Impact of Fixed External Shading Devices on Green Educational Building Assessment in Hot Summer and Warm Winter Climate

Abstract

The construction industry contributes a significant part of global energy consumption and carbon emissions. Accurately calculating and evaluating the energy consumption, economic performance, and carbon emissions regarding various types of building components is important for the energy efficiency structural design and building sustainable development. The use of external shading devices can effectively control daylight and solar heat, maintain thermal and visual comfort, especially reducing energy consumption for cooling system. Although great improvements have been achieved in ‘Assessment Standard for Green Building GB/T50378-2019’ (ASGB-2019), the current implemented Chinese green building evaluation standard, issues may have significant consequences on the implementation of new policy. The impact of fixed external shading facilities on their thermal and energy-saving performance has been highlighted in the existing research, however, their economic and environmental performance haven’t been in study. Moreover, there is a lack of effective assessment method for the fixed external shading devices focusing on their multiple performance (energy-saving, economic and environmental perspectives) in ASGB-2019.

To investigate the impact of fixed external shading devices on green educational building within the hot summer and warm winter climate region of China, the mixed research
methodology has been applied in this research project, integrating various quantitative and qualitative approaches. The qualitative measures include literature review and case study, while the quantitative approaches are comparative study and simulation analysis methods. The BESI 2024, life cycle cost analysis (LCCA), CEEB 2024 and ÉLimination Et Choix Traduisant la REalité (ELECTRE) I method have been adopted as simulation analysis methods.

The main findings are: 1) The comparative study and case study results point out that there is a low focus on the assessment of external shading design and a lack of qualitative or quantitative regulatory provision on the assessment of fixed external shading devices in ASGB-2019, establishing a foundation for introducing the multi-criteria decision analysis (MCDA) method in the subsequent study. 2) The energy-saving simulation results generate an optimum shading option among 21 proposed fixed external shading designs, which is ‘Integrated shading I’ with 6.03% of energy-saving rate of building envelope. 3) By considering energy-saving effect and three recyclable materials (e.g., merbau, aluminum, and polycarbonate), the LCCA results show that the six targeted shading cases with net present value (NPV) of life cycle cost (LCC, also can be regarded as initial investments) from high to low are Polycarbonate A, Merbau A, Polycarbonate B, Merbau B, Aluminum A and Aluminum B. 4) The carbon emission simulation results demonstrate the six shading alternatives with life cycle carbon (LCCO2) emission values from high to low are Aluminum B, Aluminum A, Polycarbonate A, Polycarbonate B, Merbau A and Merbau B. 5) Integrating the entropy weight and ELECTRE I methods, the MCDA result generates a final ranking table to suggest a most preferred shading option for the studied education building, which is Aluminum B. Further, a weighting matrix with three criteria has been proposed for the assessment improvement regarding fixed external shading devices, namely, ‘energy-saving rate of building envelope’, ‘NPV of LCC’, and ‘LCCO2 emission amount’, with the weight coefficient of 32.8%, 28.7% and 38.5% respectively.

This research proposes a mixed methodology to support MCDA method on the assessment of fixed external shading devices with consideration of energy-saving, economic and
environmental impact. A green educational building project is presented to demonstrate the use of the proposed methodology and provide a useful reference for the improvement of green building assessment in China.