At a glance
| Tool | Type | Price | Best for |
|---|---|---|---|
| CBE Clima Tool | Web app, open source | Free | A free psychrometric chart of every hour in an EPW file, with filters and overlays. |
| CBE Thermal Comfort Tool | Web app, open source | Free | Checking indoor thermal comfort against ASHRAE 55 or EN 16798 on a psychrometric chart. |
| Psychrometric Chart web app | Web app | Free | Teaching and exploring psychrometrics and bioclimatic charts, with or without a weather file. |
| Climate Consultant | Desktop app (Windows, macOS) | Free | A free psychrometric chart with 16 passive design strategy zones, in a program aimed at architects and students among others. |
| C4B | Web app | Free plan; paid plans from €59/month (cancellation takes effect after 12 billing cycles) or €599/year, with a 7-day free trial | A psychrometric chart for an address, with the share of hours each passive strategy covers. |
| EPW Insights | Web app, open source (AGPL-3.0) | Free | A free psychrometric chart with bioclimatic strategy overlays for any EPW file, in the browser. |
| Ladybug Tools | Plugins for Grasshopper (Rhino), open source | Free and open source; requires Rhino (a commercial Rhino 8 licence is US$995 in North America) | Psychrometric charts inside Rhino, for outdoor climate data or indoor simulation results. |
How to choose
Be clear about the job. For climate analysis you want a chart that plots all 8,760 hours of a weather file and overlays comfort and passive design strategy zones, in the tradition of the Olgyay and Givoni bioclimatic charts. For indoor comfort you want a tool that calculates PMV or adaptive comfort to a standard such as ASHRAE 55 or EN 16798. For HVAC design you need process lines and state-point calculations.
Look at how comfort and the strategy zones are defined. Strategy zones such as fans, thermal mass or passive solar heating are simplified boundaries, so treat the share of hours they report as a guide, and check which comfort model each tool uses.
A chart is only as representative as its weather data. A station far from the site, or an old typical year, shifts the whole cloud of hours. Tools that accept your own EPW let you test a site-specific or future weather file.
Finally, consider the outputs: interactive charts for exploring, image or SVG exports for reports, or data exports for your own analysis.
CBE Clima Tool
A free psychrometric chart of every hour in an EPW file, with filters and overlays.
- Plots all the year's weather conditions on a psychrometric chart, showing how often each condition recurs.
- Overlays another variable, such as radiation or wind speed, and filters by date, time or value.
- Natural ventilation potential and UTCI outdoor comfort in other tabs; SVG and CSV export.
CBE Thermal Comfort Tool
Checking indoor thermal comfort against ASHRAE 55 or EN 16798 on a psychrometric chart.
- PMV and adaptive comfort calculations for ASHRAE 55 and EN 16798.
- Psychrometric charts by air or operative temperature, plus relative humidity, air speed and SET charts.
- Open source, and described in SoftwareX (2020).
Psychrometric Chart web app
Teaching and exploring psychrometrics and bioclimatic charts, with or without a weather file.
- Overlays comfort metrics and psychrometric process lines, and loads EPW weather files and CSV simulation outputs.
- Transitions between absolute and relative humidity axes to show how the Givoni and Olgyay bioclimatic charts relate.
- Generates ASHRAE Standard 55 and EN 15251 comfort diagrams for reports.
Good to know
- App page dated October 2018.
Climate Consultant
A free psychrometric chart with 16 passive design strategy zones, in a program aimed at architects and students among others.
- Plots each of the 8,760 hours of an EPW file on the psychrometric chart.
- Reports the share of hours in 16 design strategy zones and generates a list of design guidelines for the location.
Good to know
- Latest Windows build listed: 6.0 Build 17 (October 2021); latest macOS build: 6.0 Build 13 (January 2020). The download page states it will not run on macOS Ventura.
C4B
We make C4BA psychrometric chart for an address, with the share of hours each passive strategy covers.
- Plots every hour of the site's typical year on a psychrometric chart, including on the Free plan with weather-station data.
- Projects on paid plans add five passive design strategy zones with the share of hours each covers: comfort range, use of fans, thermal mass with night ventilation, capture of internal heat and passive solar heating.
- Projects can use site-specific reanalysis data instead of the nearest station.
Good to know
- C4B works from a location, not an uploaded EPW, and does not export chart images or CSV/JSON data; the chart is included in the PDF report on paid plans.
EPW Insights
A free psychrometric chart with bioclimatic strategy overlays for any EPW file, in the browser.
- Psychrometric chart with bioclimatic design strategy overlays.
- Outdoor comfort (UTCI, SET, MRT) and thermal mass analyses from the same file.
- Runs locally in the browser, with nothing uploaded.
Ladybug Tools
Psychrometric charts inside Rhino, for outdoor climate data or indoor simulation results.
- The Psychrometric Chart component plots temperature and humidity from an imported EPW or from an energy simulation's indoor results.
- Companion PMV Polygon and Adaptive Chart components for comfort zones.
Good to know
- Runs inside Rhino and Grasshopper, so it assumes a Rhino licence and some visual-scripting experience.
See your site's climate before design begins
Pin any location and get climate, comfort and preliminary energy insight your whole team can read. Start with a 7-day free trial, or book a 30-minute demo.
Frequently asked questions
What is a psychrometric chart used for in architecture?
It plots air temperature against humidity. With every hour of a year's weather on it, it shows how often conditions are comfortable and which passive strategies, such as ventilation, thermal mass or passive solar heating, could extend comfort without mechanical systems.
What is a bioclimatic chart?
A temperature and humidity chart with zones for comfort and for passive design strategies. The Olgyay and Givoni bioclimatic charts are the classic examples, and many climate tools now draw similar zones on a psychrometric chart.
Is there a free online psychrometric chart?
Yes. CBE Clima Tool and EPW Insights plot a weather file's hours online for free, the CBE Thermal Comfort Tool shows comfort zones for ASHRAE 55 and EN 16798, and Andrew Marsh's Psychrometric Chart app covers both teaching and EPW plotting. C4B's Free plan includes a psychrometric chart for any address.
Can I plot my own weather file on a psychrometric chart?
Yes, in CBE Clima Tool, EPW Insights, Andrew Marsh's app, Climate Consultant and Ladybug Tools, which all read EPW files. C4B works from an address instead and does not take uploaded files.
Sources
We make C4B. Information about the other tools comes from their official websites and documentation, checked on 18 September 2026. Products and prices change, so check each vendor's site for the latest details. All product names belong to their respective owners.
- CBE Clima Tool documentation: Psychrometric Chart tab
- CBE Clima Tool documentation: overview
- CBE Clima Tool documentation: main features
- CBE Clima Tool documentation: Natural Ventilation Potential tab
- CBE Thermal Comfort Tool
- CBE Thermal Comfort Tool documentation
- Andrew Marsh: Psychrometric Chart web app
- Andrew Marsh: 3D Sun-Path web app
- Climate Consultant download page (SBSE)
- Energy Design Tools (UCLA): Climate Consultant
- EPW Insights source code and README
- Ladybug Tools primer: component index
- Ladybug Tools installation wiki
- Rhino pricing, North America
Related on C4B
Psychrometric chart and passive design
An hourly psychrometric chart and the share of hours covered by each passive design strategy.
Outdoor comfort (UTCI)
UTCI outdoor thermal comfort heatmaps by season and hour, and strategies for sun and wind exposure.
Site climate analysis
A full climate study for any location in the world, run in the browser from a single address or map pin.
C4B vs Climate Consultant
Climate Consultant is a free desktop app for EPW files; C4B runs online from any address and adds comfort, future climate and energy.
C4B vs Andrew Marsh's web apps
Free, single-purpose EPW visualisations compared with C4B's integrated analysis from an address.
C4B vs CBE Clima Tool
Both run in the browser. Clima is free and analyses EPW files; C4B works from any address and adds future climate, energy and PDF reports.
C4B vs Ladybug Tools
Ladybug is a free, flexible Grasshopper toolkit; C4B is a ready-made browser workflow from an address to a climate report.