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Thermal energy modelling, benchmarking and mapping for university campus buildings
Vaisi, Salahadin
According to the Chartered Institution of Building Services Engineering, CIBSE TM46:2008 University Campus benchmark, a college building needs 240 kWh/m2 of thermal energy and proportionally produces 45.6kg CO2 per annum. As heat consumption largely depends on the ambient temperature, this fixed-annual benchmark is not suitable because it does not deliver any difference between summer and winter. Firstly, the current research analysed the accuracy of the CIBSE TM46 ?University Campus? benchmark against the thermal consumption values presented in Display Energy Certificates (DECs). The DECs of 52 college buildings belonging to four universities in Dublin were assessed and based on the 46% discrepancy between the median of analysed samples and the CIBSE UC (University Campus) benchmark, a new benchmark of 130 kWh/m2/yr was recommended. This new benchmark is 110 kWh/m2/yr lower than the current benchmark which is a substantial improvement. The UC revised benchmark (UCrb, 130 kWh/m2/yr) was validated using Descriptive Statistics (DS). It has been found that the UCrb is a precise description of an up-to-date typical performance of college buildings in Dublin. The benefits of UCrb in terms of fossil energy saving and reduction of CO2 emissions were calibrated and the results interpreted based on CIBSE UC benchmark and DEC values. Considering the large size of college buildings, applying UCrb could decrease the fossil consumption in Irish universities dramatically because the UCrb is approximately half of the current benchmark. Secondly, Monthly Thermal Energy Models (MTEMs) which took into account the variations of heat demand during a year were generated using five key factors including mixed use approach, UCrb, activities area, heating degree days, and typical operation hours of heating systems. Two methods for generating the monthly heat models were presented based on the mixed use activities and Display Energy Certificates (DECs). Unlike many studies on energy modelling and benchmarking assuming buildings are single use, in the presented methodology the impact of mixed activities on heat consumption was considered. The results of MTEMs were compared with the CIBSE TM46 methodology and a significant development was obtained. When the absolute error of CIBSE UC benchmark for heat estimation was nearly 98% in summer months, the errors of MTEMs were less than 21%. Moreover, the results of R-squared analyses confirmed the accuracy of models. Thirdly, the methodology of MTEMs was developed and Monthly Thermal Energy Benchmarks (MTEBs) were generated for the first time in the area. Comparing the fixed-annual CIBSE UC benchmark of 240 kWh/m2/yr, MTEBs altered from 21 kWh/m2 in January to 1 and nearly zero kWh/m2 in June and July respectively. Comparing the current CIBSE TM46 university campus benchmark, MTEBs are very sensitive and compatible with the real conditions. They also share more information than an annual index. The MTEMs and MTEBs were used to generate detailed heat energy maps which showed the thermal energy density of buildings in the studied universities. Based on the maps, it was found that the buildings in a campus from viewpoint of thermal energy demand size and pattern could be classified into Periodical Thermal Consumers (PTC) and Continual Thermal Consumers (CTC). A typical college building is an example of the first group, while a swimming pool belongs to the latter group. Based on the data analyses, energy maps, and detailed study of actual thermal consumption, the concept of sharing surplus thermal energy was presented. The concept of sharing surplus heat energy between adjacent buildings in a campus compared with thermal energy storage method and the advantages of sharing surplus thermal energy were discussed. Finally, the MTEMs and MTEBs methods were validated in Grangegorman developing campus of DIT (Dublin Institute of Technology). The monthly thermal demands of campus were calculated at both the building and campus scale. The detailed information of energy demand especially the energy maps which reflect the scattering model of thermal anchor loads are important for architects, urban planners, energy professionals, and building owners to plan and manage thermal energy more efficiently and smartly at a group of buildings such as a campus rather than an individual building. In addition, the generated 3D energy maps are more user friendly and comprehensible even for public. The developed methodology in this study can be applied to design a thermal efficient campus in future by urban planners and architects.
Keyword(s): Energy modelling; Energy benchmarks; Energy estimation; Thermal energy efficiency
Publication Date:
Type: Doctoral thesis
Peer-Reviewed: Yes
Institution: Trinity College Dublin
Citation(s): VAISI, SALAHADIN, Thermal energy modelling, benchmarking and mapping for university campus buildings, Thermal Energy Modelling, Benchmarking, and Mapping for University Campus Buildings , Trinity College Dublin.School of Engineering.CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING, 2017
Publisher(s): Trinity College Dublin. School of Engineering. Disc of Civil Structural & Environmental Eng
Supervisor(s): McCormack, Sarah
First Indexed: 2017-09-08 06:35:54 Last Updated: 2017-10-25 06:23:21