While densification and congestion charges are not the only effective tools to reduce energy demand and carbon emissions, they are important as they do not have a detrimental effect on long-term economic growth, when innovation is taken into account. The employment multiplier associated with a particular regional economic stimulus is designed to yield an estimate of the total employment attributable to the stimulus per job or man-year of employment directly created. There is a possibility that different sources of renewable energy are developed in sequence and in this case the impact on the labour market is larger and does not decline immediately. Extremadura (Spain), for example, began with the development of photovoltaic power between 2007 and 2009 and then started developing high-temperature thermo-solar, maintaining the high momentum for the construction and manufacturing industries.