The building sector is thought to contribute around a tenth of global carbon emissions, and require an estimated 50 billion tonnes of sand and gravel annually.
That is enough material to build a wall 27 metres wide, and 27 metres high, around the entire planet.
This time on Shaping the Future, Heriot-Watt University chief scientist Prof Tadhg O'Donovan is with Professor Gabriela Medero.
Alongside her role as Associate Principal for Enterprise, Gabriela is the inventor of K-Briq, a low-carbon building brick made almost entirely of construction waste.
This time, we are Shaping the Future of Sustainable Buildings.
Find Heriot-Watt University online here.