Watch O-Monkey check a house type against Part O

108-second demo · silent screencast, captions included · the free Part O overheating checker

A Part O overheating assessment done in O-Monkey: the start screen, the postcode risk band, the glazing budget, one clear answer, the home from above, Appendix D and the 650 mm handle rule on a window, a house built facing east that fails and the one-tap MHCLG FAQ 2 fix that passes it, every direction and every plot, a pasted window schedule, and the Building Control report.

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What happens in the video, second by second

The clip has no narration, so here is the whole thing written out — the same text is on the video as a caption track. Every figure below is what is actually on screen at that moment.

  1. 00:00 O-Monkey opens. O-Monkey opens on a start screen with one question: what are you checking, a house or a flat?
  2. 00:03 The simplified method. It works through the simplified method of Approved Document O, in the browser.
  3. 00:07 The postcode sets the risk band. “A house”, then the postcode BH16 6HX: the chip reads “Moderate risk · BH16”. All 207 high-risk London postcode districts of Appendix C are built in.
  4. 00:11 The floor area. The floor area of the whole home: 88 m².
  5. 00:13 The reveal depth. The reveal depth, 150 mm: how far the frames sit back from the inside face of the wall, which sets the 650 mm handle rule.
  6. 00:15 Which way the front faces. The house picture turns to match the site plan: tapped to south-east, then south. The hint reads “Front faces south (S)”.
  7. 00:20 Start from a typical home. “Start from” offers a 3-bed semi, a 2-bed terrace, a 4-bed detached house or a 2-bed bungalow, a blank start, or a schedule imported from Excel, a .csv file or a PDF. The 3-bed semi puts in its seven rooms and seven windows.
  8. 00:25 The glazing budget. Before a window is drawn, “Your glazing budget” shows 9.68 to 15.84 m² of glass, by the way the most glazed side faces, and at least 7.92 m² of opening area.
  9. 00:30 One clear answer. The finished semi, the worked example, gives one answer: Passes, with 12.60 m² of glass against 15.84 m² allowed and 7.98 m² of opening area against 7.92 m² needed.
  10. 00:34 Every check at a glance. Under the gauges: all three bedrooms pass, the kitchen/dining room is the most glazed room at 24.2% against a 37% cap, and all four plots pass.
  11. 00:38 The home from above. The home from above, at the top of the windows step: the glass on each side — 6.90 m² at the back, facing north, and 5.70 m² at the front, facing south — and a tap on a side adds a window there.
  12. 00:43 Appendix D for every window. Window 1, a pair of 600 × 1200 mm casements in the living room, opens to show how it swings: 1.13 m² of equivalent area from Appendix D.
  13. 00:46 The 650 mm handle rule. The plan shows the handle stopping at the 650 mm line, so the window counts at 56.4°, not 90° (para 3.9a, MHCLG FAQ 15).
  14. 00:52 Built facing east. The front is turned to face east.
  15. 00:53 It fails. Facing east, the most glass faces west: the limit falls to 11% (9.68 m²) and the most glazed room’s cap to 22%. The answer reads “2 checks fail”.
  16. 00:56 The one-tap fix. The one-tap fix: shade the glass facing north-east round to north-west via south (solar-control glass on 9 windows) and use the high-risk glazing limits, as MHCLG FAQ 2 allows.
  17. 01:01 Passes again. Apply: it passes, and the answer keeps the change listed under “Changed by O-Monkey”, with Undo.
  18. 01:05 Every direction. Back on the worked example, Show the working opens the every-direction ring: the semi passes facing 11 of the 16 compass points and fails facing north-east round to south-east, on whole-home glazing and the most glazed room.
  19. 01:11 Every plot in its own direction. The plots: Plot 12 facing south, Plot 13 south-west and handed, Plot 14 west and Plot 15 north — all four pass.
  20. 01:15 Paste a window schedule. “Import a window schedule” takes five rows pasted from Excel.
  21. 01:18 Columns read, guesses flagged. O-Monkey maps the columns — ref, room, floor, elevation, type, frame size, glass — and the preview flags what it had to guess: opening sizes taken from the frame, and a 100 mm restrictor read from the description.
  22. 01:24 The Building Control report. Back at the answer: “Get the report · £25 +VAT”.
  23. 01:28 Appendix B filled in. Report pages 1 and 2: the summary and the checks, then Appendix B Part 1 and Part 2a filled in, with Part 3 left for the builder and the building control inspector.
  24. 01:33 Rooms, windows, directions, plots. Pages 4 and 5: the room and window schedules with the Appendix D method on every window, then the every-direction table and the plots.
  25. 01:37 £25 +VAT, verifiable. £25 +VAT per house type, every plot included, with a Report ID that Building Control can verify.
  26. 01:42 End card. Closing card — O-Monkey: do your own Part O overheating assessment. energycount.co.uk/tools/part-o-overheating-checker.

What you're seeing

Everything in the clip is free in your browser, with an i beside every box and picture how-tos for the questions people get stuck on. You only pay to export the Building Control report: £25 +VAT per house type, every plot included.

Full detail — method, standards, pricing and FAQs — is on the O-Monkey page. The clip moves quickly, so if you would rather follow it at your own pace, the box-by-box O-Monkey how-to covers every step in the video and the parts that did not fit into 108 seconds.

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O-Monkey works exactly like the clip — free in your browser, no account. Open it and try your own numbers.

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