Arup turfs out tiles

As part of British Land’s Biodiversity Programme, Arup is conducting an experimental ‘green roof’ design trial with a focus on biodiversity, from the roof of its London headquarters. The progress of the trial will be closely monitored to help inform the future design of green roofs.

Green roofs are organic roof covers on which vegetation is planted in place of traditional tiles and other coverings. As well their aesthetic value in urban environments, proponents say green roofs can help improve water retention, reduce dust, smog and noise levels, increase the life expectancy of a roof, improve thermal insulation and provide a natural habitat for animals and plants.

Arup’s 24m² design trial comprises twelve 2 metre by 1 metre plots. Each plot comprises four different substrate materials including the existing roof shingle and an extensive, commercially-available green roof system. The depth and amount of organic materials used is also varied in each plot. Any difference discovered between the developing vegetation may help to answer questions on the relative success of each of the mediums, both from an aesthetic viewpoint and in terms of their eventual contribution to biodiversity.

The aim of the trial is to test and report on the logistics of a retro-fit green roof and the use of substrate types, including recycled materials, as an alternative to commercially available green roof products.

Designed to aid in biodiversity, the trial is tailored to enhance its local ecological value, particularly in the provision of a habitat attractive to black redstarts, a protected bird species present in the local area.

The system has been designed with regard to existing roof composition and weight-bearing capacity, seeded with a cornflower and London-based wildflower meadow mix, and planted with a small number of plug plants for instant ‘greening’.

British Land is planning to provide a green roof on its new headquarters in London, the York Building, as well as for other development projects.