ASHRAE 90.1 Baseline Envelope Requirements Tool
Determine the Maximum U-Factors, C-Factors, and F-Factors for Opaque Assemblies in accordance with ASHRAE Standard 90.1-2010.
This guide and interactive tool outlines the necessary inputs and criteria for establishing Baseline Maximum U-Factors, C-Factors, and F-Factors for Opaque Assemblies, as required for the Performance Rating Method (Appendix G) or the Prescriptive Path (Section 5).
1. Interactive Selection Wizard
To retrieve the specific baseline thermal performance values, select your Climate Zone, Space-Conditioning Category, and the specific Opaque Assembly Type below.
ASHRAE 90.1 Envelope Calculator
Baseline Maximum U-Factors, C-Factors, and F-Factors (SI Units) per Tables 5.5-1 to 5.5-8.
Assessment Parameters
Result Table
Zone 4A / Non-ResOpaque Assemblies
Fenestration
Quick Thermal Converter
Utilities for calculating effective assembly performance
U-Factor ↔ R-ValueFilms=0.15
Below-Grade Wall (Effective U)
Slab F-Factor Estimator
What is a "Semiheated" Space?
A Semiheated Space is an enclosed space within a building that is heated by a system with an output capacity ≥ 10 W/m² but is not fully conditioned (i.e., falls below the capacity criteria for conditioned spaces). Examples include storage areas, mechanical rooms, or ventilated parking garage entrances requiring minimal freeze protection but not full thermal comfort.
2. Baseline Fenestration Limits
Baseline fenestration areas for new construction must generally be modeled at the proposed area or 40% of the gross wall area (Vertical) or 5% of the gross roof area (Skylight), whichever is smaller.
- Vertical Glazing (Metal Framing): Used for Curtain Walls, Storefronts.
- Vertical Glazing (Nonmetal): Vinyl, Wood, Fiberglass frames.
- Skylight (Glass w/ Curb): Standard baseline assumption for roof glazing.
*Note: Visible Transmittance (VT) for baseline models is typically derived from the SHGC or defaulted to table values (e.g., 0.19-0.76) depending on the assembly.