• Energy Research
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Abstract Useful thermal bridge performance indicators (ITBs) of existing buildings may differ from calculated thermal bridge performance derived theoretically due to actual construction conditions, such as irregular shapes and aging. To fill this gap practically, a more realistic quantitative evaluation of thermal bridge on-site needs to be considered to identify thermal behaviors throughout exterior walls and thus improve the overall insulation performance of buildings. In this study, a case study is conducted using an infrared thermal imaging method to evaluate the thermal bridge of an existing building practically. The study's main purpose is to review the thermal bridge performance indicators measured by the steady-state model under field conditions in terms of convergence and uncertainty. Bayesian Markov Chain Monte Carlo (MCMC) is used to examine the validity of the results by deriving evaluation results in the form of distribution, including uncertainty. After the measurement was completed, an analysis of the results was conducted. As a result of measurement for 3 days, it was found that the thermal bridge part had 1.221 times more heat loss than the non-thermal bridge part, which showed a 6.7% deviation from the numerical method. However, the uncertainty was 0.225 (18.4%, CI 95%), a large figure. This is due to the influence of field conditions and shows the limitations of the steady-state measurement model. Regarding the convergence of the results, the measurement results were found to converge continuously as the measurement time increased. This suggests that valid results can be obtained in the field if the measurement is performed for a sufficient time, even with a thermal bridge measurement method assuming a steady-state.

Abstract The concept of zero-energy buildings is gaining much interest, and its technical feasibilities have been demonstrated for sustainable development. Although several case studies present how effectively zero-energy performance can be achieved, there is still a lack of data understanding adopting different combined passive and active systems for zero-energy performance. In response to this gap, this study introduces new integrated systematic approaches of enabling all-electric zero-energy performance and presents these features and operating performance for each part of energy consumption contributors based on measured data over two years. Structural insulation panels, vacuum glazing with heated glass were applied as passive techniques. An air-source heat pump and package air conditioner were used for heating and cooling systems, respectively. In addition to the passive and active systems, building-integrated solar thermal and roof-integrated photovoltaic (RIPV) systems were installed to offset all the remaining energy in the house. The energy use intensity of the house was 77.98 kWh/m2·yr; heating and domestic hot water had the highest consumption. To save cooling consumption, exterior electric venetian blinds and natural ventilation were used to cut down energy consumption. The house consumed 7,368.95 kWh/yr and produced 11,439.68 kWh/yr through the RIPV, the annual RIPV surplus accounting for 35.58 % of the annual energy production. The results from this case study provide a comprehensive overview of the feasibility of different combined technologies and insights into proper design strategies to improve the performance of zero-energy houses and buildings from another point of view.