As cities across the world turn to LED streetlights to reduce carbon emissions, it might not be as cost effective as thought, said Eric Spiegel, CEO of Siemens U.S..

Cities should spend money more wisely, said Epiegel during a session of Fortune’sBrainstorm E conference on Tuesday

Studies across U.S. have found the cost of replacing old-fashioned streetlights with lower energy LED lights might not always be the most effective way of using financial budgets to reduce carbon emissions, said Spiegel.

In his opinion the biggest energy and cost savings come from smart home and commercial automation gear, which would automatically reduce energy and fuel consumption.

The German electronic component manufacturer is a leading manufacturer of smart control systems.

Cities comprise very small area of Earth’s landmass, but contribute to about 70% of carbon dioxide emissions.

Hence, many municipalities are reducing their emission through improved energy efficiency, use of renewable power sources, and installation of automated energy monitoring and controlling devices.