ASHRAE Standard 90.1-2019 Energy Cost Budget (ECB) Method
This document provides all tables, equations, and requirements needed to complete ECB energy modeling for code compliance.
1. Overview & Process
This section introduces the ECB method and explains when and why to use it. The ECB method allows designers to trade off efficiency between building systems while still meeting energy code requirements.
What is the ECB Method?
The Energy Cost Budget (ECB) Method is a performance-based compliance path in ASHRAE Standard 90.1-2019. Instead of meeting each prescriptive requirement individually, designers use whole-building energy simulation to demonstrate that the proposed building's annual energy cost does not exceed a budget building designed to minimally comply with prescriptive requirements.
Compliance Criterion: Design Energy Cost (DEC) ≤ Energy Cost Budget (ECB)
Key Concepts:
Design Energy Cost (DEC): The annual energy cost calculated for the proposed building design
Energy Cost Budget (ECB): The annual energy cost calculated for a budget building that meets prescriptive requirements
Trade-offs: Better performance in one area (e.g., lighting) can offset worse performance in another (e.g., envelope)
When to Use ECB vs. Other Compliance Paths
Choose your compliance path based on project complexity, design goals, and certification requirements. ECB is ideal when you want flexibility but still need to demonstrate code compliance.
Prescriptive
Sections 5-10
Simple buildings, standard designs
None — must meet each requirement
Not considered
ECB Method
Section 11
Complex buildings, innovative designs needing flexibility
Envelope, Lighting, HVAC, SWH
Reduce DEC only
Appendix G (PRM)
Appendix G
Beyond-code programs, LEED, incentives
All systems
Can reduce both
ECB vs. Appendix G: Key Differences
Understanding these differences is critical. ECB is for code compliance; Appendix G is for rating beyond-code performance. The budget building is constructed differently in each method.
Primary Purpose
Code compliance demonstration
Beyond-code performance rating
Budget HVAC System
Based on proposed system type (follows Figure 11.5.2)
Standardized baseline systems (Table G3.1.1-3)
Budget Envelope
Prescriptive requirements from Section 5.5
Prescriptive requirements from Section 5.5
On-site Renewables
Reduce proposed (DEC) only; NOT in budget
Can be included in both models per rules
Exceptional Calculations
Section 11.6
Section G2.5
Used For
Building permits, code compliance
LEED, utility incentives, beyond-code certifications
ECB Compliance Workflow
Follow these six steps in order. Steps 1-2 (prerequisites and mandatory) must be completed before any modeling begins. The simulation work happens in Steps 3-5.
2. Applicability (Section 11.1)
This section defines when ECB can be used and what preconditions must be met. Not all projects are suitable for ECB, verify applicability before investing in energy modeling.
Section 11 Structure Map
11.1
General
Applicability, preconditions, scope
11.2
Compliance
Five compliance gates (a-e) that must ALL be met
11.3
Trade-Off Limitations
Restrictions for alterations to existing buildings
11.4
Simulation General Requirements
Software, weather data, energy rates
11.5
Calculating DEC and ECB
Table 11.5.1 modeling rules + HVAC system rules
11.6
Exceptional Calculation Methods
Procedures for non-standard approaches
11.7
Submittals
Documentation for permits and completion
Project Types Where ECB May Be Used
New Buildings: Complete new construction projects
Additions: New conditioned space added to existing buildings
Alterations: Changes to existing buildings (with limitations per Section 11.3)
Preconditions for ECB Use
All five preconditions must be satisfied before proceeding with ECB. If any cannot be met, use the prescriptive compliance path instead.
Scope Allows Performance Path: Project scope and contracts permit performance-based compliance demonstration
AHJ Acceptance: Authority Having Jurisdiction accepts ECB method for this project type and location
Approved Software Available: Simulation program meeting Section 11.4.1 requirements is available (must be tested per ASHRAE Standard 140)
Climate Data Available: TMY or equivalent weather data is available for the project location
Energy Rates Obtainable: Actual utility rate structures can be obtained from local utilities or AHJ
Trade-Off Limitations for Alterations (Section 11.3)
Alterations have stricter limits than new construction. These rules prevent using ECB to significantly degrade existing envelope performance.
Shall not increase the overall building envelope U-factor by more than 10% compared to existing conditions
Shall not increase fenestration SHGC beyond prescriptive limits in Section 5.5
Must meet all mandatory requirements of Section 5.4 for altered components
Existing building portions may be excluded from modeling if conditions in Table 11.5.1 Category 2 are met
3. Compliance Criteria (Section 11.2)
This is the heart of ECB compliance. ALL FIVE gates must be passed. Failing any single gate means the building does not comply, regardless of how well it performs on the others.
The Five Compliance Gates
ALL FIVE gates must be met for compliance:
(a)
Meet ALL mandatory provisions
Sections 5.4, 6.4, 7.4, 8.4, 9.4, 10.4
NO — Must be met
(b)
Meet prescriptive requirements of Section 6.5 OR Section 6.6
Section 6.5 or 6.6
NO — Must be met
(c)
Meet Section 8 (Power) EXCEPT lighting controls portion
Section 8
NO — Must be met
(d)
Meet Section 10 (Other Equipment) EXCEPT motors covered by 6.5
Section 10
NO — Must be met
(e)
Design Energy Cost ≤ Energy Cost Budget
Section 11.5
YES — This is where trade-offs occur
Understanding Gate (e): The Trade-Off Gate
Gate (e) is where the performance trade-offs actually happen. If your proposed envelope is worse than prescriptive, you can compensate with better lighting or HVAC efficiency. The simulation calculates the net effect on annual energy cost.
4. Mandatory Provisions (Sections 5.4-10.4)
Mandatory provisions are non-negotiable requirements that apply regardless of compliance path. They represent minimum acceptable practice and cannot be traded off against better performance elsewhere. Review each section carefully before beginning energy modeling.
Section 5.4: Building Envelope Mandatory Provisions
These envelope requirements ensure basic construction quality and air barrier continuity. They apply to all envelope components regardless of U-factor trade-offs.
5.4.1
Insulation Installation
Install per manufacturer specifications; continuous air barrier required; insulation must fill cavity completely
5.4.2
Fenestration Ratings
All fenestration products must have NFRC ratings; site-built fenestration must be tested per NFRC 100
5.4.3.1
Building Air Leakage
Continuous air barrier required OR whole-building testing ≤0.4 cfm/ft² at 75 Pa pressure differential
5.4.3.2
Fenestration Air Leakage
Fixed fenestration: ≤0.3 cfm/ft²; Operable fenestration: ≤0.4 cfm/ft² (tested per NFRC 400)
5.4.3.3
Loading Dock Weatherseals
Cargo doors must have weatherseals to restrict air infiltration
5.4.3.4
Vestibules
Required at building entrances in Climate Zones 3-8 (with specific exceptions for revolving doors, small buildings, etc.)
Section 6.4: HVAC Mandatory Provisions
HVAC mandatory provisions cover equipment efficiency minimums, required controls, and system completion requirements. These ensure basic system functionality and efficiency.
6.4.1
Minimum Equipment Efficiencies
All HVAC equipment must meet minimum efficiencies in Tables 6.8.1-1 through 6.8.1-16
6.4.2
Load Calculations
Heating and cooling loads must be calculated per approved methods (ASHRAE Handbook, ACCA Manual N, etc.)
6.4.3.1
Thermostatic Controls
Each zone must have individual temperature control; deadband capability required
6.4.3.2
Setpoint Overlap Restriction
Deadband between heating and cooling setpoints ≥5°F (2.8°C) to prevent simultaneous heating/cooling
6.4.3.3
Off-Hour Controls
Systems must have automatic setback/setup controls, optimum start capability, and zone isolation
6.4.3.4
Shutoff Dampers
Automatic shutoff dampers required on outdoor air intakes ≥300 cfm serving single zone
6.4.3.5
Snow/Ice-Melting Controls
Automatic controls with temperature/moisture sensors required
6.4.3.6
Freeze Protection
Automatic controls that shut down after conditions normalize
6.4.3.7
Humidification/Dehumidification
Systems with both must have ≥10°F (5.5°C) deadband between setpoints
6.4.3.8
Demand Controlled Ventilation
Required for spaces ≥500 ft² with design occupancy ≥25 people per 1000 ft²
6.4.4
System Completion
Air and hydronic system balancing required; commissioning per Section 6.7.2
Section 7.4: Service Water Heating Mandatory Provisions
SWH mandatory provisions ensure efficient water heating equipment and proper piping insulation to minimize standby and distribution losses.
7.4.1
Load calculations required per approved methods
7.4.2
Minimum equipment efficiency per Table 7.8 (water heaters, boilers, storage tanks)
7.4.3
Temperature controls required; outlet temperature limiting for safety
7.4.4
Piping insulation required per Table 6.8.3-1 for all hot water piping
7.4.5
Heat traps required on storage tank inlet and outlet (unless integral to tank)
7.4.6
Swimming pool covers required when not in use; time switches on heaters and pumps
Section 8.4: Power Mandatory Provisions
Power provisions address electrical system efficiency and energy monitoring. These apply regardless of lighting system trade-offs.
8.4.1
Voltage Drop Limits
Feeders: ≤2%; Branch circuits: ≤3%; Total: ≤5%
8.4.2
Automatic Receptacle Control
50% of 125V 15/20A receptacles in offices, computer rooms, etc. must be automatically switched OFF during unoccupied hours
8.4.3
Energy Monitoring
Required for buildings ≥25,000 ft²; must record electrical energy use by major end-use category
Section 9.4: Lighting Mandatory Provisions
Lighting controls are mandatory regardless of lighting power density trade-offs. These ensure lights are not left on unnecessarily.
9.4.1.1
Local Controls
Readily accessible; maximum 2,500 ft² per control point; maximum 10,000 ft² between points
9.4.1.2
Restricted Auto-ON
Manual-ON required, OR partial auto-ON limited to ≤50% of connected power
9.4.1.3
Auto-OFF Controls
Automatic shutoff within 20 minutes of vacancy; occupancy sensors or scheduled shutoff required
9.4.1.4
Daylight-Responsive Controls
Required in primary and secondary sidelit zones and toplit zones; stepped or continuous dimming
9.4.1.5
Specific Application Controls
Additional controls for display/accent lighting, hotel/motel guest rooms, task lighting, etc.
9.4.2
Tandem Wiring
Required for recessed fluorescent luminaires in accessible ceilings
9.4.3
Exit Signs
Maximum 5W per face
9.4.4
Exterior Lighting Controls
Photosensor AND astronomical time switch required for all exterior lighting
Section 10.4: Other Equipment Mandatory Provisions
These requirements cover electric motors, elevators, and escalators — equipment often overlooked in energy modeling but with significant impact.
10.4.1
Electric Motors
Must meet minimum efficiency per Tables 10.8-1 through 10.8-5 (NEMA Premium or better)
10.4.2
Elevators
Cab lighting ≤3.14 W/ft²; ventilation must shut down when cab is stopped
10.4.3
Escalators/Moving Walkways
Must have speed reduction or shutoff when unoccupied
5. Simulation Requirements (Section 11.4)
This section specifies the technical requirements for energy simulation. Using proper software, weather data, and energy rates is essential for valid compliance documentation.
11.4.1: Simulation Program Requirements
Not all energy modeling software qualifies. The program must be capable of detailed hourly simulation and must be tested against ASHRAE Standard 140.
(a)
8760-hour annual simulation with timesteps of 1 hour or less
(b)
Model hourly variations in occupancy, lighting power, equipment power, thermostat setpoints, and HVAC system operation
(c)
Model part-load performance of HVAC equipment based on manufacturer data or AHRI standard ratings
(d)
Model air-side economizers with integrated control (economizer + mechanical cooling simultaneously)
(e)
Account for supply fan energy consumption at part-load conditions
(f)
Account for the effect of building orientation on envelope loads (solar gains)
Additional Simulation Requirements
11.4.1.2
Where systems differ significantly, model separately or apply appropriate weighting factors
11.4.1.3
Where the simulation cannot directly model an element, use approved alternate calculation procedures
11.4.1.4
Simulation program must be tested per ASHRAE Standard 140; test results must be publicly available
Approved Simulation Programs
The following programs are commonly used and have been tested per Standard 140:
EnergyPlus — DOE reference engine; used by many front-end interfaces
eQUEST — DOE-2.2 based; widely used for compliance
TRACE 700/3D — Trane commercial software
HAP — Carrier Hourly Analysis Program
IES Virtual Environment — Integrated Environmental Solutions
OpenStudio — NREL interface for EnergyPlus
11.4.2: Climate Data
Weather data must be consistent between proposed and budget models. TMY (Typical Meteorological Year) data represents average conditions over many years.
Use TMY data from ASHRAE, NREL, or equivalent approved source
Same weather file must be used for both proposed and budget models
Climate zone determined per Appendix B of Standard 90.1 or per IECC
If exact location data unavailable, use nearest representative weather station
11.4.3: Energy Rates
Energy rates convert simulated energy use to costs. Accurate rates are essential since compliance is based on cost, not energy.
Use actual utility rates as approved by AHJ
Include all applicable rate structures:
Time-of-use rates (different prices by time of day)
Demand charges (based on peak kW)
Ratchet clauses (demand locked in for multiple months)
Block rates (different prices by consumption tier)
District heating/cooling: use actual rates from district provider
On-site generation: value exported/used energy at same rate as purchased energy
Same rates must be used for both proposed and budget models
11.4.4: On-Site Renewable Energy
Unlike Appendix G, ECB treats renewables asymmetrically, they only benefit the proposed design. This prevents using renewables to offset poor building design.
Proposed Design: On-site renewable energy MAY be included (reduces DEC)
Budget Building: On-site renewable energy shall NOT be included
Exception: Where renewable energy is required by code or regulation, include in BOTH models at the minimum required capacity
6. Table 11.5.1: Modeling Requirements (All 14 Categories)
Table 11.5.1 is the core of ECB modeling. It specifies exactly how to model each building element in both the proposed and budget models. Follow these rules precisely — deviations can invalidate the compliance analysis.
Global Exception: Energy used for on-site vehicle recharging for off-site transportation shall NOT be modeled in either DEC or ECB calculations.
Category 1: Design Model
Category 1 establishes the fundamental relationship between proposed and budget models. The proposed model represents the actual design; the budget model is a modified version meeting prescriptive requirements.
Proposed Design
(a) The simulation model shall be consistent with the design documents for:
Envelope (orientation, materials, fenestration)
Lighting systems and controls
HVAC systems, equipment, and controls
Service water heating systems
(b) All conditioned spaces shall be simulated as BOTH heated AND cooled, even if only one system is installed. Thermostat setpoints and schedules shall be identical for heating-only and cooling-only spaces.
(c) Where building components or systems have not been designed:
Model at minimum mandatory + prescriptive requirements
Unknown building type classification: assume "office building"
Budget Building Design
The budget building design shall be developed by modifying the proposed design according to the specific instructions in each category of this table. All features not specifically addressed shall be identical to the proposed design.
Category 2: Additions and Alterations
For additions and alterations, existing portions of the building may be excluded from the simulation under specific conditions. This simplifies modeling while ensuring accurate comparison.
Existing portions of the building may be excluded from both proposed and budget models if ALL of the following conditions are met:
(a) Work in the excluded portions complies with applicable requirements of Sections 5-10
(b) Excluded portions are served by entirely separate HVAC systems from the addition/alteration
(c) Design temperatures and schedules at the boundary between excluded and included portions are identical
(d) Where declining block utility rates apply, the combined building and addition consumption is used to determine energy prices
Category 3: Space Use Classification
Space classification determines lighting power allowances. Choose one method and apply it consistently throughout the project, mixing methods is not permitted.
Use EITHER:
Section 9.5.1 — Building Area Method: Single LPD for entire building based on building type
Section 9.6.1 — Space-by-Space Method: Different LPD for each space type
Do NOT combine methods within a single permit application.
Exception: Where specific space types neither exist nor are designated in design documents, use the Building Area Method for those spaces.
Category 4: Schedules
Schedules drive energy use throughout the simulation year. Temperature schedules must be identical between models to ensure a fair comparison.
Required Schedule Types
Occupancy (people per zone by hour)
Lighting power (fraction of installed power by hour)
Equipment/receptacle power (fraction by hour)
Thermostat setpoints (heating and cooling by hour)
HVAC system operation (on/off, ventilation modes)
Key Rules
Temperature and humidity schedules: Shall be IDENTICAL for proposed and budget
HVAC supply fans (ventilation systems): Operate continuously during occupied hours; cycle on call for heating/cooling during unoccupied hours
Computer room supply fans: Operate continuously during BOTH occupied and unoccupied hours
Exceptions to Fan Operation
If no heating or cooling system is installed, fans may cycle during all hours
If ventilation is required for health/safety during unoccupied hours, fans shall operate during those hours
Dedicated outdoor air supply fans shall be OFF during unoccupied hours (unless required for health/safety)
Category 5: Building Envelope
Envelope modeling rules determine how walls, roofs, fenestration, and other components are represented. The budget building uses prescriptive U-factors and SHGC values.
Proposed Design
Model all envelope components per design drawings or as-built conditions.
Exceptions allowing simplification:
Assemblies representing less than 5% of the total area of that assembly type may be combined with adjacent assemblies
Exterior surfaces within 45° of each other may be combined into a single orientation
Roof surfaces: use aged solar reflectance per Section 5.5.3.1.1(a); if unavailable, use 0.30 reflectance and 0.90 emittance
Manual interior shading devices (blinds, drapes) shall NOT be modeled; permanent exterior shading (overhangs, fins) SHALL be modeled
Budget Building Design
Identical conditioned floor area, gross exterior dimensions, and orientations as proposed, EXCEPT:
(a) Opaque Assemblies:
Same heat capacity as proposed
U-factor equal to minimum requirements per Section 5.5 (new buildings) or Section 5.1.3 (alterations)
(b) Roof Surfaces:
Solar reflectance and thermal emittance per Section 5.5.3.1.1(a)
Roofs exempt from cool roof requirements: same as proposed
(c) Fenestration:
No shading projections (model as flush with wall)
If proposed fenestration area exceeds Section 5.5.4.2 limits, reduce budget fenestration proportionally to meet limits
If proposed west-facing glazing exceeds Section 5.5.4.5 limits, rotate the budget model to 0°, 90°, 180°, and 270° and average the four results
U-factor and SHGC per Tables 5.5-0 through 5.5-8 for the applicable climate zone
Visible transmittance (VT) per Section C3.6(c)
(d) Skylights:
Include in budget when required by Section 5.5.4.2.3 (toplighting requirements)
Category 6: Lighting
Lighting is often the primary trade-off opportunity in ECB. Better-than-code lighting can offset envelope deficiencies. Controls affect schedules, not installed power.
Proposed Design
(a) Complete lighting system exists → Model actual installed lighting power
(b) System designed but not installed → Calculate per Sections 9.1.3 and 9.1.4
(c) No system specified → Use Building Area Method allowance for the building type
(d) Include in lighting power:
Luminaires (all lamps and ballasts)
Task lighting
Furniture-mounted fixtures
Plug-in fixtures in dwelling units and hotel guest rooms (model identical in both proposed and budget)
(e) Lighting schedules shall reflect mandatory controls per Section 9.4.1
(f) Daylighting controls: Model directly in simulation OR adjust lighting schedules for:
Primary sidelit zones (within 1× head height from window)
Secondary sidelit zones (1× to 2× head height from window)
Toplit zones (under skylights)
(g) Non-mandatory lighting controls:
Occupancy sensors: Reduce hourly lighting schedule by (Table G3.7 reduction factor × 0.25)
Table 9.6.3 controls: Divide hourly lighting schedule by (1 + CF), where CF = sum of applicable control factors
Budget Building Design
(a) Complete system exists → Same as proposed
(b) System designed → Maximum LPD per Section 9.2; dwelling units = 6.5 W/m² (0.60 W/ft²)
(c) No system specified → Same as proposed
(d) Non-LPD-regulated fixtures → Identical to proposed
(e) Mandatory controls → Same as proposed
Note: Additional interior lighting power for non-mandatory controls (per Section 9.6.3) shall NOT be included in the budget building design.
Category 7: Thermal Blocks: HVAC Zones Designed
Thermal blocks are the zones used in the simulation. When HVAC zoning is designed, each HVAC zone becomes a thermal block (with some allowances for combining similar zones).
Rule: Each HVAC zone shall be modeled as a separate thermal block.
Zones may be combined into a single thermal block if ALL of the following are met:
Same space-use classification per Section 9.5.1 OR peak loads within ±10 Btu/h·ft² (±31 W/m²) of zone average
Adjacent to glazed exterior walls facing the same orientation (within 45°)
Served by the same HVAC system OR by HVAC systems of the same type
Operating schedules differ by no more than 40 equivalent full-load hours per week
Category 8: Thermal Blocks: HVAC Zones Not Designed
When HVAC zoning is not yet designed, create thermal blocks based on load characteristics and exposure. This ensures realistic zone behavior even before final HVAC design.
Define thermal blocks based on similar internal loads, occupancy, lighting, and schedules, PLUS:
(a) Interior vs. Perimeter:
Interior zones: More than 15 ft (4.6 m) from any exterior wall
Perimeter zones: Within 15 ft (4.6 m) of exterior wall
(b) Glazing Orientation:
Create separate perimeter zone for each major orientation (within 45°)
Include floor area within 15 ft (4.6 m) of glazed wall in that zone
(c) Ground Contact / Exposed Floors:
Zones with floor slabs on grade or over unconditioned space shall be separate from zones without these features
(d) Roof/Ceiling Exposure:
Zones with exterior ceilings or roofs shall be separate from zones without roof exposure
Category 9: Thermal Blocks: Multifamily Residential
Multifamily buildings have unique zoning requirements to capture the different exposures and load characteristics of individual dwelling units.
Minimum requirement: At least one thermal block per dwelling unit
Units with the same orientation may be combined
Corner units: May only be combined with other units sharing the same corner condition
Top floor units: May only be combined with other units having roof exposure
Ground floor units: May only be combined with other units having ground floor exposure
Category 10: HVAC Systems
HVAC system modeling differs significantly between proposed and budget. The budget system type is determined by a three-step process in Rule (j), not by copying the proposed system.
Proposed Design
(a) Complete HVAC system exists:
Model actual system type, capacities, and efficiencies
(b) System designed but not installed:
Model per design documents
Adjust equipment efficiencies to standard rating conditions per Section 6.4.1
Use manufacturer full-load and part-load performance data
Performance data shall NOT include supply fan power (model fans separately)
(c) No heating system specified:
Model as fossil fuel heating
Characteristics identical to budget building
(d) No cooling system specified:
Model as air-cooled single-zone system (one per thermal block)
Characteristics identical to budget building
Budget Building Design
System type and performance shall be determined from:
Figure 11.5.2 (system selection flowchart)
Table 11.5.2-1 (system descriptions)
Section 11.5.2 Rules (a) through (k)
Category 11: Service Water-Heating Systems
SWH modeling follows the proposed system type but uses minimum efficiency for the budget. Piping losses are not modeled in either case.
Proposed Design
(a) Complete SWH system exists:
Model actual system type, capacities, and efficiencies
(b) System designed:
Model per design documents
(c) No SWH system specified:
No service water heating shall be modeled
Piping losses: Shall NOT be modeled (in either proposed or budget)
Budget Building Design
System type: Identical to proposed
Performance: Minimum efficiency per Sections 7.4 and 7.5
Exceptions:
If proposed system type is not listed in Table 7.8, determine budget type from Table G3.1.1-2
If proposed uses combined space heating and water heating, budget shall model separate systems (boiler for space heating, water heater for SWH) each at minimum efficiency
For 24-hour facilities meeting Section 6.5.6.2 (condenser heat recovery potential), include condenser heat recovery in budget
Hot water consumption: Calculate explicitly based on fixture types, hot water volumes, entering water temperature, and leaving water temperature. Loads and usage patterns shall be identical for proposed and budget.
Category 12: Miscellaneous Loads
Miscellaneous loads (also called process loads or plug loads) must be identical in both models. This ensures the comparison focuses on regulated building systems.
Model receptacle, motor, and process loads based on building type and space use. These loads shall be identical in proposed and budget.
Include all of the following end-uses:
Exhaust fans not part of HVAC systems
Parking garage ventilation fans
Exterior building lighting (façade, grounds, parking)
Swimming pool heaters and circulation pumps
Elevators and escalators
Cooking and food preparation equipment
Refrigeration (display cases, walk-ins)
Laundry equipment
Medical and laboratory equipment
Modeling approach:
(a) Where Section 8 and 10 systems are designed: Model per Sections 8 and 10
(b) Where not designed: Model to comply with but not exceed applicable requirements
Category 13: Refrigeration
Commercial refrigeration (display cases, walk-in coolers/freezers) can be significant loads. AHRI 1200 provides standard rating procedures for these systems.
Proposed Design
Equipment rated per AHRI 1200: Model at AHRI-rated energy consumption
Equipment not rated per AHRI 1200: Model at actual capacities and efficiencies
Budget Building Design
Equipment listed in Table 6.8.1-13: Model per table requirements at actual capacities
Equipment NOT in Table 6.8.1-13: Model same as proposed
Category 14: Modeling Exceptions
Some building components may be excluded from modeling if they don't participate in trade-offs and meet prescriptive requirements. This simplifies complex models.
Proposed Design
All building elements shall be modeled per Categories 1-12.
Exception: Components may be excluded from both proposed and budget models if BOTH conditions are met:
The component's energy use does NOT affect the systems being considered for trade-off, AND
The component meets prescriptive requirements of Sections 5.5, 6.5, 7.5, and either 9.5 or 9.6
Budget Building Design
No additional exceptions beyond those in proposed design.
7. Section 11.5.2: HVAC System Rules (Rules a-k)
These rules specify exactly how to configure the budget building HVAC system. Rule (j) determines the system type; the other rules define specific parameters and performance requirements.
Rule (a): Budget Building Systems Not Listed
Any HVAC component not explicitly covered by Figure 11.5.2 or Table 11.5.2-2 should be modeled identically to the proposed design, unless mandatory/prescriptive requirements apply.
HVAC system components and parameters NOT listed in Figure 11.5.2 and Table 11.5.2-2 shall be modeled identical to the proposed design.
Exception: Where Sections 6.4 and 6.5 contain specific requirements for components, the budget building component efficiency shall be the lowest efficiency level allowed by those sections.
Rule (b): Minimum Equipment Efficiency
Budget equipment operates at code-minimum efficiency. For chillers, use Path A efficiencies which require meeting both full-load and IPLV requirements.
All HVAC equipment: Minimum efficiency (both full-load and part-load) per Section 6.4
All SWH equipment: Minimum efficiency per Section 7.4
Chillers: Use Path A efficiencies from Table 6.8.1-3
Rule (c): Supply Fan Energy in Certain Package Equipment
Some equipment ratings (EER, COP) include supply fan energy. These equations remove the fan energy so it can be modeled separately, ensuring accurate comparison.
Applies to Budget System Types: 3, 4, 6, 8, 9, 10, and 11
Where equipment efficiency ratings include supply fan energy, the efficiency shall be adjusted to remove supply fan energy using the following COPnf equations:
COPnf Equations
Capacity Basis for Efficiency Selection
6, 8, 10
Use 2.6 kW (9,000 Btu/h) for residential systems when zones are combined; otherwise use thermal block capacity ÷ number of zones
3, 4, 9, 11
Use single floor capacity when grouping identical floors
Fan modeling: Supply fans and return/relief fans shall be modeled as operating at least whenever the spaces served are occupied.
Rule (d): Minimum Outdoor Air Ventilation Rate
Ventilation rates must match between models to ensure fair comparison. Energy recovery requirements still apply to the budget building.
Outdoor air ventilation rates shall be the same for proposed and budget buildings.
Exhaust air energy recovery shall be modeled in the budget building per Section 6.5.6.1 requirements.
Exceptions:
Where the proposed design includes demand-controlled ventilation (DCV) for spaces where DCV is not required by Section 6.4.3.8, ventilation rates may differ between proposed and budget
Where the proposed design outdoor air rate exceeds the minimum required by Section 6.5.3.7, the budget building shall use the Section 6.5.3.7 minimum rate
Rule (e): Economizers
Budget economizers match the proposed type (air or water) but use standard high-limit shutoff settings from Table 11.5.2-4.
The budget building economizer shall be the same type (air economizer or water/fluid economizer) as the proposed design, per Section 6.5.1 requirements.
High-limit shutoff settings shall be per Table 11.5.2-4.
Rule (f): Preheat Coils
Where the proposed design includes preheat coils, the budget building shall also include preheat coils controlled in the same manner.
Rule (g): Supply Airflow Rates
Budget airflow is based on a standard temperature difference, ensuring consistent sizing methodology regardless of proposed design choices.
Budget building supply airflow shall be based on the largest of:
Supply-air-to-room temperature difference of 20°F (11°C), OR
Minimum outdoor airflow rate, OR
Code-required exhaust/makeup airflow rate
Where zones have multiple thermostat setpoints, use the design setpoint that yields:
The lowest supply air cooling setpoint, OR
The highest supply air heating setpoint
Return/relief fans: If included in proposed, budget shall be sized for:
Supply fan airflow minus minimum outdoor air, OR
90% of supply fan airflow
(Whichever is LARGER)
Exceptions:
Laboratory spaces: Use 17°F (9°C) supply-to-room temperature difference
Latent load-driven systems: Use the same humidity ratio difference as proposed
Rule (h): Fan System Efficiency
Fan power in the budget must not exceed prescriptive limits. If the proposed system exceeds limits, adjust proportionally.
Fan system efficiency shall equal the proposed design OR the Section 6.5.3.1 limit, whichever is smaller (more restrictive).
If the proposed design exceeds the Section 6.5.3.1 limit, reduce each fan's power proportionally to meet the limit.
Motor efficiency shall be adjusted to minimum efficiency per Section 10.4.1.
Rule (i): Equipment Capacities
Proper sizing ensures realistic simulation results. Unmet load hours indicate whether the equipment can meet the loads throughout the year.
Sizing: Equipment capacities shall be proportional to the proposed design based on sizing runs. The ratio of capacity to peak load shall be the same for both annual simulation and sizing runs, for both proposed and budget buildings.
Unmet load hours:
Maximum: ≤300 hours per year (out of 8760 total hours)
Proposed design unmet hours shall be ≤ budget building unmet hours
Exception: The building official may approve higher unmet load hours with adequate justification.
Rule (j): Determining the HVAC System — 3-Step Process
This is the critical rule for selecting budget HVAC systems. Follow all three steps in order to determine which of the 11 system types applies.
Step 1: Determine Condenser Type
Water-cooled chiller or cooling tower
Water
Evaporatively cooled equipment
Water
Air-cooled equipment
Air/None
Closed-circuit dry cooler
Air/None
District cooling
Water
No mechanical cooling
Air
No heat rejection equipment
Air
Ground-source or groundwater-source heat pump
→ Use System 6 directly
Step 2: Determine Heating Source
Electric resistance (including electric boilers)
Electric resistance
Air-source or water-source heat pump
Heat pump
Fuel-fired furnace or boiler
Fossil fuel
District heating
Fossil fuel
No heating system
Fossil fuel
Mixed fuel sources
Use primary source (largest capacity); model secondary source identical to proposed
Step 3: Determine System Category
Single-zone system serving residential spaces
Single-Zone Residential System
Single-zone system serving non-residential spaces
Single-Zone Nonresidential System
All other configurations (multi-zone, etc.)
All Other
Budget System Selection Matrix (Figure 11.5.2)
Water
Electric Resistance
System 5
System 5
System 1
Heat Pump
System 6
System 6
System 6
Fossil Fuel
System 7
System 7
System 2
Air/None
Electric Resistance
System 8
System 9
System 3
Heat Pump
System 8
System 9
System 3
Fossil Fuel
System 10
System 11
System 4
Rule (k): Kitchen Exhaust
Commercial kitchen hoods are major energy users. This rule requires demand ventilation in the budget to capture savings potential.
Applies to: Kitchens with total exhaust hood airflow greater than 5,000 cfm (2,400 L/s)
Budget building requirements:
Demand ventilation controls on 75% of total exhaust airflow
Reduce exhaust and makeup airflow by 50% for one-half of occupied hours
If proposed design uses demand ventilation, use the same schedule
Maximum hood exhaust rate per Section 6.5.7.2.2
8. Budget System Types & Complete Notes
This section provides complete specifications for all 11 budget system types, including detailed notes for configuring chillers, boilers, pumps, and controls.
Table 11.5.2-1: Budget System Descriptions (Complete)
1
VAV with parallel fan-powered boxes
VAV
Chilled water
Electric resistance
2
VAV with reheat
VAV
Chilled water
Hot-water fossil fuel boiler
3
Packaged VAV with parallel fan-powered boxes
VAV
Direct expansion
Electric resistance
4
Packaged VAV with reheat
VAV
Direct expansion
Hot-water fossil fuel boiler
5
Two-pipe fan coil
Single/two-speed
Chilled water
Electric resistance
6
Water-source heat pump
Single/two-speed
Direct expansion
Electric heat pump and boiler
7
Four-pipe fan coil
Single/two-speed
Chilled water
Hot-water fossil fuel boiler
8
Packaged terminal heat pump (PTHP)
Single-speed
Direct expansion
Electric heat pump
9
Packaged rooftop heat pump
Single/two-speed
Direct expansion
Electric heat pump
10
Packaged terminal air conditioner (PTAC)
Single-speed
Direct expansion
Hot-water fossil fuel boiler
11
Packaged rooftop air conditioner
Single/two-speed
Direct expansion
Fossil fuel furnace
Table 11.5.2-1 Complete Notes
Note (a): VAV Parallel Fan-Powered Boxes (Systems 1 and 3)
Fan-powered boxes supplement primary air with recirculated plenum air. These specifications ensure consistent modeling of zone terminal units.
Terminal unit fan size
50% of peak design primary airflow to the zone
Terminal unit fan power
0.35 W/cfm (0.74 W per L/s)
Minimum primary airflow
Equal to zone ventilation requirement per Exception 1(b) to Section 6.5.2.1
Supply air temperature
Constant at design condition
Note (b): VAV with Reheat (Systems 2 and 4)
Reheat systems use hot water coils at zone level. Minimum airflow settings significantly impact energy use.
Minimum airflow setpoint
Larger of: ventilation per ASHRAE 62.1 Simplified Procedure OR code/accreditation requirements
Supply air temperature reset
Reset UP by 5°F (2.8°C) under minimum cooling load conditions
Note (c): Direct Expansion Cooling (Systems 3, 4, 6, 8, 9, 10, 11)
Cooling fuel type shall match the proposed design (typically electricity).
Note (d): VAV Fan Control (Systems 1, 2, 3, 4)
Fan drive
Variable-speed drive required
Part-load performance
Per Table G3.1.3.15
Static pressure reset
If proposed has DDC at zone level, model static pressure reset per Section 6.5.3.2.3
Note (e): Chilled Water Systems (Systems 1, 2, 5, 7)
Complete specifications for central chilled water plants including chillers, pumps, and cooling towers.
Purchased chilled water
Use costs per Section 11.4.3
Number of chillers
Per Table 11.5.2-2
Chiller type
Per Table 11.5.2-3
CHW supply temperature
44°F (6.7°C)
CHW return temperature
56°F (13°C)
CHW supply temperature reset
Per Section 6.5.4.4
CHW pump power (if not designed)
22 W/gpm (349 kW per 1000 L/s) based on 75 ft head (23 m), 65% pump efficiency
Pump configuration
Primary-only variable flow with bypass valve
Variable-speed drive
Required when Section 6.5.4.2 applies
Cooling tower type
Open-circuit, axial-fan with VSD
Tower VSD
Required when Section 6.5.5 applies
CW approach temperature
Approach₅.₆°C Range = 10.02 - (0.24 × WB) where WB = 0.4% evaporation wet-bulb (°C); valid 55°F to 90°F (12.8°C to 32.2°C)
Tower control
Maintain leaving water temperature per Table 11.5.2-5, floating up to design temperature
CW pump power (if not designed)
19 W/gpm (301 kW per 1000 L/s) based on 60 ft head (18 m), 60% pump efficiency
Pump/chiller configuration
Each chiller has separate condenser water and chilled water pumps interlocked with associated chiller
Note (f): Fossil Fuel Boiler (Systems 2, 4, 7, 10)
Hot water boiler plant specifications for systems with hydronic heating.
Fuel type
Same as proposed design
Boiler draft
Natural draft
Number of boilers
≤600,000 Btu/h (176 kW): 1 boiler; >600,000 Btu/h: 2 equally-sized boilers
Boiler staging
As required by load
HW supply temperature
180°F (82°C)
HW return temperature
130°F (54°C)
HW supply temperature reset
Per Section 6.5.4.4
HW pump power (if not designed)
19 W/gpm (301 kW per 1000 L/s) based on 60 ft head (18 m), 60% pump efficiency
Pump configuration
Primary-only continuous variable flow
Variable-speed drive
Required when Section 6.5.4.2 applies
Note (g): Electric Heat Pump and Boiler (System 6)
Water-source heat pump loop specifications including the shared water loop, heat rejection, and supplemental heating.
Loop temperature range
60°F to 90°F (16°C to 32°C)
Heat rejection
Closed-circuit axial-fan evaporative fluid cooler
Fluid cooler fan control
Per Section 6.5.5.2
Heat addition
Boiler with same fuel as proposed; if no fuel specified, use fossil fuel
Boiler draft
Natural draft
Number of boilers
≤600,000 Btu/h (176 kW): 1 boiler; >600,000 Btu/h: 2 boilers
Boiler staging
As required by load
Loop pump power (if not designed)
22 W/gpm (349 kW per 1000 L/s) based on 75 ft head (23 m), 65% pump efficiency
Pump configuration
Variable flow with automatic shutoff at each heat pump per Section 6.5.4.5
Variable-speed drive
Required when Section 6.5.4.2 applies
Note (h): Electric Heat Pump (Systems 8 and 9)
Air-source heat pump specifications with electric backup heating staged appropriately for cold weather.
Heat pump type
Air-source with electric auxiliary heat
Thermostat
Multistage with outdoor air thermostat lockout
Auxiliary heat staging
Activates as last stage AND only when outdoor air temperature <40°F (4°C)
Note (i): Fan System Operation
Fan operation schedule shall be the same as the proposed design:
Continuous during occupied hours, OR
Cycling on call for heating or cooling
Note (j): Fan Speed Control
Budget building fans shall be one-speed or two-speed per Section 6.5.3.2 requirements, regardless of proposed design.
Table 11.5.2-2: Number of Chillers
≤300 tons (1,055 kW)
One chiller
>300 tons and <600 tons (1,055-2,110 kW)
Two chillers, sized equally
≥600 tons (2,110 kW)
Two minimum; add chillers so that no single chiller exceeds 800 tons (2,813 kW); all chillers sized equally
Table 11.5.2-3: Water Chiller Types
≤100 tons (352 kW)
Scroll or screw
Single-effect absorption, direct fired
>100 tons and <300 tons (352-1,055 kW)
Screw
Double-effect absorption, direct fired
≥300 tons (1,055 kW)
Centrifugal
Double-effect absorption, direct fired
Table 11.5.2-4: Economizer High-Limit Shutoff
Air economizer
Per Table 6.5.1.1.3
Fluid (water) economizer — integrated
Disable when operation will no longer reduce HVAC system energy use
Table 11.5.2-5: Heat-Rejection Leaving Water Temperature
5B, 5C, 6B, 8
65°F (18°C)
0B, 1B, 2B, 3B, 3C, 4B, 4C, 5A, 6A, 7
70°F (21°C)
3A, 4A
75°F (24°C)
0A, 1A, 2A
80°F (27°C)
Table G3.1.3.15: Part-Load Performance for VAV Fan Systems
This table specifies the relationship between fan airflow and fan power for variable-speed VAV systems. It represents a well-designed VSD curve.
0.00
0.00
0.60
0.41
0.10
0.03
0.70
0.54
0.20
0.07
0.80
0.68
0.30
0.13
0.90
0.83
0.40
0.21
1.00
1.00
0.50
0.30
9. Building Envelope Tables (Tables 5.5-0 through 5.5-8 Complete)
These tables provide the prescriptive envelope requirements that define the budget building's thermal characteristics. When using the ECB method, the budget building must use these exact U-factors and SHGC values based on climate zone. The proposed building can deviate from these values as long as the overall Design Energy Cost does not exceed the Energy Cost Budget.
How to Use These Tables
Determine your climate zone using ASHRAE Standard 169 or Appendix B maps
Identify building category: Nonresidential, Residential, or Semiheated
Apply values to budget model: Use these U-factors for opaque assemblies and fenestration
Remember: All U-factors are assembly U-factors including air films (except C-factors for below-grade walls)
Units and Notation
U
Overall heat transfer coefficient (includes air films)
Btu/(h·ft²·°F)
× 5.678 = W/(m²·K)
C
Thermal conductance (no air films, for below-grade)
Btu/(h·ft²·°F)
× 5.678 = W/(m²·K)
F
Slab-edge heat loss factor (perimeter-based)
Btu/(h·ft·°F)
× 1.731 = W/(m·K)
SHGC
Solar Heat Gain Coefficient (0-1 scale)
Dimensionless
No conversion
NR
No Requirement specified
—
—
WWR
Window-to-Wall Ratio
Percentage
—
Table 5.5-0: Climate Zone 0 (Extremely Hot — Humid/Dry)
Climate Zone 0 represents the most extreme hot climates (e.g., parts of Puerto Rico, US Virgin Islands, tropical locations). Cooling dominates energy use. Requirements focus on minimizing solar heat gain (low SHGC) while allowing more relaxed wall insulation requirements since heating loads are minimal. Roof insulation remains stringent due to intense solar radiation on horizontal surfaces.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.218
Metal Building
U-0.041
U-0.041
U-0.167
Attic and Other
U-0.027
U-0.027
U-0.081
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.580
U-0.580
U-0.580
Metal Building
U-0.094
U-0.094
U-0.352
Steel-Framed
U-0.124
U-0.064
U-0.352
Wood-Framed and Other
U-0.089
U-0.089
U-0.292
Walls, Below-Grade
Below-Grade Wall
C-1.140
C-1.140
C-1.140
Floors
Mass
U-0.322
U-0.322
U-0.322
Steel Joist
U-0.350
U-0.350
U-0.350
Wood-Framed and Other
U-0.282
U-0.282
U-0.282
Slab-On-Grade Floors
Unheated Slabs
F-0.73
F-0.73
F-0.73
Heated Slabs
F-0.900
F-0.900
F-0.900
Opaque Doors
Swinging
U-0.70
U-0.70
U-0.70
Nonswinging
U-0.50
U-0.50
U-1.45
Fenestration (Vertical Glazing, 0-40% WWR)
U-Factor (Fixed)
U-0.50
U-0.50
U-1.22
U-Factor (Operable)
U-0.65
U-0.65
U-1.22
SHGC (All Orientations)
0.25
0.25
0.40
Skylights (0-2% Roof Area)
U-Factor
U-0.75
U-0.75
U-1.98
SHGC
0.25
0.25
NR
Skylights (2.1-5% Roof Area)
U-Factor
U-0.75
U-0.75
U-1.98
SHGC
0.22
0.22
NR
Table 5.5-1: Climate Zone 1 (Very Hot — Humid/Dry)
Climate Zone 1 covers very hot locations like Miami, Honolulu, and South Florida. Similar to CZ 0, cooling is the dominant load. The 0.25 SHGC requirement for fenestration is very stringent, requiring high-performance solar control glazing. Mass walls have relaxed requirements (U-0.580 for nonresidential) because their thermal mass helps moderate temperature swings.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.218
Metal Building
U-0.041
U-0.041
U-0.167
Attic and Other
U-0.027
U-0.027
U-0.081
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.580
U-0.151
U-0.580
Metal Building
U-0.094
U-0.094
U-0.352
Steel-Framed
U-0.124
U-0.064
U-0.352
Wood-Framed and Other
U-0.089
U-0.089
U-0.292
Walls, Below-Grade
Below-Grade Wall
C-1.140
C-1.140
C-1.140
Floors
Mass
U-0.322
U-0.322
U-0.322
Steel Joist
U-0.350
U-0.350
U-0.350
Wood-Framed and Other
U-0.282
U-0.282
U-0.282
Slab-On-Grade Floors
Unheated Slabs
F-0.73
F-0.73
F-0.73
Heated Slabs
F-0.900
F-0.900
F-0.900
Opaque Doors
Swinging
U-0.70
U-0.70
U-0.70
Nonswinging
U-0.50
U-0.50
U-1.45
Fenestration (0-40% WWR)
U-Factor (Fixed)
U-0.50
U-0.50
U-1.22
U-Factor (Operable)
U-0.65
U-0.65
U-1.22
SHGC (All)
0.25
0.25
0.40
Skylights (0-2%)
U-Factor
U-0.75
U-0.75
U-1.98
SHGC
0.25
0.25
NR
Skylights (2.1-5%)
U-Factor
U-0.75
U-0.75
U-1.98
SHGC
0.22
0.22
NR
Table 5.5-2: Climate Zone 2 (Hot — Humid/Dry)
Climate Zone 2 includes cities like Houston, Phoenix, and Tampa. Cooling still dominates but heating becomes more significant. Wall insulation requirements begin to tighten (mass walls U-0.151 for nonresidential vs. U-0.580 in CZ 0-1). SHGC remains low at 0.25. This zone represents the transition where both envelope conductive losses and solar gains matter significantly.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.218
Metal Building
U-0.041
U-0.041
U-0.167
Attic and Other
U-0.027
U-0.027
U-0.081
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.151
U-0.123
U-0.580
Metal Building
U-0.094
U-0.084
U-0.352
Steel-Framed
U-0.084
U-0.064
U-0.352
Wood-Framed and Other
U-0.089
U-0.064
U-0.292
Walls, Below-Grade
Below-Grade Wall
C-1.140
C-1.140
C-1.140
Floors
Mass
U-0.322
U-0.087
U-0.322
Steel Joist
U-0.350
U-0.052
U-0.350
Wood-Framed and Other
U-0.282
U-0.051
U-0.282
Slab-On-Grade Floors
Unheated Slabs
F-0.73
F-0.73
F-0.73
Heated Slabs
F-0.900
F-0.900
F-0.900
Opaque Doors
Swinging
U-0.70
U-0.70
U-0.70
Nonswinging
U-0.50
U-0.50
U-1.45
Fenestration (0-40% WWR)
U-Factor (Fixed)
U-0.50
U-0.40
U-1.22
U-Factor (Operable)
U-0.65
U-0.55
U-1.22
SHGC (All)
0.25
0.25
0.40
Skylights (0-2%)
U-Factor
U-0.75
U-0.75
U-1.98
SHGC
0.25
0.25
NR
Skylights (2.1-5%)
U-Factor
U-0.75
U-0.75
U-1.98
SHGC
0.22
0.22
NR
Table 5.5-3: Climate Zone 3 (Warm — Humid/Dry/Marine)
Climate Zone 3 includes cities like Los Angeles (3B), Las Vegas (3B), Atlanta (3A), and San Francisco (3C marine). This mixed climate has meaningful heating and cooling loads. Wall requirements continue tightening. Note the SHGC requirement of 0.25 still applies to control cooling loads while fenestration U-factors remain moderate. CZ 3C (marine) has milder conditions with less extreme temperatures.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.173
Metal Building
U-0.041
U-0.041
U-0.097
Attic and Other
U-0.027
U-0.027
U-0.053
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.123
U-0.104
U-0.580
Metal Building
U-0.084
U-0.069
U-0.134
Steel-Framed
U-0.084
U-0.064
U-0.134
Wood-Framed and Other
U-0.089
U-0.064
U-0.089
Walls, Below-Grade
Below-Grade Wall
C-1.140
C-0.360
C-1.140
Floors
Mass
U-0.107
U-0.087
U-0.322
Steel Joist
U-0.069
U-0.052
U-0.350
Wood-Framed and Other
U-0.071
U-0.051
U-0.282
Slab-On-Grade Floors
Unheated Slabs
F-0.73
F-0.54
F-0.73
Heated Slabs
F-0.900
F-0.75
F-0.900
Opaque Doors
Swinging
U-0.70
U-0.50
U-0.70
Nonswinging
U-0.50
U-0.50
U-1.45
Fenestration (0-40% WWR)
U-Factor (Fixed)
U-0.46
U-0.35
U-0.83
U-Factor (Operable)
U-0.54
U-0.40
U-0.83
SHGC (All)
0.25
0.25
0.40
Skylights (0-2%)
U-Factor
U-0.65
U-0.55
U-1.17
SHGC
0.25
0.25
NR
Skylights (2.1-5%)
U-Factor
U-0.65
U-0.55
U-1.17
SHGC
0.22
0.22
NR
Table 5.5-4: Climate Zone 4 (Mixed — Humid/Dry/Marine)
Climate Zone 4 includes cities like New York (4A), Baltimore, Seattle (4C marine), and Albuquerque (4B). This is a true mixed climate where heating and cooling loads are roughly balanced. SHGC requirements relax to 0.38 in 4A and 0.40 in 4B/4C, allowing more solar gain for passive heating benefit. Window U-factors tighten significantly to U-0.38. This is often the transition point where double-pane low-e becomes necessary.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.119
Metal Building
U-0.041
U-0.041
U-0.065
Attic and Other
U-0.027
U-0.027
U-0.034
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.104
U-0.090
U-0.230
Metal Building
U-0.069
U-0.057
U-0.113
Steel-Framed
U-0.064
U-0.064
U-0.113
Wood-Framed and Other
U-0.064
U-0.064
U-0.089
Walls, Below-Grade
Below-Grade Wall
C-0.360
C-0.165
C-1.140
Floors
Mass
U-0.087
U-0.074
U-0.137
Steel Joist
U-0.052
U-0.038
U-0.069
Wood-Framed and Other
U-0.051
U-0.037
U-0.066
Slab-On-Grade Floors
Unheated Slabs
F-0.54
F-0.52
F-0.73
Heated Slabs
F-0.75
F-0.65
F-0.900
Opaque Doors
Swinging
U-0.50
U-0.50
U-0.70
Nonswinging
U-0.50
U-0.50
U-1.45
Fenestration (0-40% WWR)
U-Factor (Fixed)
U-0.38
U-0.32
U-0.55
U-Factor (Operable)
U-0.45
U-0.37
U-0.55
SHGC (4A)
0.38
0.38
0.40
SHGC (4B, 4C)
0.40
0.40
0.40
Skylights (0-2%)
U-Factor
U-0.55
U-0.50
U-0.98
SHGC
0.40
0.40
NR
Skylights (2.1-5%)
U-Factor
U-0.55
U-0.50
U-0.98
SHGC
0.35
0.35
NR
Table 5.5-5: Climate Zone 5 (Cool — Humid/Dry/Marine)
Climate Zone 5 includes cities like Chicago (5A), Denver (5B), and Portland OR (5C marine). Heating dominates but cooling remains significant. Wall insulation requirements tighten further (mass walls U-0.090). SHGC requirements are 0.38, balancing solar heat gain control with allowing passive heating. Below-grade wall insulation becomes more stringent. This zone often requires continuous exterior insulation on steel-framed walls.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.093
Metal Building
U-0.041
U-0.041
U-0.055
Attic and Other
U-0.027
U-0.027
U-0.027
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.090
U-0.080
U-0.151
Metal Building
U-0.057
U-0.052
U-0.079
Steel-Framed
U-0.064
U-0.055
U-0.090
Wood-Framed and Other
U-0.064
U-0.051
U-0.064
Walls, Below-Grade
Below-Grade Wall
C-0.165
C-0.119
C-0.580
Floors
Mass
U-0.074
U-0.064
U-0.107
Steel Joist
U-0.038
U-0.033
U-0.052
Wood-Framed and Other
U-0.037
U-0.033
U-0.051
Slab-On-Grade Floors
Unheated Slabs
F-0.52
F-0.51
F-0.58
Heated Slabs
F-0.65
F-0.58
F-0.75
Opaque Doors
Swinging
U-0.50
U-0.50
U-0.70
Nonswinging
U-0.50
U-0.50
U-0.50
Fenestration (0-40% WWR)
U-Factor (Fixed)
U-0.38
U-0.30
U-0.48
U-Factor (Operable)
U-0.45
U-0.35
U-0.48
SHGC (All)
0.38
0.38
0.40
Skylights (0-2%)
U-Factor
U-0.55
U-0.50
U-0.75
SHGC
0.40
0.40
NR
Skylights (2.1-5%)
U-Factor
U-0.55
U-0.50
U-0.75
SHGC
0.35
0.35
NR
Table 5.5-6: Climate Zone 6 (Cold — Humid/Dry)
Climate Zone 6 includes cities like Minneapolis (6A), Helena MT (6B), and Burlington VT. Heating is the primary load. Wall requirements become very stringent (mass walls U-0.080, steel-framed U-0.055). Fenestration U-factors drop to 0.36 for nonresidential, requiring high-performance double-pane or triple-pane glazing. SHGC relaxes to 0.38, allowing more solar gain for passive heating. Slab and below-grade insulation requirements increase significantly.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.063
Metal Building
U-0.041
U-0.039
U-0.049
Attic and Other
U-0.021
U-0.021
U-0.027
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.080
U-0.071
U-0.123
Metal Building
U-0.052
U-0.044
U-0.069
Steel-Framed
U-0.055
U-0.049
U-0.069
Wood-Framed and Other
U-0.051
U-0.051
U-0.064
Walls, Below-Grade
Below-Grade Wall
C-0.119
C-0.092
C-0.360
Floors
Mass
U-0.064
U-0.057
U-0.087
Steel Joist
U-0.033
U-0.033
U-0.038
Wood-Framed and Other
U-0.033
U-0.033
U-0.037
Slab-On-Grade Floors
Unheated Slabs
F-0.51
F-0.49
F-0.54
Heated Slabs
F-0.58
F-0.55
F-0.68
Opaque Doors
Swinging
U-0.50
U-0.50
U-0.50
Nonswinging
U-0.50
U-0.50
U-0.50
Fenestration (0-40% WWR)
U-Factor (Fixed)
U-0.36
U-0.27
U-0.42
U-Factor (Operable)
U-0.43
U-0.32
U-0.42
SHGC (All)
0.38
0.38
0.45
Skylights (0-2%)
U-Factor
U-0.55
U-0.50
U-0.65
SHGC
0.40
0.40
NR
Skylights (2.1-5%)
U-Factor
U-0.55
U-0.50
U-0.65
SHGC
0.35
0.35
NR
Table 5.5-7: Climate Zone 7 (Very Cold)
Climate Zone 7 includes cities like Duluth MN, Fargo ND, and parts of Alaska. Heating dominates almost entirely. Envelope requirements are very stringent across all components. Window U-factors drop to 0.33 for nonresidential (requiring triple-pane or very high-performance double-pane). SHGC increases to 0.40 to maximize passive solar heating. Slab perimeter insulation requirements are among the highest in the standard.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.048
Metal Building
U-0.035
U-0.035
U-0.041
Attic and Other
U-0.017
U-0.017
U-0.021
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.071
U-0.071
U-0.104
Metal Building
U-0.044
U-0.044
U-0.060
Steel-Framed
U-0.049
U-0.042
U-0.060
Wood-Framed and Other
U-0.042
U-0.042
U-0.051
Walls, Below-Grade
Below-Grade Wall
C-0.092
C-0.075
C-0.165
Floors
Mass
U-0.057
U-0.051
U-0.074
Steel Joist
U-0.032
U-0.032
U-0.038
Wood-Framed and Other
U-0.028
U-0.028
U-0.033
Slab-On-Grade Floors
Unheated Slabs
F-0.49
F-0.41
F-0.52
Heated Slabs
F-0.55
F-0.55
F-0.68
Opaque Doors
Swinging
U-0.50
U-0.37
U-0.50
Nonswinging
U-0.50
U-0.50
U-0.50
Fenestration (0-40% WWR)
U-Factor (Fixed)
U-0.33
U-0.27
U-0.40
U-Factor (Operable)
U-0.40
U-0.32
U-0.40
SHGC (All)
0.40
0.40
0.45
Skylights (0-2%)
U-Factor
U-0.50
U-0.50
U-0.58
SHGC
0.40
0.40
NR
Skylights (2.1-5%)
U-Factor
U-0.50
U-0.50
U-0.58
SHGC
0.35
0.35
NR
Table 5.5-8: Climate Zone 8 (Subarctic)
Climate Zone 8 represents the most extreme cold climates in the US (Fairbanks AK, northern Alaska). Heating is virtually the only concern. All envelope requirements are the most stringent in the standard. Windows require U-0.27 (triple-pane required for fixed, high-performance for operable). SHGC is highest at 0.40 to maximize any available solar heat gain. All opaque components require maximum insulation levels. Slab perimeter insulation is required at the highest level.
Roofs
Insulation Entirely Above Deck
U-0.048
U-0.048
U-0.048
Metal Building
U-0.035
U-0.035
U-0.041
Attic and Other
U-0.017
U-0.017
U-0.021
Walls, Above-Grade
Mass (HC > 7 Btu/ft²)
U-0.052
U-0.052
U-0.080
Metal Building
U-0.044
U-0.039
U-0.060
Steel-Framed
U-0.042
U-0.037
U-0.049
Wood-Framed and Other
U-0.036
U-0.036
U-0.051
Walls, Below-Grade
Below-Grade Wall
C-0.075
C-0.075
C-0.119
Floors
Mass
U-0.051
U-0.046
U-0.064
Steel Joist
U-0.032
U-0.032
U-0.038
Wood-Framed and Other
U-0.024
U-0.024
U-0.033
Slab-On-Grade Floors
Unheated Slabs
F-0.41
F-0.41
F-0.52
Heated Slabs
F-0.55
F-0.55
F-0.68
Opaque Doors
Swinging
U-0.37
U-0.37
U-0.50
Nonswinging
U-0.50
U-0.50
U-0.50
Fenestration (0-40% WWR)
U-Factor (Fixed)
U-0.27
U-0.27
U-0.40
U-Factor (Operable)
U-0.33
U-0.33
U-0.40
SHGC (All)
0.40
0.40
0.45
Skylights (0-2%)
U-Factor
U-0.50
U-0.50
U-0.58
SHGC
0.40
0.40
NR
Skylights (2.1-5%)
U-Factor
U-0.50
U-0.50
U-0.58
SHGC
0.35
0.35
NR
Envelope Requirements Summary
This summary shows key envelope values across all climate zones for quick reference. Note how requirements become progressively more stringent from CZ 0 (hot) to CZ 8 (cold).
Fenestration Area Limits (Section 5.5.4.2)
Vertical Fenestration
≤40% of gross above-grade wall area
If proposed exceeds, reduce budget proportionally
Skylights
≤5% of gross roof area
Or ≤3% for some building types
Key Trends Across Climate Zones
Mass Wall U
0.580
0.151-0.123
0.104-0.090
0.080-0.071
0.052
Steel Wall U
0.124
0.084
0.064-0.055
0.055-0.049
0.042
Fenest U (Fixed)
0.50
0.50-0.46
0.38
0.36-0.33
0.27
SHGC
0.25
0.25
0.38-0.40
0.38-0.40
0.40
Note: Values shown are for Nonresidential. Residential requirements are often more stringent, particularly for walls and fenestration U-factors.
10. HVAC Equipment Efficiency Tables
These tables provide minimum efficiency requirements for HVAC equipment. Budget building equipment must meet these efficiencies. For chillers, use Path A which requires meeting BOTH full-load and IPLV requirements.
Table 6.8.1-1: Unitary Air Conditioners and Condensing Units
Air Conditioners, Air Cooled
Split System
<65,000 Btu/h
All
SEER2 14.3 / EER2 11.7
AHRI 210/240
Single Package
<65,000 Btu/h
All
SEER2 13.4 / EER2 10.6
AHRI 210/240
Split/Single Pkg
≥65,000 and <135,000 Btu/h
Electric resistance or none
EER 11.0 / IEER 12.9
AHRI 340/360
Split/Single Pkg
≥65,000 and <135,000 Btu/h
All other
EER 10.8 / IEER 12.6
AHRI 340/360
Split/Single Pkg
≥135,000 and <240,000 Btu/h
Electric resistance or none
EER 10.6 / IEER 12.4
AHRI 340/360
Split/Single Pkg
≥135,000 and <240,000 Btu/h
All other
EER 10.4 / IEER 12.2
AHRI 340/360
Split/Single Pkg
≥240,000 and <760,000 Btu/h
Electric resistance or none
EER 9.8 / IEER 11.6
AHRI 340/360
Split/Single Pkg
≥240,000 and <760,000 Btu/h
All other
EER 9.6 / IEER 11.4
AHRI 340/360
Split/Single Pkg
≥760,000 Btu/h
Electric resistance or none
EER 9.5 / IEER 11.0
AHRI 340/360
Split/Single Pkg
≥760,000 Btu/h
All other
EER 9.3 / IEER 10.8
AHRI 340/360
Air Conditioners, Water Cooled
Split/Single Pkg
≥65,000 and <135,000 Btu/h
Electric resistance or none
EER 12.1 / IEER 14.5
AHRI 340/360
Split/Single Pkg
≥65,000 and <135,000 Btu/h
All other
EER 11.9 / IEER 14.3
AHRI 340/360
Split/Single Pkg
≥135,000 and <240,000 Btu/h
Electric resistance or none
EER 12.5 / IEER 14.5
AHRI 340/360
Split/Single Pkg
≥135,000 and <240,000 Btu/h
All other
EER 12.3 / IEER 14.3
AHRI 340/360
Split/Single Pkg
≥240,000 and <760,000 Btu/h
Electric resistance or none
EER 12.4 / IEER 14.2
AHRI 340/360
Split/Single Pkg
≥240,000 and <760,000 Btu/h
All other
EER 12.2 / IEER 14.0
AHRI 340/360
Split/Single Pkg
≥760,000 Btu/h
Electric resistance or none
EER 12.2 / IEER 13.8
AHRI 340/360
Split/Single Pkg
≥760,000 Btu/h
All other
EER 12.0 / IEER 13.6
AHRI 340/360
Condensing Units
Air Cooled
≥135,000 Btu/h
—
EER 10.5 / IEER 12.5
AHRI 365
Water/Evap Cooled
≥135,000 Btu/h
—
EER 13.5 / IEER 14.0
AHRI 365
Table 6.8.1-2: Unitary and Applied Heat Pumps
Air Cooled (Cooling Mode)
Split System
<65,000 Btu/h
All
SEER2 14.3 / EER2 11.7
—
Single Package
<65,000 Btu/h
All
SEER2 13.4 / EER2 10.6
—
Split/Single Pkg
≥65,000 and <135,000 Btu/h
Elec resist or none
EER 10.6 / IEER 12.1
—
Split/Single Pkg
≥65,000 and <135,000 Btu/h
All other
EER 10.4 / IEER 11.9
—
Split/Single Pkg
≥135,000 and <240,000 Btu/h
Elec resist or none
EER 10.1 / IEER 11.4
—
Split/Single Pkg
≥135,000 and <240,000 Btu/h
All other
EER 9.9 / IEER 11.2
—
Split/Single Pkg
≥240,000 Btu/h
Elec resist or none
EER 9.5 / IEER 10.9
—
Split/Single Pkg
≥240,000 Btu/h
All other
EER 9.3 / IEER 10.7
—
Air Cooled (Heating Mode — 47°F db/43°F wb outdoor)
Split System
<65,000 Btu/h
—
—
HSPF2 7.5
Single Package
<65,000 Btu/h
—
—
HSPF2 6.7
Split/Single Pkg
≥65,000 and <135,000 Btu/h
—
—
COP 3.3
Split/Single Pkg
≥135,000 Btu/h
—
—
COP 3.2
Water Source (86°F Entering Water Cooling / 68°F Heating)
Water Source HP
<135,000 Btu/h
—
EER 13.0
COP 4.3
Groundwater Source (59°F Entering Water Cooling / 50°F Heating)
Groundwater HP
<135,000 Btu/h
—
EER 18.0
COP 3.7
Ground Source Closed Loop (77°F Entering Cooling / 32°F Heating)
Ground Loop HP
<135,000 Btu/h
—
EER 14.1
COP 3.1
Table 6.8.1-3: Water Chilling Packages: Path A (for ECB)
For ECB compliance, use Path A efficiencies. Path A requires meeting BOTH full-load COP and IPLV COP. Path B (not shown) allows trade-off between full-load and part-load but is typically used for Appendix G.
Air-Cooled Chillers (with condenser)
Air Cooled
<150 tons
2.96
4.16
AHRI 551/591
Air Cooled
≥150 tons
2.96
4.21
AHRI 551/591
Air-Cooled Chillers (without condenser)
Air Cooled
All Capacities
3.16
4.50
AHRI 551/591
Water-Cooled Positive Displacement
Positive Displ
<75 tons
4.69
5.82
AHRI 551/591
Positive Displ
≥75 and <150 tons
4.90
5.96
AHRI 551/591
Positive Displ
≥150 and <300 tons
5.33
6.40
AHRI 551/591
Positive Displ
≥300 and <600 tons
5.59
6.81
AHRI 551/591
Positive Displ
≥600 tons
5.86
7.18
AHRI 551/591
Water-Cooled Centrifugal
Centrifugal
<150 tons
5.33
5.82
AHRI 551/591
Centrifugal
≥150 and <300 tons
5.59
5.96
AHRI 551/591
Centrifugal
≥300 and <400 tons
5.86
6.40
AHRI 551/591
Centrifugal
≥400 and <600 tons
5.86
6.61
AHRI 551/591
Centrifugal
≥600 tons
6.17
7.02
AHRI 551/591
Absorption Chillers
Single-Effect, Air Cooled
All
COP 0.55
NR
AHRI 560
Single-Effect, Water Cooled
All
COP 0.70
NR
AHRI 560
Double-Effect, Indirect Fired
All
COP 1.00
1.05
AHRI 560
Double-Effect, Direct Fired
All
COP 1.00
1.05
AHRI 560
Table 6.8.1-4: PTAC and PTHP Efficiency Equations
PTAC/PTHP efficiency varies by capacity. Use these equations to calculate the required efficiency for the specific equipment size.
7,000
11.9
11.9
3.34
9,000
11.3
11.3
3.23
12,000
10.4
10.4
3.08
15,000
9.5
9.5
2.92
Table 6.8.1-6: Warm-Air Furnaces
Warm-Air Furnace, Gas
All
AFUE 80%
10 CFR 430
Warm-Air Furnace, Oil
All
AFUE 83%
10 CFR 430
Warm-Air Unit Heater, Gas
All
Ec 80%
ANSI Z83.8
Warm-Air Unit Heater, Oil
All
Ec 80%
UL 731
Table 6.8.1-7: Gas- and Oil-Fired Boilers
Hot-Water Boilers
Gas-Fired
<300,000 Btu/h
AFUE 82%
10 CFR 430
Gas-Fired
≥300,000 and ≤2,500,000 Btu/h
Et 82%
10 CFR 431
Gas-Fired
>2,500,000 Btu/h
Ec 82%
10 CFR 431
Oil-Fired
<300,000 Btu/h
AFUE 84%
10 CFR 430
Oil-Fired
≥300,000 and ≤2,500,000 Btu/h
Et 84%
10 CFR 431
Oil-Fired
>2,500,000 Btu/h
Ec 84%
10 CFR 431
Steam Boilers
Gas-Fired
<300,000 Btu/h
AFUE 80%
10 CFR 430
Gas-Fired
≥300,000 and ≤2,500,000 Btu/h
Et 79%
10 CFR 431
Gas-Fired
>2,500,000 Btu/h
Et 79%
10 CFR 431
Oil-Fired
<300,000 Btu/h
AFUE 82%
10 CFR 430
Oil-Fired
≥300,000 and ≤2,500,000 Btu/h
Et 81%
10 CFR 431
Oil-Fired
>2,500,000 Btu/h
Et 81%
10 CFR 431
Table 6.8.1-7: Heat Rejection Equipment
Open-Circuit Cooling Towers
Open Circuit
Propeller/Axial
≥40.2 gpm/hp (6.03 L/s per kW)
CTI ATC-105/STD-201
Open Circuit
Centrifugal
≥20.0 gpm/hp (3.00 L/s per kW)
CTI ATC-105/STD-201
Closed-Circuit Cooling Towers
Closed Circuit
Propeller/Axial
≥16.1 gpm/hp (2.42 L/s per kW)
CTI ATC-105S/STD-201
Closed Circuit
Centrifugal
≥8.0 gpm/hp (1.20 L/s per kW)
CTI ATC-105S/STD-201
Evaporative Condensers
Evap Condenser
Propeller/Axial — Ammonia
≥160,000 Btu/h per hp (13.6 COP)
ASHRAE 64
Evap Condenser
Propeller/Axial — Other
≥135,000 Btu/h per hp (11.5 COP)
ASHRAE 64
Evap Condenser
Centrifugal — Ammonia
≥110,000 Btu/h per hp (9.4 COP)
ASHRAE 64
Evap Condenser
Centrifugal — Other
≥95,000 Btu/h per hp (8.1 COP)
ASHRAE 64
Air-Cooled Condensers and Dry Coolers
Air-Cooled Condenser
All
≥69,000 Btu/h per hp (5.9 COP)
AHRI 460
Dry Cooler
Propeller/Axial
≥14.0 gpm/hp (2.10 L/s per kW)
AHRI 410
Dry Cooler
Centrifugal
≥7.0 gpm/hp (1.05 L/s per kW)
AHRI 410
Table 10.8-1: Electric Motor Efficiency
These minimum motor efficiencies apply to general-purpose motors covered by Section 10.4.1. Budget building motors must meet these requirements.
1
85.5%
85.5%
40
94.1%
93.0%
1.5
86.5%
86.5%
50
94.1%
93.0%
2
86.5%
86.5%
60
94.5%
93.6%
3
89.5%
89.5%
75
94.5%
93.6%
5
89.5%
89.5%
100
95.0%
94.1%
7.5
91.7%
91.0%
125
95.0%
94.5%
10
91.7%
91.0%
150
95.4%
95.0%
15
92.4%
91.7%
200
95.4%
95.0%
20
93.0%
91.7%
250
95.4%
95.0%
25
93.6%
92.4%
300
95.4%
95.4%
30
93.6%
92.4%
500
95.8%
95.8%
11. Lighting Power Density Tables
Lighting is often the primary trade-off opportunity in ECB. These tables provide the maximum allowed lighting power density (LPD) for the budget building. The proposed building can use less than these values to offset other deficiencies.
Table 9.5.1: LPD Using Building Area Method (Complete)
Automotive Facility
0.75
8.1
Convention Center
0.64
6.9
Courthouse
0.79
8.5
Dining: Bar Lounge/Leisure
0.80
8.6
Dining: Cafeteria/Fast Food
0.76
8.2
Dining: Family
0.71
7.6
Dormitory
0.53
5.7
Exercise Center
0.72
7.8
Fire Station
0.56
6.0
Gymnasium
0.76
8.2
Health-Care Clinic
0.81
8.7
Hospital
0.96
10.3
Hotel/Motel
0.56
6.0
Library
0.83
8.9
Manufacturing Facility
0.82
8.8
Motion Picture Theater
0.44
4.7
Multifamily
0.51
5.5
Museum
0.55
5.9
Office
0.79
8.5
Parking Garage
0.15
1.6
Penitentiary
0.69
7.4
Performing Arts Theater
0.84
9.0
Police Station
0.66
7.1
Post Office
0.65
7.0
Religious Building
0.67
7.2
Retail
0.84
9.0
School/University
0.72
7.8
Sports Arena
0.76
8.2
Town Hall
0.69
7.4
Transportation
0.50
5.4
Warehouse
0.48
5.2
Workshop
0.91
9.8
Table 9.6.1: LPD Using Space-by-Space Method (Complete)
Common Space Types
Atrium — First 40 ft (12.2 m) in height
0.03 per ft
0.10 per m
Atrium — Above 40 ft (12.2 m) in height
0.02 per ft
0.07 per m
Audience/Seating Area — Permanent
0.63
6.8
Audience/Seating Area — Temporary
0.43
4.6
Banking Activity Area
0.61
6.6
Classroom/Lecture/Training
0.71
7.6
Conference/Meeting/Multipurpose
0.97
10.4
Copy/Print Room
0.31
3.3
Corridor
0.41
4.4
Courtroom
1.20
12.9
Computer Room
0.94
10.1
Dining Area
0.65
7.0
Electrical/Mechanical Room
0.43
4.6
Emergency Room
1.88
20.2
Enclosed Office
0.74
8.0
Exam/Treatment Room
1.40
15.1
Food Preparation
1.09
11.7
Guest Room
0.41
4.4
Laboratory — General
1.11
12.0
Laundry/Washing Area
0.53
5.7
Loading Dock — Interior
0.47
5.1
Lobby — Elevator
0.64
6.9
Lobby — Hotel
0.51
5.5
Lobby — Motion Picture Theater
0.23
2.5
Lobby — Office/General
0.84
9.0
Locker Room
0.52
5.6
Lounge/Breakroom
0.59
6.4
Nurse Station
0.87
9.4
Open Plan Office
0.61
6.6
Operating Room
1.89
20.3
Parking Area — Interior
0.15
1.6
Patient Room
0.62
6.7
Pharmacy Area
1.68
18.1
Physical Therapy Room
0.91
9.8
Recovery Room
1.15
12.4
Restroom
0.63
6.8
Sales Area
1.05
11.3
Stairwell
0.49
5.3
Storage
0.42
4.5
Waiting Area
0.54
5.8
Workshop
1.26
13.6
Retail Spaces
Dressing/Fitting Room
0.51
5.5
Mall Concourse
0.82
8.8
Industrial/Manufacturing
Detailed Manufacturing
0.80
8.6
Equipment Room
0.43
4.6
High Bay (>25 ft)
0.86
9.3
Low Bay (≤25 ft)
0.86
9.3
Table 9.6.3: Control Factors for Additional Lighting Power
When non-mandatory lighting controls are installed beyond code requirements, the lighting schedule is adjusted to account for their energy-saving effect. Divide the schedule by (1 + CF).
Manual continuous dimming + separate control of general and task lighting
0.05
Must control ≥50% of luminaires
Programmable multi-level dimming (≥3 levels)
0.05
—
Occupancy sensor + automatic continuous dimming — Daylit spaces
0.10
—
Occupancy sensor + automatic continuous dimming — Non-daylit spaces
0.05
—
Workstation-specific personal manual dimming
0.05
—
Workstation-specific occupancy sensor + automatic dimming
0.10
—
Usage: If control factor CF = 0.10, divide hourly lighting schedule values by (1 + 0.10) = 1.10
Table G3.7: Occupancy Sensor Reduction Factors (Complete)
For non-mandatory occupancy sensors, reduce the lighting schedule by (Reduction Factor × 0.25). This accounts for periods when spaces are unoccupied during scheduled operating hours.
Auditorium
0.10
Locker Room
0.45
Bank/Office — Banking Activity
0.10
Lounge/Breakroom
0.45
Classroom/Lecture/Training
0.30
Medical/Clinical Care
0.10
Computer Room
0.35
Museum
0.10
Conference/Meeting/Multipurpose
0.35
Office — Enclosed
0.30
Convention Center
0.35
Office — Open Plan
0.15
Copy/Print Room
0.30
Parking Garage Area
0.15
Corridor
0.25
Pharmacy Area
0.05
Courtroom
0.15
Police/Fire Station
0.10
Dining Area
0.35
Post Office — Sorting Area
0.05
Electrical/Mechanical
0.45
Religious Building
0.15
Emergency Room
0.10
Restroom
0.45
Exam/Treatment Room
0.20
Retail Sales Area
0.15
Food Preparation
0.05
Stairwell
0.75
Gymnasium/Exercise Center
0.25
Storage
0.45
Hospital Corridor
0.20
Transportation (Air/Train/Bus)
0.15
Hospital Patient Room
0.45
Waiting Area
0.20
Hotel Guest Room
0.45
Warehouse — Bulk Storage
0.45
Laboratory
0.25
Warehouse — Fine Material
0.30
Library
0.35
Workshop
0.20
Lobby
0.30
All Other
0.10
Usage: For enclosed office (factor = 0.30), reduce lighting schedule by 0.30 × 0.25 = 0.075 (7.5%)
12. Service Water Heating Tables
Service water heating efficiency requirements apply to the budget building. The proposed building may have better efficiency for trade-off purposes.
Table 7.8: Service Water Heating Equipment Efficiency (Complete)
Electric Storage Water Heaters
Electric Storage
≤12 gal (45 L)
—
UEF ≥ 0.93
10 CFR 430
Electric Storage
>12 gal and ≤55 gal
—
UEF ≥ 0.95 – (0.00035 × V)
10 CFR 430
Electric Storage
>55 gal and ≤100 gal
—
UEF ≥ 2.06 – (0.0061 × V)
10 CFR 430
Electric Storage
>100 gal
—
SL ≤ 0.8 + (27/Vm)
ASHRAE 90.1
Gas Storage Water Heaters
Gas Storage
≤75,000 Btu/h
≤55 gal
UEF ≥ 0.64 – (0.0009 × V)
10 CFR 430
Gas Storage
≤75,000 Btu/h
>55 gal and ≤100 gal
UEF ≥ 0.78 – (0.0018 × V)
10 CFR 430
Gas Storage
>75,000 Btu/h
<4,000 Btu/h·gal
Et ≥ 80%; SL ≤ (Q/800 + 110√V)
ANSI Z21.10.3
Gas Storage
>75,000 Btu/h
≥4,000 Btu/h·gal
Et ≥ 80%; SL ≤ (Q/800 + 110√V)
ANSI Z21.10.3
Oil Storage Water Heaters
Oil Storage
≤105,000 Btu/h
≤50 gal
UEF ≥ 0.60 – (0.0006 × V)
10 CFR 430
Oil Storage
>105,000 Btu/h
<4,000 Btu/h·gal
Et ≥ 78%; SL ≤ (Q/800 + 110√V)
UL 732
Oil Storage
>105,000 Btu/h
≥4,000 Btu/h·gal
Et ≥ 80%; SL ≤ (Q/800 + 110√V)
UL 732
Instantaneous Water Heaters
Electric Instant
<12 kW
—
UEF ≥ 0.91
10 CFR 430
Electric Instant
≥12 kW
—
Et ≥ 99%
ANSI Z21.10.3
Gas Instantaneous
<200,000 Btu/h
—
UEF ≥ 0.82
10 CFR 430
Gas Instantaneous
≥200,000 Btu/h
—
Et ≥ 80%
ANSI Z21.10.3
Hot-Water Supply Boilers
HW Supply Boiler, Gas
≥300,000 Btu/h and ≤12,500,000 Btu/h
—
Et ≥ 80%
AHRI 1500
HW Supply Boiler, Oil
≥300,000 Btu/h and ≤12,500,000 Btu/h
—
Et ≥ 80%
AHRI 1500
Pool Heaters
Pool Heater, Gas
All Sizes
—
Et ≥ 82%
AHRI 146
Pool Heater, Oil
All Sizes
—
Et ≥ 78%
AHRI 146
Pool Heater, Heat Pump
All Sizes
—
COP ≥ 4.0
AHRI 1160
Heat Pump Water Heaters
Heat Pump WH
≤24 amps and ≤250 volts
—
UEF ≥ 2.20
10 CFR 430
Heat Pump WH
>24 amps or >250 volts
—
COP ≥ 2.2
AHRI 1200
Variable Definitions:
V = Rated storage volume (gallons)
Vm = Measured storage volume (gallons)
Q = Nameplate input rate (Btu/h)
UEF = Uniform Energy Factor
Et = Thermal efficiency (%)
SL = Standby loss (Btu/h for electric; %/h for gas/oil)
Table G3.1.1-2: Baseline Service Water Heating System
When the proposed SWH system type is not in Table 7.8, use this table to determine the budget building SWH configuration.
Assembly
Storage water heater
Electric
Education
Storage water heater
Gas
Food Service — Fast Food
Instantaneous water heater
Gas
Food Service — Full Service
Instantaneous water heater
Gas
Grocery Store
Instantaneous water heater
Gas
Healthcare — Hospital
Instantaneous water heater
Gas
Healthcare — Outpatient
Storage water heater
Gas
Hotel/Motel (≤150 rooms)
Storage water heater
Gas
Hotel/Motel (>150 rooms)
Instantaneous water heater
Gas
Manufacturing/Industrial
Storage water heater
Gas
Multifamily Residential — Common Areas
Instantaneous water heater
Gas
Office
Storage water heater
Electric
Public Order and Safety
Storage water heater
Gas
Religious Worship
Storage water heater
Gas
Residential Dwelling Units
Per proposed fuel type
Per proposed
Retail — Stand Alone
Storage water heater
Electric
Retail — Strip Mall
Storage water heater
Electric
School — Primary/Secondary
Storage water heater
Gas
School — University
Storage water heater
Gas
Warehouse (nonrefrigerated)
Storage water heater
Electric
13. Fan Power & Economizer Tables
Fan power limits and economizer requirements are mandatory provisions. The budget building must comply with these requirements, and the proposed building fan power affects simulation results.
Table 6.5.3.1-1: Fan Power Limitation
Constant Volume
0.40
0.85
Variable Volume
0.50
1.06
Table 6.5.3.1-2: Fan Power Pressure Drop Adjustments (Complete)
These adjustments increase the allowable fan power when specific components add pressure drop to the system. Calculate total allowable fan power by adding applicable adjustments to the base limit.
Credits (Reduce Allowable Fan Power)
No central cooling coil in system
-0.70
-0.0625
No central heating coil in system
-0.40
-0.0358
Return/Exhaust Air Systems
Ducted return required by code/accreditation
+0.50
+0.0447
Exhaust system required by code/accreditation
+0.25
+0.0224
Filtration
Particulate filtration MERV 9 through 12
+0.30
+0.0268
Particulate filtration MERV 13 through 15
+0.60
+0.0536
Particulate filtration MERV 16 and greater
+0.80
+0.0715
Carbon or other gas-phase air cleaning
+0.80
+0.0715
Biosafety cabinet
+0.40
+0.0358
Energy Recovery
Energy recovery device ≥75% sensible effectiveness
+0.70
+0.0626
Energy recovery device ≥60% and <75% sensible eff.
+0.50
+0.0447
Sound Attenuation
Sound attenuation section (fans serving NC ≤ 35)
+0.15
+0.0134
Laboratory/Specialty Exhaust
Exhaust system for fume hoods with final filters
+0.80
+0.0715
Exhaust system serving laboratory or vivarium
+0.35
+0.0313
Other
Evaporative humidifier or cooler in series with coil
+0.40
+0.0358
Dehumidification coil in series with cooling coil
+0.50
+0.0447
Fully ducted supply and return systems
+0.20
+0.0179
Table 6.5.1.1.3: Economizer High-Limit Shutoff (Complete)
High-limit shutoff determines when the economizer disables and the system switches to mechanical cooling. Different control strategies are appropriate for different climate zones.
0A, 0B
NR
NR
NR
NR
1A
75°F (24°C)
NR
28 Btu/lb (65 kJ/kg)
NR
1B
75°F (24°C)
OA < RA
28 Btu/lb
NR
2A
75°F (24°C)
NR
28 Btu/lb
OA < RA
2B
75°F (24°C)
OA < RA
28 Btu/lb
NR
3A
75°F (24°C)
NR
28 Btu/lb
OA < RA
3B, 3C
75°F (24°C)
OA < RA
28 Btu/lb
NR
4A
70°F (21°C)
NR
25 Btu/lb (58 kJ/kg)
OA < RA
4B, 4C
75°F (24°C)
OA < RA
28 Btu/lb
NR
5A
70°F (21°C)
OA < RA
25 Btu/lb
OA < RA
5B, 5C
75°F (24°C)
OA < RA
28 Btu/lb
NR
6A
70°F (21°C)
OA < RA
25 Btu/lb
OA < RA
6B
75°F (24°C)
OA < RA
28 Btu/lb
NR
7, 8
75°F (24°C)
OA < RA
28 Btu/lb
NR
Notes:
OA < RA = Outside air temperature is less than return air temperature
NR = Not Recommended for this climate zone
Table 6.5.1.1: Economizer Requirements
0A, 0B, 1A, 1B
No
—
2A, 2B
Yes
≥65,000 Btu/h (19 kW)
3A, 3B, 3C
Yes
≥54,000 Btu/h (16 kW)
4A, 4B, 4C
Yes
≥54,000 Btu/h (16 kW)
5A, 5B, 5C
Yes
≥54,000 Btu/h (16 kW)
6A, 6B
Yes
≥54,000 Btu/h (16 kW)
7
Yes
≥54,000 Btu/h (16 kW)
8
Yes
≥54,000 Btu/h (16 kW)
Table 6.5.6.1: Exhaust Air Energy Recovery Requirements (Excerpt)
Energy recovery is required when systems exceed certain size and outdoor air thresholds. This table shows minimum design supply fan airflow requiring energy recovery.
0A, 0B, 1B
NR
NR
NR
NR
NR
NR
1A
NR
NR
NR
NR
NR
≥1,000 cfm
2A
NR
NR
NR
NR
≥5,500 cfm
≥1,500 cfm
3A
NR
NR
NR
≥5,500 cfm
≥2,000 cfm
≥1,000 cfm
4A
NR
NR
≥5,500 cfm
≥2,000 cfm
≥1,000 cfm
≥500 cfm
5A
NR
≥5,500 cfm
≥2,500 cfm
≥1,000 cfm
≥500 cfm
≥0 cfm
6A
NR
≥4,500 cfm
≥2,000 cfm
≥1,000 cfm
≥0 cfm
≥0 cfm
7
NR
≥2,500 cfm
≥1,000 cfm
≥500 cfm
≥0 cfm
≥0 cfm
8
≥2,500 cfm
≥1,000 cfm
≥0 cfm
≥0 cfm
≥0 cfm
≥0 cfm
Notes: NR = Not Required; ≥0 cfm = Required for all systems; Energy recovery effectiveness ≥50% sensible or enthalpy
14. Piping & Duct Insulation Tables
Piping and duct insulation are mandatory requirements. These tables specify minimum insulation thickness based on pipe size, fluid temperature, and duct location.
Table 6.8.3-1: Piping Insulation Thickness (Complete)
Heating Systems (Hot Water, Steam, Steam Condensate)
>350
250
2.5"
3.0"
3.5"
3.5"
3.5"
251-350
200
2.0"
2.5"
2.5"
3.0"
3.0"
201-250
150
1.5"
2.0"
2.0"
2.5"
2.5"
141-200
125
1.0"
1.5"
1.5"
1.5"
1.5"
105-140
100
0.5"
1.0"
1.0"
1.0"
1.0"
Cooling Systems (Chilled Water, Refrigerant, Brine)
40-55
75
0.5"
0.5"
1.0"
1.0"
1.0"
<40
75
1.0"
1.0"
1.5"
1.5"
1.5"
Notes:
Insulation thickness shown in inches
For piping exposed to outdoor conditions, increase thickness by 0.5 inches
Conductivity range: 0.22-0.28 Btu·in./(h·ft²·°F) at mean temperature
Table 6.8.2-1: Minimum Duct Insulation R-Value
Exterior
Ventilated Attic
Unconditioned Space
Exterior
Other
1-2
R-6
R-8
R-4
R-4
None
3-4
R-6
R-8
R-6
R-4
None
5-8
R-8
R-8
R-8
R-6
R-4
15. Submittal Requirements (Section 11.7)
Documentation requirements are essential for permit approval. Section 11.7 specifies exactly what must be submitted for permit application and upon project completion.
11.7.1 — General Requirements
Compliance documentation per Section 4.2.2:
4.2.2.1
Construction documents including all pertinent data and features in sufficient detail for plan review
4.2.2.2
Supplemental information including calculations, worksheets, compliance forms, manufacturer literature
4.2.2.3
Operating and maintenance manuals per Sections 5.7.3.2, 6.7.3.2, 7.7.3.2, 8.7.3.2, 9.7.3.2, 10.7.3.2
11.7.2 — Permit Application Documentation (15 Required Items)
(a)
Energy Cost Results
ECB for budget building AND DEC for proposed design
(b)
Simulation Program
Program name AND version number
(c)
Project Overview
Number of stories (above/below grade), typical floor size, building uses, gross area of each use, whether spaces are conditioned
(d)
Energy Feature List
All energy-related features; document ALL features that differ between ECB and DEC
(e)
Mandatory Compliance
Demonstration of compliance with Sections 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4
(f)
Building Drawings
Elevations AND floor plans
(g)
Thermal Block Diagram
Diagram showing thermal blocks used in simulation
(h)
Modeling Assumptions
Explanation of significant modeling assumptions
(i)
Backup Calculations
U-factors, NFRC ratings, end uses per Table 11.5.1 Category 1(a)
(j)
Simulation Reports
Input AND output reports; energy breakdown by end-use; unmet load hours for BOTH models
(k)
Energy Rates
Purchased energy rates used in simulation
(l)
Error Messages
Explanation of any error or warning messages from simulation
(m)
Exceptional Calculations
If used: predicted energy savings, cost savings, narrative description, theoretical/empirical support
(n)
Renewable Energy
DEC reduction from on-site renewable energy systems
(o)
Standard 140 Compliance
Software version AND link to ASHRAE Standard 140 test results
11.7.3: Completion Requirements (Within 90 Days of Occupancy)
5.7.3
Envelope
Air leakage verification; insulation documentation; O&M manuals
6.7.3
HVAC
Equipment location and performance; duct and pipe configuration with sizes; terminal flow rates; O&M manuals; service agency contacts; control sequences and setpoints; system balancing report (zones >5,000 ft² / 460 m²)
7.7.3
SWH
Record documents and manuals per industry standards
8.7.3
Power
Record documents and manuals per industry standards
9.7.3
Lighting
Record documents and manuals per industry standards
10.7.3
Other Equipment
Record documents and manuals per industry standards
16. Compliance Checklists
Use these checklists to ensure all requirements are addressed during the ECB compliance process. Check off each item as it is completed.
Pre-Modeling Checklist
☐ ECB method appropriate for project type verified
☐ AHJ acceptance of ECB compliance path confirmed
☐ Approved simulation software obtained (Standard 140 tested)
☐ TMY climate data gathered for project location
☐ Utility rate schedules obtained from local utilities
☐ Design documents compiled (architectural, mechanical, electrical, plumbing)
☐ Climate zone identified per Appendix B or IECC
Mandatory Requirements Checklist
☐ Section 5.4 envelope mandatory provisions met (insulation, fenestration ratings, air leakage, vestibules)
☐ Section 6.4 HVAC mandatory provisions met (equipment efficiency, controls, DCV)
☐ Section 6.5 or 6.6 HVAC prescriptive requirements met
☐ Section 7.4 SWH mandatory provisions met (efficiency, piping insulation, heat traps)
☐ Section 8.4 power mandatory provisions met (voltage drop, receptacle control, monitoring)
☐ Section 9.4 lighting mandatory provisions met (controls, tandem wiring, exit signs)
☐ Section 10.4 other equipment mandatory met (motor efficiency, elevators, escalators)
Model Development Checklist
☐ Proposed model reflects design documents for envelope, lighting, HVAC, SWH
☐ All conditioned spaces modeled as BOTH heated AND cooled
☐ Temperature and humidity schedules identical in proposed and budget
☐ Envelope modeled per drawings; budget using prescriptive values from Tables 5.5-0 to 5.5-8
☐ Lighting power calculated correctly; budget at maximum LPD per Section 9.2
☐ Thermal blocks properly defined per Categories 7-9
☐ Proposed HVAC mapped to correct budget system type per Rule (j)
☐ SWH modeled correctly; budget at minimum efficiency per Table 7.8
☐ Miscellaneous loads identical in proposed and budget
☐ Fan power within limits per Table 6.5.3.1-1 (with adjustments from 6.5.3.1-2)
☐ Economizers modeled per Section 6.5.1 requirements
Results Verification Checklist
☐ DEC ≤ ECB (primary compliance criterion)
☐ Unmet load hours ≤ 300 for both proposed and budget models
☐ Proposed unmet load hours ≤ budget unmet load hours
☐ No simulation errors; all warnings explained
☐ Energy end-use breakdown is reasonable and documented
☐ Results reviewed for reasonableness (comparison to similar buildings)
Documentation Checklist (15 Items per Section 11.7.2)
☐ (a) Energy cost results — DEC and ECB values
☐ (b) Simulation program — Name and version
☐ (c) Project overview — Building description and spaces
☐ (d) Energy feature list — All features, noting differences between models
☐ (e) Mandatory compliance — Demonstration for all sections
☐ (f) Building drawings — Elevations and floor plans
☐ (g) Thermal block diagram — Zone layout for simulation
☐ (h) Modeling assumptions — Key assumptions documented
☐ (i) Backup calculations — U-factors, ratings, end uses
☐ (j) Simulation reports — Input/output with energy breakdown and unmet hours
☐ (k) Energy rates — Utility rate schedules used
☐ (l) Error messages — Explanations for any errors/warnings
☐ (m) Exceptional calculations — If applicable
☐ (n) Renewable energy — If applicable
☐ (o) Standard 140 compliance — Version and test results link
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