The Museum of London opened in 1976 on the historic London Wall and is a few minutes’ walk from St Paul’s Cathedral. A visionary approach to roofing had been adopted on a building that, will not only green as much of the exposed roofs as possible, but also provide a strong research aspect for future green roof projects. As with many buildings, the original roofs needed to be upgraded or replaced, at the same time as being brought up to date using environmental and sustainable solutions.

Through the recommendation of waterproofing and green roof manufacturer Bauder Ltd, the Museum invited Dusty Gedge, one of the UK’s leading independent green roof consultants, to work directly with them to design 3500m² of varying habitats that encompassed the museum’s sustainable vision and help in the provision of environments that would attract a range of wildlife, as well as being able to help the city adapt to climate change.

The specification

An independent consultant had previously carried out an energy model on the Museum of London buildings. When the museum inputted the green roof specification, it showed a potential energy saving of 10% per year, as well as a reduction on the future replacement costs of the heating and cooling plant. 

Some of the green roofs were funded through Drain London, a partnership project led by the Greater London Authority and funded by Defra. The project aims to better understand surface water flood risk across London, with a view to promote interventions (such as green roofs) to reduce surface water flooding. The museum has used the Bauder green roof system and worked closely with Dan Costen of Bauder and the roofing contractor Russell Trew Ltd, to deliver the various green roof spaces.

These include:

• The refurbishment of the lower garden in the central courtyard with hard landscaping
• The installation of Bauder’s new wildflower blanket to the upper garden in the central courtyard (funded through Drain London)
• Plug planting the roofs of the recently completed garden and terrace rooms that provide high-quality corporate hire (matching the colour scheme chosen for the rotunda garden refurbishment and integrated with the new rainwater harvesting system funded by Renaissance London)
• An integrated sustainable urban drainage system (SuDS)
• Plug planting in other individual small roof areas including outside the boardroom and committee rooms
• Two different planting schemes on an area of the main museum roof where the Drain London Project aims to carry out water attenuation research

The result

Retrofitting green roofs will help to realise the Mayor of London’s ambition, to increase green cover in central London by 5% by 2030. The Museum of London is one of the largest retrofit green roof projects in the City and is certainly to be commended for allowing its roofs to be used for research purposes. Not only will it provide a benchmark for best practice, but it also demonstrates that retrofitting green roofs onto existing buildings is both environmentally and economically viable and is the way forward in helping London adapt to climate change.

Bauder Total Green Roof System (BTGRS) with XF 301 Sedum System

Advocacy

Gavin McCourt MRICS, Project Manager for The Museum of London said:

“In producing the business case for installing green roofs, reference was made to the extensive published documents on the benefits of green roofs. In this case as the museum building had already been energy modelled by outside consultants, it was decided to input the green roof specification into the model. The results showed a potential energy saving of 10% per year, as well as a reduction in future replacement costs for heating and cooling plant. These factors, combined with the longer life cycle replacement of green roofs compared with normal felt roofing systems, enabled me to produce a robust business case for green roofs. With increasing energy prices the economic benefits of installing green roofs can only become more viable.”

Dusty Gedge added:

“One of the major issues that London faces is flash floods during the summer, when sudden rainfall levels overwhelm the current drainage network. With the support of Drain London we will be researching the rainwater run-off for different green roofs. This will help us validate the kind of roofs and depth of substrates that will negate the costly effects that the sudden rainfall has on the infrastructure of the City.”