such work could develop a more programmatic approach to which combinations and sequences of financial instruments publicprivate partnerships and capacity building provide the best leveraging of private investment in the most costeffective way this report seeks to improve the understanding of this gap and what can be done about it the many benefits of ee improvements increased energy security reduced energy costs costeffectiveness and environmental benefits have been described in detail elsewhere the weo estimates that over of the energy mix to move the world towards a scenario could be reached through the introduction of existing ee technologies this efficiency potential should be an attractive investment opportunity as energy efficiency measures in the buildings sector generally have netnegative cost abatement opportunities albeit with higher upfront costs that require additional financing the estimated savings from the complete implementation of the iea building recommendations are an annual exajoules ej by iea a