Flat 4, 88 Onslow Gardens, London, SW7 3BS

Flat 4 is a one-bedroom mid-terrace house in London (SW7 3BS). It has a recorded floor area of 61 m² (around 657 sq ft), construction records dating it to before 1900 and council tax band F. At 61 m² this is the 2nd smallest of 5 units on EPC record in the building, where floor areas span 56–224 m². The building's EPC ratings span E to C, with this unit at the bottom. On EPC score it ranks last in the building (51 versus a best of 78). The latest certificate (November 2018) shows an E (score 51), well below the UK norm with real room to improve. The rating has held steady at E across 2 certificates since November 2008. Between certificates, wall efficiency went from Very Poor to Poor and lighting went from Very Poor to Average; while hot-water efficiency dropped from Poor to Very Poor. The recommended improvements would lift it to B (score 84), a 3-band jump. Main heating runs on electricity.

It hasn't traded since August 2005, a hold of 21 years that's notably long for the area. Across 1996–2005, sale prices on this property compounded at 12.8% per year. Today's modelled estimate of £832,000 sits 88.9% above the 2005 sale of £440,388. On a £-per-square-foot basis, the last sale (£671/sq ft) was about 35.8% below the postcode norm. It lags the bulk of the postcode on energy efficiency (less efficient than 85% of similar EPCs).