance curves
- Part-load operation and controls
- Distribution systems and losses
Key Notes
- Common HVAC systems: VAV, CAV, heat pump, chiller-boiler, DX, radiant, DOAS.
- Equipment performance is modeled using curves (e.g., EIR vs. temperature, PLR vs. efficiency).
- Part-load performance is critical; many systems operate below design load most of the time.
- Distribution losses include duct leakage, fan heat, and pipe losses; model per ASHRAE 90.1 or measured.
- Controls include economizers, setback, demand-controlled ventilation (DCV), and optimal start.
- System selection affects energy use; e.g., VAV with reheat vs. radiant with DOAS.
Must Know
- ASHRAE 90.1 minimum efficiency requirements for equipment (e.g., chiller COP, boiler efficiency).
- Part-load ratio (PLR) and its effect on efficiency curves.
- Economizer types (dry-bulb, enthalpy) and control logic.
- Fan and pump affinity laws: flow ∝ speed, power ∝ speed^3.
Field and Exam Application
- Modeling a VAV system with variable speed fans and hot water reheat.
- Comparing energy use of a chiller plant with constant vs. variable speed pumps.
- Evaluating the benefit of a DOAS with energy recovery for a humid climate.
High-Yield Distinctions
- DX vs. chilled water: DX has lower first cost but part-load efficiency varies.
- Constant volume vs. variable volume: CV simpler but less efficient at part load.
- Air-cooled vs. water-cooled condenser: water-cooled more efficient but requires cooling tower.
Common Pitfalls
- Using design-day efficiency for annual simulation; part-load efficiency is different.
- Neglecting fan and pump heat gains in cooling load calculations.
- Modeling economizer without proper control sequence (e.g., high limit shutoff).
Review Tasks
- Plot a typical chiller efficiency curve vs. leaving water temperature.
- Simulate a VAV system with and without economizer and compare energy.
- Review ASHRAE 90.1 tables for minimum equipment efficiency.
Internal Loads and Operational Schedules
Syllabus Focus
- Lighting power density and controls
- Plug and process loads
- Occupancy schedules and diversity
- Service hot water loads
Key Notes
- Lighting power density (LPD) per ASHRAE 90.1 (building area method or space-by-space).
- Lighting controls: occupancy sensors, daylight harvesting, time clocks reduce energy.
- Plug loads include computers, monitors, printers; use typical values (e.g., 0.5-1.5 W/ft²).
- Occupancy schedules define when people are present; diversity factors account for simultaneous use.
- Service hot water (SHW) loads depend on occupancy and fixture efficiency; model per ASHRAE 90.1.
- Process loads (e.g., data centers, kitchens) must be modeled separately with appropriate schedules.
Must Know
- ASHRAE 90.1 LPD allowances for different space types.
- Typical occupancy density (people/1000 ft²) for offices, classrooms, etc.
- Schedule development: hourly fractions for occupancy, lighting, equipment.
- Internal heat gain components: sensible and latent from people, lights, equipment.
Field and Exam Application
- Modeling a daylight harvesting system that dims lights near windows.
- Reducing plug loads through power management software and modeling savings.
- Sizing SHW system based on occupancy schedule and fixture flow rates.
High-Yield Distinctions
- Sensible vs. latent heat: people emit both; lights and equipment mostly sensible.
- LPD vs. lighting energy: LPD is installed power; energy depends on hours and controls.
- Occupancy diversity vs. coincidence factor: diversity is average vs. peak; coincidence is simultaneous peak.
Common Pitfalls
- Using default schedules without adjusting for actual operation (e.g., 24/7 vs. 9-5).
- Ignoring plug load variability (e.g., weekends vs. weekdays).
- Overestimating lighting energy savings from controls without proper modeling.
Review Tasks
- Create an hourly schedule for a typical office building occupancy.
- Calculate LPD for a space using ASHRAE 90.1 space-by-space method.
- Model a building with and without daylighting controls and compare lighting energy.
ASHRAE Standard 90.1 Compliance Modeling
Syllabus Focus
- Compliance paths: prescriptive, performance, energy cost budget
- Baseline building design and modeling rules
- Proposed design modeling
- Documentation and reporting for compliance
Key Notes
- ASHRAE 90.1 offers three compliance paths: prescriptive, performance (energy cost budget), and (in some editions) the Appendix G performance rating method.
- For performance path, a baseline building is modeled per Appendix G rules (e.g., same geometry, different HVAC system type).
- Proposed design includes actual efficiency, controls, and renewable energy.
- Energy cost budget method compares proposed vs. baseline energy cost; must show ≤ baseline.
- Baseline HVAC system type depends on building area and fuel type (e.g., System 1 for residential, System 5 for office).
- Documentation requires input/output reports, summary of assumptions, and compliance forms.
Must Know
- ASHRAE 90.1 Appendix G baseline system selection table.
- Baseline envelope: same U-factors as proposed but with prescriptive minimums.
- Baseline lighting: same LPD as proposed but without advanced controls.
- Baseline HVAC efficiencies: use minimum efficiency from 90.1 tables.
Field and Exam Application
- Modeling a proposed high-performance office building vs. baseline per Appendix G.
- Demonstrating compliance for a LEED energy performance credit using 90.1.
- Evaluating trade-offs between envelope and HVAC upgrades in a performance model.
High-Yield Distinctions
- Prescriptive vs. performance: prescriptive meets specific requirements; performance allows trade-offs.
- Energy cost budget vs. energy performance index (EPI): ECB uses cost; EPI uses energy units.
- Baseline HVAC system types: System 1 (PTAC), System 5 (VAV with reheat), System 7 (VAV with fan-powered boxes).
Common Pitfalls
- Using incorrect baseline system type for the building area and fuel.
- Modeling baseline envelope with better U-factors than allowed (must use prescriptive minimum).
- Forgetting to include baseline HVAC efficiencies from the correct table.
Review Tasks
- Select baseline HVAC system for a 50,000 ft² office building with electric cooling and gas heating.
- Model a simple building in both proposed and baseline configurations and compare energy cost.
- Review ASHRAE 90.1 Appendix G baseline rules for envelope and lighting.
Simulation Physics and Data Interpretation
Syllabus Focus
- Heat transfer fundamentals
- Psychrometrics and HVAC loads
- Simulation algorithms and convergence
- Output analysis and reporting
Key Notes
- Heat transfer modes: conduction, convection, radiation; all modeled in energy simulation.
- Psychrometrics: dry-bulb, wet-bulb, dew point, humidity ratio, enthalpy; used for coil and cooling tower calculations.
- Simulation algorithms include heat balance method (ASHRAE) or weighting factors (older).
- Convergence criteria ensure stable results; time steps (e.g., 6 per hour) affect accuracy.
- Outputs include annual energy, peak loads, unmet hours, and end-use breakdown.
- Data interpretation involves comparing to benchmarks (e.g., EUI) and identifying anomalies.
Must Know
- Heat balance method: solves energy balance for each surface and zone at each time step.
- Psychrometric processes: sensible cooling, cooling with dehumidification, evaporative cooling.
- Common simulation time steps: 15 minutes (4 per hour) to 1 hour.
- Unmet load hours: ASHRAE 90.1 allows ≤ 300 unmet hours for compliance.
Field and Exam Application
- Diagnosing high cooling energy by analyzing psychrometric conditions and coil performance.
- Interpreting simulation output to identify oversized equipment causing short cycling.
- Using sensitivity analysis to determine which input parameters most affect EUI.
High-Yield Distinctions
- Heat balance vs. weighting factor: heat balance more accurate; weighting factor faster but less precise.
- Sensible vs. latent cooling: sensible reduces temperature; latent removes moisture.
- EUI (energy use intensity) vs. cost: EUI in kBtu/ft² or kWh/m²; cost depends on rates.
Common Pitfalls
- Using too large a time step (e.g., 1 hour) for systems with short cycling.
- Ignoring latent loads in humid climates leading to undersized dehumidification.
- Misinterpreting unmet hours: some may be acceptable if within standard limits.
Review Tasks
- Plot a psychrometric chart and trace a cooling and dehumidification process.
- Run a simulation with different time steps and compare results.
- Calculate EUI for a sample building and compare to CBECS benchmarks.
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 ASHRAE Handbook fundamentals for heat transfer and psychrometrics.
- Practice modeling a simple building from scratch using EnergyPlus or similar.
- Understand baseline vs. proposed modeling rules in ASHRAE 90.1 Appendix G.
- Familiarize yourself with calibration criteria per ASHRAE Guideline 14.
- Review common HVAC system types and their part-load performance characteristics.
- Check ASHRAE certification candidate resources for any updates to exam content.
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.