One of the challenges faced by energy modelers and policy makers is the quantification of both achieved and forecasted energy savings associated with different energy efficiency policy measures. The case of Latvia’s first and second Energy Efficiency Action Plans is used to illustrate the application of two evaluation and modeling approaches: the top-down method and system dynamics modeling. The paper presents how improper use of the top-down method fails to capture energy user responses to changing conditions in the event of economic crises, and how the result may lead to absurd conclusions. The simulation results from the systems dynamics model are used to investigate inhabitants’ responses to different energy efficiency policy tools.