Energy Modeling

Applications & Benefits

Accurate load calculations are fundamental for sizing HVAC systems and ensuring optimal performance. They account for design temperatures, building envelope, internal heat gains, and ventilation requirements.

Building energy modeling complements load calculations by simulating real-world building performance, guiding design decisions related to energy efficiency, costs, sustainability, and compliance.

Energy modeling supports both new construction and retrofit projects by enabling:

Code compliance
High-performance building design
Qualification for tax credits and utility incentives
Identification of energy-saving opportunities

To achieve precise load calculations, energy modeling, and compliance with energy efficiency standards, rely on reputable software rather than hand calculations or rule-of-thumb estimates.

Software

HVAC load calculation: Cool Calc Manual J, Elite CHVAC, Wrightsoft Right-Suite Universal, Trane TRACE 700 / TRACE 3D Plus, Carrier HAP
Energy modeling & compliance: EnergyPro, EnergyPlus, eQUEST, CBECC-Com / CBECC-Res, COMcheck – ASHRAE 90.1 / IECC code compliance
Specialized analysis: DOE-2 – Energy simulation engine, AIRMaster+ – Compressed air system analysis (DOE tool)

Industry Standards & Guidelines

ACCA Manuals

Manual J – Residential load calculations
Manual S – Residential equipment selection
Manual D – Residential duct design
Manual N – Commercial load calculations
Manual Q – Commercial duct design
Manual T – Air distribution
Manual P – Psychometrics

SMACNA Standards

Best practices for ductwork design, fabrication, and installation

ASHRAE Standards

ASHRAE 90.1 – Energy Standard for Buildings Except Low-Rise Residential Buildings
ASHRAE 62.1 – Ventilation for Acceptable Indoor Air Quality
ASHRAE 55-2023 – Thermal Environmental Conditions for Human Occupancy

California-Specific Resources

California Building Standards Code (CBSC) / Title 24
- Part 6 – California Energy Code (CEC):
- Part 11 – California Green Building Standards Code (CALGreen): A voluntary code promoting higher sustainability and energy efficiency.
Energy Code Ace

Regulatory Codes & Energy Compliance

CEC: Energy efficiency for building systems, including envelope, HVAC, lighting, and water heating

IECC: International Energy Conservation Code for residential and commercial energy compliance

DOE Regulations: Federal energy use and performance standards

Energy Code Ace: Compliance support platform for California Title 24 documentation and reporting

California-Specific Energy Compliance

Title 24 – California Building Standards Code (CBSC)

Part 6: California Energy Code – Establishes mandatory minimum energy efficiency standards for buildings, covering lighting, building envelope, HVAC, and water heating systems.
Part 11 – California Green Building Standards Code (CALGreen): A voluntary code promoting higher sustainability and energy efficiency.

Energy Code Ace – Online resource for California energy code guidance and compliance.

Compliance methods:

Prescriptive path: Rule-based, most commonly used
Performance path: Flexible, simulation-based for design trade-offs

Documentation:

CF1R-Pre or CF1R-Perf forms (R = residential)

Note: Title 24 compliance is not always required for mechanical or plumbing replacements classified as repairs rather than alterations.

CALGreen (Part 11 of Title 24)

CALGreen promotes sustainable building practices, focusing on:

Energy and water efficiency
Indoor environmental quality
Material/resource conservation
Waste reduction and recycling