Investigation of sustainable energy technologies and energy performance prediction for deep energy retrofit in single-family houses
Publication Date
December 13, 2022
Creator
Abstract
According to the EU Commission projection (2016/547/EU), the current average renovation rate is far below the expected rate of 3% to achieve carbon neutrality in building sectors by 2050. This is due to the fact that, during the building retrofit optimisation process, the decision-making criteria and objectives are generally optimised separately, and homeowners' motivations are often ignored or not carefully defined in most research especially. In Europe, 68% of residential building stocks are single-family houses in European countries with roughly 54% constructed before the 1970s with poor energy efficiency. However, few studies address the issue of ‘Rapid and accurate energy-economic performance prediction of deep energy retrofit in single-family houses’ over the past decades. Recently, this issue has been discussed in limited research via the Black- or White-box based building energy models to predict post-retrofit energy-economic performance. Applying the Black-box models, low accuracy occurs due to inadequate data, neglect of coupling effects in deep energy retrofit combinations and lack of complex heat transfer phenomena in single-family houses. Conversely, the White-box models with time-consuming and numerous dynamic simulations are found to be cumbersome.
This PhD research aimed at investigating a rapid and accurate Energy-Flow based Ensemble Calibration (EF-EC) model for energy prediction of deep energy retrofit in single-family houses using the high-efficient sustainable retrofit technologies, which will be integrated with homeowners’ engagement in a novel Motivation-Objective-Criteria (MOC) based retrofit approach to optimize the final retrofit decisions.
In this research, innovative envelop retrofit technologies include façade insulation, glazing insulation and efficient daylighting pipe technologies, which can be used to reduce the thermal energy and electricity load for both heating and cooling requirements. Innovative energy system retrofit technologies includes 1) liquid desiccant-based air cooler and dehumidifier, and 2) solar assisted heat pump. Numerical models have been established for each technology with validation by measurement in either laboratory or field test, with results data to clearly identify and calibrate the performance under real conditions. The EF-EC model is applied in a case study building representing a single-family house constructed in the 1960s in northern Italy with poor insulation and high energy consumption under the typical Mediterranean climatical context. Furthermore, 17 retrofit measures are proposed by the RezBuild Project Consortium, and classified into passive, active and renewable categories, with a domain of 20,735 comprehensive energy retrofit combinations generated. Retrofit motivations are categorised into three typical types: 1) Self-living, 2) Rental or sale, and 3) Investment, under five objectives: Energy Reduction Rate (ERR), Initial Investment (II), Discounted Payback Period (DPP), Bills Reduction Rate (BRR) and Carbon Reduction Rate (CRR). A UK semi-detached house is applied as the reference building to investigate the impact of homeowners’ engagement on the decision-making of various retrofit measures.
Compared with the IES VE simulation results, the maximum discrepancy of the EF-EC model is 6% with an absolute discrepancy of 2.9 kWh/m2, where the energy reduction rate is in the range of 76% - 89%. Therefore, the calculation discrepancy has been improved by 63% - 75%. This research using the EF-EC model could save up to 90% of calculation time, with 0.72s computing time on a single combination. According to the cost-optimal results neglecting homeowners’ motivation, it is evident that the mismatch of optimal retrofit combinations occurs between the minimum Initial Investment (II) and Discounted Payback Periods (DPP), with optimal ERR of 72%-79% and 82%-93%, respectively. The sensitivity analysis results are conducted, indicating that the optimal retrofit measures and baseline energy consumption input are in good agreement, with a 10% discrepancy. Thus, the proposed inclusive Motivation-Objective-Criteria approach can incorporate homeowners’ engagement in the building retrofitting design process, serving as a decision-making supporting tool to accelerate building retrofit with maximised user acceptance and market penetration.
Item Type
ethesis
Thesis Type
PhD
Subjects (LC)
Associated Schools / Departments
Department of Architecture and Built Environment (UK)
eprints ID
71170
UoN Repository URI
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Thesis manuscript.pdf
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Full-text
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Examined. Final version
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10.75 MB
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Adobe PDF
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