Opal House, Flat 13, 4 Merrivale Mews, Milton Keynes, MK9 2EL

Opal House is a two-bedroom semi-detached house in Milton Keynes (MK9 2EL). It has a recorded floor area of 62 m² (around 667 sq ft), construction records dating it to 2007 onwards and council tax band C. At 62 m² this is the 6th smallest of 25 units on EPC record in Opal House, where floor areas span 52–70 m². The building's EPC ratings span C to B, with this unit at the bottom. On EPC score it ranks last in the building (75 versus a best of 88). Other recorded features include a balcony. The latest certificate (July 2020) shows a C (score 75), near the top of the C band. Earlier certificates rated it B (July 2009); the latest reading is one band lower. Between certificates, lighting went from Average to Very Good; while window efficiency dropped from Very Good to Good and hot-water efficiency dropped from Very Good to Good.

It hasn't traded since July 2009, a hold of 17 years that's notably long for the area. That sale fell during the post-crash dip, which often skews comparisons against later neighbouring sales. It lags the bulk of the postcode on energy efficiency (less efficient than 72% of similar EPCs). Today's modelled estimate of £195,000 is 25.8% above the 2009 sale price. On a £-per-square-foot basis, the last sale (£232/sq ft) was about 18% below the postcode norm.