Tag Archives: Green Roofs

Making & Growing

This section of the MakingLewes site is about making and growing, the connections between the two, and their integration with buildings and the built environment.

You can find information on these pages about green roofs and rooftop urban agriculture and also currently less known approaches, for instance Zero Acreage and Building-Integrated Farming.

This whole aspect of the natural world, and particularly urban food production, integrated into the buildings and built fabric has been a fast developing field of activity in the last few years, so Making & Growing aims to document, reference and inspire through a set of wide-ranging examples of what’s going on out there.

A partial spur to this section is that Lewes, through organisations like CommonCause and TransitionTown Lewes, has been more directly involved in parts of this conversation than many towns of a comparable size and scale. Even though the town is relatively small, having been a pioneer of farmers’ markets, local produce and other food related initiatives, Lewes could grow this story, making next steps towards integrating leading edge urban agriculture and green infrastructure into both old and new parts of the town’s fabric, particularly in the various industrial and public buildings and public spaces. If Lewes is close to farmed, and produce growing land that doesn’t need to close down the potential for greening the town’s built fabric. And of course this doesn’t even begin the discussion about turning Tesco’s roof space into an organic urban food-growing laboratory…

We hope, therefore, you find this Making & Growing section nourishing food for thought and action.

Green Roofs – Gardens in the Sky

Green roofs have become increasingly popular in the last years, seen as an easy and accessible way to add ecological value to building projects. When in full bloom, as well as many other times in the year, green roofs can also make a world of difference, turning grey into vibrant colourful cityscape rooflines, acting as air pollution filters, absorbing water run-off, and easing temperatures.

On the continent, particularly in the German-speaking world (Germany, Austria and Switzerland), green roofs have long been part of the roofed landscape, first developing in the 70’s and 80’s. More recently the US, Canada, Japan and Singapore have seen a sharp uptake in green roofs. In Germany by 2001 over 40% of councils were offering incentives for green roofs. By comparison Britain has been slower to take on green roofs, although interest has grown in recent years. One estimate concluded there was 200 million square metres of roof-space that could be adopted to green roof use with either no or only small changes needed.

Primary benefits

There are various benefits to green roofs, with primary environmental benefits including:

  • Reducing rain and storm water run-off, generally in tandem with a sustainable urban drainage system
  • Reducing energy use: green roof improves insulation and lessens energy requirements
  • Increasing biodiversity:  with less and less ‘on ground’ suitable habitats, green roofs can mimic some biodiversity habitats and needs
  • Improving air quality and improving water quality: can help remove airborne particles, heavy metals and volatile organic compounds from the local atmosphere, which also helps with water quality.
  • Creating a more pleasant environment, particularly in densely populated and built upon urban areas, without sizeable open green spaces
  • Helping to mitigate climate change; plants hold moisture, and provide bulk to moderate temperature changes
  • In cities green roofs can reduce what’s called the Urban Heat Island Effect. Where there is extensive built fabric, i.e. cities, solar heat gets stored up in the city fabric overnight and while released when temperature falls, will raise the average temperature by a mean average of 4 degrees compared to temperatures in the countryside.

Main structural green roof elements and types

As a starting point green roofs require a waterproof membrane between the roof and the earth substrate. Beyond this the depth and design of green roofs are quite diverse, ranging from lightweight and superlight (12 mm drainage board), extensive (less than 100 mm) and intensive (over 200 mm.)

Main green roof types

Mat-Based, (consisting of pre-grown mats of sedum or meadow flowers placed on water retentive material/substrate) Substrate based, (growing layers supporting plants) and biodiverse and wildlife (locally sourced aggregates and natural features from which specifically chosen flora and fauna grow.) Further info on different roof types, best practice etc here.

Main plants used in green roofs

Vegetation and plant choices are critical, requiring tough, hardy and long living plants. Sedum is the archetypal green roof plant as it is very draught resistant. However it has gained a mixed reputation as it has been widely used (or abused) on super thin substrate green roofs that contain very low-diversity and poor plant growth. Herbaceous flowering plants, grasses and an increasing interest and use of native wild flowers. Further information here.

This information has been partially taken from the Green Roof Guide, an invaluable source of authoritative guidance on green roofs in the UK climate and environment.

Further short cuts to green roof guidance:

 Design

Construction Practice

Wildlife Green Roof Guidance

Sheffield bus stop green roofs

2 Sheffield 2 Bus Shelter

In collaboration with Sheffield Groundworks, Sheffield City Council have installed green roofs on a number of the roofs of bus shelters across the city. Those who have visited the city will know what a concrete jungle parts of the city are, with bus shelters bringing rare greenery to the gritty urban environment while also acting as filters to air pollution from traffic exhaust. Might this not be taken a few stages further?

 

Sharrow School, Sheffield

 

1 Sharrow School Green Roof 1

Sharrow School, close to the city centre, features one of the most ambitious green roof projects in the country. Sharrow is on a sloping hill and the new primary school (as of 2009) was designed to be on several levels, and therefore several roof layers, which double up as outdoor learning spaces and green roofs. The 2000sq metres of multi-level roofs contain a number of habitats, from Peak District limestone grassland, wildflower meadows, urban brownfield sites to a wetland area with a small pond. The roofs have been the first in the country to be granted local nature reserve status.

Dalston Roof Park

5 Dalston Roof Park 1 film club

One of north London’s more recent hipsters quarters, Dalston, mixes a fair share of bubbling creative activities with serious social challenges. Dalston Roof Park  has been set up for three years in Ashton Street,  (possibly twinned with Lewes’s former Socialist Republic of Leicester Road) as a social enterprise atop a mixed-use workspace building to be used for all sorts of social and community activities, from open-air movies in bed (I kid you not!) community bake offs, local company’s product launches, and music and party type activities.5 Dalston Roof Park 2 garden

The Muse – Bere Architects

4 Bere green roof 2

The Muse has been until recently the work studio for Bere Architects, and remains home to its founder, Justin Bere. While Bere, the architect, and Bere the practice have become known as leading advocates of the Passivhaus approach to zero energy design, the building they work from has also been featured as one of the most attractive and photogenic roof garden projects in London, earning features in the National Geographic. Bere, (in the architectural mode) has created a fantastic roof garden within a very tight urban space round the back of Islington Square.4 Bere Green roof 1

The Green Roof Centre – Sheffield leads the way!

1 Sharrow School Green Roof 1

 

In Britain, the midlands city of Sheffield is at the forefront of developments with green roofs. Planning rules for the city require all new buildings over 1000 square metres, or more than ten houses, to integrate 80% of vegetated cover. Policy and initiatives have been influenced by the Green Roof Centre, which is part of Sheffield University’s Landscape Architecture department. The Centre has been conducting green roof experiments for the past decade, including Sharrow school, (pictured) and several of the rooftops of the university’s new buildings, as well as on various other buildings across South Yorkshire. To date there are over a 120 green roof building projects in the one time steel city.