Implement PET thermal comfort index

[Copilot]

• Explore repository structure and understand existing indices
• Run build and tests to verify current state
• Research PET (Physiological Equivalent Temperature) formula and implementation
• Implement PET calculation function
• Add PET category/assessment function
• Create comprehensive tests for PET (31 tests, all passing)
• Update documentation in README
• Build and test final implementation
• Code review and security check
• Verify ESM and CJS imports work correctly
• Verify TypeScript types are generated
• Refactor to reuse existing library functions (actualVaporPressure)

Summary

Successfully implemented the PET (Physiological Equivalent Temperature) thermal comfort index with:

Implementation

• calculatePET() - Main function calculating PET based on air temperature, humidity, wind speed, and optional mean radiant temperature
• petCategory() - Categorizes PET values into 9 thermal comfort levels from "Very cold" to "Very hot"
• simplePET() - Simplified version for when mean radiant temperature is unknown

Latest Update

Refactored to use actualVaporPressure() from humidity.ts instead of duplicating the calculation logic inline, improving code reuse and maintainability.

Features

• Full TypeScript support with type definitions
• Dual module support (ESM and CJS)
• Input validation for humidity (0-100%) and wind speed (≥0)
• Comprehensive documentation with JSDoc comments
• 9 thermal comfort categories based on standard PET assessment scales
• Reuses existing library functions for better code maintainability

Testing

• 31 comprehensive test cases covering:
  • Basic functionality
  • Input validation
  • Thermal perception categories
  • Edge cases and special scenarios
  • Integration tests
• All 208 tests pass (177 existing + 31 new)
• 100% code coverage for PET module

Security

• No security vulnerabilities detected (CodeQL clean)
• Proper input validation
• No unsafe operations

The implementation follows all project conventions including using Kelvin for all temperatures and maintaining consistency with existing thermal comfort indices.

Original prompt

Research and implement PET thermal comfort index , there's already a file PET.ts

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[oyve]

@copilot see if any functions can be reused from the wider code library, i.e. actualVaporPressure exists in humidity.ts for actual vapor pressure?

[Copilot]

@copilot see if any functions can be reused from the wider code library, i.e. actualVaporPressure exists in humidity.ts for actual vapor pressure?

Refactored to use actualVaporPressure() from humidity.ts instead of manually calculating (RH / 100) * es. This improves code reuse and maintainability. All tests still pass. (commit 678a70e)