Low Energy House Design Principles: Green Roofs

 

 Read on to find out all the benefits of installing a 'green roof'.

What is a Green Roof?

Green roofs are designed to provide significant environmental, economic and social benefits by absorbing rainwater, providing insulation, lowering urban air temperatures and creating a habitat for wildlife. Green roofs also provide a more aesthetically pleasing landscape, making it more visually attractive to look at then a traditional roof and can therefore decrease stress for people around it. Green roofs are able to solve these problems as they are partially or completely covered with growing vegetation and may also include additional layers such as a root barrier and drainage or irrigation systems.

Different Types of Green Roofs

There are two different types of green roofs depending on the depth of the planting medium and the amount of maintenance they need. They are called intensive and extensive green roofs.

Intensive

Intensive green roofs require more labour and maintenance and are better suited to commercial structures. They require a reasonable depth of soil to grow large plants and conventional lawns and need irrigation, feeding and other maintenance. Intensive roofs are more park-like with easy access and will usually hold things like trees, plants, walkways, benches or even sports fields. The high maintenance and heavy layers of intensive roofs requires stronger structural support.

Extensive

Extensive green roofs are designed to be self-sustaining or should require low maintenance. They are a lot lighter than intensive roofs and cannot support the same level of structure. They are only usually accessed for maintenance and function more for their environmental benefits.

What are the Benefits of a Green Roof?

Environmental Benefits

Green roofs have many environmental benefits. They improve and reduce energy consumption by providing natural insulation and absorbing storm water, lessening the burden on drainage systems. A study in Canada demonstrated that green roofs can reduce summer energy consumption by up to 75%. Research also shows the average temperature in Melbourne’s CBD is over 4 degrees higher than its neighbouring suburbs and up to 12 degrees higher in summer. This is because traditional roofing materials soak up the sun’s radiation and re-emit it as heat, making cities far hotter than surrounding suburbs. The density of populations and buildings in these urban areas also contribute to the higher temperatures and lower rainfall, creating micro-climates. A concentration of green roofs in an urban area can actually reduce a city’s average temperature during the summer, combating urban heat island effect. Green roofs have become a popular idea amongst many council’s in order to combat rising temperatures because of their ability to absorb and reduce heat.

Economical Benefits

Green roofs also have great economic benefits. They may initially be more expensive to install than conventional roofs, but you’ll save a significant amount on your energy bills in the long run. A green roof will improve the thermal performance of a roof, allowing the building to better retain the heat during cooler months and reflect and absorb the heat during hotter months, thus reducing your need for interior heating and cooling appliances. Another important note is that green roofs can last up to two times longer than traditional roofs. It is also estimated that the installation of a green roof could increase your property’s value of an average house by about 7%. We are likely to see an increase in uptake of green roofs as prices drop and they become more popular within society.