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.