There is increasing focus on emissionsEmissions and pollution. Currently, aluminium smeltersAluminium smelter report on a yearly basis, and average values based on measurementsMeasurements are considered sufficient. To meet stricter requirements and further reduce emissionsEmissions, the industry needs systems for online emissionsEmissions monitoring with predictive capabilities. The ambition should be to move from a reporting—after methodology towards an online temporal and spatial representation of the emissionsEmissions, both inside and outside the process areas and plants—in short, to establish better measurementMeasurements techniques and emissionEmissions models. Hydro and Alcoa are now cooperating with Cybernetica, Nemko Norlab, SINTEF, and NTNU in a project called New Emissions Surveillance solutions for the AluminiumAluminium Industry—NESA. In this article, the overall concept of the system developed in the project is presented. Focus then shifts to pot roomPot room ventilationVentilation and emissionsEmissions, demonstrating that sophisticated simulationsSimulation can be represented by simplified models running significantly faster than real time. Furthermore, the novel use of low-cost online sensorsSensors demonstrates how emissionsEmissions from pot roomPot room activities can be quantified. Finally, the links to dispersion modelling are explored briefly.