One Undershaft, or the Trellis as it is less formally known, forms a part the most recent tranche of proposed building developments in the City of London. At a height of 309.6 metres (1016 feet), the same height as the Shard [1], it seeks to challenge the Shard’s dominance of the London skyline, becoming its larger and more box-like dramatic foil to the North of the river. It has, however, been hit with an objection owing to the loss of daylight to surrounding green space.
To see images of the proposed building development, click here.
St Helen’s Square
St Helen’s Square is the outdoor area at the centre of the dispute. It is a popular area for workers in the district to meet and take lunch, and serves as valuable open space in an increasingly built up area. It is furthermore one of “few places” left in the City of London where “sunlight actually reaches the ground” [2], although the plans for the Trellis place this ideal into jeopardy. The overshadowing would be caused partly by the height of the building, but exacerbated by plans for a podium garden jutting out from the 10th floor of the building, which overhangs the square.
What Does the Guidance Say?
Guidance regarding daylight, sunlight and overshadowing is given in a document prepared by the Buildings Research Establishment (BRE) [3]. For outdoor areas the recommendation is that at least half of outdoor gardens and amenity space in the vicinity of development should receive at least two hours of sunlight at ground level on March 21st. There is a further recommendation that the proportion of any garden or open space which receives 2 hours of direct sunlight on March 21st should be at least 80% of its former proportion. The limitation of this guidance is that it is guidance and ‘amenity space’ is quite loosely defined. In this case the conflict has arisen because St Helen’s square has not been assessed as part of the overshadowing assessment [4]. Many people who live and work in the vicinity have raised objections on the grounds that it is one of few such spaces that do have access to a decent amount of sunlight [5].
Why not Break a Record?
The eagle-eyed observer might at this point be wondering why, if Eric Parry Architects are already going to the effort of designing a building of this height, they don’t break the record for the tallest building in the UK by simply altering the design to make it a few centimetres taller. The reason for this is that the proposed building height of 309.6 metres is the maximum height possible without infringing airspace.
There is an area of airspace above central London with a minimum flying altitude of 609.6 metres (2000 feet), one of the surveillance minimum altitudes at Heathrow to be more precise [6]. There is a requirement of 300 metres clearance of this altitude, giving an absolute building height limit of 309.6 metres for all buildings in this region. We therefore don’t expect any buildings to break this UK height record any time soon – not in central London at least.
Pager Power
Pager Power now offers Daylight, Sunlight and Overshadowing Assessments, to help you ensure that your development doesn’t come up against this same roadblock. Click here to find out more.
For tall developments, Pager Power undertakes Aviation Assessments to ensure your development can coexist with nearby aerodromes. Click here to find out more.
References
[1] Joshua Oliver and Ian Smith (2024) “City of London Delays Decision on New Tallest Building” Financial Times, July 2. Available at: https://www.ft.com/content/533a4dd2-8143-4f39-b59d-af8e2e30394d. Accessed July 15, 2024.
[2] Jen Mills (2024) “New London skyscraper as tall as Shard in doubt over sunlight and packed lunches” Metro, July 3. Available at: https://metro.co.uk/2024/07/03/new-london-skyscraper-tall-shard-doubt-sunlight-packed-lunches-21150824/?ito=article.mweb.share.top.link. Accessed July 15, 2024.
[3] Buildings Research Establishment. (2022). Site layout planning for daylight and sunlight: A guide to good practice. Third Edition.
[4] 1 Undershaft DSO Assessment, Overshadowing. Available at: https://www.planning2.cityoflondon.gov.uk/online-applications/applicationDetails.do?activeTab=documents&keyVal=S6C4BQFHGT700. Environmental Statement Volume III: Appendix 12.4 – DSOAccessed July 15, 2024.
[5] City of London, Comments for Planning Application 23/01423/FULEIA. Available at: https://democracy.cityoflondon.gov.uk/documents/s205000/ Full%20Public%20Comments%20PDF%201%20Undershaft%20-%20reduced.pdf. Accessed July 15, 2024.
[6] NATS AIS AIRAC 07/24. Heathrow Airport Chart 5-1. Available at: https://nats-uk.ead-it.com/cms-nats/opencms/en/Publications/AIP/. Accessed July 15, 2024.
Thumbnail image accreditation: Charlie Harris (2022) from Unsplash.com. Last accessed on 16.07.2024. Available at: https://unsplash.com/photos/a-view-of-a-city-with-tall-buildings-XPOuUuUp3_4
