House Prices per Metre² in England & Wales

[0.2.0] — 2026-03-19

Data vintages

Source	v0.1.0	v0.2.0
HM Land Registry PPD	to Jan 2026 (~22.5M rows)	to March 2026 (~29.3M rows)
EPC bulk export	per-LA ZIPs, epc.opendatacommunities.org	single monolithic CSV, get-energy-performance-data.communities.gov.uk (March 2026)
UBDC PPD→UPRN lookup	unchanged — covers to Jan 2022	unchanged
ONS CPI	D7BT Jan 1988–Jan 2026	unchanged

The EPC source changed to the new MHCLG GOV.UK One Login API which delivers a single 5.7 GB CSV assembled from all local authority feeds. Four CSV parsing issues were encountered and fixed; see research/epc-csv-data-quality.md.

Methodology changes

CPI price deflation — real Jan-2026 £/m²

All sale prices are now inflation-adjusted to January 2026 pounds before aggregation, using the ONS CPI All Items monthly series (series ID: D7BT, Jan 1988–Jan 2026, OGL v3.0). The adjustment converts each transaction price to real terms: adjusted_price = price × CPI[Jan-2026] / CPI[sale_month].

This avoids mixing 1995 pounds with 2024 pounds in the same aggregate. Postcode districts where most sales occurred before 2010 were systematically understated in nominal terms; the real-terms figure makes districts comparable regardless of when their housing stock turned over.

The headline column in both output CSVs is now adj_price_per_sqm (real Jan-2026 £/m²). The nominal price_per_sqm is retained as a reference column.

• Research note: research/cpi-deflator-choice.md
• Issue: #67 | PR: #72

New and changed output columns

Column	Type	Description
adj_price_per_sqm	int	Headline. Real Jan-2026 £/m² (CPI-adjusted)
price_per_sqm	int	Nominal £/m² at time of sale — retained for reference

Match statistics

Tier	Count	Share
Tier 1 — UPRN exact match	9,255,768	31.6%
Tier 2 — address normalisation	7,321,554	25.0%
Unmatched	12,705,953	43.4%
Total PPD sales	29,283,275

The match rate dropped from 76.9% (v0.1.0) to 56.6%. This is structural: the PPD gained ~6.8M rows (all post-Jan 2022 transactions) that fall outside the UBDC UPRN lookup's coverage window. The absolute number of matched records is broadly unchanged (~16.6M vs ~17.3M). See research/uprn-coverage-in-epc-data.md for a detailed breakdown.

Summary statistics (postcode district, 2,277 districts)

Metric	Value
Districts included	2,277
Total matched sales	16,577,322
Median real adj price	£3,058/m²
Most expensive district	W1S — £35,462/m² (real Jan-2026)
Least expensive district	TS2 — £733/m² (real Jan-2026)
Top 5 district rankings	W1S, WC2A, WC2R, W1B, W1K — stable vs v0.1.0
Bottom 5 district rankings	TS2, TS1, BD3, CF43, DN31 — stable vs v0.1.0

Key commits and PRs

Commit / PR	Description
PR #72 ebe8619	CPI inflation adjustment
PR #78	EPC download: migrate to new MHCLG API
4e09bf1	fix: atomic download — no partial file on interrupt
bc2e1a5	fix: strict_mode=false — handle backslash-escaped JSON in EPC CSV
943efbe	fix: pin quote/escape — prevent single-quote column misdetection
6630a73	fix: null_padding=true — handle short/stub rows
fed70dd	fix: parallel=false — allow null_padding with quoted newlines
f6ff4ab	perf: two-pass EPC dedup to stay within 2 GB memory limit

---

[0.1.0] — 2026-03-19

First versioned release of the UK house price per m² analysis.

Data sources

Source	Coverage	Licence
HM Land Registry Price Paid Data	Standard residential sales to individuals, Aug 2007–Jan 2026	OGL v3.0
DLUHC Energy Performance Certificates	All domestic lodgements, England & Wales	OGL v3.0
UBDC PPD–UPRN lookup	Transactions up to Jan 2022	Open data, University of Glasgow
GeoLytix postcode district boundaries	—	OGL v3.0

Methodology

1. Sale selection

Transactions are filtered to standard residential sales to private individuals (transaction_category = 'A'). New-build and established property are both included. Leasehold and freehold are both included.

2. EPC–sale matching (three tiers)

Tier 1 — UPRN exact match Each sale is joined to the UBDC Price Paid–UPRN lookup table (doi:10.20394/agu7hprj), which provides a Unique Property Reference Number for transactions up to January 2022. That UPRN is then joined to the EPC register to retrieve the most recent certificate lodged _before or on the sale date_. This is the highest-confidence tier.

Tier 2 — Address normalisation match For sales after January 2022 (where no UPRN link exists) and for any earlier sales that failed tier 1, the sale address is normalised: sub-address, building name/number, and street name are concatenated and lowercased, punctuation stripped. The normalised string is matched against the same normalised form in the EPC register, restricted to the same postcode. The most recent EPC before the sale date is selected.

Tier 3 — Postcode fallback Remaining unmatched sales are assigned the median floor area of all EPCs within the same postcode. This tier is lower confidence and flagged in the data.

_Temporal selection note:_ in all tiers, the EPC selected is the most recent certificate lodged on or before the sale date. This avoids using post-sale improvements to infer the floor area at the time of sale.

3. Aggregation

Price per m² for each postcode district is computed as:

price_per_sqm = Σ(sale_price) / Σ(floor_area_m²)

This is a value-weighted aggregate — not a mean of per-property ratios — so that large properties contribute proportionally to the result.

Districts with fewer than 10 matched sales are excluded from the output.

4. Output

• price_per_sqm_postcode_district.csv — primary output: one row per postcode district
• price_per_sqm_lsoa.csv — LSOA-level aggregation (experimental)
• postcode_districts.geojson — boundary-joined GeoJSON for the web map

Key commits (reproducibility)

To reproduce this analysis, check out commit da82e13 (the HEAD at time of release) and follow the pipeline instructions in PLAN.md and CLAUDE.md.

Commit	Description
91920ab	Initial pipeline setup
31aeb42	First full pipeline run — outputs committed
cee3740	Add tier-3 normalisation (address-string matching)
8929d3b	Regenerate CSVs incorporating tier-3 matches
30ef34a	Confirm UBDC lookup coverage ends at Jan 2022
049aa57	Add output page with choropleth map
da82e13	Temporal EPC selection in tier-1 join (HEAD at v0.1.0)

Summary statistics (at release)

Metric	Value
Total sales	22,503,694
Matched with floor area	~77%
Districts included	2,279
Median price per m²	£1,986
Data range	Aug 2007–Jan 2026
Most expensive district	W1S — £24,184/m²
Least expensive district	TS2 — £504/m²