Data visualization and analysis of energy flow on a multi-zone building scale

- Sankey diagrams helped in visualizing building-level energy flows and associated costs.
- The aim of this study is to make operational problems more visible and quantifiable.
- This approach helped to understand the interrelated variables that affect building performance.
- This approach resulted in estimating and understanding the impact of unmeasured energy flows.
- The survey results revealed that Sankey diagrams are useful for facilitating decision making.

Modern commercial buildings' resource consumption is metered at various levels of spatial and temporal resolution to track and reduce energy use and greenhouse gas emissions. However, not all data that could be used to detect faults or identify efficiency improvements are available due to the cost of meters and inaccessibility of the data they produce. In the field of building operation, building performance simulation (BPS) can help in quantifying unmeasured energy flows, for instance solar gains, heat loss from infiltration, etc. Furthermore, integrating building information modeling (BIM) in building operation and maintenance can decrease operation risk and costs, as well as maintain facility management quality. However, in practice there is a lack of efficient utilization of this application by building operators. The aim of this paper is to provide an integrated framework to estimate and visualize energy flows and the associated cost. The framework consists of 1) developing a BIM model, 2) converting the BIM model to a BPS model, 3) calibrating the model, and 4) visualizing energy and cost flows using Sankey diagrams. The study demonstrates this framework on a real-world case study, and hence provides a comprehensive energy use assessment on the building level to facilitate the decision-making by building operators. Finally, the results of a survey that was deployed to a sample user group to assess the usability and effectiveness of the proposed Sankey diagrams are provided.