The planned renovation of the Palm House and Waterlily House at the Royal Botanic Gardens (RGB), Kew aims to create the first heritage net-zero glasshouses of their kind, conserving two iconic heritage buildings while radically adapting the engineering for a more sustainable future.
Constructed between 1844 and 1848 employing techniques derived from the shipping industry, the Palm House epitomised innovative technology. Complementary to the Palm House, the Waterlily House was built in 1852 and was specifically designed to exhibit Victoria amazonica, the world’s largest waterlily. Both buildings are currently exhibit significant signs of deterioration, and without intervention, the listed buildings and tropical plants they safeguard risk permanent loss. Since its opening, the Palm House has undergone regular restorations, primarily driven by the adverse effects of high humidity and inadequate ventilation on the structure. The most recent restoration was undertaken in the 1980s.
RBG Kew’s aspiration to modernise the heritage landmarks into the 21st century requires pioneering sustainable engineering. With the ambitious goal of achieving net zero, the renovation projects presents an opportunity to once again position the iconic Palm House at the forefront of innovation.
Currently powered by inefficient 1980s gas boilers, the Palm House’s transition to renewable energy sources and the protection of the 1300 plants it houses represent a significant milestone in its storied history. To accomplish this ambitious goal, the needs of horticulturists, engineers, and architects must be harmoniously balanced, a challenge that has not previously been undertaken for a building of this magnitude.
“This is a pivotal moment in the history of Kew. With sustainability at the core of our mission, this project exemplifies our commitment to safeguarding both the environment and cultural heritage. The transformation of the Palm House and Waterlily House into net-zero icons will not only protect irreplaceable plants but serve as a beacon of what sustainable heritage can achieve,” says Richard Deverell, Director of RBG Kew.
The redevelopment is being led by the Kew Capital Projects Team who, together with Hugh Broughton Architects and Cundall engineers, have undertaken years of rigorous testing to strike the difficult balance between energy efficiency and the specific needs of the tropical plants housed within. According to Kew, along with the conservation architects, Historic England, and other advisors, will ensure that the Victorian charm of buildings will be preserved and historic fabric respected.
Some of the kew features of the planned renovation includes: replacement of 16,500 glass panes with high-performance sealed glazing; use of bespoke silicone gaskets to reduce heat loss; fully electrified air and water source heat pump system; maximised rainwater storage and irrigation system upgrade; and sensitive conservation of original materials and finishes.
The relocation and propagation of plant specimens by Kew’s horticulturists has started. Although the project is not anticipated to commence until 2027, lasting approximately four to five years, visitors to the Palm House will already see specialised work in repotting, air-layering, and relocating plants to ensure the survival of over 1,000 plant species housed within. Two state-of-the-art glasshouses, one permanent and one temporary, have been constructed for the cultivation of tropical plants, each employing advanced systems to manage temperature, humidity, and lighting more sustainably.
Tom Pickering, Head of Glasshouse Collections at RBG Kew, explains: “At the heart of this project is the need to protect the extraordinary plant collections housed in the Palm House and Waterlily House. Besides being beautiful, many have cultural, scientific and conservation value, and replacing these collections is unimaginable. Achieving net zero in these historic buildings is an unprecedented task, it’s a complex challenge which must consider the interplay of horticulture, climatic control, engineering, and architecture.”
Hugh Broughton, Hugh Broughton Architects,added: “The Palm House and Waterlily House at Kew Gardens are instantly recognisable icons of Victorian innovation. This exciting project will help to conserve and decarbonise these inspiring glasshouses and make them more accessible to a wider audience. The design elegantly reflects Kew’s ambitious Climate Positive 2030 strategy, reminding us of the fragility of the rainforests and our role in their protection.”
This ambitious project is expected to cost in the region of £60 million. According to RBG Kew they have raised a third of the capital required for the renovation from organisations such as Defra, Julia Rausing Trust, World Monuments Fund Britain and is now seeking support for the remaining funds. Donations received from their appeal will directly support the renovation of the Palm House and Waterlily House.
