Above Us Only Green

In February 2011 the roofs of the All Saints Building changed colour from grey to green. Two green roofs were installed on the upper and lower roofs of the MMU’s All Saints building covering a total area of 607.2m² which alongside the green roof on the newly built MMU Business School will collectively make these the biggest green roofs in the City of Manchester.

What is a Green Roof?

A green roof is a layer of vegetation that sits on top of an existing roof structure. Green roofs come in many shapes and guises but generally the main distinction is based on whether the roof is extensive or intensive.

Extensive Green Roofs

• lightweight layers of free-draining material
• low-growing, hardy, drought-tolerant vegetation such as sedum / stonecrop plants
• require relatively little maintenance

Intensive Green Roofs

• heavier more complex systems
• can have a variety of landscape features which may include water management systems
• relatively deep substrates often over 20cm in depth
• contain a variety of plants including trees, shrubs, perennials, grasses and annuals
• require significant levels of maintenance

All Saints Green Roof Construction

The two green roofs on the All Saints Building can be classified as Extensive green roofs and both have been planted with sedum / stonecrop plants. The green roof construction contains a number of different layers as can be seen from the diagram below. Each layer performs a specific function, the drainage board for example retains rainwater for irrigating the plants and the insulation layer helps to prevent loss of heat from inside the building below.

So what’s the point of putting a Green Roof
on a building like All Saints?

Green Roofs don’t just look pretty – they provide a range of benefits:

Financial

• Reduced heating bills as result of improved insulation
• Reduced cooling bills as a result of insulation against Ultra Violet rays
• Increased life span of existing roof owing to protection against the elements – by at least double
• Potential reduction in drainage discharge costs owing to enhanced water holding capabilities – Utilities providers may offer up to 50% discount on surface water treatment for businesses with Green Roofs

Environmental

• Reduction in surface water runoff following rainfall which can help to reduce the causes of flash flooding
• Reflecting the sun and evaporative cooling – lowering temperatures
• Trapping airborne pollution such as PM10 particulates which are known to cause respiratory disease
• Provide important habitats for birds and insects, in particular bees
• Educating and inspiring – Fresh way of raising awareness of climate change – showing how everyone can help

Social

• Where opportunities for green space are limited green roofs can provide an important green backdrop. Green space is well known to have benefits for psychological wellbeing.

Research

Staff and students from the MMU will be monitoring the impact that the new green roof has on energy insulation by using thermal imaging cameras to detect how much heat is lost from the roof space below. A baseline survey has already been undertaken to establish how much heat was lost before the installation of the green roof.

A camera has also been installed on the roof that will be able to provide a live feed to students and to assist with recording bird and insect species visiting the roof.

Funding and Partners

The All Saints Green Roof project has been developed in partnership between the Manchester Metropolitan University, Community Forests North West Limited, Red Rose Forest and Manchester City Council as part of the wider Corridor initiative.

Funding for the project has been provided by the MMU, Manchester City Council and the European Union’s INTERREG IV B fund as part of the VALUE Project.