Quantity and Quality

A small Python library and CLI for calculating and reporting the energy quantity, Exergy Factor, and accessible exergy of individual energy streams. It can also account for the Applied Exergy that reaches an end-use task.

Try the calculator · Paper · Practical cookbook · Physical models · Validation

One Product Stack

The shared path is: discover the missing quality field, standardize the record, then turn it into an auditable decision.

Conventional energy records usually provide only a quantity:

1 MWh

Quantity and Quality adds the number that is usually missing:

1 MWh_th, fx = 0.170 [Th = 80 C, T0 = 20 C]

Here fx is the Exergy Factor: accessible useful-work potential per unit of energy. The example contains about 0.170 MWh_ex relative to a 20 °C sink.

The thermodynamics are established. This project makes them easy to apply in a calculator, spreadsheet, script, database, API, or AI-agent workflow.

What It Does

• Calculates energy quantity, fx, and accessible exergy for electrical, mechanical, thermal, fluid, chemical, radiative, electromagnetic, nuclear, plasma, and separation streams.
• Calculates quantity from measurements such as power and time, torque and speed, mass and heating value, temperature change, fluid state, irradiance, field strength, or reaction extent.
• Handles biomass and bioenergy without inventing a universal factor for variable feedstocks.
• Reports friction, rolling resistance, and aerodynamic drag as mechanical work dissipated to heat and exergy destruction.
• Cleans existing CSV, JSON, JSONL, Excel, DataFrame, SQL, stream, and URL data.
• Keeps primary, secondary, final, and useful energy separate from Applied Exergy and from the resulting energy service.
• Uses the same JSON-shaped calculation contract from Python, the CLI, HTTP, and agent discovery.

The browser calculator stays intentionally simple. Advanced and auditable paths live in the library, CLI, schemas, and optional API.

Install

python -m pip install quantity-and-quality

The command is quantity-quality; the import is quantity_quality.

Optional integrations are installed only when needed:

python -m pip install "quantity-and-quality[scenario]"  # YAML scenarios
python -m pip install "quantity-and-quality[api]"       # HTTP API
python -m pip install "quantity-and-quality[fluids]"    # Real-fluid properties

Quick Start

Calculate a known stream

quantity-quality calc thermal \
  --quantity 1 --unit MWh_th --source-c 80 --sink-c 20

80 C heat to 20 C sink
report: 1 MWh_th, fx = 0.170 [Th = 80 C, T0 = 20 C]
accessible exergy: 0.169899 MWh_ex

The equivalent Python call is:

import quantity_quality as qq

record = qq.thermal(1, "MWh_th", source_c=80, sink_c=20)
print(record.full_notation)
print(record.accessible_exergy, record.accessible_exergy_unit)

Other direct calculations include:

quantity-quality calc electricity --quantity 1 --unit MWh
quantity-quality calc fuel --quantity 1 --fuel "natural gas" --basis HHV
quantity-quality calc cooling --quantity 1 --unit MWh_cooling \
  --cold-service-c 7 --ambient-sink-c 30
quantity-quality calc custom --quantity 1 --unit MWh --fx 0.73

Calculate from physical inputs

One request shape works from Python, the CLI, or HTTP:

{
  "stream_type": "heat",
  "mass_flow_kg_s": 2.5,
  "duration_hours": 8,
  "specific_heat_kj_kg_k": 4.186,
  "source_c": 80,
  "return_c": 50,
  "sink_c": 20
}

quantity-quality calculate examples/stream-calculation.json --json

Packaged examples cover shaft work, steam condensation, biomass, drag, electromagnetic fields, D–T reaction products, and plasma:

quantity-quality calculate examples/mechanical-shaft.json --json
quantity-quality calculate examples/steam-condensation.json --json
quantity-quality calculate examples/biomass-calculation.json --json
quantity-quality calculate examples/aerodynamic-drag.json --json
quantity-quality calculate examples/electromagnetic-field.json --json
quantity-quality calculate examples/dt-fusion-neutron.json --json
quantity-quality calculate examples/plasma-state.json --json

See the physical-stream guide and the focused fields, plasma, and nuclear guide for model assumptions and boundaries.

Clean existing records

quantity-quality clean energy.csv --output energy_qq.csv

The cleaner recognizes common fields such as energy_kwh, supply_temp_f, fuel_type, fx, and exergy_factor. It adds notation, accessible exergy, reference context, assumptions, warnings, and validation issues.

records = qq.clean_records(
    [
        {"asset": "Grid meter", "energy_kwh": 845, "reference_id": "electricity-delivered"},
        {"asset": "Kiln exhaust", "energy_kwh": 2738, "supply_temp_f": 1005.8},
        {"asset": "Unknown stream", "quantity": 2.738, "unit": "kWh_th", "fx": 0.64},
    ]
)

Account for what reaches the task

Use a separate end-use account when multiple boundaries are known:

quantity-quality account examples/end-use-accounting.json --json

primary energy -> secondary energy -> final energy -> useful energy -> energy service
primary exergy -> secondary exergy -> final exergy -> Applied Exergy

Applied Exergy is the exergy crossing the last device-to-task boundary. It is not useful energy: useful energy can contain both exergy and anergy. Energy services are the outcomes people want—such as a comfortable occupied home, a cold beer, or passenger-miles—and use outcome units rather than energy units.

The library derives Applied Exergy from useful.quantity × useful.fx, from final exergy × end_use_exergy_efficiency, or from a directly supplied value. Independent paths must agree.

See the dataset compatibility guide for primary, secondary, final, and useful data, including substitution-method records.

The Model

For an energy quantity:

X_A = E × fx

For an energy rate:

Xdot_A = P × fx

For heat at a constant source temperature:

fx = 1 - T0 / Th

For sensible heat cooling from Ts to Tr with constant heat capacity:

fx = 1 - T0 ln(Ts/Tr) / (Ts - Tr)

Temperatures are evaluated in kelvin. Thermal records should declare their reference temperature; fuels should declare HHV or LHV.

Exergy exists because a stream is distinguishable from a declared environment or task boundary. A temperature, pressure, chemical, electrical, mechanical, or radiative difference can support work. At equilibrium, the relevant difference and exergy vanish. The library includes that evidence in each record's distinguishability field; it does not apply a second factor because fx already quantifies the work-bearing difference.

A quantity comparison

Examples below use a 20 °C reference sink:

Equal energy quantities are not necessarily equal useful-work resources. This library calculates and reports that difference; downstream tools can decide how to use it.

Interfaces for Software and Agents

Discover supported stream types and exact request schemas instead of guessing field names:

quantity-quality capabilities --json
quantity-quality capabilities --json-schema
quantity-quality schema --json-schema

The optional HTTP service exposes the same deterministic calculations:

python -m pip install "quantity-and-quality[api]"
quantity-quality serve-api

GET  /v1/capabilities
GET  /v1/calculate/schema
POST /v1/calculate
GET  /v1/accounting/schema
POST /v1/account

Request a hosted key at exergyfactor.com or use the endpoint directly. Terms acceptance is a required request field:

curl https://api.exergyfactor.com/v1/api-keys/request \
  -H "Content-Type: application/json" \
  -d '{"email":"you@example.com","accept_terms":true}'

The applicable hosted-service terms are published at exergyfactor.com/terms.html.

Open http://127.0.0.1:8000/docs for interactive API documentation. Invalid requests return stable error codes and identify the field that needs attention.

The packaged schemas are:

data/quantity_quality_record.schema.json
data/stream_calculation_request.schema.json
data/energy_accounting_request.schema.json
data/conformance_contract_v1.json
data/conformance_contract_v1.schema.json

The reference-data guide defines fields, notation, precision, verification, schemas, bundled examples, and the website export.

Accuracy and Scope

The package starts with transparent reference defaults for screening, then lets users replace them with site-specific measurements. It labels estimates, retains model and source provenance, and rejects inputs outside a model's stated domain rather than silently inventing a result.

Important boundaries include:

• Biomass and heterogeneous fuels have no universal factor; moisture, composition, ash, heating value, and basis matter.
• Friction and drag are losses. Their incoming mechanical work, residual heat exergy, and exergy destruction are reported separately.
• Nuclear reaction-product energy is not reactor heat or electricity. Neutrons, charged particles, neutrinos, photons, heat, and electrical output remain separate streams at their actual boundaries.
• Plasma's built-in model is an ideal classical inventory. Advanced distributions can supply independently evaluated mean energy and quality.
• Substitution-method primary energy is a counterfactual accounting quantity, not a physical stream at that magnitude, so it is not assigned physical exergy.

The permanent test suite covers exact identities, equation conformance, domain checks, real public-data fixtures, package builds, and wheel installation across supported Python versions. See numerical validation for benchmarks, tolerances, data revisions, and the full live-data test.

The versioned cross-product contract pins shared equations, explicit reference conditions, tolerances, invalid-input behavior, notation, and the reference-data SHA-256. Both Python packages and the browser calculator execute the applicable cases in CI. The web export also publishes the source package version and hash.

Documentation

Project Boundary

This repository is the canonical reporting standard and deterministic stream-calculation layer. It does not model technologies, emissions, health, or economics; The Exergy Imperative consumes this layer for those downstream decisions. Exergy Factor is the simple public acquisition and calculator surface over the same reference data.

Contributing, Citation, and License

Corrections to published numbers, sourced reference examples, documentation improvements, and real-dataset adoption reports are welcome. See CONTRIBUTING.md and SECURITY.md.

Machine-readable citation metadata is in CITATION.cff. GitHub also renders it through Cite this repository in the repository sidebar.

Released under the MIT License.