The basic unit of this site is the research summary. The summaries are organized into four major categories:
To browse the summaries by category, click on the major category name below and follow the instructions.
This section of the database includes summaries of research papers related to the various materials used in creating a green roof, especially growing media and plants.
Growing medium is the particulate matter or substrate that anchors plant roots and sustains the growth of the plants. Growing media differ in their composition (e.g., minerals, aggregates, organic matter), grain size distribution, density, water and air content, depth and weight. Different growing media contribute in varying degrees to achieving the various benefits of green roofs, e.g., retaining storm water, acting as a fire retardant, and providing insulation to the building. Research on growing media focuses on the ability of different media to achieve these benefits, on performance of the various types of growing media under different growing conditions (e.g., climatic conditions) and their suitability for different plants.
Plants are the most visible component of a green roof, and are the primary contributors to the roof's aesthetic functions – providing a pleasant viewscape or an environment for leisure activities. Plants also help achieve bio-physical benefits in that they absorb greenhouse gases, create habitat, retain storm water, and act as a fire retardant. Much plant research focuses on the ability of various species to perform these functions, especially the biophysical ones. Plant research also pertains to the adaptability of various species to different growing conditions, including prevailing temperatures, amount of precipitation, and salt concentrations.
Other components of a green roof covered in this section of the database include waterproofing, drainage systems, and irrigation. Finally, this section also includes research on standards and guidelines related to green roof construction.
Green roof infrastructure finds itself in a precarious position: its numerous benefits accrue primarily to the public sector, yet in order to be effective it must be implemented by the private sector. Furthermore, this technology must be implemented on a large scale if it is to deliver major public benefits such as storm water run-off reduction and urban heat island effect mitigation. For both these reasons, the key benefits of green roof infrastructure will not be achieved without some form of supportive public policy. While national and regional governments have important roles to play in this regard, municipal authorities must take the lead in green roof policy development. A local public-private partnership can provide the impetus for private building owners and developers to install green roofs, allowing for dissemination of this technology to the extent that it will be beneficial to the general public.
No other green building technology offers as many benefits as green roofs. From improving energy efficiency and reducing the urban heat island effect to providing much needed green spaces that help reduce stress and create jobs, green roofs can deliver enormous benefits. These benefits accrue to both the private and public sectors. Private benefits are those that flow to the building owner, occupants or users. Reduced heating or cooling costs would be an example of a private benefit. Public benefits are those that accrue to the neighbourhood, the municipal government, region or global community. Reduction in storm water run-off and improved air quality] are examples of public benefits. In general, public benefits are greater than the private benefits, which is the main reason why supportive policies are needed to encourage private investment in green roof technology.
Many of the social and bio-physical benefits of green roofs have an economic dimension that can help compensate for the added cost of a green roof. For example, increased longevity of the roof membrane can result in lower maintenance and replacement costs. Most green roofs will also help building owners save on energy costs for heating and cooling. Depending on the type and design of the green roof system, other cost saving opportunities for the building owner may include a reduction in the size of HVAC equipment, a reduction in the amount of insulation used in the building, and the potential to reduce or eliminate roof drains. Other economic benefits accrue to the wider community. This could include cost savings from increased storm water retention and longer lifetimes for public infrastructure. Green roofs can improve local economic performance by enhancing worker productivity and creativity. Research in the area of economic benefits usually involves modelling various green roof scenarios to determine the potential economic gains.