14 July 2022 · By Fran Williams. Photography by Kilian O'Sullivan

Constructed of cross-laminated timber, The Tree House pavilion is the centrepiece of Elephant Park in south London, part of a wider regeneration scheme led by Lendlease

The park is part of a £2.3 billion regeneration scheme of the former Heygate Estate delivered by Lendlease, where over 3,000 new homes are being created and new public green spaces have been established.

Trees and nature are the inspiration behind the Bell Phillips-designed pavilion, which encircles a mature London plane tree while providing a café kiosk, bookable multifunctional internal space and public roof terrace that takes visitors up into the tree canopy.

Working within the framework of the park, designed by landscape designer Gillespies, the pavilion aims to be a key gateway into the park from Sayer Street.

Two of the volumes house black box functions such as refuse stores, washrooms and plant. Within the third volume, an 18m2 servery kiosk is positioned towards the prominent southern corner of the site. This can be divided into two with the options to serve the Sayer Street entrance, the multifunctional space or both.

To allow for a range of uses and seasonal weather changes, this central space can be closed off to form an internal room or opened to the wider park setting, with the upper terrace to act as an events space for art classes, exhibitions, screenings or an elevated gallery to overlook the programmable events spaces below.

The triangular structure is formed of CLT with sustainably sourced timber cladding and bamboo decking. The concrete slab has been specified with an admixture of ground granulated blast furnace slag and where possible materials have been left untreated and exposed.

The under-construction community pavilion was hit by a fire in August 2021 and the first floor was damaged.

The building seeks to celebrate and enhance the biodiversity of the surrounding park. The Tree House is wrapped around an existing mature London plane tree, one of the 128 trees retained from the site’s previous use. The terrace was a vitally important part of our conceptual design, with a desire to give visitors a new, elevated vantage point on the surrounding landscape. With the movement of the trees and the play of light through the canopy, it will be a quiet and peaceful place to simply detach from the hustle and bustle of everyday life.

To make sure the pavilion and trees were able to co-exist, ground penetrating radar was used to map the tree roots and ensure that the concrete slab and screw piles were laid without causing harm or future damage. The thickness and layout of the concrete raft was carefully designed to minimise impact on the existing tree roots. Above ground, branches were 3D scanned to ensure that the building would not impact adversely on the tree canopy.

The planting design for the roof terrace aids the creation of a vibrant piece of public realm, featuring a selection of herbaceous plants and low mound-forming shrubs that will be able to thrive in half-shaded conditions. The plants will offer structure to the space and seasonal variations in colour.

The materials selected for the pavilion are deliberately natural and unfinished so that they will naturally weather and age over time, bedding the pavilion into the surrounding park. Hari Phillips, director, Bell Phillips Architects

We and the architects wanted to avoid the typical approach: a greenwash construction, where a steel frame, is clad in wood. Instead, the structure was to be intrinsically friendly, open and legible and, as far as possible, unclad. The walls, and roof are formed with CLT panels that are left exposed in the soffit and internal spaces, but these aren’t, in themselves, stiff enough nor strong enough to create the long spans and cantilevers that give the building the sense of floating in the air that Bell Phillips had envisioned.

Concerns about potential overcrowding on the top deck lead to a taller stronger balustrade than we would normally use but gave the opportunity to make this act, not only as a balustrade but as a primary structural element, supporting the long spans and projecting cantilevers. We developed a distribution of the diagonal bars, gently leaning forward and backwards around the perimeter that formed the strutting of a truss, geometrically locking step with regular triangular braces. We always strive for succinct, light solutions and are happy that here the structure exists as a part of the building. Steve Webb, director, Webb Yates Engineers

We are so fortunate to have one of the greatest natural assets within our neighbourhood, the London plane trees, which have been the inspiration behind the architecturally striking and sustainable pavilion at the heart of our green oasis. The team at Bell Phillips has helped bring our vision to life by designing a memorable space that provides the community with somewhere to host events, relax with a coffee, meet friends or just sit and watch the world go by. We hope it will become a much-loved addition to this growing neighbourhood.”

The Tree House at Elephant Park builds on the successes of Bell Phillips’ recent pavilion schemes in Southwark Park and Granary Square, and its flexibility will increase activity in and around the park throughout the year as it hosts various community events and gatherings.

Lendlease aims for Elephant Park to set new benchmarks in sustainable, urban development. And with this in mind, the consideration of embodied carbon led to the choice of the main structure of The Tree House being formed in cross-laminated timber alongside sustainably-sourced timber cladding and bamboo decking. This low-impact approach to construction and fabrication means the building minimises embodied carbon, and its operation has a similarly low-impact effect on the environment.

Kristy Lansdown, project director, Lendlease

Start on site December 2021 Completion June 2022 Gross internal floor area N/A Gross (internal + external) floor area 135m² Construction cost Undisclosed Architect Bell Phillips Architects Client Lendlease (Elephant & Castle) Planning consultant DP9 M+E consultant Ritchie + Daffin Structural engineer Webb Yates Arboricultural consultant Treework Environmental Fire consultant The Fire Surgery Quantity surveyor Gardiner Theobald Lighting consultant Speirs + Major Landscape designer Gillespies Access consultant Lord Consulting Building control Southwark Building Control Main contractor Charles Edwards/Hybrid Structures CAD software used Revit

Percentage of floor area with daylight factor >2% 100% of relevant spaces (multi-purpose space) Percentage of floor area with daylight factor >5% 85% of relevant spaces (multi-purpose space) On-site energy generation Nil Annual mains water consumption 1.71 m3/occupant (doesn't include park irrigation and waterplay) Airtightness at 50Pa Estimated 3 m3/h.m2 Heating and hot water load 67 kWh/m2/yr Overall area-weighted U-value 0.6 W/m2K (walls, floor, roof) Embodied/whole-life carbon –73,863 kgCO2eq/m2 Annual CO2 emissions 23.1 kgCO2eq/m2

Tags Bell Phillips Architects Elephant Park Pavilion

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