Cyber-Physical Energy Systems (CPES) exploit the potential of information technology to boost energy efficiency while minimising environmental impacts. CPES can help manage energy more efficiently by providing a functional view of the entire energy system so that energy activities can be understood, changed, and reinvented to better support sustainable practices. CPES can be applied at different scales from Smart Grids and Smart Cities to Smart Enterprises and Smart Buildings. Significant technical challenges exist in terms of information management, leveraging real-time sensor data, coordination of the various stakeholders to optimize energy usage. In this talk I describe an approach to overcome these challenges by re-using the Web standards to quickly connect the required systems within a CPES. The resulting lightweight architecture leverages Web technologies including Linked Data, the Web of Things, and Social Media. The paper describes the fundamentals of the approach and demonstrates it within an Enterprise Energy Management scenario smart building.