Pyeongchan Ihm

Implementation of a building foundation heat transfer model in EnergyPlus

In this article, a two-dimensional transient ground-coupled numerical model for slab-on-grade foundation is developed and integrated into EnergyPlus. A verification analysis is first presented to ensure that the developed building foundation heat transfer module is properly implemented within EnergyPlus. Then, predictions from the developed model are compared with those obtained from a simplified building foundation model currently used in EnergyPlus. Finally, the impact of several foundation insulation configurations on the annual variation of both heating and cooling loads is investigated for a one-storey single-family ranch house. The results show that the developed foundation heat transfer module accounts more accurately for the effects of the ground thermal mass than the foundation model currently used in EnergyPlus. In particular, it was found that annual heating and cooling loads can be overestimated by over 20% for a typical residential building if ground-coupled heat transfer calculations are not fully integrated in EnergyPlus.

Design Optimization of Energy Efficient Office Buildings in Tunisia

Optimal and cost-effective energy efficiency design and operation options are evaluated for office buildings in Tunisia. In the analysis, several design and operation features are considered including orientation, window location and size, high performance glazing types, wall and roof insulation levels, energy efficient lighting systems, daylighting controls, temperature settings, and energy efficient heating and cooling systems. First, the results of the optimization results from a sequential search technique are compared against those obtained by a more time consuming brute-force optimization approach. Then, the optimal design features for a prototypical office building are determined for selected locations in Tunisia. The optimization results indicate that utilizing daylighting controls, energy efficient lighting fixtures, and low-e double glazing, and roof insulation are required energy efficiency measures to design high energy performance office buildings throughout climatic zones in Tunisia. In particular, it is found that implementing these measures can cost-effectively reduce the annual energy use by 50% compared to the current design practices of office buildings in Tunisia.