Environmentally-friendly concrete made from a variety of the cannabis plant is being used on a new £6.2m project at an eco-centre in Powys.
Hemcrete being sprayed onto Cat's new building
Made from hemp and called hemcrete, the mixture is being applied to walls at the Centre for Alternative Technology (Cat), near Machynlleth.
A lot of energy is used to make the common form of concrete in comparison to its "greener" cousin, said Cat.
Hemp is legal and part of the cannabis species, which includes marijuana.
It is identical in appearance to the illegal drug, but it lacks the narcotic qualities.
HEMP IS USED TO PRODUCE
Hemp is grown in the UK and is recognised to be a versatile crop and is used to make many retail products.
Hemcrete, made from hemp stalks, lime and a small quantity of cement, produces less carbon emissions than conventional concrete, said Cat.
The product is being sprayed onto heraklith (woodwool) boards at Cat's new Wales Institute for Sustainable Education (Wise).
The £6.2m training and conference venue will extend the eco-centre's courses in subjects such as sustainable architecture and solar power for electricians.
"The new building will be an inspiring place for them to study, embodying all the principles taught within it," said Wise project officer Phil Horton.
An artist's impression of Cat's new Wise building
"All the heating and electricity in the Wise building will come from a range of renewable sources.
"This includes a combined heat and power plant burning woodchips, solar panels for electricity and hot water, hydroelectric turbines and several wind turbines."
Other energy and carbon-saving techniques include rammed earth walls, which will make up a circular 200-seater lecture theatre.
When finished, Wise will have 24 twin hotel-style rooms, classrooms, workshops, a laboratory, offices, lecture rooms, and a restaurant and a bar.