What it does
This tool runs the AES Simplified Method overheating compliance check per Approved Document O (Building Regulations 2010, 2021 edition). It calculates the four AD-O Part O criteria for a single dwelling — whole-house maximum glazing area, most-glazed-room maximum glazing area, total minimum free area, and per-bedroom minimum free area — and produces a verdict plus an AES-branded .docx report. Dynamic thermal modelling (CIBSE TM59) is a separate workflow and is not covered by this tool.
Quick start
- Add Drawing in the topbar. Upload DXF (preferred) or PDF — typically one file each for ground floor plan, first floor plan, and elevations.
- On the left, click each page in the list to set its Page label and Role (Plan / Elevation / Both). For multi-elevation sheets, leave Role as Elevation and use Façade regions (see below).
- Calibrate scale on each page — click "Calibrate", draw a line between two points of a known distance, type that distance in metres.
- On elevation pages with more than one elevation drawn on the same sheet, use + Façade to tag each elevation rectangle as FRONT / REAR / LEFT / RIGHT. Windows you draw inside a region will inherit that façade automatically.
- On plan pages, draw a Floor outline tracing the dwelling's internal perimeter. Repeat for each floor — the sum gives the total dwelling floor area. (Or skip and enter the total manually in the right pane.)
- For each bedroom and for the most-glazed room, use + Room polygon to capture floor area + room name. Other rooms don't need polygons.
- On elevations, use + Window box to drag rectangles around each opening pane on every window in turn. Use + Bay window for bay assemblies (asks for centre + side panel dimensions). Measure every window individually rather than duplicating — the small variations between identical-looking windows matter for accuracy.
- For each window, use 📐 Measure on drawing inside the edit dialog to drag rectangles around each glazed pane (excluding the frame).
- Fill in the Dwelling Inputs in the right pane: country, postcode, cross-vent, orientation, most glazed room, number of bedrooms.
- Review the Results panel — each criterion shows Pass / Fail with shortfall, plus an overall verdict.
- Click 📄 Report in the topbar to generate the Word document.
Key concepts
- Page roles. Plan pages host room polygons + floor outlines. Elevation pages host window boxes + façade regions. The "Both" role enables every tool simultaneously for sheets that mix plan and elevation views.
- Snap to vertex. On DXF pages, when you're drawing close to an existing line endpoint or intersection, the cursor snaps to it (orange marker). Lets you measure off the drawing accurately.
- Window types. Side Hung and Top Hung have a calculated opening angle from your reach geometry. Door is for openable doors counted for ventilation (French / patio / bi-fold; the SLIDING half of a sliding door — fixed half is Fixed Pane). Fixed Pane is anything that doesn't open: fixed windows, side-lights next to doors, fanlights, glass in a door leaf, the fixed half of a slider. Hover any option in the Type dropdown for the full guidance.
- Opening vs glazing area. The opening rectangle (A × B) is the openable pane outline; the glazing area is just the glass, excluding the frame. Measure both — opening drives free area, glazing drives solar gain.
- Expert settings. Reaching distance (default 0.65 m), handle-to-window (0.02 m), and discharge coefficient (0.62) are CIBSE / AD-O defaults — change only with a project-specific basis.
What's happening in the background
- Calc engine ported cell-for-cell from the AES Simplified Tool Excel (
Background sheet).
- Opening angle for Side / Top Hung windows comes from the AD-O reach geometry: G98 = (reach − inner-face) + handle ≈ 0.49 m by default. θ = ASIN(G98 ÷ swing-perpendicular-dim).
- Equivalent free area per window = A × B × angle-factor ÷ Cd. Angle factor is aspect-ratio-banded after CIBSE TM59.
- Risk classification from postcode (first half). Manchester M1–M50 override applied per AES house style.
- Report generation runs Pyodide in your browser, populating an AES Word template. The first generation downloads ~10 MB of Python runtime; subsequent ones are instant.
- All processing happens locally in your browser — nothing is uploaded.
Saving and reopening a project
Important: the tool runs entirely in your browser and doesn't auto-save. Click Save in the topbar to download a .aes-oh JSON snapshot of the project (rooms, windows, outlines, inputs, page settings). Save that file into the project's SharePoint folder. Use Load later to resume.
Tip: save after major milestones (initial measurements, draft windows, report-ready). Drawings (DXF / PDF) are NOT embedded in the JSON; re-add them via the topbar after Load.
Tips
- DXF problems? If a drawing looks incomplete or behaves oddly, contact Andrew McManus with the .dxf file and a screenshot of what you're seeing — some architects' export settings produce files our parser can't fully read, and we can usually adjust the tool or advise on a workaround.
- Wrong page role stops the relevant tool button from enabling. Set Role on the left and the tool will activate.
- Click on any annotation (window rect, room polygon, floor outline) on the canvas to open its edit dialog — Delete, Redraw, Rename all available there.
