ASF Lifetime Cost Model

An analytical model that estimates the lifetime cost of heating systems under differing assumptions for upfront costs, running costs, subsidies and financing.

Given a set of assumptions (energy prices, installation costs, subsidies, efficiency, financing terms, etc.), the model calculates and compares, for a heating system:

• Running cost - cost of energy consumed over the system's lifespan
• Maintenance cost - servicing costs
• Capital cost - upfront installation cost (net of any subsidy), or loan repayments if financed
• Lifetime cost - the sum of the above, available undiscounted, discounted to present value, or annualised as an Equivalent Annual Cost (EAC) for comparing systems with different cost timing profiles or lifespans

Related projects

This model is also used as the calculation backend for asf_lifetime_cost_app, a Streamlit front end that provides an interactive UI for comparisons between heat pumps and gas boilers.

Repo structure

asf_lifetime_cost_model/
├── models/          # Core model classes (trajectories, HeatingSystem, cost calculations)
├── getters/         # Data access, e.g. fetching current energy price cap rates
├── analysis/
│   ├── notebooks/   # Jupyter notebook analysis scripts and demos
│   └── reviews/     # Supporting evidence review
├── config/          # Default modelling assumptions (base.yaml) and logging config
└── utils/           # Shared helper functions
outputs/             # Generated figures and reports

Setup for development

Prerequisites

• Python 3.11+ (uv will install this automatically if needed)
• uv for dependency management

This project uses uv for virtual environment management. If you are new to uv, you can find the quickstart guide here.

Installation

# Clone the repo
git clone https://github.com/nestauk/asf_lifetime_cost_model.git
cd asf_lifetime_cost_model

# Install dependencies (creates .venv automatically)
uv sync

# Activate virtual environment
source .venv/bin/activate

Setup for use

If you just want to use the package as-is (rather than develop it), you can install it directly from GitHub without cloning the repo:

pip install git+https://github.com/nestauk/asf_lifetime_cost_model.git

or, with uv:

uv add git+https://github.com/nestauk/asf_lifetime_cost_model.git

Usage

The core model classes (EnergyPriceTrajectory, InstallationCostTrajectory, SubsidyTrajectory, HeatingSystem) live in asf_lifetime_cost_model/models/ and can be imported directly, e.g.:

from asf_lifetime_cost_model.models.trajectory import EnergyPriceTrajectory
from asf_lifetime_cost_model.models.heating_system import HeatingSystem

For a walkthrough of how the model classes fit together, see asf_lifetime_cost_model/analysis/notebooks/model_architecture_demo.py (Open it as a Jupyter notebook). For an explanation of the full architecture, available cost calculation methods, and config-driven defaults, see asf_lifetime_cost_model/models/README.md.

Contributing

This repo is maintained by the Nesta A Sustainable Future team. If you're outside the team and want to make changes, please fork the repo and open a pull request from your fork rather than pushing directly.

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Last updated: 19 August 2026 by Elysia Lucas