Selected Articles丨Application of Passive Techniques in Green Public Buildings and Analysis of Carbon Emission Contributions

Author Introduction

First Author: Zhu Rongxin, Doctoral Candidate, Senior Engineer, research direction is green building, low-carbon building, currently employed by China Academy of Building Research Co., Ltd.

Corresponding Author: Liu Maolin, Master's Candidate, Senior Engineer, research direction is healthy building, currently employed by China Academy of Building Research Co., Ltd.

 

Funding Project

Yunnan Provincial Key Research and Development Plan Project (202303AC100005); “14th Five-Year Plan” National Key Research and Development Plan Project (2022YFC3803800)

This article summarizes and analyzes the application of passive techniques in 340 green public buildings of different climate zones and star ratings in China from 2016 to 2023, and studies the carbon emission levels of 39 of these projects. It explores the relationship between the application of passive techniques in green public buildings and operational carbon emissions, providing useful references for the low-carbon design of green public buildings.
 

Research Object

 

The author has compiled statistics on 340 public buildings (including office buildings, commercial buildings, and school buildings) that have obtained different star ratings of green buildings using the 2014 and 2019 versions of the Green Building Evaluation Standard. The time of obtaining the identification is 2016-2023. Among them, a total of 303 projects used the 2014 version of the standard, and a total of 37 projects used the 2019 version of the standard; the number of one-star, two-star, and three-star green building projects are 90, 179, and 34 respectively; the number of projects in severely cold regions, cold regions, hot summer and cold winter regions, hot summer and warm winter regions, and temperate regions are 13, 49, 245, 27, and 6 respectively.

 

Research Method

 

• Carbon Emission Calculation

In the five major climate zones, the number and star rating distribution of the 340 green public building projects are not uniform. The author selected 39 representative green public building projects for carbon emission calculation. The specific distribution and number of star ratings of green public building carbon emissions in each climate zone are shown in Figure 1. Combining existing project data, the carbon emissions in the stages of building material production and transportation, construction, and operation were mainly calculated.

 

 

• Passive Technology

Passive technology refers to maximizing the use of climate conditions, building envelope structures, and indoor functional space layout to enable buildings to have a certain degree of self-regulation, effectively reducing the disturbance of the indoor environment by the outdoor environment, suppressing large fluctuations in indoor thermal humidity, lighting, and other environmental factors, and thus making every effort to avoid the use of mechanical systems to assist, in order to reduce equipment energy consumption and carbon emissions.

The author has sorted out the passive technologies in the 2014 and 2019 versions of the Green Building Evaluation Standard, as shown in Table 1.

 

 

A total of 9 categories, which can be divided into natural ventilation, natural lighting, envelope structure optimization, renewable energy, shape optimization, plane layout, adaptable design, and increased green space. The application of passive technology in public buildings is reflected by the average score rate of the relevant clauses of 340 green public building projects. The average score rate refers to the ratio of the average score of all projects in the clause to the full score of the clause. The average score rate of control items is not calculated, and the weighted average of the average score rate of scoring items in the two versions of the standard is taken. The average score rate can be used to generally measure the application of a certain passive technology in green buildings of different climate zones and star ratings nationwide. The higher the average score rate, the better the application of the technology.

 

Results and Analysis

 

• Carbon Emission Level

Improving the star rating of green buildings can significantly reduce the overall average carbon emissions of buildings, and the higher the star rating, the more significant the carbon reduction effect. The average carbon emissions of green public buildings with different star ratings are shown in Figure 2.

 

 

Compared with the average carbon emissions of one-star and two-star green public buildings, the carbon reduction rates of three-star green buildings are 26.29% and 10.04% respectively. The carbon emissions from building material production and transportation in one-star, two-star, and three-star green public buildings gradually increase with the increase in star rating, but the change is not large. Operational carbon emissions, however, decrease significantly with the increase in star rating. Based on one-star and two-star green public buildings, the reduction rates of three-star green building operational carbon emissions are 13.62% and 32.51% respectively.

Operational carbon emissions of green public buildings with different star ratings are shown in Figure 3.

 

 

As shown in Figure 3, in the operational carbon emissions of green public buildings with different star ratings, the carbon sources from high to low are HVAC (48.15%), power system and terminal (32.37%), kitchen equipment (13.10%), lighting (6.02%), and water resources (0.36%). In terms of the average absolute value of carbon emissions, the difference in average operational carbon emissions of green public buildings with different star ratings is mainly due to HVAC carbon emissions. Compared with the average HVAC system carbon emissions of one-star and two-star green public buildings, the average carbon reduction rates of three-star green buildings are 48.83% and 25.33% respectively.

 

• Application of Passive Technology

The average score rate of passive technology in green public buildings with different star ratings is shown in Figure 4.

 

 

As shown in Figure 4, the application of passive technology is positively correlated with the star rating of green public buildings. The higher the star rating of green buildings, the higher the average score rate of passive technology. Compared with one-star green public buildings, two-star and three-star green public buildings have adopted a wider variety of passive technologies, and the application effect of the same type of passive technology is also better.

The average score rate of the 9 passive technology clauses in green public buildings with different star ratings is shown in Figure 5.

 

 

Clause 1 is a comprehensive technology, involving optimization design of shape, plane layout, and space scale, and its application is relatively good. The requirements of the two versions of the Green Building Evaluation Standard for this technology are relatively broad, and points can be obtained as long as optimization design is carried out according to the relevant energy efficiency standards.

Clauses 2, 3, and 4 aim to enhance the natural ventilation of buildings. The average score rate of clauses 2 and 3 in green public buildings with different star ratings is relatively high, while the average score rate of clause 4 in one-star green public buildings is relatively low, indicating that although measures to enhance natural ventilation have been taken, the ventilation effect is not ideal.

Clause 5 has a great impact on the energy consumption and carbon emissions of building HVAC. However, the initial investment for enhancing the building's insulation performance is relatively large, so the application in one-star and two-star green public buildings is not ideal.

Clause 6 concerns renewable energy utilization. Initial investment is substantial, and application is positively correlated with green building star rating. The highest score for this clause is achieved when renewable energy provides both heating and cooling, followed by domestic hot water. Photovoltaic power generation is less frequently applied.

Clause 7 concerns adaptive indoor space design. Three-star green public buildings show good application, while one- and two-star buildings show less ideal application.

Clause 8 concerns natural daylighting. Application is positively correlated with green building star rating; higher star ratings show higher adoption rates.

Clause 9 concerns shading measures. This is the least ideally applied technology, indicating that the return on investment for shading technology in actual projects is not high. This technology requires further research and development in conjunction with actual building needs.

 

• Passive Technology and Carbon Emission Coupling Analysis

The application of passive technologies is negatively correlated with the operational carbon emissions of green public buildings, with a correlation coefficient R ² =0.9136. Higher average scores for passive technologies correspond to lower operational carbon emissions in green public buildings, as shown in Figure 6. This indicates that for the building as a whole, in addition to active energy-saving and carbon reduction technologies, the adoption of more passive technologies helps to reduce carbon emissions in green public buildings, and the carbon reduction effect is significant.

 

 

The linear relationship between the average score rate of the nine passive technology clauses and operational carbon emissions is shown in Figure 7.

 

 

Figure 7 shows that in green buildings of different star ratings, the linear correlation coefficients R between the average score rates of clauses 4, 5, 6, and 8 and building operational carbon emissions ² are all greater than 0.8, indicating that these passive technology clauses have a significant impact on the operational carbon emissions of green buildings; in particular, clauses 4, 6, and 8, with R ²  all greater than 0.9.

Based on statistical information from 340 green public buildings, improving indoor natural ventilation, utilizing renewable energy, and enhancing natural daylighting have a significant impact on the operational carbon emissions of green buildings, which is basically consistent with the conclusions of Pan Yiqun et al. and Guo Zhenwei et al. The linear correlation coefficients R between the average score rates of clauses ²  1, 2, 3, 7, and 9 and operational carbon emissions are all less than 0.8, indicating that these passive technology clauses have a relatively small impact on the carbon emissions of green buildings, especially clause 7 on adaptive design, which has a negligible impact on the operational carbon emissions of green buildings according to project statistical information.

 

Conclusion

 

Based on a review and analysis of the application of passive technologies in 340 green public building projects of different climate zones and star ratings in China from 2016 to 2023, and the calculation of carbon emission levels for 39 projects, the following conclusions are drawn.

(1) The total carbon emissions of green public buildings in different climate zones during material production and transportation, construction, and operation are closely related to the green building star rating. The higher the star rating, the lower the total carbon emissions. In terms of carbon emission reduction contributions, operational carbon emissions contribute the most. Higher-star green buildings have lower operational carbon emissions; however, material production and transportation stages show higher carbon emissions for higher-star buildings; construction-stage carbon emissions account for a small proportion and their impact can be ignored.

(2) In terms of operational carbon emissions, the carbon emission intensity from high to low is HVAC, power systems and end-use, kitchen equipment, lighting, and water resources, with the main difference being HVAC system carbon emissions; higher-star green buildings have lower HVAC system carbon emissions.

(3) The application of passive technologies is positively correlated with the star rating of green public buildings. In general, the higher the star rating of a green building, the more passive technologies are used, and the better the application of passive technologies. The average score rate and application effect of passive technology clauses for three-star green buildings are far better than those for one- and two-star green buildings.

(4) The application of passive technologies is negatively correlated with the operational carbon emissions of green public buildings. The higher the average score rate of passive technology clauses, the lower the operational carbon emissions of green public buildings. Improving indoor natural ventilation, utilizing renewable energy, and enhancing natural daylighting have a significant impact on the operational carbon emissions of green buildings, while the impact of other passive technologies is lower.

 

 

 

Citation format: Zhu Rongxin, Liu Maolin, Li Jiayun, et al. Application of Passive Technologies in Green Public Buildings and Analysis of Carbon Emission Contributions [J]. Green Building, 2025, 17(3): 1-5, 10.

Reprinted from Green Building Magazine