25a, High Street, Sutton, SM1 1DJ

25a is an end-of-terrace house in Sutton (SM1 1DJ). It has a recorded floor area of 17 m² (around 183 sq ft), construction records dating it to 1976-1982 and council tax band D. At 17 m² this is the smallest unit on EPC record across the building (17–58 m²). The building's EPC ratings span E to D, with this unit at the bottom. On EPC score it ranks last in the building (39 versus a best of 67). The latest certificate (March 2021) shows an E (score 39), well below the UK norm with real room to improve. Earlier certificates rated it D (July 2014); the latest reading is one band lower. Between certificates, wall efficiency went from Very Poor to Average, roof efficiency went from Very Poor to Poor and window efficiency went from Poor to Average; while hot-water efficiency dropped from Average to Very Poor and main heating dropped from Good to Very Poor. The recommended improvements would lift it to C (score 72), a 2-band jump. Main heating runs on electricity.

Across 2017–2018, sale prices on this property compounded at 36.8% per year. Today's modelled estimate of £271,000 is 83.1% below the 2018 sale of £1,600,000, an unusual pattern given regional price growth and worth checking against the EPC condition. On a £-per-square-foot basis, the last sale (£8,744/sq ft) was about 5891.6% above the typical sold price in the postcode. At 17 m² it sits well below the postcode median (46 m² across 7 EPCs), making it one of the more compact homes locally. It lags the bulk of the postcode on energy efficiency (less efficient than 86% of similar EPCs). Sold September 2018 for £1,600,000.