A series mining the PhD thesis on London and UK office buildings (Azhari, 2025). Key takeaway. There is no single answer to what is a building in UK data: four agencies keep four definitions, and stock-level energy work has to build a synthesis, the Self-Contained Unit.
Most risk-of-ruin Monte Carlo resamples a strategy's realised P&L, which quietly bakes in the good luck you are trying to stress and understates the tail. Here is the correction that made my honest drawdown distribution far fatter than my first one, plus the relative gate a long-only sleeve actually needs. First person, British English, illustrative numbers only.
A series mining the PhD thesis London and UK Office Buildings: Investigating Energy Use and Landlord-Tenant Influences (Azhari, 2025). Random Forest and a simple linear regression finished in a statistical dead heat on electricity EUI, so interpretability tipped the decision to the simpler model.
Everyone sells walk-forward validation as proof a strategy is out-of-sample. It is not. I ran my own walk-forward pipeline on pure random-walk noise and it still produced a healthy positive stitched Sharpe, because out-of-sample is a property of provenance, not partitioning. Here is the random-walk control that tells you whether your pipeline, or your edge, produced the number.
A series mining the PhD thesis on London and UK office buildings (Azhari, 2025). Key takeaway. Hybrid work did not deliver the linear energy saving the headlines implied: some demand shrinks when occupancy drops, base-building load holds steady, and fresh-air ventilation actually grows.
Look-ahead bias is the default state of careless backtest code, not an exotic edge case, and it survives review because it reads as ordinary pandas. Here is the corrupt-the-future causality test I now gate on: poison every price after a date, then assert nothing computed before it moves. If the past shifts when you poison the future, the strategy is reading ahead.
A series mining the PhD thesis on London and UK office buildings (Azhari, 2025). Key takeaway. Greater London holds 30 per cent of office floor area and 24 per cent of office premises in England and Wales, which makes it a clean proxy for some questions, a misleading one for others, and a context-dependent proxy for many.