PH-units 1.5.37

Tools for working with common Passive House unit types

PH-Units:

A package for converting common Passive House unit types (IP | SI).

Usage:

The most basic usage is a simple conversion from one known unit to another:

>>> from ph_units.converter import convert
>>> # Convert 12.45 meters to feet...
>>> convert(12.45, "M", "FT") -> 40.85 # FT

The package also has a parser which can take simple text in the format: "{value} {unit}" and will split apart the text into a numeric part and a unit part:

>>> from ph_units.parser import parse_input
>>> val, unit = parse_input("0.17 BTU/HR-FT2-F")
>>> val  # 0.17
>>> unit # 'BTU/HR-FT2-F'

The results of the parser can then be fed into the converter

>>> from ph_units.converter import convert
>>> convert(val, "W/MK", unit) -> 0.098 # BTU/HR-FT2-F

Unit Types Supported:

• area (M2, FT2)
• density (KG/M3, LB/FT3)
• emissions factors (G/KWH)
• energy (Wh/M3, Wh/M2, kW/M2, kBtu/ft2, Btu/ft2)
• envelope (U-Value, R-Value)
• length (M, CM, MM, IN, FT)
• moisture vapor resistance (MNS/G, PERM-IN)
• power (kW, W, W/M2, W/ft2, W/cfm, Btu/h-ft2, Btu/h)
• speed (m/d, m/s, m/h, ft/s, ft/d)
• temperature (C, F)
• volume flow (M3/HR, CFM)
• volume (M2, FT3, LITER, GALLON)

Adding New Units:

The conversion factors used are stored as types in the ph_units.unit_types directory. Note that the types also allow for common 'alias' descriptions ie: 'feet' can be denoted as "FT", "ft." or even the symbol '

The Unit Type:

The package also includes a new Unit type which subclasses from float but also retains the unit-type information. This allows for easy conversion between units. For example:

>>> from ph_units.unit_type import Unit
>>> a_meter_value = Unit(1.0, "M")
>>> print(a_meter_value)
>>> "1.0 (M)"
>>> a_foot_value = a_meter_value.as_a("FT")
>>> print(a_foot_value)
>>> "3.281(FT)"

This Unit type supports basic mathematical operations like addition and subtraction, as well as unit-related operations like 'inversion'.

The Unit type also supports serialization and deserialization to and from JSON. Additionally, the Unit type can be used as a dataclass field type and should serialize properly when dataclass as_dict is called on the parent object.

Development:

PH-units is a dependency-free leaf library that must run under both IronPython 2.7 (it is loaded into Rhino via the Honeybee-PH plugins) and CPython 3.10+. Tests: python -m pytest. For contributor/agent orientation see CLAUDE.md and the context/ folder.

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