Stone Federation President David Richardson has dismissed as \'spin\' a claim by the British Precast Concrete Federation that concrete paving is greener than imported sandstone.

Concrete paving has suffered most from the massive increase in use of natural sandstone and granite in hard landscaping projects and the \'greener than stone\' claim made in a statement by the Precast Concrete Federation, which likes to be known as British Precast, is part of the fight back.

It supports its claim using the UK Ecopoints \'greenness\' evaluation system developed by BRE in Garston, Hertfordshire, where David Richardson is director of construction consultancy.

Ecopoints use a whole raft of environmental criteria to give an overall rating of the environmental impact of products.

According to these criteria, British Precast\'s example shows that British-made precast concrete paving has half the environmental impact of imported Indian sandstone.

But, says David, the claim is based on one quarry compared with one concrete product and it is understandable that British Concrete will have been selective in the comparison they have chosen. He suggests the poor score of the Indian stone is probably more to do with a long lorry journey across India than the sea voyage from India to England.

According to the Freight Transport Association, ships emit on average 15g of carbon per tonne carried per kilometre, compared with 130g by an HGV.

Also some, but not all, precast products are manufactured using cement made from ground granulated blastfurnace slag (GGBS), which produces one tenth the amount of CO2 in manufacture as ordinary portland cement.

"It\'s not a fair comparison," David told NSS. "We all know stone is a very sustainable material and what they have done here is put a spin on this to show this particular sandstone in a very poor light. A better challenge would have been to compare their product with a locally produced sandstone."I think they have taken a study and managed to skew the data very much in favour of what they want to see."

But however the British Precast figures were arrived at, they emphasise David Richardson\'s warning that stone has to shout about its green credentials if it is to stay in the frame in the construction industry.

He says Stone Federation will be producing an interim report showing how green stone is in areas such as energy and water consumption this summer with a fuller report before the end of the year. He anticipates the BRE\'s Green Guide due out in September will also emphasise stone\'s environmental credentials.

And, he says the Federation will ensure the information reaches the right audience.