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CBE Thermal Comfort Tool

Free web-based thermal comfort calculations per ASHRAE, ISO, and EN standards

Open-source web application for calculating and visualizing thermal comfort indices according to ASHRAE 55-2023, ISO 7730:2005, and EN 16798-1:2022 standards. Supports PMV/PPD calculations, adaptive comfort models, and advanced features like SolarCal, dynamic clothing, and elevated airspeed methods.

EstablishedOpen Source (GPL-3.0)
Founded 1997 · ~50,000 annual users worldwide (engineers, architects, researchers, educators, facility managers, policymakers)
Website →← All Tools
WHY IT EXISTS

Why This Tool Exists

The Problem

Design teams struggle to evaluate occupant thermal comfort throughout the design process, requiring manual calculations or expensive proprietary software. There is no accessible tool for architects and engineers to quickly compare comfort scenarios, visualize comfort boundaries, or validate design against industry standards.

The Solution

Provides a free, open-source web interface for thermal comfort calculations following ASHRAE, ISO, and EN standards. Allows users to input environmental conditions and occupant variables, instantly visualizing comfort zones on psychrometric charts and comparing design scenarios. Supports batch uploads for annual simulations and exceedance analysis.

USAGE

How You Use It

Delivery Method
SaaSWeb ApplicationOpen Source
Disciplines
Architecture, Mep Engineering, Sustainability
Workflows
Practice & Business Development
Project Phases
Design Development, Construction Documentation
Project Types
Commercial, Residential, Healthcare, Education, Industrial, Mixed-Use, Institutional
TRANSPARENCY

Data Transparency

Exactly what this tool uses and how

Input
What it needs
Required:Air temperature, Mean radiant temperature, Relative humidity, Metabolic rate, Clothing level
Optional:Air velocity, Operative temperature, Local air temperature, Globe temperature, Project schedule data, Building simulation data
Formats:Web form input, CSV upload for batch calculations, Time-series data (.csv), Building simulation outputs
Output
What you get
Format:Thermal comfort metrics and interactive visualizations
Fields:PMV (Predicted Mean Vote), PPD (Predicted Percentage Dissatisfied), SET (Standard Effective Temperature), CE (Clothing Equivalent), Thermal sensation scale, Acceptability limits per standard, Exceedance percentages (annual/seasonal), Comfort zone boundaries on psychrometric chart
Algorithm
How it works
Model:ASHRAE 55-2023, ISO 7730:2005, and EN 16798-1:2022 standard models
Accuracy:Based on validated standard models; accuracy depends on input data quality and standard applicability
Privacy
How your data is protected
Retention:Web-based tool; user-uploaded data persistence not publicly specified
Training:Not publicly specified whether uploaded data used for model improvement
Compliance:Academic institution hosted (UC Berkeley), No SOC 2 or ISO 27001 certification mentioned
API
Integration
Endpoint:No public API documented; GitHub repository available for self-hosting
Method:REST API not publicly exposed
USE CASES

Use Cases

  • ·Evaluating occupant comfort in new HVAC designs vs. baseline conditions
  • ·Comparing naturally ventilated vs. air-conditioned design scenarios
  • ·LEED v4 EQ Credit Thermal Comfort documentation and verification
  • ·Annual exceedance analysis for energy efficiency trade-offs
  • ·Teaching thermal comfort fundamentals to architecture and engineering students
  • ·Post-occupancy validation of building performance against design assumptions
  • ·Parametric design studies exploring airspeed, temperature, and clothing effects
PRICING

Pricing

Free
Completely free (no login required)
Pro
N/A
Enterprise
N/A
Sources & Research NotesResearch date: 2026-04-03
Data Sources (6)
Fields Checked (18)
problem, solution, deliveryMethod, disciplines, projectPhases, projectTypes, isOpenSource, license, maturityStage, yearFounded, customerBase, input-formats, output-structure, algorithm-approach, algorithm-models, pricing, useCases, control-features
Not Found (8)
integrations, api-documentation, privacy-policy-specific, data-retention-days, compliance-certifications, soc2-iso27001, vendor-contact-info, api-ratelimit
About this research: This record summarizes the cited sources and fields checked. A research date does not establish hands-on testing. Consult the original sources for current details and limitations.
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