21b, Chiltern Street, Aylesbury, HP21 8BN

21b is a two-bedroom semi-detached house in Aylesbury (HP21 8BN). It has a recorded floor area of 40 m² (around 431 sq ft), construction records dating it to 1967-1975 and council tax band A. At 40 m² this is the smallest unit on EPC record across the building (40–179 m²). The building's EPC ratings span E to C, with this unit at the bottom. The latest certificate (July 2012) shows an E (score 50), well below the UK norm with real room to improve. The recommended improvements would lift it to C (score 72), a 2-band jump. Main heating runs on electricity. The latest certificate is from July 2012, so improvements made since then won't be reflected.

At 40 m² it sits well below the postcode median (68 m² across 17 EPCs), making it one of the more compact homes locally. It lags the bulk of the postcode on energy efficiency (less efficient than 71% of similar EPCs). Last changed hands 10 years ago, in April 2016. Across the public record there are 4 sales, relatively high churn for a single property. Across 1999–2016, sale prices on this property compounded at 5.8% per year. Today's modelled estimate of £141,000 is 28.2% above the 2016 sale price. On a £-per-square-foot basis, the last sale (£255/sq ft) was about 32.6% above the typical sold price in the postcode.