Understanding the effects of climate change on building indoor thermal conditions is of importance for providing a comfortable thermal environment for occupants. Some multi-family dwellings have already been listed as heritage in China (hereinafter referred to as heritage apartments), limiting modifications to the building envelope. However, the effect of climate change on thermal comfort in heritage apartments with a compact interior (i.e. without a living room) built before the 1980s in different Chinese climate zones has seldom been studied. This study focuses on the current and future thermal comfort in two-bedroom heritage apartments in China. The study was conducted for two different Chinese climate zones, that is, a cold climate zone (Beijing), and a hot summer and cold winter climate zone (Shanghai) and both current climate scenarios (typical meteorological years) and future climate scenarios (2050) were used. The results indicate, among other things, increases of 58%–60% and 41%–44% in the predicted average number of overheating hours in 2050 compared to the current climate for the studied bedrooms on the first floor in dwellings in Beijing and Shanghai, respectively.

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Building integrated photovoltaic (BIPV) applications are key to increase the share of renewable energy in the built environment. A large potential for BIPV deployment is related to building facades. The assessment of BIPV facades depends on the accurate modelling of exterior convective heat transfer coefficients (eCHTC). However, eCHTC models commonly used in BIPV modelling tend to be simplified. This paper proposes a simulation framework that combines detailed computational fluid dynamics with a multi-physics BIPV model to investigate the influence of eCHTC on the performance of BIPV facades (cell temperature and power). The evaluation is performed for different building geometries, wind speeds, wind directions, solar irradiations, and ambient temperatures. The results show that local variations in eCHTC can cause variations in cell temperature up to 42 °C between the BIPV modules across the facade. These temperature differences are associated with differences in power up to 17% across the BIPV facade. In general, lower temperatures (and higher power output) occur near the edges of the facade while higher temperatures (and lower power output) occur at the middle and at the bottom of the facade. Therefore, a detailed assessment of wind effects is recommended in order to verify the local operating conditions of the BIPV modules. The framework and findings presented in this work are relevant for applications in which the knowledge of the local behaviour is important, such as degradation studies.@en

Building integrated photovoltaic (BIPV) systems provide an opportunity for renewable energy generation in the built environment. In order to quantify the BIPV potential, numerical models of varying levels of complexity have been developed. This paper investigates how the complexity of BIPV models affects their predictions. The study starts with a detailed multi-physics BIPV model that combines a high-resolution one-diode model with physics-based thermal and airflow models. Next, simplifications are introduced into the model. The model predictions are compared to experimental data from a BIPV curtain wall installed in a test building in Leuven, Belgium. The results show that the detailed BIPV model is capable of estimating the BIPV daily energy yield with an average difference of 6.2 % (2.0 % for clear sky days) and the back-of-module temperature with an average difference of 1.74 °C. The use of a linear power model instead of a high-resolution one-diode model affects the average differences, but not significantly: 8.7 % for daily energy yield predictions (4.5 % for clear sky days) and 1.71 °C for temperature predictions. The use of two different empirical temperature correlations instead of a physics-based approach increases the average temperature difference to 3.5 and 4.4 °C. The average difference in daily energy yield increases to 10.2 and 10.4 %, respectively (5.9 and 5.5 % for clear sky days). These findings indicate that the detailed version of multi-physics BIPV model provides the best agreement with experimental data, but it is still possible to reduce the model complexity with acceptable accuracy.@en

Building integrated photovoltaic (BIPV) is a key concept for the realisation of sustainable buildings. Despite the progress in BIPV modelling, the use of sensitivity analysis (SA) is still scarce in the BIPV literature. SA can help the modeller to identify which model inputs influence the model outputs the most. This paper presents a simulation framework that combines global SA methods with a multi-physics BIPV model. The analysis focuses on the performance of naturally ventilated BIPV facade elements (cell temperature and power). Building performance indicators, such as the total heat flux to the building interior and the building wall temperature, are also analysed. Inputs to the SA include convective heat transfer coefficients, cavity airflow rate, and weather conditions. As expected, the SA results were found to be highly dependent on the range selected for the inputs. For a narrow variation in weather conditions, the exterior convective heat transfer coefficient was identified as the input with the strongest influence on the BIPV performance. Results also showed that cavity ventilation becomes more important as the exterior convective heat transfer decreases. These findings indicate the need for accurate models to represent exterior convective heat transfer in BIPV facades and corroborate the importance of cavity ventilation.@en

Building integrated photovoltaic (BIPV) systems are considered a promising solution to increase the share of renewable energy in the built environment. To evaluate the BIPV performance at the building level, the implementation of BIPV models in building performance simulation tools is an essential step. This paper presents the development of a multi-physics BIPV model for the simulation of BIPV facades within the openIDEAS framework for building and district energy simulations. The model couples a high-resolution electrical model to physics-based thermal and airflow models. The combination of these two modelling approaches is not common in BIPV models, particularly for building performance simulations. The model predictions are compared to three months of experimental data from a naturally ventilated BIPV module installed in the facade of a test building in Leuven, Belgium. A good agreement is obtained in terms of both BIPV energy yield and temperature. The error in daily energy yield estimations is on average below 3 % and the error in the monthly energy yield is below 2%. The back-of-module temperature is predicted with a MAE lower than 2 °C and RMSE lower than 5 °C.@en

Building integrated photovoltaic (BIPV) technology has gained attention as a solution to achieve low energy buildings. However, unlike conventional PV applications, BIPVs typically operate at non-optimal orientation, imposed by the building geometry. Moreover, the building integration reduces the heat exchange to the exterior, leading to higher temperatures. This paper investigates the performance of BIPV modules in different locations by simulating a representative office room in a high-rise building having a BIPV facade. The locations considered are Riyadh (Saudi Arabia), Seville (Spain), Naples (Florida, USA), Cape Town (South Africa), and Munich (Germany). The facade is vertical and faces the equator for all locations. Results show the highest annual BIPV energy yield occurs in Seville, followed by Cape Town, Riyadh, and Naples. In terms of monthly yields, the highest values are observed in Riyadh and Seville in wintertime. Monthly yield is more uniform over the year in Munich, while important differences between summer and winter have been obtained for Riyadh. These results confirm the influence of the latitude on the BIPV yield, with equator-facing facades in high latitudes receiving up to 40 % less irradiation compared to a horizontal surface, with important reductions especially in the summer. In these locations, the use of west and east facades may be necessary to achieve a balanced profile over the year. Moreover, the highest average cell temperatures occur in Riyadh, Naples and Seville, while lowest temperatures are verified in Cape Town and Munich, which is consistent with the corresponding ambient temperatures. Finally, with lower BIPV temperatures and relatively high solar irradiation, Cape Town achieves the highest performance ratio (PR) values. Conversely, the combination of high solar irradiation and high temperatures leads to lower PR values in Riyadh and Seville.@en