One of the joys of a living green roof is that it can actually help to keep a building cool. Read more in this article.

The UK is a strange country. In winter we spend money and use valuable fuel to heat the inside of our buildings. In summer, we use fuel to cool them down. Very old buildings often have thick walls that help to regulate their temperature. Super modern buildings have lots of features to help them conserve energy. But what of garden offices? Workshops? Animal housing? These are frequently used buildings that tend to be very poorly insulated. How could we, as homeowners improve things?

scandinavian green roof
This traditional scandinavian turf roof is a great way to insulate against extreme temperatures

A green roof offers all year round insulation

Thanks to TV advertising and government initiatives, we’re all quite savvy when it comes to loft insulation and double/triple glazing. However, those may not be suitable for all buildings.
Another form of easily-installed insulation is a green roof.  A green roof offers a layer of insulation against summer heat and winter cold.   Temperatures beneath a living roof tend to be more stable from day to night.  They are cooler in summer and warmer in winter.  Which in turn reduces the need for heating or for air conditioning.

What IS a green roof?

A green roof is a layer of vegetation that has deliberately been planted on top of a building. There are a myriad of different types of green roof. From wild flower roofs to low maintenance sedum roofs to actual roof gardens producing fruit and vegetables.
In this article, we’re going to be looking at sedum roofs and at wild flower roofs.

cycle shed with green roof
This green roof cycle shed near Teddington Lock in London was made with Meadowmat Wild Flower Matting.

How much insulation does a green roof offer?

A living roof is a bit like a blanket. It will insulate against cold in the winter and against heat in the summer by trapping air near to the surface of the roof. How much insulation it offers varies according to the depth of the growing medium, the type and size of the plants and how wet it is.
In summer time, a wild flower roof with 150mm of growing medium and dense planting up to 90cm tall will offer more insulation against heat than a sedum roof. A sedum roof has around 20mm of growing medium and 15cm plants.

However, the sedum roof weighs considerably less than the wild flower roof, costs less to install, is easier to care for and still offers more insulation than nothing at all.

sedum green roof gazebo
Enviromat sedum matting makes a beautiful, interesting and light weight green roof. Seen here on a gazebo it can also be used on stables, summerhouses and extensions.

There’s a fine balance between ecology and engineering. Between what the buildings can support and the resulting benefits. Remember, those layers of growing medium and plants will add extra pressure on to the supporting walls so always consult a structural engineer before embarking on a green roof project.

Other benefits of green roofing

The benefits of a green roof are not just in insulation. These are just a few of the ways that a green roof can help a building, its occupants and the wider environment.
Insulates against noise (ideal for garden offices)

  • Protects waterproofing from UV light – in some cases it can triple the lifespan of the waterproofing
  • Reduces rainwater runoff and therefore pressure on drainage systems
  • Provides food, habitat and resting places for wildlife
  • Great PR – demonstrate to the world that you care about the environment
  • Filters dust and pollutants from the air
  • Helps reduce the urban heat island effect
  • Reduces energy usage
  • Moderates the temperature inside the building

Where to find out more about green roofing

Visit our sister site at www.enviromat.co.uk for more information on the benefits, specification, installation and maintenance of living green roofs