Green Star is a rating system for all projects that provides an international standard for comparing the environmental impact and long-term sustainability of a development. A ‘crop coefficient’ (Kc) is used to quantify a crop’s water consumption.
A landscape’s water consumption has the greatest impact on the Green Star credit rating. Both the plant species, as well as the irrigation system both impact the efficiency of water usage on the site.
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Calculating the Landscape’s Impact – Green Star Crop Coefficient
A ‘crop coefficient’ is an agronomic multiplier to quantify the water requirements of plants. It is a number (between 0.1 & 1) and quantifies how ‘thirsty’ a plant variety is in any particular climate. A higher crop coefficient is given to a species that typically needs more water to not just survive, but also thrive.
To understand the water usage holistically, it is important to consider the quantity or area of each proposed species on the site. Green Star refer to this as ‘calculating the area weighted crop coefficient’. This is used to create an average for the site based on the quantities proposed of each type of plant.
Visualizing Crop Coefficients – Plant Species
Plant species that are native to the local area of a subject site would typically consume minimal water, compared to exotic introduced species that are unfamiliar with the climate.
In Brisbane’s climate there are many native species that are true and tested for low water use such as Bottlebrush (Callistemon sp.), Spider Flower (Grevillea sp.) and Paperbark (Melaleuca sp.).
Often species that are found in rainforests and other wet environments, such as lush ferns and broadleaf species, typically demand more water than species naturally found in dry rural environments. Eucalypt trees (Eucalyptus sp.), Grass trees (Xanthorrhoea sp.) and Bottle trees (Brachychiton sp) are species that consume minimal water.
Preferred Design Outcomes
Landscape design including the careful selection of species, plays a crucial role in creating environmentally responsible developments. Gone are the days of throwing in any old exotic plant that is used time and time again because ‘that’s what we used before’.
Careful selection of indigenous species that are appropriate to the climate, have limited water consumption properties, are hardy and drought tolerant, attract fauna and are visually appealing create landscapes that improve and safeguard our environment today and into the future.
Contact Citicene to learn more about how we can deliver a sustainable landscape for your project using low crop coefficient species that protect and enhance our environment.
