Designing Environmentally Sustainable Computer Systems Using Networks of Exergo-Thermo-Volume Building Blocks

As regulation and competition drives the creation of environmentally sustainable systems, cradle-to-cradle life-cycle assessment (LCA) methodologies are becoming increasingly commonplace. However, existing LCA techniques are often laborious and costly to implement. Moreover, while LCA provides great insight into the impact of a given product or service, the translation of LCA outputs into iterative design inputs is not straightforward. A tighter linkage between product design and LCA methods is desired. In this paper, we propose creating such a linkage through the method of “exergo-thermo-volumes”. Specifically, we consider the design of an enterprise server with multiple heat dissipating components. Each of these heat dissipating components can be represented as an exergo-thermo-volume (ETV). Simultaneously, the cooling solution that removes heat from each of these components is also treated as an ETV. We show that the optimal system design can be determined through superposition of each of these ETVs with appropriately coupled boundary conditions. The resulting ETV representation of discretized heat sources and companioned cooling solutions essentially leads to the creation of an ETV network, which can then be optimized for the minimum sustainability footprint. We find that the optimal solution predicted by the exergo-thermo-volume approach matches those that would be predicted intuitively based on general design-for-environment and thermal management practices, but — using the current approach — we are also able to quantitatively show the difference between the optimal and sub-optimal choices. We conclude by demonstrating the applicability of the exergo-thermo-volume approach for the sustainable design of an enterprise server.