Slaoo

Reduce financial and regulatory uncertainty of home decarbonization by transforming EPC and planning data into personalized investment roadmaps to predict property value increases and feasibility

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Green Brick

Team Slaoo
February 2026

Inspiration

Homeowners want to decarbonise to help the environment and reduce bills, and with banks offering green mortgages for energy efficient homes, making our homes sustainable is becoming more important by the day. However, they are deterred by financial and regulatory uncertainty. We realised that while data for energy performance (EPC), property values, and planning permissions exists, it is fragmented and inaccessible to the average person. We wanted to build a tool that replaces guessing with planning, turning green home retrofitting into a transparent, strategic investment rather than a source of stress.

What it does

Green Brick is a full-stack dashboard that provides a personalised roadmap for home energy efficiency. By entering an address and a budget, users receive:

  • Predictive ROI: Calculations of the "Green Premium'': the specific property value increase expected from upgrades like solar panels or heat pumps, based on historical data and corrected for inflation.
  • Feasibility Rating: A "High/Medium/Low'' score based on other surrounding planning approvals within a given radius for similar projects, and conservation area status.
  • Environmental Impact: Metrics on annual CO2 reduction and energy savings (kWh).
  • Compliance Tracking: A visual status of whether the property is "on track'' to meet government targets (like reaching EPC Band C).

How we built it

We built an asynchronous system to handle complex data aggregation:

  • Backend: A FastAPI server that orchestrates external integrations.
  • Planning Data: IBex API to fetch and filter historical planning applications within a 500\text{m}radius to determine local approval trends.
  • Energy & Value: We integrated with Open Data Communities (EPC API) for energy metrics and the HM Land Registry for local property sale averages.
  • Geocoding: We used OpenStreetMap (Nominatim) and Mapbox GL JS to visualise property locations and local retrofit examples on an interactive map.
  • ROI Logic: A custom algorithm in Python to calculate the net premium increase. For example, moving from EPC Band D to C applies a 5% market premium to the property value:

Challenges we ran into

  • Data Fragmentation: Matching a user’s address across the EPC database, Land Registry, and planning records was difficult due to varying formats. We solved this by building a re-usable EPCClient that uses regex to extract house numbers and postcodes for better matching accuracy.
  • Real-time ROI Calculation: Building a logic that considers both the annual energy savings and the one-off property value jump required careful balancing to ensure the ROI wasn't over-promised.
  • Asynchronous Orchestration: Ensuring the frontend remained responsive while the backend performed several different API lookups required the use of httpx for asynchronous requests.

Accomplishments that we're proud of

  • Planning Insight: Successfully filtering raw planning data to show users actual examples of "Approved'' solar or insulation projects nearby.
  • The "Green Premium'' Model: Developing a logic that uses real historical data to prove that sustainability is a smart financial investment, not just a cost.
  • The User Experience: Creating a clean, DM Sans-styled dashboard that simplifies complex data into actionable stats, like "CO2 reduction equivalent to planting X trees.''

What we learned

Building Green Brick taught us that the technical side of the energy transition is actually ahead of the decision-making side. While the hardware exists it seems home owners aren't moving forward due to financial risks and planning rules being too opaque. We realised that high-level advice doesn't help as much as hyper-local data; showing a user what others in their neighbourhood have performed and the effects of it helps eliminate doubt. We built reliable pipeline to pull and clean data from fragmented sources like the HM Land Registry, the domestic EPC register, and the Ibex planning database. We found that by doing the heavy lifting of aggregating this messy data into a single dashboard, we could provide clear, actionable numbers that replace general anxiety with a practical plan.

What's next for Green Brick

  • LLM Insights: Integrating Gemini to generate personalised "Retrofit Roadmaps'' that explain specific regulatory requirements.
  • Grant Integration: Automatically deducting government subsidies (like the Boiler Upgrade Scheme) from the total cost.
  • Contractor Marketplace: Connecting users directly with the installers responsible for the "Approved'' examples shown on the map.
  • Portfolio View: Allowing landlords to manage and track compliance across multiple properties at once.
  • Search Up using points to better align with Ibex API and ensure valid look ups when addresses change.
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