How We Calculate Your 0–100 Score
A transparent, data-driven approach to home energy performance. Every formula, weighting, and data source is published. Built on open data, continuously evolving with community input and measured validation.
- 01 6 weighted components (Envelope 25%, Heating 25%, ...)
- 02 Continuous scoring curves (no step jumps)
- 03 Sources: EPC, TABULA, PVGIS, OSM + research digest
- 04 Goes beyond EPC A — rewards prosumer features (storage, grid export)
How the 0-100 Score Works (v1.2)
Our score is a continuous 0-100 metric that builds on government data like EPC, enriched with real-world sources. It's designed to reward every improvement, updating as your home evolves.
Unlike static ratings, our score uses continuous curves for smooth progression — no discrete jumps. For example, improving insulation from R-20 to R-30 gradually increases your score based on performance curves.
Continuous Scoring Curves
Metrics like U-values (thermal transmittance) map to scores via smooth curves. Lower U-value = higher score, with diminishing returns at extremes.
COP to Score Mapping
Heat pump COP (Coefficient of Performance) is scored on a curve: ASHP from 3-4.3, GSHP 4+, benchmarked against regional averages.
Weighted Aggregation
Component scores are weighted and summed to your final 0-100 score. Region-specific normalization ensures fairness.
6 Component Breakdown
Your score is composed of six weighted components, each fed by multiple data sources for accuracy.
Envelope
25%Assesses insulation, airtightness, and thermal performance of walls, roof, floors, and windows.
Data Sources
- EPC (U-values, fabric)
- TABULA (typologies)
- OSM (geometry)
- SAP 10.2 (benchmarks)
- ResStock (US)
- Video research (478 YT digest → 200+ tech)
- Podcast research (5 series, 50+ eps)
Heating
25%Evaluates heating system efficiency, including boilers, heat pumps, and distribution.
Data Sources
- EPC (system type, efficiency)
- SAP 10.2 (COP curves)
- Octopus (tariffs)
- Video research (ASHP/GSHP data)
Ventilation
10%Measures air quality systems and heat recovery efficiency.
Data Sources
- EPC (vent type)
- TABULA
- Video research (MVHR recovery rates)
Water
10%Analyzes hot water heating and efficiency.
Data Sources
- EPC (water heating)
- SAP 10.2
- Video research (benchmarks)
Solar
15%Calculates on-site renewable generation potential and performance.
Data Sources
- PVGIS (solar irradiance)
- OSM (roof area)
- EPC (existing PV)
- ResStock (US)
Storage/Grid
15%Evaluates battery storage, self-consumption, and grid integration.
Data Sources
- Octopus (tariffs)
- Video research (self-consumption rates)
- EPC (if applicable)
Our Technology Database
200+ technologies researched across 7 categories. Continuously updated from research pipeline (YouTube, ArXiv, Google Scholar).
Envelope and Insulation
35 technologies
Heating and Cooling
45 technologies
Ventilation and Air Quality
20 technologies
Water Heating and Efficiency
15 technologies
Renewables and Solar
25 technologies
Storage and Grid Integration
35 technologies
Smart Controls and Automation
25 technologies
Scoring Curves Explained
We use mathematical curves to map raw metrics to 0-100 sub-scores, ensuring smooth progression and realistic diminishing returns.
U-Value → Score (Envelope)
Lower U-values (better insulation) yield higher scores via a sigmoid curve. Example: Wall U-0.18 (R-31) scores ~85, improving to U-0.12 (R-47) reaches 95.
COP → Score (Heating)
Heat pump efficiency on a linear-to-exponential curve. ASHP COP 3.5 scores 70, 4.3 scores 90; GSHP 4+ can exceed 95.
Other Examples
- MVHR recovery: 90% → 80 score, 95% → 95 score
- Battery self-consumption: 30% → 40 score, 60% → 85 score
- Solar yield: Normalized to roof potential via PVGIS
Beyond Net Zero: Buildings as Batteries
EPC A is not the finish line — it's just where the government stops counting. Our score goes to 100 because homes can do more than minimise consumption. They can generate, store, and export energy; respond to grid signals; and become active nodes in a distributed virtual power plant.
A score of 100/100 represents an energy-positive prosumer home — one that generates approximately 6,000 kWh/year from solar while consuming only 4,000 kWh, resulting in a net export of roughly −2,000 kWh/year for a typical UK 3-bed semi. The home doesn't just pay its own energy bill — it credits it.
Thermal Mass as Storage
Buildings store energy as heat in walls, floors, and thermal mass — free batteries that need no chemistry. Hedar et al. (2023, Building Simulation) quantified this: homes provide grid flexibility through thermal inertia, pre-heating or pre-cooling during cheap/clean grid windows and coasting through peaks. Our score rewards homes with high thermal mass and smart scheduling capability.
Heat Pumps for Load Shifting
A heat pump paired with a well-insulated building envelope is a controllable thermal load. Power-to-Heat during surplus renewable periods stores energy in the building fabric itself. On Octopus Agile or similar dynamic tariffs, a smart ASHP can run predominantly on cheap overnight electricity, shifting kilowatt-hours from grid-stress periods to off-peak abundance.
Solar + Battery + V2G
Rooftop solar generates. A home battery (10–20 kWh) stores and time-shifts. Vehicle-to-Grid (V2G) adds 40–80 kWh of EV battery into the equation. Together, these create a system that can island during grid stress events and sell power back at peak prices — turning household energy into a revenue stream rather than a cost centre.
Every Home as a VPP Node
A single prosumer home is interesting. One million of them, coordinated via demand response APIs, form a virtual power plant (VPP) that can provide gigawatt-scale grid balancing services. Evolving Home's score is designed to track and reward each home's contribution potential — not just its own consumption efficiency.
What Score 100 Actually Means
(UK 3-bed semi)
vs 4,000 kWh consumed
prosumer asset
Research basis: Hedar et al. (2023) "Buildings as Batteries: Leveraging Thermal Inertia for Grid Flexibility," Building Simulation journal. Heat pump Power-to-Heat storage validated against UK Climate Change Committee demand flexibility estimates.
What is live today vs planned
Actively used in scoring
- EPC fabric descriptions (walls/roof/floor/windows)
- EPC heating, hot water, ventilation fields
- Airtightness when available
- Solar annual generation when enriched
- Storage/grid flags (battery, VPP, TOU)
Used for recommendations / priors
- SAP 10.2 benchmark ranges
- Research digest (videos/podcasts)
- TABULA / ResStock archetype references
- Tariff heuristics (Octopus-style TOU logic)
Planned enrichments
- Measured smart-meter validation set
- OSM geometry coupling in core score
- Thermal-camera and on-site evidence
- Public contribution pipeline for model updates
Known limitations (current model)
- Some component mappings are still rule-based and text-driven.
- Confidence and uncertainty are estimated from input completeness, not measured calibration error.
- Validation dataset includes both measured and benchmark archetypes; measured sample is still small.
Our Open Methodology Commitment
Everything here is open and community-driven. Full formulas, data sources, and update logs are published. We believe energy scoring should be auditable — not a black box controlled by assessors or vendors.
Learn More in Our Manifesto