Background House bricks are often burned from natural clay, a process that consumes large quantities of energy and causes environmental pollution, especially in rural areas, where small brick factories use ovens fuelled by cheap coal, wood, etc. Sand-limestone bricks need only 30% of the energy used to make bricks from clay. Sand-limestone bricks are usually the most economic stone, especially for small industrial buildings, cellar constructions and low-cost family housing. Heating is expensive, and various technologies have been developed to improve the thermal insulation capacity of bricks. One way is to add Styrofoam, polystyrene and other plastics, which are vaporised during the process of clay burning (> 1 800 °C). The most energy efficient alternative is the sand-limestone brick because it needs a temperature of only 150°C for baking. Objectives The project aimed to improve the thermal insulation capacity of sand-limestone bricks. It would do this by replacing the added plastics with sewage sludge, containing water, sand, minerals and organics. Biogas reactors would be used to produce fuel gas from sewage sludge for manufacturing limestone bricks and the surplus energy generated would be used for sludge drying. The primary objective of the project was to implement, test and verify a combined process of limestone manufacturing and sewage sludge treatment, which would result in reduced energy consumption and zero waste production. Although this combined process may be more complicated than operating two separate processes, the integration of the two processes into one single system offered significant advantages: Better thermal insulation capacity of the sand-limestone bricks; Very low energy consumption; Zero waste during the manufacturing process; and Use of sewage sludge instead of sludge disposal. Expected results: The main output of this LIFE Environment project would be the implementation of a new manufacturing process for sand-limestone bricks (“EcoBricks”). The new process would: Achieve around 0.12 W/mk thermal conductivity, i.e. 60 % better thermal insulation capacity than conventional sand-limestone bricks and 95 % better than conventional bricks burnt from clay; Save 0.5 m³ Styrofoam/Polystyrene per tonne of bricks by replacing plastics with organics from sludge; Substitute freshwater with liquid in the sewage sludge for the production process; Replace 10% of sand with sewage sludge.Results The project did not start.