Carbon

Environmental Impact of Transporting Slate

Due to the increased scarcity of domestic UK slate supplies, suppliers have to look abroad to source natural slates more frequently. Natural roofing slates are imported into the UK from various sources around the globe, with the most common being Spain, Brazil and China.

Slates are usually transported via 40 tonne articulated truck, then from the quarry to a designated port and then to the UK via sea. The carbon emissions generated in this transportation process will greatly increase the slates overall environmental impact – which is an increasing concern.

Luckily the nearest out of these – the North Western region of Spain – supplies 60% of the natural slate for use worldwide, which greatly decreases the environmental impact when being used in the UK.

Research shows that emissions for transporting slates from North Western Spain to Britain equates to as little as 800kg per 24 tonne container. This is much less than the equivalent amount of slate from other parts of the globe:

• Quarries 200km North of Belo Horizonte in Brazil to the UK resulted in 4401kg per container
• Quarries in China to the UK create 8000kg of emissions per container.

All commodities have environmental impacts, but with increased awareness and the need for reduced emission, Spanish slate is continually increasing in popularity as a roofing material in the UK.

The following information outlines the environmental benefits of using slate compared to other popular products.

Climate Change

By simply building a roof for an average house (100m²) with natural slate instead of fibre cement can avoid the creation of 6.2 tons of CO² emissions. This is the equivalent of the pollution created by an average car over 30,000km (18,600 miles).

Natural Slate
3,800 kg eq CO² / 100m² roofing

Fibre Cement
10,000 kg eq CO² / 100m² roofing

Zinc
5,500 kg eq CO² / 100m² roofing

*source: www.greenbooklive.com

Water Extraction

Through the use of natural slate as a roofing material instead of fibre cement for the cover of your house (100m²), you could save up to 35,000 litres of water. This is the equivalent of an average person’s water consumption over 228 days.

Natural Slate
65,000 litres / 100m² roofing

Fibre Cement
100,000 litres / 100m² roofing

Zinc
440,000 / 100m² roofing

Fossil Fuel Depletion

Using natural slate instead of fibre cement over the roof of your house (100m²) saves 17,000 kWh, which is roughly the equivalent to the annual electricity consumption of an average house in the UK.

Natural Slate
24,722 kWh of electricity for a 100m² roof

Fibre Cement
41,722 kWh of electricity for a 100m² roof

Zinc
39,000 kWh of electricity for a 100m² roof

Environmental Impact Life Cycle Analysis

The environmental impact of a material is measured by taking into account all processes and raw materials which the end product requires. This includes the initial extraction through to waste management and incorporates the total from every stage which the product goes through.

The internationally accepted methodology for the quantification of environmental impacts is the Life Cycle Assessment, under the ISO 14044: 2006 standard, Environmental Management – Life cycle assessment – Requirements and guidelines.

Natural slate is a roofing material with less environmental impact compared to others due to its simple manufacturing process. Once the material is extracted, natural slate only needs to be cut to size, packaged and distributed – whereas other materials will require extensive processing.

Other products have much more complex manufacturing processes when compared to slate, which in turn gives a higher environmental impact. For example; zinc consumes a large amount of electrical energy during its manufacture. Other examples include ceramic tiles or fibre cement, which both involve high temperature processes that consume large amounts of energy.

Average embodied energy, embodied carbon and life expectancy of roofing materials: