Energy Simulation - Building Energy Modeling

<h3>Learning Objectives</h3> <ul> <li>Understand the purpose and applications of building energy modeling (BEM)</li> <li>Distinguish between design-phase and compliance energy modeling</li> <li>Identify key stakeholders and their modeling needs</li> <li>Recognize industry-standard simulation engines and tools</li> </ul>

<h3>What is Building Energy Modeling?</h3> <p>Building Energy Modeling (BEM) is the process of using computer-based simulation to predict a building's energy consumption. Unlike peak load calculations that determine equipment sizing, energy modeling simulates building performance over an entire year (8,760 hours) to estimate annual energy use, utility costs, and carbon emissions.</p>

<h3>Applications of Energy Modeling</h3> <table class="table table-bordered"> <tr><th>Application</th><th>Purpose</th><th>Typical Accuracy</th></tr> <tr><td>Code Compliance</td><td>Demonstrate building meets energy code (Title 24, ASHRAE 90.1)</td><td>+/- 15-20%</td></tr> <tr><td>Design Optimization</td><td>Compare HVAC system alternatives, envelope options</td><td>Relative comparison</td></tr> <tr><td>Green Building Certification</td><td>LEED, WELL, Living Building Challenge credits</td><td>+/- 15-25%</td></tr> <tr><td>Utility Incentives</td><td>Qualify for rebates based on energy savings</td><td>+/- 10-20%</td></tr> <tr><td>Financial Analysis</td><td>Life-cycle cost analysis, ROI calculations</td><td>+/- 20-30%</td></tr> <tr><td>Operational Benchmarking</td><td>Compare actual vs. predicted performance</td><td>Calibrated: +/- 5-10%</td></tr> </table>

<h3>Simulation Engines</h3> <p><strong>EnergyPlus</strong> - DOE flagship simulation engine, used by most professional tools. Performs detailed heat balance calculations with sub-hourly timesteps. Free and open-source.</p> <p><strong>DOE-2.2</strong> - Legacy engine still used by eQUEST and some Title 24 compliance tools. Uses weighting factors instead of heat balance.</p> <p><strong>TRACE 700/3D Plus</strong> - Trane commercial tool combining load calculations and energy analysis.</p> <p><strong>HAP (Carrier)</strong> - Carrier Hourly Analysis Program for loads and energy.</p>

<h3>Energy Modeling vs. Load Calculations</h3> <table class="table table-bordered"> <tr><th>Aspect</th><th>Load Calculations</th><th>Energy Modeling</th></tr> <tr><td>Time Period</td><td>Design day (peak conditions)</td><td>8,760 hours (full year)</td></tr> <tr><td>Purpose</td><td>Equipment sizing</td><td>Annual energy/cost prediction</td></tr> <tr><td>Weather Data</td><td>Design conditions (0.4%, 1%, 2%)</td><td>TMY (Typical Meteorological Year)</td></tr> <tr><td>Output</td><td>BTU/hr, CFM, tons</td><td>kWh, therms, $/year, kBTU/SF</td></tr> <tr><td>Schedules</td><td>Assumed full occupancy</td><td>Hourly occupancy, lighting, equipment profiles</td></tr> </table>

<h3>Key Terminology</h3> <ul> <li><strong>EUI (Energy Use Intensity)</strong> - Annual energy per square foot (kBTU/SF/yr). Primary metric for comparing building performance.</li> <li><strong>Source Energy</strong> - Total energy including generation and transmission losses. Electric multiplier typically 2.5-3.0x site energy.</li> <li><strong>Site Energy</strong> - Energy consumed at the building meter.</li> <li><strong>Baseline Building</strong> - Reference building meeting minimum code requirements for comparison.</li> <li><strong>Proposed Building</strong> - The actual design being evaluated.</li> </ul>

<h3>Learning Objectives</h3> <ul> <li>Understand hourly simulation calculation sequence</li> <li>Explain heat balance methodology vs. weighting factors</li> <li>Describe the role of timesteps and convergence</li> <li>Interpret hourly simulation results</li> </ul>

<h3>Why 8760 Hours?</h3> <p>A full year contains 8,760 hours (365 days x 24 hours). Annual simulation captures:</p> <ul> <li>Seasonal variations in heating and cooling loads</li> <li>Part-load equipment operation and efficiency</li> <li>Occupancy schedule variations (weekday/weekend/holiday)</li> <li>Time-varying utility rates (time-of-use, demand charges)</li> <li>Solar geometry changes throughout the year</li> </ul>

<h3>Simulation Calculation Sequence</h3> <p>For each hour of the simulation, the engine performs these calculations in sequence:</p> <ol> <li><strong>Read Weather Data</strong> - Temperature, humidity, solar radiation, wind speed from TMY file</li> <li><strong>Calculate Solar Position</strong> - Sun angles for shading and solar heat gain calculations</li> <li><strong>Evaluate Schedules</strong> - Determine current occupancy, lighting, equipment levels</li> <li><strong>Surface Heat Balance</strong> - Calculate heat transfer through envelope (conduction, convection, radiation)</li> <li><strong>Zone Air Heat Balance</strong> - Sum all gains/losses to determine zone load</li> <li><strong>HVAC System Response</strong> - Model equipment operation to meet zone loads</li> <li><strong>Plant Equipment</strong> - Calculate chiller, boiler, cooling tower operation</li> <li><strong>Energy Consumption</strong> - Convert equipment operation to electricity, gas consumption</li> </ol>

<h3>Heat Balance Method (EnergyPlus)</h3> <p>EnergyPlus uses the heat balance method, which solves simultaneous equations for outside surface heat balance, inside surface heat balance, and zone air heat balance. This method is more accurate than weighting factors because it accounts for thermal mass effects dynamically, handles non-standard constructions accurately, models radiant heat transfer between surfaces, and supports sub-hourly timesteps for better accuracy.</p>

<h3>Timesteps and Convergence</h3> <table class="table table-bordered"> <tr><th>Timesteps/Hour</th><th>Minutes</th><th>Use Case</th></tr> <tr><td>1</td><td>60</td><td>Quick annual runs, simple buildings</td></tr> <tr><td>4</td><td>15</td><td>Standard accuracy (recommended)</td></tr> <tr><td>6</td><td>10</td><td>Complex HVAC controls</td></tr> <tr><td>12</td><td>5</td><td>Radiant systems, high thermal mass</td></tr> <tr><td>60</td><td>1</td><td>Research, demand response studies</td></tr> </table>

<h3>Interpreting Hourly Results</h3> <p>Key hourly outputs to review:</p> <ul> <li><strong>Unmet Hours</strong> - Hours when HVAC cannot maintain setpoint (should be less than 300 hrs/yr)</li> <li><strong>Peak Demand</strong> - Maximum hourly kW for utility demand charges</li> <li><strong>Load Profiles</strong> - Hourly heating/cooling patterns</li> <li><strong>Equipment Runtime</strong> - Hours of operation for each piece of equipment</li> </ul>

<h3>Learning Objectives</h3> <ul> <li>Understand TMY file format and data sources</li> <li>Select appropriate weather files for different applications</li> <li>Interpret key weather parameters for energy modeling</li> <li>Account for climate change in future projections</li> </ul>

<h3>Typical Meteorological Year (TMY)</h3> <p>TMY files contain hourly weather data representing typical conditions. They are created by selecting the most representative month from a multi-year dataset (typically 15-30 years) for each calendar month, then concatenating them into a single year.</p>

<h3>TMY Generations</h3> <table class="table table-bordered"> <tr><th>Version</th><th>Period</th><th>Stations</th><th>Notes</th></tr> <tr><td>TMY</td><td>1948-1980</td><td>229</td><td>Original NREL dataset, obsolete</td></tr> <tr><td>TMY2</td><td>1961-1990</td><td>239</td><td>Improved solar data, still used by some tools</td></tr> <tr><td>TMY3</td><td>1991-2005</td><td>1,020</td><td>Current standard for most applications</td></tr> <tr><td>TMYx</td><td>2004-2018</td><td>1,800+</td><td>Updated data, includes climate change</td></tr> </table>

<h3>Weather File Formats</h3> <ul> <li><strong>EPW (EnergyPlus Weather)</strong> - Standard format for EnergyPlus, CSV-based with header</li> <li><strong>BIN (DOE-2)</strong> - Binary format for DOE-2 and eQUEST</li> <li><strong>CTZ (California)</strong> - California Climate Zones for Title 24</li> <li><strong>WYEC2</strong> - Weather Year for Energy Calculations</li> </ul>

<h3>Key Weather Parameters</h3> <table class="table table-bordered"> <tr><th>Parameter</th><th>Units</th><th>Impact on Simulation</th></tr> <tr><td>Dry-Bulb Temperature</td><td>F or C</td><td>Sensible heating/cooling loads, infiltration</td></tr> <tr><td>Wet-Bulb Temperature</td><td>F or C</td><td>Latent loads, cooling tower performance</td></tr> <tr><td>Relative Humidity</td><td>%</td><td>Dehumidification loads, comfort</td></tr> <tr><td>Direct Normal Irradiance (DNI)</td><td>W/m2</td><td>Solar heat gain through windows</td></tr> <tr><td>Diffuse Horizontal Irradiance (DHI)</td><td>W/m2</td><td>Skylight loads, north-facing windows</td></tr> <tr><td>Global Horizontal Irradiance (GHI)</td><td>W/m2</td><td>Total solar on horizontal surface</td></tr> <tr><td>Wind Speed</td><td>m/s</td><td>Infiltration, convection coefficients</td></tr> <tr><td>Wind Direction</td><td>degrees</td><td>Stack effect, natural ventilation</td></tr> </table>

<h3>California Climate Zones (Title 24)</h3> <p>California uses 16 climate zones for Title 24 compliance with specific CTZ2 weather files: CZ1-Arcata (cool coastal), CZ3-Oakland (mild marine), CZ6-Los Angeles (coastal southern), CZ9-Burbank (inland valley), CZ12-Sacramento (hot valley), CZ15-Palm Springs (hot desert).</p>

<h3>Climate Change Considerations</h3> <p>For long-term analysis (20+ years), consider using future weather files such as Morphed TMY (adjusted using climate projections) or AMY (Actual Meteorological Year showing warming trends). Typical adjustment is +2-4F average temperature by 2050, resulting in increased cooling loads, decreased heating loads, and shifted peak demand.</p>

<h3>Learning Objectives</h3> <ul> <li>Model wall, roof, and floor constructions with accurate thermal properties</li> <li>Understand fenestration modeling (U-factor, SHGC, VLT)</li> <li>Account for thermal bridging and assembly U-values</li> <li>Model infiltration and air barrier performance</li> </ul>

<h3>Opaque Envelope Constructions</h3> <p>Each construction is modeled as layers from outside to inside. Example Steel Stud Wall: Exterior Air Film (R-0.17), Face Brick (R-0.44), Air Gap (R-0.97), Rigid Insulation (R-7.5), Gypsum Sheathing (R-0.56), Steel Stud + Batt (R-13 nominal, R-6.5 effective), Interior Gypsum (R-0.45), Interior Air Film (R-0.68). Assembly R-value: R-16.8 (U-0.059).</p>

<h3>Material Thermal Properties</h3> <table class="table table-bordered"> <tr><th>Property</th><th>Units</th><th>Typical Range</th></tr> <tr><td>Thermal Conductivity (k)</td><td>BTU-in/hr-ft2-F</td><td>0.1 (insulation) to 300 (steel)</td></tr> <tr><td>Density</td><td>lb/ft3</td><td>0.5 (foam) to 150 (concrete)</td></tr> <tr><td>Specific Heat</td><td>BTU/lb-F</td><td>0.2 to 0.4 (most materials)</td></tr> <tr><td>Thermal Resistance (R)</td><td>hr-ft2-F/BTU</td><td>0.1 to 7.0 per inch</td></tr> </table>

<h3>Thermal Bridging</h3> <p>Metal framing significantly reduces effective R-value:</p> <table class="table table-bordered"> <tr><th>Framing Type</th><th>Cavity Insulation</th><th>Effective R-value</th></tr> <tr><td>2x4 Wood @ 16in o.c.</td><td>R-13 batt</td><td>R-11.3</td></tr> <tr><td>2x6 Wood @ 16in o.c.</td><td>R-19 batt</td><td>R-16.0</td></tr> <tr><td>3-5/8in Steel @ 16in o.c.</td><td>R-13 batt</td><td>R-6.0</td></tr> <tr><td>6in Steel @ 16in o.c.</td><td>R-19 batt</td><td>R-7.1</td></tr> </table>

<h3>Fenestration Properties</h3> <p><strong>U-Factor</strong> - Overall heat transfer coefficient (BTU/hr-ft2-F). Lower is better. Code typical: 0.36-0.55</p> <p><strong>SHGC (Solar Heat Gain Coefficient)</strong> - Fraction of solar radiation admitted (0-1). Lower reduces cooling load but also daylighting. Code typical: 0.25-0.40</p> <p><strong>VLT (Visible Light Transmittance)</strong> - Fraction of visible light transmitted (0-1). Higher is better for daylighting. Typical: 0.4-0.7</p>

<h3>Infiltration Modeling</h3> <p>Air leakage significantly impacts energy use. Model using: Air Changes per Hour (ACH) - typical 0.15-0.50 ACH; Flow per Area - 0.04 CFM/SF (tight) to 0.25 CFM/SF (leaky); Blower Door Derived - ACH50 from testing with wind/stack coefficients.</p>

<h3>Best Practices</h3> <ul> <li>Use NFRC-rated values for windows, not center-of-glass</li> <li>Include curtain wall spandrel panels separately from vision glass</li> <li>Model skylights with actual tilt and orientation</li> <li>Account for floor slab edge losses in perimeter zones</li> <li>Verify assembly U-values against ASHRAE 90.1 Appendix A</li> </ul>

<h3>Learning Objectives</h3> <ul> <li>Model common HVAC system types in energy simulation</li> <li>Understand part-load performance curves</li> <li>Configure system controls and setpoints</li> <li>Account for simultaneous heating and cooling</li> </ul>

<h3>HVAC System Types for Simulation</h3> <table class="table table-bordered"> <tr><th>System Type</th><th>Applications</th><th>Key Parameters</th></tr> <tr><td>Packaged Single Zone (PSZ)</td><td>Small retail, classrooms</td><td>EER, heating efficiency, supply fan power</td></tr> <tr><td>Packaged VAV (PVAV)</td><td>Medium office, retail</td><td>Part-load curves, minimum flow, reheat type</td></tr> <tr><td>VAV with Chiller/Boiler</td><td>Large office, hospitals</td><td>Chiller COP/IPLV, boiler efficiency, pump power</td></tr> <tr><td>Fan Coil Units</td><td>Hotels, apartments</td><td>Fan power, coil effectiveness</td></tr> <tr><td>VRF/VRV</td><td>Office, mixed-use</td><td>COP curves, heat recovery factor</td></tr> <tr><td>Ground-Source Heat Pump</td><td>Schools, office</td><td>Ground loop design, entering water temp</td></tr> </table>

<h3>Part-Load Performance</h3> <p>Equipment efficiency varies with load. IPLV (Integrated Part-Load Value) weights performance: IPLV = 0.01A + 0.42B + 0.45C + 0.12D where A=COP at 100% load, B=COP at 75% load, C=COP at 50% load, D=COP at 25% load.</p>

<h3>Chiller Efficiencies</h3> <table class="table table-bordered"> <tr><th>Chiller Type</th><th>Full-Load COP</th><th>IPLV COP</th></tr> <tr><td>Air-Cooled Scroll</td><td>2.8-3.2</td><td>4.0-4.5</td></tr> <tr><td>Air-Cooled Screw</td><td>2.9-3.3</td><td>4.5-5.0</td></tr> <tr><td>Water-Cooled Screw</td><td>5.0-5.8</td><td>6.5-7.5</td></tr> <tr><td>Water-Cooled Centrifugal</td><td>5.5-6.5</td><td>8.0-10.0</td></tr> <tr><td>Water-Cooled Magnetic Bearing</td><td>6.0-7.0</td><td>10.0-12.0</td></tr> </table>

<h3>Fan and Pump Modeling</h3> <p>Fan power varies with cube of flow (affinity laws): Power2/Power1 = (Flow2/Flow1)^3. Key inputs include Design Flow (CFM), Total Static Pressure (3-6in WG for VAV), Fan Efficiency (60-75% centrifugal), Motor Efficiency (90-95%), and VFD Efficiency (95-97%).</p>

<h3>Supply Air Temperature Reset</h3> <ul> <li><strong>Fixed SAT</strong> - Constant 55F (baseline)</li> <li><strong>OA Reset</strong> - SAT increases as OA decreases (55F at 80F OA, 65F at 50F OA)</li> <li><strong>Demand-Based Reset</strong> - SAT based on zone cooling requests (most efficient)</li> </ul>

<h3>Economizer Modeling</h3> <p>Free cooling when outside air conditions permit. Economizer can provide 10-30% cooling energy savings depending on climate. Types include Dry-Bulb (enable when OA temp less than 70F), Differential Enthalpy (enable when OA enthalpy less than return air), and Differential Dry-Bulb.</p>

<h3>Learning Objectives</h3> <ul> <li>Create realistic hourly schedules for building simulation</li> <li>Understand schedule impacts on energy results</li> <li>Apply code-required schedules for compliance modeling</li> <li>Model holidays and seasonal variations</li> </ul>

<h3>Why Schedules Matter</h3> <p>A 100,000 SF office building with 1.0 W/SF lighting operating 12 hrs/day uses 438,000 kWh/year. Same lighting operating 8 hrs/day uses 292,000 kWh/year - a 33% difference from schedules alone.</p>

<h3>Schedule Types</h3> <table class="table table-bordered"> <tr><th>Schedule Type</th><th>Values</th><th>Controls</th></tr> <tr><td>Fractional</td><td>0.0 to 1.0</td><td>Lighting, equipment, occupancy</td></tr> <tr><td>Temperature</td><td>Degrees F</td><td>Heating/cooling setpoints</td></tr> <tr><td>On/Off</td><td>0 or 1</td><td>Equipment availability, fan operation</td></tr> </table>

<h3>Typical Office Schedules</h3> <p><strong>Occupancy (weekday):</strong> 0% midnight-6am, ramp to 90% by 9am, 50% at lunch, 90% afternoon, ramp down to 0% by 8pm.</p> <p><strong>Lighting (weekday):</strong> 5% overnight base, ramp to 90% by 8am, maintain through day, ramp down after 5pm.</p> <p><strong>Equipment (weekday):</strong> 40% overnight base load (servers, etc.), 90% during occupied hours.</p>

<h3>Thermostat Schedules</h3> <p><strong>Cooling:</strong> Weekday Occupied 75F, Unoccupied 85F setback. <strong>Heating:</strong> Weekday Occupied 70F, Unoccupied 60F setback.</p>

<h3>ASHRAE 90.1 Baseline Schedules</h3> <table class="table table-bordered"> <tr><th>Building Type</th><th>Hours/Week</th><th>Key Features</th></tr> <tr><td>Office</td><td>55</td><td>M-F 8am-6pm, Sat 8am-1pm</td></tr> <tr><td>Retail</td><td>70</td><td>M-Sat 9am-9pm, Sun 11am-6pm</td></tr> <tr><td>School</td><td>50</td><td>M-F 7am-4pm, summer off</td></tr> <tr><td>Hospital</td><td>168</td><td>24/7 operation</td></tr> <tr><td>Hotel</td><td>168</td><td>24/7, varied by space type</td></tr> </table>

<h3>Holiday Schedules</h3> <p>Standard US federal holidays: New Years Day, MLK Day, Presidents Day, Memorial Day, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving, Christmas.</p>

<h3>Daylight Savings Time</h3> <p>Energy models should account for DST (2nd Sunday March to 1st Sunday November in US), affecting daylighting harvesting, peak cooling timing, and time-of-use utility rates.</p>

<h3>Learning Objectives</h3> <ul> <li>Calculate lighting power density (LPD) and equipment power density (EPD)</li> <li>Model occupant sensible and latent heat gains</li> <li>Apply diversity factors for realistic peak loads</li> </ul>

<h3>People Loads</h3> <table class="table table-bordered"> <tr><th>Activity</th><th>Total BTU/hr</th><th>Sensible</th><th>Latent</th></tr> <tr><td>Seated, quiet</td><td>350</td><td>245</td><td>105</td></tr> <tr><td>Office work</td><td>450</td><td>250</td><td>200</td></tr> <tr><td>Standing, light work</td><td>550</td><td>275</td><td>275</td></tr> <tr><td>Walking (3 mph)</td><td>1,000</td><td>400</td><td>600</td></tr> <tr><td>Heavy work</td><td>1,500</td><td>580</td><td>920</td></tr> </table>

<h3>Lighting Power Density (LPD)</h3> <table class="table table-bordered"> <tr><th>Space Type</th><th>ASHRAE 90.1-2022</th><th>Title 24-2022</th></tr> <tr><td>Office - Open Plan</td><td>0.61 W/SF</td><td>0.55 W/SF</td></tr> <tr><td>Office - Private</td><td>0.74 W/SF</td><td>0.65 W/SF</td></tr> <tr><td>Conference Room</td><td>0.97 W/SF</td><td>0.80 W/SF</td></tr> <tr><td>Corridor</td><td>0.41 W/SF</td><td>0.35 W/SF</td></tr> <tr><td>Retail Sales</td><td>1.05 W/SF</td><td>0.95 W/SF</td></tr> <tr><td>Laboratory</td><td>1.11 W/SF</td><td>1.00 W/SF</td></tr> </table>

<h3>Equipment Power Density (EPD)</h3> <table class="table table-bordered"> <tr><th>Space Type</th><th>Typical W/SF</th><th>High W/SF</th></tr> <tr><td>Office - Standard</td><td>0.75</td><td>1.50</td></tr> <tr><td>Office - High-Density</td><td>1.50</td><td>3.00</td></tr> <tr><td>Laboratory</td><td>2.00</td><td>10.00</td></tr> <tr><td>Data Center</td><td>50.00</td><td>150.00</td></tr> </table>

<h3>Heat Gain Distribution</h3> <table class="table table-bordered"> <tr><th>Load Type</th><th>Radiant</th><th>Convective</th><th>Latent</th></tr> <tr><td>People</td><td>30%</td><td>40%</td><td>30%</td></tr> <tr><td>Lighting (LED)</td><td>30%</td><td>70%</td><td>0%</td></tr> <tr><td>Equipment</td><td>20%</td><td>80%</td><td>0%</td></tr> </table>

<h3>Diversity Factors</h3> <p>Not all loads occur simultaneously. Building-Level Diversity: 0.7-0.9 for lighting, 0.5-0.8 for receptacles.</p>

<h3>Learning Objectives</h3> <ul> <li>Understand EnergyPlus input/output file structure</li> <li>Configure simulation parameters for accurate results</li> <li>Use EP-Launch, OpenStudio, and other interfaces</li> <li>Troubleshoot common simulation errors</li> </ul>

<h3>EnergyPlus Overview</h3> <p>EnergyPlus is the DOE flagship building energy simulation engine. It performs detailed heat balance calculations at sub-hourly timesteps. Key features: Free and open-source, Cross-platform (Windows, Mac, Linux), No graphical interface (uses text input files), Extensive documentation.</p>

<h3>File Structure</h3> <table class="table table-bordered"> <tr><th>File</th><th>Extension</th><th>Description</th></tr> <tr><td>Input Data File</td><td>.idf</td><td>Building model definition</td></tr> <tr><td>Weather File</td><td>.epw</td><td>Hourly weather data</td></tr> <tr><td>Output:Variable</td><td>.csv/.eso</td><td>Hourly results</td></tr> <tr><td>HTML Report</td><td>.html</td><td>Summary tables</td></tr> <tr><td>Error File</td><td>.err</td><td>Warnings and errors</td></tr> </table>

<h3>J∆S Engineering Suite Integration</h3> <p>The software exports to EnergyPlus IDF format: Zones/Spaces to Zone objects, Walls/Roofs/Floors to BuildingSurface:Detailed, Windows/Doors to FenestrationSurface:Detailed, Constructions to Construction and Material objects, HVAC Systems to HVACTemplate objects.</p>

<h3>EnergyPlus Interfaces</h3> <ul> <li><strong>EP-Launch</strong> - Simple GUI for running simulations</li> <li><strong>OpenStudio</strong> - Full graphical modeling environment</li> <li><strong>DesignBuilder</strong> - Commercial GUI with extensive libraries</li> <li><strong>J∆S Engineering Suite</strong> - Direct IDF export with templates</li> </ul>

<h3>Simulation Workflow</h3> <ol> <li>Create Geometry - Define zones, surfaces, fenestration</li> <li>Assign Constructions - Apply wall/roof/floor assemblies</li> <li>Define Internal Loads - People, lights, equipment with schedules</li> <li>Configure HVAC - System type, controls, setpoints</li> <li>Select Weather File - TMY for location</li> <li>Run Sizing - Design day calculations</li> <li>Run Annual Simulation - Full 8760-hour simulation</li> <li>Review Results - Check for errors, analyze outputs</li> </ol>

<h3>Common Errors</h3> <table class="table table-bordered"> <tr><th>Error</th><th>Cause</th><th>Solution</th></tr> <tr><td>Surface does not surround zone</td><td>Zone not enclosed</td><td>Check vertices, add surfaces</td></tr> <tr><td>Node not found</td><td>HVAC connection error</td><td>Verify node names</td></tr> <tr><td>Temperature out of range</td><td>Undersized equipment</td><td>Increase capacity</td></tr> </table>

<h3>Learning Objectives</h3> <ul> <li>Understand Title 24 Part 6 compliance pathways</li> <li>Perform prescriptive and performance compliance analysis</li> <li>Generate CEC-required compliance documents</li> </ul>

<h3>Title 24 Part 6 Overview</h3> <p>California Building Energy Efficiency Standards (Title 24, Part 6) are the most stringent in the US. Updated every 3 years (current: 2022, effective Jan 1, 2023). Requires certified energy consultant for performance path.</p>

<h3>Compliance Pathways</h3> <table class="table table-bordered"> <tr><th>Pathway</th><th>Complexity</th><th>Flexibility</th><th>Documentation</th></tr> <tr><td>Prescriptive</td><td>Simple</td><td>Low</td><td>NRCC-PRF</td></tr> <tr><td>Performance</td><td>Complex</td><td>High</td><td>NRCC-PRF + MCH + ENV</td></tr> </table>

<h3>Prescriptive Requirements</h3> <table class="table table-bordered"> <tr><th>Component</th><th>CZ3</th><th>CZ12</th><th>CZ15</th></tr> <tr><td>Roof U-factor</td><td>U-0.048</td><td>U-0.048</td><td>U-0.048</td></tr> <tr><td>Wall U-factor</td><td>U-0.069</td><td>U-0.069</td><td>U-0.069</td></tr> <tr><td>Window U-factor</td><td>U-0.36</td><td>U-0.36</td><td>U-0.36</td></tr> <tr><td>Window SHGC</td><td>0.25</td><td>0.22</td><td>0.22</td></tr> </table>

<h3>Performance Path</h3> <p>Compare proposed building to Standard Design: Compliance Margin = (Standard TDV) - (Proposed TDV). Must be greater than or equal to 0 to pass.</p>

<h3>2022 Title 24 Key Updates</h3> <ul> <li><strong>Battery Storage</strong> - Required for most nonresidential greater than 10,000 SF</li> <li><strong>PV Systems</strong> - Required for many building types</li> <li><strong>Heat Pump Baseline</strong> - Electric heat pump is now baseline for many systems</li> <li><strong>Demand Response</strong> - Lighting controls capable of automated DR</li> </ul>

<h3>Compliance Documentation</h3> <table class="table table-bordered"> <tr><th>Form</th><th>Description</th></tr> <tr><td>NRCC-PRF</td><td>Performance Certificate</td></tr> <tr><td>NRCC-ENV</td><td>Envelope Components</td></tr> <tr><td>NRCC-MCH</td><td>Mechanical Systems</td></tr> <tr><td>NRCC-LTI</td><td>Indoor Lighting</td></tr> <tr><td>NRCC-ELC</td><td>Electrical Power (PV/battery)</td></tr> </table>

<h3>Approved Software</h3> <p>CBECC-Com (free CEC tool), EnergyPro (commercial), IES-VE (with CEC module), J∆S Engineering Suite (exports to CBECC-Com format).</p>

<h3>Learning Objectives</h3> <ul> <li>Understand TDV methodology and purpose</li> <li>Calculate TDV energy from hourly consumption</li> <li>Interpret TDV multipliers by fuel type and time</li> </ul>

<h3>What is TDV?</h3> <p>Time Dependent Valuation (TDV) is California method for weighting energy use based on when it occurs. Instead of treating all kWh equally, TDV assigns higher values to energy used during peak demand periods when electricity is most expensive and carbon-intensive.</p>

<h3>TDV Calculation</h3> <p>TDV Energy = sum over 8760 hours of (Energy[hour] x TDV_Multiplier[hour]). Result in TDV-kBTU.</p>

<h3>TDV Multiplier Patterns</h3> <table class="table table-bordered"> <tr><th>Time Period</th><th>Summer</th><th>Winter</th></tr> <tr><td>Night (12am-6am)</td><td>0.5-1.0</td><td>0.8-1.2</td></tr> <tr><td>Morning (6am-12pm)</td><td>1.0-2.0</td><td>1.5-2.5</td></tr> <tr><td>Afternoon Peak (12pm-7pm)</td><td>3.0-8.0</td><td>1.0-2.0</td></tr> <tr><td>Evening (7pm-12am)</td><td>1.5-3.0</td><td>2.0-3.5</td></tr> </table>

<h3>TDV Components</h3> <p>Energy Cost (wholesale price), Capacity Cost (power plant cost), T and D Losses (higher at peak), Ancillary Services (grid stability), Environment (carbon costs).</p>

<h3>Design Implications</h3> <p>TDV encourages designs that reduce peak demand:</p> <ul> <li><strong>Thermal Mass</strong> - Pre-cool overnight, coast through peak</li> <li><strong>Cool Roofs</strong> - Reduce afternoon cooling loads</li> <li><strong>Window Shading</strong> - Block afternoon sun on west facades</li> <li><strong>Battery Storage</strong> - Shift load from peak to off-peak</li> </ul>

<h3>TDV vs. Source Energy</h3> <table class="table table-bordered"> <tr><th>Metric</th><th>TDV Energy</th><th>Source Energy</th></tr> <tr><td>Time Variation</td><td>Yes (8,760 values)</td><td>No (constant)</td></tr> <tr><td>Electric Multiplier</td><td>0.5 to 8.0</td><td>~2.5-3.0 fixed</td></tr> <tr><td>Used By</td><td>Title 24</td><td>ASHRAE 90.1, LEED</td></tr> </table>

<h3>Learning Objectives</h3> <ul> <li>Understand ASHRAE 90.1 Appendix G methodology</li> <li>Create baseline building models per Table G3.1</li> <li>Calculate energy cost budget and design energy cost</li> </ul>

<h3>Compliance Paths</h3> <table class="table table-bordered"> <tr><th>Path</th><th>Description</th><th>Flexibility</th></tr> <tr><td>Prescriptive</td><td>Meet all individual requirements</td><td>Low</td></tr> <tr><td>Trade-off</td><td>Envelope Component Trade-off</td><td>Medium</td></tr> <tr><td>Energy Cost Budget</td><td>Compare annual energy cost</td><td>High</td></tr> <tr><td>Appendix G (PRM)</td><td>Performance Rating Method</td><td>Highest</td></tr> </table>

<h3>Appendix G Overview</h3> <p>Percent Improvement = (Baseline Cost - Proposed Cost) / Baseline Cost x 100%. LEED v4.1: 6% = 1 point, 50% = 18 points.</p>

<h3>Baseline Building Rules (Table G3.1)</h3> <p><strong>Envelope:</strong> Same geometry as proposed, meets prescriptive requirements, WWR capped at 40%, skylight capped at 5%.</p>

<h3>HVAC Baseline Systems</h3> <table class="table table-bordered"> <tr><th>Building Type</th><th>Heating</th><th>Baseline System</th></tr> <tr><td>Small (less than 25k SF, 3 floors or less)</td><td>Any</td><td>System 3: PSZ-AC</td></tr> <tr><td>Medium (25k+ SF, 3 floors or less)</td><td>Electric</td><td>System 4: PSZ-HP</td></tr> <tr><td>Large (more than 3 floors or 150k+ SF)</td><td>Fossil</td><td>System 7: VAV Reheat</td></tr> <tr><td>Large</td><td>Electric</td><td>System 8: VAV PFP Boxes</td></tr> </table>

<h3>Baseline Efficiencies</h3> <table class="table table-bordered"> <tr><th>Equipment</th><th>Baseline</th></tr> <tr><td>Packaged AC (less than 65 kBTU/hr)</td><td>14.0 SEER2</td></tr> <tr><td>Packaged AC (65-135 kBTU/hr)</td><td>11.2 EER</td></tr> <tr><td>Air-Cooled Chiller</td><td>10.1 EER / 12.7 IPLV</td></tr> <tr><td>Gas Boiler</td><td>80% Et</td></tr> </table>

<h3>Documentation Requirements</h3> <p>Narrative, Input/output forms, Energy model files, Baseline vs. proposed tables, Exceptional calculations.</p>

<h3>Learning Objectives</h3> <ul> <li>Calculate annual energy costs from simulation results</li> <li>Apply utility rate structures (TOU, demand, tiered)</li> <li>Perform life-cycle cost analysis</li> </ul>

<h3>Utility Rate Structures</h3> <p><strong>Flat Rate:</strong> Single price per kWh. <strong>Tiered:</strong> Price increases with usage. <strong>Time-of-Use:</strong> Different prices by time period. <strong>Demand Charges:</strong> $/kW based on peak 15-minute demand.</p>

<h3>TOU Example Rates</h3> <table class="table table-bordered"> <tr><th>Period</th><th>Summer</th><th>Winter</th></tr> <tr><td>Off-Peak</td><td>$0.08/kWh</td><td>$0.07/kWh</td></tr> <tr><td>Mid-Peak</td><td>$0.12/kWh</td><td>$0.09/kWh</td></tr> <tr><td>On-Peak</td><td>$0.25/kWh</td><td>$0.10/kWh</td></tr> </table>

<h3>Life-Cycle Cost Analysis</h3> <p>Life-Cycle Cost = Initial Cost + PV(Energy) + PV(Maintenance) + PV(Replacement) - PV(Salvage)</p> <table class="table table-bordered"> <tr><th>Parameter</th><th>Typical Value</th></tr> <tr><td>Analysis Period</td><td>20-30 years</td></tr> <tr><td>Discount Rate</td><td>3-7%</td></tr> <tr><td>Energy Escalation</td><td>2-4%/year</td></tr> </table>

<h3>Simple Payback</h3> <p>Simple Payback = Incremental First Cost / Annual Energy Savings. Example: $50,000 / $12,500/yr = 4.0 years.</p>

<h3>System Comparison</h3> <table class="table table-bordered"> <tr><th>System</th><th>First Cost</th><th>Annual Energy</th><th>Payback</th></tr> <tr><td>Baseline VAV</td><td>$500,000</td><td>$85,000</td><td>--</td></tr> <tr><td>High-Eff VAV</td><td>$550,000</td><td>$70,000</td><td>3.3 yr</td></tr> <tr><td>VRF System</td><td>$600,000</td><td>$55,000</td><td>3.3 yr</td></tr> <tr><td>GSHP System</td><td>$750,000</td><td>$45,000</td><td>6.3 yr</td></tr> </table>

<h3>Utility Incentives</h3> <p>Prescriptive Rebates ($/unit), Custom Rebates (kWh savings), Design Assistance, Federal Tax Credits (179D, ITC).</p>

<h3>Learning Objectives</h3> <ul> <li>Size photovoltaic systems using simulation</li> <li>Model PV production in energy analysis</li> <li>Integrate battery storage with building loads</li> </ul>

<h3>PV System Sizing Example</h3> <p>Building annual load: 500,000 kWh. Sacramento (5.2 peak sun hours). System losses: 14%. Production: 1,632 kWh/kW-year. Required: 306 kW DC (765 modules at 400W).</p>

<h3>Net Metering Policies</h3> <table class="table table-bordered"> <tr><th>Policy</th><th>Description</th><th>Value</th></tr> <tr><td>Full Retail</td><td>Exports at retail rate</td><td>Highest</td></tr> <tr><td>NEM 2.0</td><td>TOU-based credits</td><td>High</td></tr> <tr><td>NEM 3.0</td><td>Avoided cost exports</td><td>Medium</td></tr> <tr><td>Feed-in Tariff</td><td>Fixed export rate</td><td>Varies</td></tr> </table>

<h3>Battery Storage</h3> <p>Peak shaving example: Shift 4 hours of 200 kW peak. Energy needed: 800 kWh. With 80% DoD: 1,000 kWh battery. Round-trip efficiency: 85-90%.</p>

<h3>Title 24 Requirements (2022)</h3> <p><strong>PV:</strong> Required for most nonresidential, sized by floor area. <strong>Battery:</strong> Required for buildings greater than 10,000 SF with PV.</p>

<h3>Zero Net Energy (ZNE)</h3> <p>ZNE Definition: Annual Production greater than or equal to Annual Consumption. Typical EUI targets: Office 25-35 kBTU/SF, Retail 20-30 kBTU/SF, School 20-30 kBTU/SF.</p>

<h3>Learning Objectives</h3> <ul> <li>Generate professional energy analysis reports</li> <li>Document modeling assumptions and inputs</li> <li>Create LEED and compliance documentation packages</li> </ul>

<h3>Report Types</h3> <table class="table table-bordered"> <tr><th>Report</th><th>Audience</th><th>Content</th></tr> <tr><td>Executive Summary</td><td>Owner, PM</td><td>Key metrics, recommendations</td></tr> <tr><td>Design Analysis</td><td>Design Team</td><td>System comparisons</td></tr> <tr><td>Code Compliance</td><td>Building Official</td><td>Required forms, certificates</td></tr> <tr><td>LEED Documentation</td><td>GBCI</td><td>Model narrative, forms</td></tr> </table>

<h3>Executive Summary Contents</h3> <p>Project Information, Annual Energy Use (kWh, therms), EUI (kBTU/SF/yr), Annual Energy Cost, Peak Demand (kW), Carbon Emissions (MT CO2e/yr), Comparison to benchmarks, Recommendations.</p>

<h3>Energy End-Use Summary Example</h3> <p>Cooling: 36%, Fans: 19%, Lighting: 17%, Equipment: 15%, Heating: 5%, Pumps: 6%, DHW: 2%. Site EUI: 26.0 kBTU/SF.</p>

<h3>LEED Documentation Package</h3> <p>Energy Model Narrative (building description, envelope, HVAC, schedules), Minimum Energy Performance Calculator, Baseline/Proposed Comparison Tables, Simulation Output Files, Professional Certification.</p>

<h3>Quality Assurance Checklist</h3> <ul> <li>Building area matches architectural drawings</li> <li>Envelope values match specifications</li> <li>Equipment efficiencies match schedules</li> <li>Unmet hours less than 300 heating and 300 cooling</li> <li>Results pass sanity check against benchmarks</li> </ul>

<h3>J∆S Engineering Suite Reports</h3> <p>Annual Energy Summary, Monthly Profiles, ASHRAE 90.1 Compliance, Title 24 NRCC Forms, LEED Template, EnergyPlus Export.</p>

<h3>Best Practices</h3> <ul> <li>Document all assumptions in model narrative</li> <li>Include sensitivity analysis for uncertain inputs</li> <li>Provide clear recommendations with cost/benefit</li> <li>Archive model files with project documents</li> </ul>