# ASHRAE 90.1-2019 Appendix G Baseline Model ### Table of Contents 1. [Overview](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#1-overview) 2. [Prerequisites and Initial Setup](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#2-prerequisites-and-initial-setup) 3. [Building Geometry and Envelope](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#3-building-geometry-and-envelope) 4. [HVAC System Selection and Configuration](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#4-hvac-system-selection-and-configuration) 5. [Lighting Systems](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#5-lighting-systems) 6. [Service Water Heating](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#6-service-water-heating) 7. [Schedules and Internal Loads](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#7-schedules-and-internal-loads) 8. [Additional Systems](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#8-additional-systems) 9. [Simulation Settings and Verification](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#9-simulation-settings-and-verification) 10. [Performance Cost Index Calculation](https://claude.ai/chat/6f70bb78-00b1-42bd-b8a3-de78ac8f9edc#10-performance-cost-index-calculation) *** ### Executive Summary: Baseline Model Development Process This is the step-by-step workflow for building an Appendix G baseline model in Better Building. The phases are roughly in order, though you'll inevitably bounce between them when something doesn't work the first time. #### Phase 1: Project Setup and Data Collection

Step	Action	Reference
1.1	Identify climate zone from ASHRAE 169 or project location	Section 2.1
1.2	Classify building area type(s) and space functions	Section 2.1
1.3	Calculate gross conditioned floor area and count floors	Section 2.1
1.4	Obtain approved weather file (TMY3/TMY2)	Section 2.2
1.5	Gather proposed design documents (geometry, schedules, loads)	Section 2.1

#### Phase 2: Building Geometry and Envelope

Step	Action	Reference
2.1	Copy proposed geometry exactly (floors, areas, thermal blocks)	Section 3.1
2.2	Calculate baseline WWR from Table G3.1.1-1 or use proposed (max 40%)	Section 3.5.1
2.3	Redistribute fenestration to match baseline WWR per facade	Section 3.5.1
2.4	Remove all shading devices; make windows flush with walls	Section 3.5.3
2.5	Look up envelope U-factors from Tables G3.4-1 to G3.4-8	Section 3.4
2.6	Create baseline constructions: roof (above-deck), walls (steel-frame), floors (steel-joist)	Section 3.3
2.7	Apply fenestration properties (U-factor, SHGC, VT) using SimpleGlazingSystem	Section 3.5.2
2.8	Set roof surface properties (reflectance=0.30, emittance=0.90)	Section 3.7
2.9	Calculate and apply baseline infiltration rate (I75Pa = 5.1 L/s·m² at 75 Pa)	Section 3.8
2.10	Adjust skylight area to 3% or less if proposed exceeds that	Section 3.6

#### Phase 3: HVAC System Selection and Configuration

Step	Action	Reference
3.1	Determine building type category (Residential/Nonresidential/Public Assembly/Heated-only)	Section 4.1
3.2	Select baseline system from Table G3.1.1-3 based on type, floors, area, climate	Section 4.2
3.3	Check for exceptions: mixed use >20,000 ft², labs, computer rooms, unusual loads	Supplemental Doc
3.4	Assign systems to zones (single-zone systems per block; VAV systems per floor)	Section 4.4
3.5	Look up equipment efficiencies from Tables G3.5.1-G3.5.6	Section 4.5
3.6	Configure sizing parameters (1.15× cooling, 1.25× heating)	Section 4.6
3.7	Set up sizing runs with correct schedule assumptions	Section 4.7
3.8	Calculate baseline fan power using Section G3.1.2.9 formulas	Section 4.8
3.9	Add VAV fan part-load curve (cubic polynomial)	Section 4.9
3.10	Configure economizer by climate zone (required in 2B, 3B-C, 4C, 5-8 except 5A/6A limits)	Section 4.10
3.11	Add energy recovery if supply ≥2,400 L/s and OA ≥70% (50% effectiveness)	Section 4.11
3.12	Configure hot water loop: boiler count, 82°C supply, OA reset to 66°C	Section 4.12
3.13	Configure chilled water loop: chiller type/count, 6.7°C supply, OA reset to 12°C	Section 4.13
3.14	Add cooling tower (axial, variable-speed, 3.23 L/s·kW)	Section 4.14
3.15	Set VAV minimum flows (30% or OA requirement, whichever greater)	Section 4.15
3.16	Add supply air temperature reset (+2.3°C at minimum load)	Section 4.16
3.17	Configure heat pump auxiliary heat lockout (<4°C outdoor) if applicable	Section 4.17
3.18	Add preheat coils for Systems 5-8 (setpoint = room heating minus 11°C)	Section 4.18

#### Phase 4: Lighting Systems

Step	Action	Reference
4.1	Look up baseline LPD for each space type from Table G3.7	Section 5.1
4.2	Apply mandatory automatic shutoff (buildings >500 m²)	Section 5.2
4.3	Add occupancy sensors only where mandatory (break rooms, conference, classrooms)	Section 5.2
4.4	Do NOT add daylight responsive controls beyond mandatory spaces	Section 5.2
4.5	Calculate exterior lighting from Table G3.6 allowances	Section 5.3

#### Phase 5: Service Water Heating

Step	Action	Reference
5.1	Select baseline SWH type from Table G3.1.1-2 (gas or electric by building type)	Section 6.1
5.2	Apply minimum efficiency from Section 7.4.2	Section 6.2
5.3	Keep SWH loads identical to proposed design	Section 6.3
5.4	Add condenser heat recovery if criteria of Section 6.5.6.2 are met	Section 6.4

#### Phase 6: Schedules and Internal Loads

Step	Action	Reference
6.1	Copy ALL schedules exactly from proposed (occupancy, lighting, equipment, thermostat)	Section 7.1
6.2	Keep thermostat setpoints and throttling range identical	Section 7.2
6.3	Set HVAC fans to run continuously during occupied, cycle during unoccupied	Section 7.3
6.4	Copy all receptacle and process loads exactly from proposed	Section 7.4

#### Phase 7: Additional Systems

Step	Action	Reference
7.1	Model elevators if in proposed (motor power, cab ventilation, cab lighting)	Section 8.1
7.2	Model refrigeration using AHRI 1200 ratings or Tables G3.10.1/G3.10.2	Section 8.2
7.3	Model transformers only if proposed exceeds Table 8.4.4 efficiency	Section 8.3
7.4	Apply motor efficiencies from Table G3.9.1	Section 8.4

#### Phase 8: Simulation Execution

Step	Action	Reference
8.1	Configure simulation for full 8,760 hours	Section 9.1
8.2	Run sizing simulations first (see detailed procedure below)	Section 4.7
8.3	Run baseline at 0° rotation, record annual energy cost	Section 10.1
8.4	Run baseline at 90° rotation, record annual energy cost	Section 10.1
8.5	Run baseline at 180° rotation, record annual energy cost	Section 10.1
8.6	Run baseline at 270° rotation, record annual energy cost	Section 10.1
8.7	Verify unmet load hours are 300 or less for each run	Section 9.2
8.8	If UMLH exceeds 300, resize equipment incrementally per Section 2.7.2 of PRM Manual	Supplemental Doc

**Detailed Sizing Run Procedure (Step 8.2)** Sizing runs determine baseline equipment capacities. Get this wrong and you'll either have unmet load hours (undersized) or an artificially inflated baseline energy cost (oversized beyond the required factors). Neither outcome helps your compliance case. **Design Day Configuration** Create two design days using climate data for your location: | Design Day | Purpose | Temperature Source | | ------------------ | ------------------------------------ | --------------------------- | | Cooling Design Day | Size cooling coils, chillers, towers | 0.4% annual cooling DB/MCWB | | Heating Design Day | Size heating coils, boilers | 99.6% annual heating DB | **Schedule Assumptions (This Is Where People Get Tripped Up)** The schedules used during sizing runs are NOT the same as annual simulation schedules:

Sizing Run	Internal Loads (Occupants, Lights, Equipment)	Infiltration
Cooling	Use HIGHEST hourly value from annual schedules, applied to entire design day	Use HIGHEST hourly value
Heating	Use LOWEST hourly value from annual schedules, applied to entire design day	Use HIGHEST hourly value

Why highest infiltration for both? Because infiltration is always a load to overcome, whether you're heating or cooling. Cold air leaking in during winter adds heating load. Hot humid air leaking in during summer adds cooling load. **Exception for Residential Dwelling Units:** Cooling sizing uses the most-used weekday schedule (not peak values) for infiltration, occupants, lighting, and equipment. **Thermostat Schedule:** Use the most typical 24-hour profile from the annual simulation for both sizing runs. **Sensible and Latent Load Considerations** The default sizing approach uses a 20°F (11°C) supply-to-room temperature difference for airflow calculations. This works when sensible loads drive your design. However, if your proposed building's airflow was sized based on latent loads exceeding sensible loads (humid climates, commercial kitchens, natatoriums, labs with high moisture generation), the baseline must use the same supply-air-to-room humidity ratio difference that drove the proposed design. The baseline doesn't get a free pass on dehumidification requirements. For cooling coil capacity, Better Building calculates both sensible and latent components. The 15% oversizing factor applies to total capacity (sensible plus latent combined). **Oversizing Factors** Apply these at the zone level to coil loads, NOT to airflow rates: | Component | Oversizing Factor | Application Level | | ---------------- | -------------------- | ------------------------- | | Cooling capacity | 1.15 (15%) | Zone coil loads | | Heating capacity | 1.25 (25%) | Zone coil loads | | Supply airflow | 1.00 (no oversizing) | Zone level | | Plant equipment | 1.00 (no oversizing) | Based on coincident loads | System-level airflow is the sum of zone design airflows (coincident sizing). Plant capacity is based on coincident system loads, not the sum of individual system peaks. **Better Building Sizing Configuration** ```idf Sizing:Parameters, 1.25, !- Heating Sizing Factor 1.15; !- Cooling Sizing Factor SimulationControl, Yes, !- Do Zone Sizing Calculation Yes, !- Do System Sizing Calculation Yes, !- Do Plant Sizing Calculation Yes, !- Run Simulation for Sizing Periods No, !- Run Simulation for Weather File Run Periods (set No for sizing only) No, !- Do HVAC Sizing Simulation for Sizing Periods 1; !- Maximum Number of HVAC Sizing Simulation Passes ``` **Orientation for Sizing Runs** Run sizing calculations for each of the four baseline orientations (0°, 90°, 180°, 270°). Use the largest capacity from any orientation as your baseline equipment size. This ensures the baseline can handle loads regardless of rotation. **Verifying Sizing Results** After sizing runs complete, check the Better Building sizing reports. The Zone Sizing Summary shows calculated airflows and coil capacities per zone. The System Sizing Summary confirms system airflows sum correctly from zones. The Plant Sizing Summary lets you check chiller and boiler capacities against coincident loads. And the Component Sizing Summary shows autosized values for all equipment. If any component shows "Autosized" with a value of 0 or something obviously wrong, you have an input error upstream. **What To Do When Unmet Load Hours Exceed 300** If your baseline shows more than 300 UMLH after applying standard oversizing, check the proposed model first. If proposed also has high UMLH, the problem is usually schedules (HVAC availability not matching occupancy) or zone minimum airflows set incorrectly. If only baseline has high UMLH for cooling, increase zone airflow by 10% for zones with more than 150 UMLH and by 5% for zones with 50-150 UMLH. Then resize cooling equipment to match increased airflows and resize chillers and towers proportionally. If only baseline has high UMLH for heating, use the same airflow adjustment procedure, resize heating coils for increased airflows, and resize boilers proportionally. For heat pumps, increase coil capacity rather than auxiliary heat. #### Phase 9: Results Processing | Step | Action | Reference | | ---- | --------------------------------------------------------------------------- | ------------ | | 9.1 | Average the four rotation energy costs to get Baseline Building Performance | Section 10.1 | | 9.2 | Calculate PCI = Proposed Performance / Baseline Performance | Section 10.2 | | 9.3 | Compare PCI to Building Performance Factor (BPF) from Table 4.2.1.1 | Section 10.3 | | 9.4 | Document compliance: PCI at or below BPF indicates compliance | Section 10.3 | #### Quick Decision Flowchart ``` START │ ▼ ┌─────────────────────────────────────┐ │ 1. What is the climate zone? │ │ → Determines envelope values, │ │ HVAC system, economizer req. │ └─────────────────────────────────────┘ │ ▼ ┌─────────────────────────────────────┐ │ 2. What is the building type? │ │ • Residential → System 1 or 2 │ │ • Public Assembly → System 3/4 │ │ or 12/13 │ │ • Heated-only → System 9 or 10 │ │ • Other Nonresidential → Check │ │ floor count and area │ └─────────────────────────────────────┘ │ ▼ ┌─────────────────────────────────────┐ │ 3. For Nonresidential: │ │ 3 floors or less AND <2,300 m² │ │ → System 3 or 4 │ │ 4-5 floors OR 2,300-14,000 m² │ │ → System 5 or 6 │ │ >5 floors OR >14,000 m² │ │ → System 7 or 8 │ └─────────────────────────────────────┘ │ ▼ ┌─────────────────────────────────────┐ │ 4. Climate zone determines heating: │ │ Zones 0-3A → Systems 1,3,5,7 │ │ Zones 3B-8 → Systems 2,4,6,8 │ └─────────────────────────────────────┘ │ ▼ ┌─────────────────────────────────────┐ │ 5. Apply exceptions in order: │ │ a. Mixed residential/nonres │ │ d. Heated-only zones │ │ e. Cooled zones in Sys 9/10 │ │ f. Computer rooms │ │ c. Laboratory spaces │ │ b. Internal load differences │ └─────────────────────────────────────┘ │ ▼ END ``` #### Critical "Same as Proposed" Items The following must be identical in baseline and proposed models: | Item | Cannot Be Different | | ----------------------- | ------------------------------------------ | | Building geometry | Floors, areas, thermal blocks | | Weather file | Same TMY file | | Schedules | Occupancy, lighting, equipment, thermostat | | Internal loads | Receptacles, process, occupancy | | Service hot water loads | Usage patterns and quantities | | Simulation period | 8,760 hours | #### Critical "Must Be Different" Items The following must follow baseline rules (not proposed design): | Item | Baseline Requirement | | ---------------------- | --------------------------------- | | Envelope U-factors | From Tables G3.4-1 to G3.4-8 | | SHGC and VT | From Tables G3.4-1 to G3.4-8 | | WWR | From Table G3.1.1-1 or 40% max | | Infiltration rate | 5.1 L/s·m² at 75 Pa (1.0 cfm/ft²) | | HVAC system type | From Table G3.1.1-3 | | Equipment efficiency | Minimum from Tables G3.5.x | | Fan power | Calculated per Section G3.1.2.9 | | Lighting power density | From Table G3.7 | | SWH system type | From Table G3.1.1-2 | *** ### 1. Overview #### 1.1 Purpose of Appendix G Appendix G (the Performance Rating Method) provides a methodology to demonstrate compliance with minimum energy standards as an alternative to prescriptive compliance. It also lets you quantify energy performance that exceeds standard requirements, which matters for rating programs like LEED. The basic concept: you build two simulation models of the same building. One represents your actual proposed design. The other represents a hypothetical "baseline" building that meets code minimums using standardized systems. Compare the energy costs, and you get a performance ratio. #### 1.2 Key Concept: Performance Cost Index (PCI) ``` Performance Cost Index (PCI) = Proposed Building Performance / Baseline Building Performance ``` A PCI below 1.0 means the proposed design performs better than baseline. The baseline building represents a "minimally code-compliant" building using the same geometry but with standard-compliant systems. #### 1.3 What This Guide Covers This guide focuses only on the baseline model requirements. The baseline building is an automated transformation of the proposed building with standardized envelope properties, prescribed HVAC system types, standard lighting power densities, and default service water heating systems. The proposed model is your actual design. That's on you. *** ### 2. Prerequisites and Initial Setup #### 2.1 Required Information Before Starting Before creating the baseline model, gather the following: | Information | Source | Use | | ---------------------------- | ------------------------------ | ------------------------------- | | Climate Zone | ASHRAE 169 or project location | Envelope values, HVAC selection | | Building Area Type | Project documents | HVAC system type, WWR, SWH type | | Gross Conditioned Floor Area | Architectural drawings | HVAC system selection | | Number of Floors | Architectural drawings | HVAC system selection | | Building Orientation | Site plan | Rotation analysis | | Space Classifications | Program documents | Lighting power densities | #### 2.2 Weather Data Requirements (Section G2.3) Use the SAME weather file for both proposed and baseline models. This seems obvious, but people occasionally forget. Use TMY3, TMY2, or equivalent hourly weather data. Select data representative of the actual construction site. The rating authority must approve the weather file for the project location. #### 2.3 Simulation Program Requirements (Section G2.2) Better Building meets all Appendix G simulation requirements: 8760 hours per year simulation, hourly schedule variations, thermal mass effects, 10+ thermal zones capability, part-load performance curves, capacity and efficiency correction curves, air economizer modeling, and design load calculations. Make sure your Better Building version is tested per ASHRAE Standard 140. *** ### 3. Building Geometry and Envelope #### 3.1 Geometry Requirements (Table G3.1, No. 1 & 5) The baseline building must have the same number of floors as proposed design, same conditioned floor area as proposed design, and same thermal block configuration as proposed design. You're not redesigning the building. You're swapping out the systems. #### 3.2 Building Orientation Rotation (Table G3.1, No. 5a) Run 4 simulations at 0°, 90°, 180°, and 270° rotation. Average the results to get baseline building performance. This removes any orientation advantage the proposed design might have. A building that happened to land on a favorable site orientation doesn't get credit for luck. **Better Building Implementation:** ```idf Building, Building Name, !- Name 0, !- North Axis (degrees) - Change to 0, 90, 180, 270 Suburbs, !- Terrain 0.04, !- Loads Convergence Tolerance Value 0.4, !- Temperature Convergence Tolerance Value (deltaC) FullInteriorAndExterior, !- Solar Distribution 25, !- Maximum Number of Warmup Days 6; !- Minimum Number of Warmup Days ``` **Exceptions (no rotation required if):** Building orientation is dictated by site constraints (documented), or vertical fenestration area varies by less than 5% on each orientation. #### 3.3 Opaque Envelope Assemblies (Table G3.1, No. 5b) Use these mandatory construction types for baseline: | Component | Required Assembly Type | Reference | | ----------------- | ------------------------------ | ------------- | | Roofs | Insulation Entirely Above Deck | Appendix A2.2 | | Above-Grade Walls | Steel-Framed | Appendix A3.3 | | Below-Grade Walls | Concrete Block | Appendix A4 | | Floors | Steel-Joist | Appendix A5.3 | | Slab-on-Grade | Unheated F-factors | Appendix A6 | The baseline always uses steel-framed walls and steel-joist floors regardless of what the proposed design actually has. This is intentional. It creates a consistent comparison point. **Better Building Implementation (Example Roof):** ```idf ! First, get U-factor from Tables G3.4-1 through G3.4-8 for your climate zone ! Example: Climate Zone 4A, Nonresidential = U-0.360 W/m²·K Construction, Baseline Roof Construction, !- Name Roof Membrane, !- Outside Layer Roof Insulation, !- Layer 2 Metal Decking; !- Layer 3 Material, Roof Insulation, !- Name MediumSmooth, !- Roughness 0.158, !- Thickness (m) - Calculated to achieve U-0.360 0.049, !- Conductivity (W/m-K) 265, !- Density (kg/m3) 837; !- Specific Heat (J/kg-K) ``` #### 3.4 Baseline U-Factor and SHGC Values Step 1: Identify your climate zone. Step 2: Determine building use (Residential/Nonresidential/Semiheated). Step 3: Look up values in Tables G3.4-1 through G3.4-8. **Climate Zone 4A Example (Nonresidential):** | Component | Maximum U-Factor | Unit | | ------------------------------- | ---------------- | ------ | | Roof (insulation above deck) | 0.360 | W/m²·K | | Above-grade wall (steel-framed) | 0.705 | W/m²·K | | Below-grade wall | C-6.473 | W/m²·K | | Floor (steel-joist) | 0.296 | W/m²·K | | Slab-on-grade (unheated) | F-1.264 | W/m·K | | Swinging door | 3.975 | W/m²·K | | Non-swinging door | 8.233 | W/m²·K | #### 3.5 Fenestration (Windows): Area and Properties **3.5.1 Window-to-Wall Ratio (WWR)** **For building types in Table G3.1.1-1:** | Building Area Type | Baseline WWR | | ------------------------------- | ------------ | | Grocery store | 7% | | Healthcare (outpatient) | 21% | | Hospital | 27% | | Hotel/motel (75 rooms or fewer) | 24% | | Hotel/motel (>75 rooms) | 34% | | Office (465 m² or less) | 19% | | Office (465-4650 m²) | 31% | | Office (>4650 m²) | 40% | | Restaurant (quick service) | 34% | | Restaurant (full service) | 24% | | Retail (stand alone) | 11% | | Retail (strip mall) | 20% | | School (primary) | 22% | | School (secondary/university) | 22% | | Warehouse (non-refrigerated) | 6% | **For building types NOT in Table G3.1.1-1:** Use proposed design WWR or 40%, whichever is smaller. Distribute on each facade in same proportion as proposed. **3.5.2 Fenestration Properties** From Tables G3.4-1 through G3.4-8 based on Climate Zone and WWR. Example for Climate Zone 4A, Nonresidential, 30-40% WWR: U-factor is Uall = 3.24 W/m²·K, SHGC is SHGCall = 0.39, VT is VTall = 0.43. **Better Building Implementation:** ```idf WindowMaterial:SimpleGlazingSystem, Baseline Glazing, !- Name 3.24, !- U-Factor (W/m2-K) 0.39, !- Solar Heat Gain Coefficient 0.43; !- Visible Transmittance Construction, Baseline Window, !- Name Baseline Glazing; !- Outside Layer ``` **3.5.3 Shading Devices** All vertical fenestration shall be flush with exterior wall. No shading projections shall be modeled. Manual shading devices (blinds) are not modeled. Yes, this means your beautiful brise-soleil doesn't help the baseline. That's the point. #### 3.6 Skylights (Table G3.1, No. 5e) Skylight area equals proposed design area OR 3%, whichever is smaller. If proposed exceeds 3%, reduce baseline proportionally to reach 3%. Properties come from Tables G3.4-1 through G3.4-8. #### 3.7 Roof Surface Properties (Table G3.1, No. 5f,g) ```idf ! Baseline roof surface properties - MANDATORY ! Solar Reflectance: 0.30 ! Thermal Emittance: 0.90 ! Roof Albedo: 0.30 Material, Roof Membrane, !- Name VeryRough, !- Roughness 0.0095, !- Thickness (m) 0.16, !- Conductivity (W/m-K) 1121, !- Density (kg/m3) 1460, !- Specific Heat (J/kg-K) 0.90, !- Thermal Absorptance (emittance) 0.70, !- Solar Absorptance (1 - reflectance = 1 - 0.30) 0.70; !- Visible Absorptance ``` #### 3.8 Building Envelope Infiltration (Table G3.1, No. 5h) **Baseline air leakage rate:** I75Pa = 5.1 L/s·m² at 75 Pa **Conversion formulas (Section G3.1.1.4):** For floor area method: ``` IFLR = 0.112 × I75Pa × S / AFLR ``` For above-grade wall area method: ``` IAGW = 0.112 × I75Pa × S / AAGW ``` Where S is total building envelope area (m²), AFLR is gross floor area (m²), and AAGW is above-grade wall area (m²). **Better Building Implementation:** ```idf ZoneInfiltration:DesignFlowRate, Zone1 Infiltration, !- Name Zone1, !- Zone Name Infiltration Schedule, !- Schedule Name Flow/ExteriorWallArea, !- Design Flow Rate Calculation Method , !- Design Flow Rate (m3/s) , !- Flow per Zone Floor Area 0.000571, !- Flow per Exterior Surface Area (m3/s-m2) - CALCULATED , !- Air Changes per Hour 1, !- Constant Term Coefficient 0, !- Temperature Term Coefficient 0, !- Velocity Term Coefficient 0; !- Velocity Squared Term Coefficient ``` *** ### 4. HVAC System Selection and Configuration #### 4.1 System Type Selection Process Step 1: Determine Building Type Category. Options are Residential (dormitory, hotel, motel, multifamily), Nonresidential (all others), Public assembly (worship, theaters, arenas, convention centers, etc.), or Heated-only storage. Step 2: Count Floors (including basement, excluding parking). Step 3: Calculate Gross Conditioned Floor Area. Step 4: Identify Climate Zone. Climate Zones 0-3A use different systems than Zones 3B, 3C, 4-8. Step 5: Use Table G3.1.1-3 to Select System. #### 4.2 Baseline HVAC System Types (Table G3.1.1-3) | Building Type & Size | Zones 0-3A | Zones 3B,3C,4-8 | | ----------------------------------------------------------------------------------- | ---------------------------- | ------------------------- | | **Residential** | System 1 (PTAC) | System 2 (PTHP) | | **Public assembly <11,000 m²** | System 3 (PSZ-AC) | System 4 (PSZ-HP) | | **Public assembly 11,000 m² or more** | System 12 (SZ-CV-HW) | System 13 (SZ-CV-ER) | | **Heated-only storage** | System 9 | System 10 | | **Retail, 2 floors or fewer** | System 3 (PSZ-AC) | System 4 (PSZ-HP) | | **Other nonres, 3 floors or fewer AND <2,300 m²** | System 3 (PSZ-AC) | System 4 (PSZ-HP) | | **Other nonres, 4-5 floors AND <2,300 m² OR 5 floors or fewer AND 2,300-14,000 m²** | System 5 (Pkg VAV w/ Reheat) | System 6 (Pkg VAV w/ PFP) | | **Other nonres, >5 floors OR >14,000 m²** | System 7 (VAV w/ Reheat) | System 8 (VAV w/ PFP) | #### 4.3 System Descriptions (Table G3.1.1-4) | System | Type | Fan Control | Cooling | Heating | | -------------------- | --------------------------------- | --------------- | ------------- | ------------------- | | 1. PTAC | Packaged terminal AC | Constant Volume | DX | Hot-water boiler | | 2. PTHP | Packaged terminal HP | Constant Volume | DX | Electric heat pump | | 3. PSZ-AC | Packaged rooftop AC | Constant Volume | DX | Fossil fuel furnace | | 4. PSZ-HP | Packaged rooftop HP | Constant Volume | DX | Electric heat pump | | 5. Pkg VAV w/ Reheat | Packaged rooftop VAV | VAV | DX | Hot-water boiler | | 6. Pkg VAV w/ PFP | Packaged VAV w/ fan-powered boxes | VAV | DX | Electric resistance | | 7. VAV w/ Reheat | VAV with chilled water | VAV | Chilled water | Hot-water boiler | | 8. VAV w/ PFP | VAV with fan-powered boxes | VAV | Chilled water | Electric resistance | | 9. Heating only | Warm air furnace, gas | Constant Volume | None | Gas furnace | | 10. Heating only | Warm air furnace, electric | Constant Volume | None | Electric resistance | | 11. SZ-VAV | Single-zone VAV | VAV | Chilled water | See note\* | | 12. SZ-CV-HW | Single-zone CV | Constant Volume | Chilled water | Hot-water boiler | | 13. SZ-CV-ER | Single-zone CV | Constant Volume | Chilled water | Electric resistance | \*System 11: Zones 0-3A = Electric resistance; Other zones = Hot-water boiler #### 4.4 Zone Assignment Rules For Systems 1, 2, 3, 4, 9, 10, 11, 12, 13: Each thermal block gets a separate system. For Systems 5, 6, 7, 8: Each FLOOR gets a separate system (floors with identical blocks can be grouped). **Special Cases:** For significantly different zones (>31.2 W/m² peak load difference OR >40 equivalent FLH/week schedule difference), use System 3 or 4 regardless of base system. Laboratory spaces with >7,100 L/s exhaust use System 5 or 7. Computer rooms with specific criteria use System 11. Hospitals always use System 5 or 7 regardless of climate zone. #### 4.5 Equipment Efficiencies (Section G3.1.2.1) Use minimum efficiency levels from Tables G3.5.1 through G3.5.6. **Key efficiency values (excluding fan power):** **Air Conditioners (Table G3.5.1):** | Size | COPnfcooling | | ----------------------- | ------------ | | <19 kW (single-package) | 3.0 | | 19-40 kW | 3.5 | | 40-70 kW | 3.4 | | 70-223 kW | 3.5 | | 223 kW or more | 3.6 | **Heat Pumps, Cooling Mode (Table G3.5.2):** | Size | COPnfcooling | | ------------- | ------------ | | <19 kW | 3.0 | | 19-40 kW | 3.4 | | 40-70 kW | 3.2 | | 70 kW or more | 3.1 | **Heat Pumps, Heating Mode (Table G3.5.2):** | Size | Condition | COPnfheating | | ------------- | -------------- | ------------ | | <19 kW | - | 3.4 | | 19-40 kW | 8.3°C outdoor | 3.4 | | 19-40 kW | -8.3°C outdoor | 2.3 | | 40 kW or more | 8.3°C outdoor | 3.4 | | 40 kW or more | -8.3°C outdoor | 2.1 | **Water Chillers (Table G3.5.3):** | Type | Size | COP | IPLV | | ------------ | --------------- | ---- | ---- | | Screw/Scroll | <528 kW | 4.45 | 5.20 | | Screw/Scroll | 528-1055 kW | 4.90 | 5.60 | | Screw/Scroll | 1055 kW or more | 5.50 | 6.15 | | Centrifugal | <528 kW | 5.00 | 5.25 | | Centrifugal | 528-1055 kW | 5.55 | 5.90 | | Centrifugal | 1055 kW or more | 6.10 | 6.40 | **Boilers (Table G3.5.6):** | Size | Efficiency | Type | | --------- | ---------- | ------------ | | <88 kW | 80% AFUE | - | | 88-733 kW | 75% Et | Max capacity | | >733 kW | 80% Ec | Hot water | #### 4.6 Equipment Sizing (Section G3.1.2.2) Cooling equipment: 1.15 × sizing run capacity (15% oversize). Heating equipment: 1.25 × sizing run capacity (25% oversize). Plant capacity: Based on COINCIDENT loads. **Better Building Sizing Parameters:** ```idf Sizing:Parameters, 1.15, !- Heating Sizing Factor (use 1.25 for heating coils) 1.15; !- Cooling Sizing Factor Sizing:Zone, Zone Name, !- Zone Name SupplyAirTemperature, !- Zone Cooling Design Supply Air Temperature Input Method 12.8, !- Zone Cooling Design Supply Air Temperature (C) - 11°C delta , !- Zone Cooling Design Supply Air Temperature Difference SupplyAirTemperature, !- Zone Heating Design Supply Air Temperature Input Method 50, !- Zone Heating Design Supply Air Temperature (C) , !- Zone Heating Design Supply Air Temperature Difference 0.0085, !- Zone Cooling Design Supply Air Humidity Ratio (kg-H2O/kg-air) 0.008, !- Zone Heating Design Supply Air Humidity Ratio (kg-H2O/kg-air) SZ DSOA Object, !- Design Specification Outdoor Air Object Name , !- Zone Heating Sizing Factor , !- Zone Cooling Sizing Factor DesignDay, !- Cooling Design Air Flow Method , !- Cooling Design Air Flow Rate , !- Cooling Minimum Air Flow per Zone Floor Area , !- Cooling Minimum Air Flow 0, !- Cooling Minimum Air Flow Fraction DesignDay, !- Heating Design Air Flow Method , !- Heating Design Air Flow Rate , !- Heating Maximum Air Flow per Zone Floor Area , !- Heating Maximum Air Flow 0.3; !- Heating Maximum Air Flow Fraction ``` #### 4.7 Sizing Run Requirements (Section G3.1.2.2.1) **For Cooling Sizing:** Use HIGHEST hourly schedule values for internal loads. Apply to entire design day. **For Heating Sizing:** Use LOWEST hourly schedule values for internal loads (occupants, lighting, equipment). Use HIGHEST hourly values for infiltration. ```idf SizingPeriod:DesignDay, Cooling Design Day, !- Name 7, !- Month 21, !- Day of Month SummerDesignDay, !- Day Type 33.3, !- Maximum Dry-Bulb Temperature (C) 10.7, !- Daily Dry-Bulb Temperature Range , !- Dry-Bulb Temperature Range Modifier Type , !- Dry-Bulb Temperature Range Modifier Schedule WetBulb, !- Humidity Condition Type 23.8, !- Wetbulb at Maximum Dry-Bulb ... SizingPeriod:DesignDay, Heating Design Day, !- Name 1, !- Month 21, !- Day of Month WinterDesignDay, !- Day Type -17.8, !- Maximum Dry-Bulb Temperature (C) 0, !- Daily Dry-Bulb Temperature Range ... ``` #### 4.8 Fan System Power (Section G3.1.2.9) **Baseline fan power calculation:** **Systems 1 and 2 (PTAC/PTHP):** ``` Pfan = CFM × 0.0001416 kW (where CFM is L/s) ``` **Systems 3-8 and 11-13:** ``` Pfan = (input kW) / (fan motor efficiency) Where input kW from Table G3.1.2.9: - Constant-volume (Systems 3, 4, 12, 13): kWi = Ls × 0.0015 + A - Variable-volume (Systems 5-8): kWi = Ls × 0.0021 + A - Variable-volume (System 11): kWi = Ls × 0.001 + A A = Pressure drop adjustment per Section 6.5.3.1.1 Ls = Design supply airflow (L/s) ``` **Better Building Implementation:** ```idf Fan:SystemModel, Baseline VAV Fan, !- Name Always On, !- Availability Schedule Name AHU Supply Outlet Node, !- Air Inlet Node Name AHU Fan Outlet Node, !- Air Outlet Node Name Autosize, !- Design Maximum Air Flow Rate (m3/s) Continuous, !- Speed Control Method 0.2, !- Electric Power Minimum Flow Rate Fraction 622.0, !- Design Pressure Rise (Pa) - CALCULATED 0.9, !- Motor Efficiency 1.0, !- Motor In Air Stream Fraction AUTOSIZE, !- Design Electric Power Consumption (W) PowerPerFlowPerPressure, !- Design Power Sizing Method 840, !- Electric Power Per Unit Flow Rate (W/(m3/s)) 1.66667, !- Electric Power Per Unit Flow Rate Per Unit Pressure 0.7, !- Fan Total Efficiency VAV Fan Curve, !- Electric Power Function of Flow Fraction Curve Name , !- Night Ventilation Mode Pressure Rise , !- Night Ventilation Mode Flow Fraction , !- Motor Loss Zone Name 0.0, !- Motor Loss Radiative Fraction General; !- End-Use Subcategory ``` #### 4.9 VAV Fan Part-Load Performance (Section G3.1.3.15) Use either Method 1 (table) or Method 2 (equation): **Method 2 Equation:** ``` Pfan = 0.0013 + 0.1470×PLR + 0.9506×PLR² - 0.0998×PLR³ ``` **Better Building Curve:** ```idf Curve:Cubic, VAV Fan Curve, !- Name 0.0013, !- Coefficient1 Constant 0.1470, !- Coefficient2 x 0.9506, !- Coefficient3 x**2 -0.0998, !- Coefficient4 x**3 0.0, !- Minimum Value of x 1.0, !- Maximum Value of x 0.0, !- Minimum Curve Output 1.0; !- Maximum Curve Output ``` #### 4.10 Air Economizers (Section G3.1.2.6) **Economizer Requirements by System and Climate:** | Climate Zone | Systems 3-8, 11-13 | | -------------------------- | ------------------- | | 0A, 0B, 1A, 1B, 2A, 3A, 4A | NO economizer | | All others | Economizer REQUIRED | **High-Limit Shutoff (Table G3.1.2.7):** | Climate Zone | Dry-Bulb Set Point | | ------------------------------------ | ------------------ | | 2B, 3B, 3C, 4B, 4C, 5B, 5C, 6B, 7, 8 | 24°C | | 5A, 6A | 21°C | **Better Building Implementation:** ```idf Controller:OutdoorAir, OA Controller 1, !- Name Relief Air Outlet Node, !- Relief Air Outlet Node Name Return Air Inlet Node, !- Return Air Node Name Mixed Air Node, !- Mixed Air Node Name Outside Air Inlet Node, !- Actuator Node Name autosize, !- Minimum Outdoor Air Flow Rate (m3/s) autosize, !- Maximum Outdoor Air Flow Rate (m3/s) DifferentialDryBulb, !- Economizer Control Type ModulateFlow, !- Economizer Control Action Type 24, !- Economizer Maximum Limit Dry-Bulb Temperature (C) , !- Economizer Maximum Limit Enthalpy , !- Economizer Maximum Limit Dewpoint Temperature , !- Electronic Enthalpy Limit Curve Name -100, !- Economizer Minimum Limit Dry-Bulb Temperature NoLockout, !- Lockout Type FixedMinimum; !- Minimum Outdoor Air Schedule Name ``` #### 4.11 Exhaust Air Energy Recovery (Section G3.1.2.10) **Required when:** Design supply air capacity is 2,400 L/s or more AND minimum outdoor air is 70% or more of supply. **Recovery requirement:** 50% enthalpy recovery ratio. **Exceptions (no recovery required):** Spaces not cooled and heated below 16°C; toxic, flammable, corrosive exhaust; commercial kitchen hoods (Type 1); heating systems in Zones 0-3; cooling systems in Zones 3C, 4C, 5B, 5C, 6B, 7, 8; largest exhaust less than 75% of outdoor airflow. #### 4.12 Hot Water System Configuration (Sections G3.1.3.2-G3.1.3.5) **Number of Boilers:** 1,400 m² conditioned area or less gets 1 boiler. More than 1,400 m² gets 2 equal-sized boilers. **Hot Water Temperatures:** Design supply is 82°C, design return is 54°C. **Hot Water Temperature Reset (Section G3.1.3.4):** At outdoor temp of -7°C or below, supply is 82°C. At outdoor temp of 10°C or above, supply is 66°C. Linear interpolation between. **Hot Water Pump Power:** 300 W·s/L (or 220 W·s/L for purchased heat). **Better Building Implementation:** ```idf SetpointManager:OutdoorAirReset, HW Temp Reset Manager, !- Name Temperature, !- Control Variable 82, !- Setpoint at Outdoor Low Temperature (C) -7, !- Outdoor Low Temperature (C) 66, !- Setpoint at Outdoor High Temperature (C) 10, !- Outdoor High Temperature (C) HW Supply Outlet Node; !- Setpoint Node Name ``` #### 4.13 Chilled Water System Configuration (Sections G3.1.3.7-G3.1.3.11) **Number and Type of Chillers (Table G3.1.3.7):** | Peak Cooling Load | Chillers | | ---------------------- | ----------------------------------------------- | | 1,055 kW or less | 1 water-cooled screw | | >1,055 kW to <2,110 kW | 2 water-cooled screw (equal) | | 2,110 kW or more | 2+ water-cooled centrifugal (max 2,813 kW each) | **Chilled Water Temperatures:** Design supply is 6.7°C, design return is 13°C. **Chilled Water Temperature Reset (Section G3.1.3.9):** At outdoor temp of 27°C or above, supply is 7°C. At outdoor temp of 16°C or below, supply is 12°C. Linear interpolation between. **Chilled Water Pump Power:** Primary (constant) is 140 W·s/L. Secondary (variable) is 210 W·s/L. For 1,055 kW capacity or more, use variable-speed secondary with 25% minimum flow. **Condenser Water Pump Power:** 300 W·s/L (constant volume). #### 4.14 Cooling Tower Configuration (Section G3.1.3.11) **Tower characteristics:** Type is axial-fan, open-circuit. Fan control is variable-speed. Efficiency is 3.23 L/s·kW. **Design approach calculation:** ``` Approach = 10.02 - (0.24 × WB) Where WB = 0.4% evaporation design wet-bulb temperature (°C) Valid for WB from 12.8°C to 32.2°C ``` **Leaving water temperature setpoints (Table G3.1.3.11):** | Climate Zone | Leaving Water Temp | | ------------------------------------- | ------------------ | | 5B, 5C, 6B, 8 | 18°C | | 0B, 1B, 2B, 3B, 3C, 4B, 4C, 5A, 6A, 7 | 21°C | | 3A, 4A | 24°C | | 0A, 1A, 2A | 27°C | #### 4.15 VAV Minimum Flow Set Points **Systems 5 and 7 (VAV with Reheat):** (Section G3.1.3.13) ``` Minimum = MAX of: - 30% of zone peak airflow - Minimum outdoor air rate - Code-required airflow ``` **Systems 6 and 8 (VAV with PFP):** (Section G3.1.3.14) PFP fan size is 50% of peak primary airflow. PFP fan power is 0.74 W per L/s. Minimum primary airflow is 30% or OA requirement (whichever larger). #### 4.16 Supply Air Temperature Reset (Section G3.1.3.12) **For Systems 5-8 and 11:** Reset cooling supply air temperature higher by 2.3°C at minimum cooling load. **Better Building Implementation:** ```idf SetpointManager:Warmest, SAT Warmest Reset, !- Name Temperature, !- Control Variable VAV Air Loop, !- HVAC Air Loop Name 12.8, !- Minimum Setpoint Temperature (C) 15.1, !- Maximum Setpoint Temperature (C) - 12.8 + 2.3 MaximumTemperature, !- Strategy Supply Air Temp Nodes; !- Setpoint Node or NodeList Name ``` #### 4.17 Heat Pump Auxiliary Heat Control (Section G3.1.3.1) **For Systems 2 and 4:** Auxiliary heat energized only when outdoor temp is below 4°C. Heat pump continues to operate while auxiliary is energized. ```idf ZoneHVAC:WaterToAirHeatPump, ... 4.0, !- Maximum Outdoor Dry-Bulb Temperature for Supplemental Heater Operation (C) ... ``` #### 4.18 Preheat Coils (Section G3.1.3.19) **For Systems 5-8:** Include preheat coil with fixed setpoint = (Room heating setpoint minus 11°C). Example: If room heating setpoint is 21°C, preheat setpoint is 10°C. *** ### 5. Lighting Systems #### 5.1 Interior Lighting Power Density (Table G3.1, No. 6) **Baseline LPD determination:** Use Table G3.7 (Space-by-Space Method) for baseline interior lighting. **Selected values from Table G3.7:** | Space Type | LPD (W/m²) | Occupancy Sensor Reduction | | ------------------------------ | ---------- | -------------------------- | | Office, Enclosed | 11.84 | 30% | | Office, Open Plan | 11.84 | 15% (30% for workstation) | | Conference Room | 13.99 | None | | Corridor | 5.38 | 25% | | Lobby | 13.99 | 25% | | Restroom | 9.69 | 45% | | Storage Room, 4.6 m² or larger | 8.61 | 45% | | Classroom | 13.99 | None/30% | | Retail Sales Area | 18.30 | 15% | | Dining, Family | 22.60 | 35% | | Guest Room | 11.84 | 45% | #### 5.2 Baseline Lighting Controls **Mandatory baseline controls:** Automatic shutoff in buildings over 500 m². Occupancy sensors in employee lunch and break rooms, conference and meeting rooms, and classrooms (except shop, lab, PreK-12). **NOT included in baseline:** Daylight responsive controls (beyond those spaces). Additional occupancy sensors. **Better Building Implementation:** ```idf Lights, Zone1 Lights, !- Name Zone1, !- Zone Name Office Lighting Schedule, !- Schedule Name Watts/Area, !- Design Level Calculation Method , !- Lighting Level (W) 11.84, !- Watts per Zone Floor Area (W/m2) , !- Watts per Person 0.0, !- Return Air Fraction 0.7, !- Fraction Radiant 0.2, !- Fraction Visible 1.0; !- Fraction Replaceable ``` #### 5.3 Exterior Lighting (Table G3.6) **Tradable exterior lighting baseline values:** | Application | Baseline LPD | | ----------------------- | ------------------------- | | Parking lots and drives | 1.6 W/m² | | Walkways <3m wide | 3.3 W/linear metre | | Walkways 3m or wider | 2.2 W/m² | | Plaza areas | 2.2 W/m² | | Stairways | 10.8 W/m² | | Main entries | 98 W/linear metre of door | | Other doors | 66 W/linear metre of door | | Canopies | 13.5 W/m² | | Open sales areas | 5.4 W/m² | *** ### 6. Service Water Heating #### 6.1 System Type Selection (Table G3.1.1-2) **Baseline SWH system by building type:** | Building Area Type | Baseline System | | ----------------------- | --------------------------- | | Hotel, Motel, Dormitory | Gas storage water heater | | Hospital, Gymnasium | Gas storage water heater | | School/University | Gas storage water heater | | Restaurant (all types) | Gas storage water heater | | Office, Retail | Electric resistance storage | | Courthouse, Library | Electric resistance storage | | Warehouse, Workshop | Electric resistance storage | | Healthcare clinic | Electric resistance storage | | All others | Gas storage water heater | #### 6.2 Efficiency Requirements Use minimum efficiency from Section 7.4.2 tables. #### 6.3 Loads and Usage Service water heating loads shall be IDENTICAL in proposed and baseline models. Exceptions: Documented water conservation measures (low-flow fixtures), heat recovery from drain water, or alternative sanitizing (reduced temperature). #### 6.4 Condenser Heat Recovery (Section G3.1, No. 11d) **Required in baseline when:** Large, 24-hour facilities meeting prescriptive criteria of Section 6.5.6.2. *** ### 7. Schedules and Internal Loads #### 7.1 Schedule Requirements (Table G3.1, No. 4) Schedules shall be IDENTICAL in proposed and baseline models. This includes occupancy schedules, lighting power schedules, equipment power schedules, thermostat setpoint schedules, and HVAC system operation schedules. **Exceptions allowing different schedules:** Nonstandard efficiency measures (automatic controls) approved by rating authority, automatic lighting controls, automatic natural ventilation, demand control ventilation, automatic SWH load reduction. **Never different schedules for:** Manual controls, occupancy. #### 7.2 Thermostat Settings Temperature control setpoints and schedules must be IDENTICAL in proposed and baseline. Temperature control throttling range must be IDENTICAL. #### 7.3 HVAC Fan Schedules **Standard operation:** Fans ON continuously during occupied hours. Fans cycle ON/OFF to meet loads during unoccupied hours. **Exceptions:** Health/safety mandated ventilation keeps fans ON. Systems primarily serving computer rooms keep fans ON. Systems with no heating/cooling installed cycle fans. #### 7.4 Receptacle and Process Loads (Table G3.1, No. 12) Receptacle and process loads shall be IDENTICAL in proposed and baseline models. This includes office equipment, computers, cooking equipment, medical/laboratory equipment, and manufacturing equipment. **Better Building Implementation:** ```idf ElectricEquipment, Zone1 Equipment, !- Name Zone1, !- Zone Name Equipment Schedule, !- Schedule Name Watts/Area, !- Design Level Calculation Method , !- Design Level (W) 10.76, !- Watts per Zone Floor Area (W/m2) , !- Watts per Person 0.0, !- Fraction Latent 0.5, !- Fraction Radiant 0.0; !- Fraction Lost ``` *** ### 8. Additional Systems #### 8.1 Elevators (Table G3.1, No. 16) When proposed includes elevators, baseline must model elevator motor power, cab ventilation fans, and cab lighting. **Baseline cab characteristics:** Ventilation fan is 0.69 W/L·s. Lighting is 33.79 W/m². Both operate continuously. **Motor power calculation:** ``` kW = (Weight of car + Rated load - Counterweight) × Speed × 0.00981 / η_mechanical Pm = kW / η_motor ``` Where (from Tables G3.9.2 and G3.9.3): Buildings with 4 stories or fewer use hydraulic, no counterweight, 58% mechanical efficiency. Buildings with more than 4 stories use traction, counterweight = car + 40% rated load, 64% mechanical efficiency. #### 8.2 Refrigeration (Table G3.1, No. 17) **If refrigeration is AHRI 1200 rated:** Use rated energy. **If listed in Tables G3.10.1/G3.10.2:** Use table values. **If not listed:** Model same as proposed. #### 8.3 Distribution Transformers (Table G3.1, No. 15) **Model in baseline ONLY IF:** Proposed design transformers exceed Table 8.4.4 efficiency requirements. When modeled, use Table 8.4.4 efficiency with same capacity/load ratio as proposed. #### 8.4 Motors (Table G3.9.1) Use baseline motor efficiencies from Table G3.9.1: | Shaft Power (kW) | Efficiency (%) | | ---------------- | -------------- | | 0.8 | 82.5 | | 1.1-1.5 | 84.0 | | 2.2-3.7 | 87.5 | | 5.6-7.5 | 89.5 | | 11.1-14.9 | 91.0 | | 18.7-22.4 | 92.4 | | 29.8-37.3 | 93.0 | | 44.8 | 93.6 | | 56.0 | 94.1 | | 74.6-93.3 | 94.5 | | 111.9-149.2 | 95.0 | *** ### 9. Simulation Settings and Verification #### 9.1 Simulation Period ```idf SimulationControl, Yes, !- Do Zone Sizing Calculation Yes, !- Do System Sizing Calculation Yes, !- Do Plant Sizing Calculation Yes, !- Run Simulation for Sizing Periods Yes, !- Run Simulation for Weather File Run Periods No, !- Do HVAC Sizing Simulation for Sizing Periods 1; !- Maximum Number of HVAC Sizing Simulation Passes RunPeriod, Annual, !- Name 1, !- Begin Month 1, !- Begin Day of Month , !- Begin Year 12, !- End Month 31, !- End Day of Month , !- End Year Sunday, !- Day of Week for Start Day Yes, !- Use Weather File Holidays and Special Days Yes, !- Use Weather File Daylight Saving Period No, !- Apply Weekend Holiday Rule Yes, !- Use Weather File Rain Indicators Yes; !- Use Weather File Snow Indicators ``` #### 9.2 Unmet Load Hours Limit (Section G3.1.2.3) Unmet load hours must be 300 hours or less (of 8,760) for BOTH proposed and baseline models. **Better Building Verification:** Check output variable `Zone Thermal Comfort ASHRAE 55 Adaptive Model Temperature` or review unmet hours in tabular reports. ```idf Output:Table:SummaryReports, AllSummary; !- Report 1 Name ``` #### 9.3 Required Output Variables ```idf Output:Variable,*,Facility Total Electric Demand Power,Hourly; Output:Variable,*,Facility Total Gas Rate,Hourly; Output:Meter,Electricity:Facility,Hourly; Output:Meter,NaturalGas:Facility,Hourly; Output:Meter,InteriorLights:Electricity,Hourly; Output:Meter,InteriorEquipment:Electricity,Hourly; Output:Meter,Fans:Electricity,Hourly; Output:Meter,Pumps:Electricity,Hourly; Output:Meter,Heating:Electricity,Hourly; Output:Meter,Cooling:Electricity,Hourly; Output:Meter,Heating:NaturalGas,Hourly; Output:Meter,WaterSystems:NaturalGas,Hourly; ``` #### 9.4 Energy Cost Calculation (Section G2.4.2) **Options:** Actual utility rates for purchased energy, or state average prices from DOE EIA. Do NOT mix rate sources in same project. ```idf UtilityRate:Simple, Commercial Electric, !- Name Electricity:Facility, !- Meter Name USD, !- Currency /kWh, !- Per Unit Value or Cost 0.10, !- Cost per Unit Value or Cost 0.00; !- Demand Charge ``` *** ### 10. Performance Cost Index Calculation #### 10.1 Four-Rotation Baseline Procedure Run baseline model at 0° rotation and record annual energy cost. Run baseline model at 90° rotation and record annual energy cost. Run baseline model at 180° rotation and record annual energy cost. Run baseline model at 270° rotation and record annual energy cost. Average the four costs to get Baseline Building Performance. #### 10.2 PCI Calculation ``` PCI = Proposed Building Performance / Baseline Building Performance Where: - Proposed Building Performance = Annual energy cost from proposed model - Baseline Building Performance = Average of four rotation runs ``` #### 10.3 Compliance Determination **For minimum standard compliance (Section 4.2.1.1):** ``` PCI must be at or below Building Performance Factor (BPF) from Table 4.2.1.1 ``` BPF values vary by climate zone and building type. **For rating programs (e.g., LEED):** Lower PCI means better performance. Calculate percent improvement as (1 minus PCI) × 100%. #### 10.4 Summary Checklist Before submitting, verify: * Same weather file used for proposed and baseline * Same simulation program used for both * Baseline rotated and averaged (4 orientations) * Unmet load hours 300 or less for both models * Envelope U-factors match climate zone requirements * SHGC values match climate zone and WWR requirements * Correct HVAC system type selected * Equipment efficiencies at minimum levels * 15% cooling oversizing, 25% heating oversizing * Fan power calculated per formulas * Economizer included/excluded per climate zone * Schedules identical (except approved automatic controls) * Internal loads identical * Energy costs calculated consistently *** ### Appendix A: Quick Reference Tables #### A.1 Climate Zone Envelope Summary | Zone | Roof U | Wall U | Floor U | Slab F | Window U | SHGC | | ---- | ------ | ------ | ------- | ------ | -------- | --------- | | 0-1 | 0.360 | 0.705 | 1.986 | 1.264 | 6.93 | 0.25 | | 2 | 0.360 | 0.705 | 0.296 | 1.264 | 6.93 | 0.25 | | 3 | 0.360 | 0.705 | 0.296 | 1.264 | 3.24 | 0.25-0.39 | | 4 | 0.360 | 0.705 | 0.296 | 1.264 | 3.24 | 0.39 | | 5 | 0.360 | 0.479 | 0.296 | 1.264 | 3.24 | 0.39-0.49 | | 6 | 0.360 | 0.479 | 0.214 | 1.264 | 3.24 | 0.39-0.49 | | 7 | 0.360 | 0.365 | 0.214 | 1.264 | 3.24 | 0.49 | | 8 | 0.273 | 0.365 | 0.214 | 0.935 | 2.61 | 0.40 | Values are for Nonresidential buildings. Check Tables G3.4-1 through G3.4-8 for specific conditions. #### A.2 HVAC System Quick Selection | Floors | Area (m²) | Type | Zone 0-3A | Zone 3B-8 | | ---------- | ------------ | ----------- | --------- | --------- | | 3 or fewer | <2,300 | Nonres | Sys 3 | Sys 4 | | 4-5 | <2,300 | Nonres | Sys 5 | Sys 6 | | 5 or fewer | 2,300-14,000 | Nonres | Sys 5 | Sys 6 | | >5 | Any | Nonres | Sys 7 | Sys 8 | | Any | >14,000 | Nonres | Sys 7 | Sys 8 | | Any | Any | Residential | Sys 1 | Sys 2 | --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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