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Title: A computational and empirical analysis of the thermal performance of insulating concrete formwork
Author: Mantesi, Eirini
ISNI:       0000 0004 7970 8924
Awarding Body: Loughborough University
Current Institution: Loughborough University
Date of Award: 2018
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The research presented in this EngD thesis focused on Insulated Concrete Formwork (ICF), a site-based, Modern Method of Construction (MMC). An ICF wall consists of modular prefabricated Expanded Polystyrene Insulation (EPS) hollow blocks and cast insitu concrete. The blocks are assembled on site and the concrete is poured into the void. Once the concrete has cured, the insulating formwork stays in place permanently, providing very low U-values and high levels of airtightness. ICF is often thought of as just an insulated panel acting thermally as a lightweight structure. There is a view that the internal layer of insulation isolates the thermal mass of the concrete from the internal space and interferes with thermal interaction. Despite evidence of ICF's enhanced thermal storage capacity (compared to a lightweight timber-frame panel with equivalent insulation), there is still a gap in understanding when attempting to quantify the effect of the thermal mass within ICF. Using computational analysis (Building Performance Simulation -BPS) and empirical evaluation (monitoring data), the aim of the EngD research was to analyse the aspects that affect the thermal performance of ICF; to develop an understanding about its thermal behaviour and its response to dynamic heat transfer; and, to investigate how the latter is affected by the inherent thermal inertia of the concrete core. An initial inter-model comparison using different state-of-the-art simulation tools showed a high range of variability in their simulation results for the same ICF building (up to 57% difference in the predictions provided by nine BPS tools). However, further analysis indicated that this discrepancy was mostly attributed to the modelling decisions of the user (intentional or unintentional - i.e. relying on the default settings of the tools without appreciating the sensitivity of the model), rather than the actual capabilities of the tools. Once the simulation models were calibrated with information from the monitoring project, BPS tools were able to predict with good accuracy the performance of ICF. In terms of internal air temperatures, the difference between simulation predictions and monitoring results was less than RMSE = 0.25°C during warm weather and around RMSE = 0.45°C during cold weather. The error between simulation and reality in the annual heating energy demand was found to be very low and equal to RMSE = 0.6kWh, indicating that the calibrated simulation models were able to predict the energy consumption of the building accurately. Nevertheless, despite the good agreement between simulation predictions and monitoring results, the analysis indicated there was still a level of modelling uncertainty allied to the representation of solar radiation, and ICF was found to be affected by the availability of solar radiation. The combined results of the empirical evaluation to an in-depth computational analysis showed that, in terms of energy consumption and internal thermal condition, an ICF building behaves mostly as a heavyweight structure. The concrete core of ICF is not as thermally decoupled from the internal space as it is commonly expected. The thermal inertia of the concrete in ICF reduces the dynamic heat transmission of the wall, resulting ultimately in a relatively stable internal environment (up to 37% reduced heat losses were evident in the ICF building when compared to a lightweight structure with equal levels of insulation).
Supervisor: Not available Sponsor: EPSRC ; Aggregate Industries UK Ltd
Qualification Name: Thesis (Eng.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Built Environment and Design not elsewhere classified ; ICF ; Thermal mass ; Building performance simulation ; Inter-model comparison ; Modelling uncertainty ; Sensitivity analysis ; Thermal monitoring ; Empirical validation ; Calibrated simulation ; Dynamic heat transmission