Get efficiency from ‘cool’ plants

September 09 - Professional landscaping can lead to significant energy savings in facilities, based on reduced thermal loads in and around buildings. JIM VAUGHAN from the Australian Landscape Industry Association (ALIA) explains how natural turf, mulch and plants can add life to your air-conditioning units while cutting operating costs.World Environment Day promotes the use of natural products such as turf grass and plants, along with professional landscape installation and ongoing maintenance, to cool and streamline the environment around residential, commercial or industrial facilities.

Not only are properly landscaped buildings more comfortable, but research is also showing that plants can generate significant energy savings compared to other paving materials like gravel or concrete.

The landscape industry in Australia undertook a major research project in November 2007 to identify the thermal benefits of professional landscaping and the use of natural horticulture products (natural turf grass, plants, soils and mulches) when used within residential, commercial and industrial facilities. It included investigation into the energy consumption in maintaining lower temperatures in buildings through use of air-conditioning units when comparing hard (concrete and brick) versus soft green landscaping. The project highlighted the many benefits of living landscape elements in lowering surrounding temperatures.

CONCRETE JUNGLE
The urban environment is becoming more like a ‘concrete jungle’ daily as a result of population growth and the value of land. In an attempt to fit more people into smaller areas residential block sizes have been reduced and house sizes have increased, exacerbating the ‘urban heat island’ effect. Urban environments can be made much more liveable by professionally incorporating natural lawns and gardens into the surrounding and adjacent areas. Past drought conditions in many states have incorrectly driven a shift away from gardens or living landscape components to utilise more hard surfaces. However, it is proven that there is a reduction in the liveability of such areas due to the thermal effect and heat generation of hard scapes. Considerable international research is available on the thermal benefits of green life compared with built hard surfaces and land types in an urban environment, especially in the harsh Australian landscape.

ALTERNATIVE MATERIALS
The investigation undertaken at the Department of Primary Industries in Queensland consisted of six test plots, each two square metres, with a one-metre buffer zone between each plot. The plots consisted of the following landscape materials to allow comparison:

• Natural turf grass (green couch)
• Artificial turf (3rd generation)
• Concrete (pre-existing slabs>
• Paving (120mmX60mm pavers in pale terra-cotta colour)
• Mulch (25mm pine bark nuggets)
• Gravel (10–25mm angular multi-coloured stone).

Automated temperature readings were taken at different heights above the six different landscape materials and were logged utilising automated technology every six minutes at heights of 0cm, 50cm, and 100cm for a period of four weeks during the hottest part of the Queensland summer. Preliminary readings were also taken during winter but not utilised in this project.

OUTCOMES
Concrete and paving had significantly higher minimum temperatures, suggesting that the materials were able to store heat. Natural turf grass had the lowest maximum temperatures, with artificial turf significantly higher in line with concrete and paving. The results of the average temperatures showed that artificial turf was significantly higher on average than all other materials other than concrete. Natural turf grass was significantly lower than concrete and artificial turf and lower than gravel, paving and mulch at all [height] levels. Surprisingly, artificial turf showed higher maximum temperatures and was significantly different to concrete, paving and natural turf grass every day of the study and higher than gravel on 17 out of the 22 days investigated.
Many hard elements are utilised these days to reduce maintenance and provide water use efficiency. However, environmentally friendly natural landscaping significantly decreases costs through energy savings and also improves cosmetic appearance, which can add value to a property – something that has been proven by the Real Estate Institute of Australia.

In summary, it is important to understand the ratios of living and non-living components required in a landscape design so that thermal benefits can be realised within the facility. Potential energy saving is proven, as the cooling properties of natural vegetation mitigate air-conditioning costs and other energy-absorbing elements.
Always consult your professional landscape contractor, designer and supplier by contacting your state landscape contracting association to ensure the correct product is suitable for your project.

GREEN ROOF
Just for Interest: The newly completed (2009) Vancouver Convention Centre features a six-acre green roof, the largest in Canada and the largest non-industrial green roof in North America. The roof has 400,000 native plants and various natural turf grasses, as well as hives for 60,000 bees. The architects advise that “The roofline landscape will have the ability to retain stormwater, releasing excess amounts slowly, clean particulate matter from this water, clean pollutants from the air, and provide habitat for insects and birds in the urban environment. The usually benign roof landscape will be transformed into a rich and diverse urban sanctuary.”

Jim Vaughan is the chief executive officer of the Australian Landscape Industry Association (ALIA).

More information
ALIA    www.landscapingaustralia.com.au

This article first appeared in the August-September 09 issue of ‘Facility Management’.