Long-term carbon intensity reduction potential of K-12 school buildings in the United States
Introduction
To mitigate climate change caused by greenhouse gas (GHG), the United States (U.S.) has outlined a pathway to reduce carbon emissions 50 % by 2030 [1] and 80 % by 2050 [2]. Being one of the significant infrastructures in the U.S., K-12 school buildings, including primary and secondary schools, have a great potential to reduce carbon emissions. According to the climate advocacy organization Generation180, school facilities annually emit about 72 million metric tons of carbon dioxide, which is equivalent to the emissions from about 8.6 million homes [3]. Currently, more than 30 % of school buildings are constructed before 1960 and are underperforming [[4], [5]]. The underperforming buildings are buildings with low energy efficiency and high carbon emission intensity. Carbon intensity, which is the kilograms of carbon dioxide equivalent emitted per square meter, is one of the emerging metrics to measure the carbon emissions of buildings [[6], [7], [8]]. Hence, it is critical for the policymaker to know the reduction potential of carbon intensity for underperformed buildings by adopting building retrofit measures. The high operating cost of the K-12 school buildings also forces public administrations to make strategic decisions concerning the refurbishment of the school building stock. According to the 2012 Commercial Buildings Energy Consumption Survey (CBECS) conducted by the U.S. Energy Information Administration (EIA), schools annually spend around $8 billion on utility bills [9]. Moreover, reducing the carbon intensity of K-12 school buildings is a good practice for promoting sustainable development for the pupils and their families [10].
The existing study has proved the effectiveness of building retrofits to reduce carbon intensity in specific cities [[11], [12]]. There are several building retrofit measures that have the potential to reduce carbon intensity, such as increasing the insulation of the building envelope, improving the efficiency of the HVAC system, and adjusting the lighting power density of buildings [[13], [14], [15], [16], [17], [18], [19], [20], [21]]. Moreover, building retrofits have a positive economic impact on reducing the operational costs of buildings, which can be an incentive for stakeholders to adopt the building retrofit measures, reducing carbon intensity as a result [22]. Gamarra et al. indicated that schools could reduce the fossil energy demand of the building in the operation and maintenance phase via building retrofits in a hot climate zone [23]. Many researchers realize that carbon intensity reduction on the county level is very important to achieve low-carbon development goals [[24], [25], [26], [27]].
However, challenges remain regarding presenting comprehensive carbon intensity inventories at the county level. For the U.S., the situation becomes particularly difficult because of the significant geographical and social-economic diversity across the country. Furthermore, generating comprehensive carbon intensity inventories requires very detailed carbon accounting for each county as well as a comprehensive understanding of the local climate. Compared with states, counties have various definitions regarding their boundaries and non-centralized statistics, which produce uncertainties in carbon intensity calculation. Facing this challenge, a method emphasized on a county-by-county basis is needed to predict the carbon intensity reduction potential of school buildings. Carbon assessment on a county-by-county basis is a key research direction in the field of carbon neutrality. Understanding carbon intensity at the county and regional levels have been highlighted in the carbon management literature [[26], [28], [29]].
The above literature review reveals that there is no existing method for predicting the large-scale carbon intensity reduction potential of K-12 school buildings on a county-by-county basis. To fill the gap, this study investigates the large-scale carbon intensity reduction potential of K-12 school buildings on a county-by-county basis, which is not fully investigated yet. Furthermore, the new methods proposed in this paper can also be applied to any aggregated commercial buildings in the continental U.S. Based on the result of building energy modeling, the dynamic carbon emission factor of electricity is used to explore the carbon intensity reduction potential of commercial buildings on a county-by-county basis in the continental U.S. Then, to calculate the aggregated carbon intensity reduction of commercial buildings, the weighting values of floor area calculated from the existing construction database are considered. According to the research objective, this study adopts this method to comprehensively assess the carbon intensity reduction potential of K-12 school buildings in the continental U.S. on a county-by-county basis.
The rest of this paper is organized as follows: Section 2 introduces the methodology of predicting county-by-county based carbon intensity reduction potential of aggregated commercial buildings; Section 3 describes the application of this method in K-12 school buildings including building energy model preparation, information on building locations, building retrofit measures and weighting values of floor area between primary and secondary school buildings; Section 4 presents the results of carbon intensity reduction of K-12 school buildings; Section 5 discusses the spatiotemporal variability of the long-term carbon intensity reduction of K-12 school buildings. Finally, Section 6 concludes and discusses future work.
Section snippets
Methodology
This study develops a method to comprehensively assess the long-term carbon intensity reduction potential of aggregated commercial buildings in the continental U.S. at the county level, as shown in Fig. 1: (1) energy prediction for a commercial building, (2) carbon emission prediction for a commercial building, and (3) carbon intensity reduction potential of aggregated commercial buildings. Following these three steps, the carbon intensity reduction potential of aggregated commercial buildings
Study design
According to the method developed in section 2, we select the K-12 school building as an application of this method. This section provides the overview of K-12 school buildings energy model including primary and secondary school building models, weather features for simulation, values for building retrofit measures, and the weighting value to calculate the aggregated carbon intensity reduction.
Results
With the section 2 methodology and section 3 study design, the energy use intensity (EUI) reduction of K-12 school buildings by adopting the building retrofit measures can be predicted. Then the long-term carbon intensity reduction potential of K-12 school buildings in the U.S. is predicted on a county-by-county basis.
Comparison of U.S. map from 2022 to 2050
In subsection 4.2, the large-scale carbon intensity reduction potential has been shown on a county-by-county basis. This section further discusses the change of large-scale carbon intensity reduction from 2022 to 2050.
Conclusion
Based on the prediction of electricity sources in the next 30 years, this study develops a method to comprehensively assess the long-term carbon intensity reduction potential of aggregated commercial buildings in the continental U.S. at the county level. As an application of this method, this study investigates the county-by-county based (around 3000 counties) carbon intensity reduction of K-12 school buildings with eight building retrofits from 2022 to 2050 in the continental U.S. (excluding
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgement
This research was supported by the National Science Foundation under Awards No. CBET-2110171.
References (50)
- et al.
A multi-criteria approach to affordable energy-efficient retrofit of primary school buildings
Appl. Energy
(2020) - et al.
Carbon emission of energy efficient residential building
Procedia Eng.
(2015) - et al.
The effect of building retrofit measures on CO2 emission reduction – A case study with U.S. medium office buildings
Energy Build.
(2021) - et al.
Long-term carbon emission reduction potential of building retrofits with dynamically changing electricity emission factors
Build. Environ.
(2022) Improving energy efficiency through the design of the building envelope
Build. Environ.
(2010)- et al.
Passive building energy savings: a review of building envelope components
Renew. Sustain. Energy Rev.
(2011) - et al.
Cost benefits analysis and emission reductions of optimum thickness and air gaps for selected insulation materials for building walls in Maldives
Energy
(2010) - et al.
Optimizing the insulation thickness of walls and roofs of existing buildings based on primary energy consumption, global cost and pollutant emissions
Energy
(2018) - et al.
A novel operation approach for the energy efficiency improvement of the HVAC system in office spaces through real-time big data analytics
Renew. Sustain. Energy Rev.
(2020) - et al.
Energy saving potential and strategies for electric lighting in future north european, low energy office buildings: a literature review
Energy Build.
(2011)
Energy saving claims for lighting controls in commercial buildings
Energy Build.
The economic impacts of carbon emission trading scheme on building retrofits: a case study with U.S. medium office buildings
Build. Environ.
Energy and water consumption and carbon footprint of school buildings in hot climate conditions. Results from life cycle assessment
J. Clean. Prod.
Spatio-temporal dynamic evolution of carbon emission intensity and the effectiveness of carbon emission reduction at county level based on nighttime light data
J. Clean. Prod.
Carbon emission governance zones at the county level to promote sustainable development
Land
Spatially explicit carbon emissions at the county scale
Resour. Conserv. Recycl.
Development of a framework of carbon accounting and management on the township level in China
J. Environ. Manage.
Plug-load densities for energy analysis: K-12 schools
Energy Build.
Hygrothermal and energy retrofit planning of masonry façade historic building used as museum and office: a cultural properties case study
Energy
Minimizing delivered energy and life cycle cost using Graphical script: an office building retrofitting case
Appl. Energy
Research on deepening design and construction of cross-sea tunnel based on the principle of prefabricated building
IOP Conf. Ser. Earth Environ. Sci.
Cited by (4)
Regional carbon emission reduction prediction via retrofits of commercial buildings with a case study of US school buildings in hot climates
2023, Building Simulation Conference ProceedingsTowards smart communities: Evaluation of solar photovoltaic panels on a parking depot
2023, Proceedings - 2023 IEEE International Conference on Environment and Electrical Engineering and 2023 IEEE Industrial and Commercial Power Systems Europe, EEEIC / I and CPS Europe 2023