An elementary approach to evaluating the thermal self-sufficiency of residential buildings with thermal energy storage

Abstract

Thermal energy storage (TES) is a cornerstone of the global energy transition, contributing to better integration of renewable energy. Nevertheless, there are major challenges in the diffusion of TES such as selection of the optimum system size, system inte-gration, and optimization. A key target for using TES is to in-crease the thermal self-sufficiency of a building or an entire dis-trict. Unlike the usual definition of total energy self-sufficiency, thermal self-sufficiency focuses only on the heating aspect of a system. Thus, thermal self-sufficiency measures the ability of a system to meet its heating demand from local renewable energy sources. Thermal self-sufficiency is an important metric for practitioners and researchers in the design, optimization, and evaluation of energy systems, especially when considering TES. Unfortunately, there is no comprehensive method in the scientific literature for determining thermal self-sufficiency based on an-nual consumption considering TES. Hourly energy profiles and simulations are required to determine thermal self-sufficiency. This article aims to close this gap and presents a new method for evaluating and estimating thermal self-sufficiency for a building with a TES. Using this approach, the upper and lower limits of the building thermal self-sufficiency are derived for various heat storage capacities and annual heat demands, demonstrating the impact of a TES on the system. In addition, the approach is largely technology agnostic. The new approach helps to quantify the effects of integrating TES on the share of renewable energies and the degree of self-sufficiency that can be achieved, thereby supporting the design of efficient heating/energy systems.