Energy consumption in buildings is an important matter for thefuture. In order to reach a sustainable future, both new and oldbuildings must become more energy efficient. This thesisinvestigates how the electricity consumption can be reduced inexisting buildings containing laboratories. This project had twomajor goals. The first goal was to find specific actions toimprove the electricity energy efficiency of The ÅngströmLaboratory, Sweden. The Ångström Laboratory is owned andadministered by the public company Akademiska Hus and rented byUppsala University. The second was to propose a procedure of howto make an arbitrary building containing laboratories moreelectricity efficient. The results indicate that a lot of energycan be saved by optimizing the ventilation of the laboratories. Byreplacing the current ventilation fans with more efficient fans,the potential annual savings were calculated to 0.57 GWh whichcorresponds to 4.2 % of the total annual electricity consumption.By reducing the air-flow in the fume hoods outside working hoursthe electricity consumption in the ventilation system can belowered. The potential savings for this were calculated to 0.31GWh (2.3 %). By modifying the ventilation system of the differentcorridors in such a way that laboratories and offices are placedin opposite ends of the corridor, the operation of ventilationfans can be optimized for laboratories and for officesrepectively. The savings for this were calculated to be 0.07 GWhper year (0.5 %). Another identified opportunity for energysavings in the Ångström building is the replacement of currentlighting fixtures with more efficient systems (typically LED basedsystems). This has the potential to save 0.17 GWh per year.