A 12-storey building in Cape Town's city centre is the world's tallest to be constructed from hempcrete blocks and hemp building materials.

Hempcrete blocks are made of hemp shiv – the chopped up, woody core of the cannabis plant – and a formulated lime mix.

These blocks are carbon negative, with more carbon taken out of the atmosphere by the growth of the cannabis plant than emitted by its production and application. The plant-based building material also has great thermal insulation qualities, lowering the need for heating and cooling systems which saves on energy bills.

As South African companies move more towards lowering their carbon footprints and saving energy, the construction of a multi-storey building at 84 Harrington Street in Cape Town is a defining moment for this environmentally conscious push.

It also comes amid fresh plans to commercialise and industrialise the cannabis industry, with government highlighting the sector's potential for employment and benefits to the economy.

"I bought 84 Harrington in 2016, with the idea being that it would become the flagship Hemporium store, a steak restaurant, and house the 'Hemp Hotel', a place where people can experience living in a hemp-constructed space," said Duncan Parker, founding partner and CEO of Hemporium, a local hemp company founded in 1996 that produces a range of clothing, accessories, cosmetics, and other products.

Hemporium constructed Africa's first Hemp Home, which was selected as a World Design Capital 2014 project, and, since then, has played an instrumental role in the construction of five more hemp buildings.

"From a sustainability and eco-construction perspective, we wanted to take hemp construction in South Africa to the next level, while also contributing to the inspiring hemp construction projects being undertaken globally."

Afrimat, one of South Africa's leading producers of bricks, blocks, pavers, and ready-mix concrete, was involved in the project through its subsidiary, Afrimat Hemp. This division of the building materials company focuses on carbon-neutral construction and unlocking value in the industrial hemp sector.

"Afrimat Hemp has developed its own formulated lime binder for hempcrete and is producing hempcrete blocks at one of its commercial block plants," said Boshoff Muller, the managing director of Afrimat Hemp.

The 12-storey building, with 50 apartments, at 84 Harrington Street, built in partnership with Wolf & Wolf Architects, has been named as the tallest building made of hempcrete in the world.

Muller told Business Insider SA that this was confirmed by Steve Allin of the International Hemp Building Association, globally renowned for documenting hempcrete projects around the world. The previous record belonged to a project in Italy, "Case nel verde", a nine-storey building with 24 units.