HDD/CDD Calculator

A Python library for calculating Heating Degree Days (HDD) and Cooling Degree Days (CDD) from multiple weather data sources, including:

• U.S. National Weather Service (NWS) API – forecast data
• Meteostat – global historical weather data

The package also supports:

• Automated alignment of energy usage CSV data with degree days
• Linear regression analysis between degree days and energy consumption
• Visualization of regression results
• An included example dataset for quick testing
• A simple CLI to run the full workflow and save the plot

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✨ Features

• Calculate HDD/CDD for any location by latitude/longitude
• Custom base temperature support
• Retrieve degree day data for specific date ranges
• Two data sources: NWS (U.S. forecast) and Meteostat (global historical)
• CSV utilities for loading and aligning energy consumption data
• Linear regression between degree days and energy usage
• Matplotlib visualization of results
• CLI example that runs end-to-end and saves a screenshot
• Clear error handling and type hints
• PyPI-ready packaging

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📦 Installation

From PyPI:

pip install hdd-cdd-calculator

Optional extras:

pip install hdd-cdd-calculator[dev]   # dev tools (pytest, linting, typing)
pip install hdd-cdd-calculator[viz]   # includes matplotlib for plotting

From source:

git clone https://github.com/rmkenv/hdd_cdd_calculator.git
cd hdd_cdd_calculator
pip install -e .[dev]

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🚀 Basic Usage

NWS Data Source

from hdd_cdd_calculator import get_degree_days

results = get_degree_days(
    lat=38.8977,
    lon=-77.0365,
    start_date="2023-06-01",
    end_date="2023-06-07",
    source="nws"
)

for r in results:
    print(f"{r.date} | High: {r.high_temp}°F | Low: {r.low_temp}°F | HDD: {r.hdd} | CDD: {r.cdd}")

Meteostat Data Source

from hdd_cdd_calculator import get_degree_days

results = get_degree_days(
    lat=40.7128,
    lon=-74.0060,
    start_date="2023-06-01",
    end_date="2023-06-30",
    source="meteostat"
)

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📂 Working with Energy CSVs

Expected CSV headers:

date,kwh,mmbtu,gal

Load Energy Data

from hdd_cdd_calculator import read_energy_data_from_csv
energy_values = read_energy_data_from_csv("energy_data.csv", column="kwh")

Align CSV & Degree Days → Regression → Plot

from hdd_cdd_calculator import (
    get_degree_days_for_period,
    align_energy_with_degree_days,
    perform_regression,
    plot_regression
)
import pandas as pd

# Step 1: Fetch HDD data
dd_results = get_degree_days_for_period(
    lat=40.7128,
    lon=-74.0060,
    start_date="2023-06-01",
    end_date="2023-06-10"
)

# Step 2: Align with CSV
energy_vals, hdd_vals = align_energy_with_degree_days(
    dd_results,
    "examples/sample_energy_data.csv",
    energy_column="kwh",
    degree_day_type="hdd"
)

# Step 3: Fit regression
model = perform_regression(hdd_vals, energy_vals)
print(f"Slope: {model.coef_:.2f}, Intercept: {model.intercept_:.2f}")

# Step 4: Plot and save
plot_regression(
    pd.Series(hdd_vals),
    pd.Series(energy_vals),
    model,
    save_path="examples/regression_plot.png"  # Save file in examples/
)

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⚡ Quick Try (With Included Dataset)

We include a complete dataset + CLI workflow.

From the repo root or after installing:

python -m hdd_cdd_calculator --example

This will:

1. Fetch HDD data for NYC (June 1–10, 2023)
2. Align with examples/sample_energy_data.csv
3. Perform regression
4. Display a plot and save it to examples/regression_plot.png

Example Output

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📖 API Overview

Data fetching

• get_degree_days_for_location(...)
• get_degree_days_for_period(...)
• fetch_meteostat_data(...)
• get_degree_days(...) — unified source selector

CSV utilities

• read_energy_data_from_csv(path, column="kwh")
• read_energy_data_with_dates(path, column="kwh")
• align_energy_with_degree_days(degree_days, csv, energy_column="kwh", degree_day_type="hdd")

Analysis

• perform_regression(degree_days, energy_usage)
• plot_regression(degree_days, energy_usage, model, save_path=None, show=True)

Utilities

• validate_coordinates(...)
• calculate_degree_days(...)
• Temperature conversions: fahrenheit_to_celsius(...), celsius_to_fahrenheit(...)

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🧪 Development

Clone and install with developer tools:

git clone https://github.com/rmkenv/hdd_cdd_calculator.git
cd hdd_cdd_calculator
pip install -e .[dev]

Run tests:

pytest

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📜 License

MIT License — see LICENSE for details.

Author: Ryan Kmetz