London office building boom: planning, viability and retrofit notes for engineers
Reviewed by Tom Sullivan

First reported on The Construction Index
30 Second Briefing
Changes to London’s planning system to prioritise office redevelopment could unlock £262bn of investment and an £84bn economic boost, with the London Property Alliance and Knight Frank warning of an 11 million sq ft office shortfall over the next five years in the central activities zone. Some 147 million sq ft – 56% of central stock – is “secondary” space likely to miss 2030 sustainability standards, while prime and Grade A vacancy is at 0.8% and 1.7% respectively and only 12 single floors above 40,000 sq ft remain. Developers cite rising construction, labour and finance costs plus expanding planning obligations as tipping many retrofit and rebuild schemes into non-viability.
Technical Brief
- Between 2018–2023, 14 million sq ft of office space was removed from the CAZ.
- CAZ geography broadly matches London Underground Zone 1, concentrating redevelopment in highest‑value, highest‑constraint locations.
- Some 147 million sq ft of “secondary” stock is expected to breach mandatory 2030 sustainability requirements.
- Only 12 single office floors above 40,000 sq ft remain available for large corporate consolidation.
- Active occupier requirements total 10 million sq ft, driven mainly by financial and professional services.
- Pipeline delivery is 15.4 million sq ft for 2025–2029, much of it already pre‑let or non‑core.
- Developers identify rising construction, labour and finance costs plus expanding planning obligations as the key viability drag.
- London Property Alliance seeks to classify major offices as “economic infrastructure” to justify streamlined planning and regulation.
Our Take
With only 0.8–1.7% availability in prime and Grade A stock against a projected 11 million sq ft shortfall, central London is moving into the kind of supply-constrained environment that, in our infrastructure coverage, typically accelerates deep retrofit programmes rather than pure new-build pipelines.
The 147 million sq ft of secondary space in London’s CAZ gives owners such as Landsec and Grosvenor Property a large pool of candidates for ESG-led refurbishment; in our database, similar sustainability-tagged office pieces often flag tightening energy-performance rules as a key driver for upgrading this type of stock.
A 15.4 million sq ft delivery pipeline versus 10 million sq ft of active requirements suggests that timing and specification risk will be critical for London Property Alliance members, as late-cycle completions that miss top-tier sustainability or amenity benchmarks tend to be discounted in other UK office markets we track.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
Related Articles
Related Industries & Products
Construction
Quality control software for construction companies with material testing, batch tracking, and compliance management.
Mining
Geotechnical software solutions for mining operations including CMRR analysis, hydrogeological testing, and data management.
QCDB-io
Comprehensive quality control database for manufacturing, tunnelling, and civil construction with UCS testing, PSD analysis, and grout mix design management.


