Building Services Engineering Research & Technology

Managing thermal loss is a key topic that needs further investigation as it has a direct link to reducing the energy load in buildings. One of these thermal loss management methods can be the use of shading devices. Dynamic thermal models normally used at the early stages of the building design can play an important role in the decision-making process regarding the use of shading devices. This paper presents the results of a real-world study assessing the potential of using a sealed cellular blind as a passive energy conservation method, where the real-world results are compared with the simulated results generated with environmental design solutions limited thermal analysis software (EDSL Tas) and integrated environmental solutions virtual environment (IES VE). During the real-world study, a positive impact of having blinds was seen whereby the window surface temperature increased and office heating energy consumption was lowered. Both software tools were able to predict a similar trend of results for the window surface temperature in with and without blind scenarios whereas for energy consumption although in the presence of a blind a consistent correlation is seen between measured and calculated values but not without a blind. This can be attributed to the inability of the software tools in demonstrating the effect of infiltration in the absence of a blind or shading device i.e., a clear window scenario.

Elevator safety is closely related to public safety. Overspeed governor is a crucial part of the elevator safety system. Its inspection and calibration involve the measurement of tripping velocity. The frequently-used contact-type measurement method has risks. This paper proposes a non-contact image-recognizing measurement method by the camera, which includes the processes of rotor centre recognition, feature points matching, and tripping switches recognition. The velocity curve can be obtained by feature points displacement based on the rotor centre. Tripping switches recognition can determine the electrical and mechanical tripping velocities in the speed curve. The experimental results demonstrate that the proposed method has no significant difference from the common contact-type measurement method, while it significantly eliminates the risks of physical damage and improves measurement safety. Moreover, this paper proposes the deduction and calculation of measurement uncertainty decided by camera performance. Due to the enhancement of measuring safety, the proposed method will have further application in the field of elevator inspection.

Practical application: The research on tripping velocity measurement for overspeed governor in this paper is principally based on image recognition with the help of a camera. The experiment result indicates that the proposed method is capable of completing the speed measurement for the overspeed governor without contact. The proposed method significantly mitigates the risks of physical damage and improves measurement safety rather than the contact-type measurement method. The proposed non-contact image-recognizing method can substitute for the existing contact-type method and contributes to the inspection, maintenance, and management of elevators, which will have further application prospects.

Ventilation systems include a variety of components for which necessary pressure loss data is often unavailable. Computational fluid dynamics simulations could substitute for expensive measurements, but validation simulations with suitable data are crucial to assess model uncertainties. Existing CFD validation studies either did not focus specifically on pressure losses, only covered few components, or did not include recent developments in turbulence modelling. In the present work, 33 bends, 4 gates and 2 tees were simulated using a consistent approach. Computational fluid dynamics simulations were validated with published data: rectangular high-edge and wide-edge bends from the experimental dataset of Sprenger, gates and diverging tees from the SMACMA guide. The considered flows cover important basic flow phenomena: deflection, splitting and flow separation. The 39 components were simulated with three turbulence models at 14 Reynolds numbers. The simulations predicted pressure loss coefficients accurately for various components. Cases with strong flow separation regions were most challenging. The model prediction uncertainty was assessed by carrying out simulations with three selected turbulence models. As in the experimental data from Sprenger, the simulations showed a distinct dependence of pressure loss coefficients on the Reynolds number for bends. In contrast, for abrupt deflections and flow separation at sharp edges, the Reynolds number dependency was minor.

During the regulation process of VAV systems, the supply air volume changes with the real time load changes, which will cause the fresh air volume to deviate from its set value. Insufficient fresh air results in poor IAQ, whereas an excessive fresh air increases energy consumption. Therefore, an effective method to control the fresh air volume is essential for VAV systems. Based on the differential pressure control theory, two improved control methods—the fresh air section static pressure control method and the critical air volume control method—are proposed herein. Three control methods were compared through experimental study. The results indicate that differential pressure in the first improved method is higher than that in the differential pressure control method, which increases the ease of measurement. However, both these methods have approximately 15% to 25% errors when the supply air volume is small. The critical air volume control method provides more precise control of the fresh air volume, and eliminates deviations at small supply air volumes. Furthermore, the fan power is reduced as well. Investigation has demonstrated that the critical air volume control method is energy-efficient, and can provide new insights into optimized energy-saving control methods for VAV systems.

The present work aims to optimize the thermal behavior of a building envelope by combining sensitivity analysis (SA) and multi-objective optimization (MOO). An existing classroom located in Marrakech city was considered a case study building. The building model was analyzed under six Moroccan climate zones. The SA was applied on 16 design variables and performed using the Morris method implemented in the tool Simlab to rank each design variable based on its influence on the objective function (overall energy demand). The SA results showed that the solar absorptance of the internal roof, wall, and ground floor and the ground hollow core slab thickness impacted less the overall energy demand. Therefore, the only remaining variables showing the most relevant effect will be optimized afterward. The optimization phase was conducted by coupling the generic optimization tool GenOpt with TRNSYS. The optimum solution was selected based on the Pareto front approach. The obtained results assessed the effectiveness of the adopted methodological approach in significant minimization of the required thermal loads. Furthermore, the values of each optimum design variables set differ from one climate zone to another; leading to energy demand reduction varying from 30 to 42%, in comparison with the original design building.

Current energy and climate policies are formulated and implemented to mitigate and adapt to climate change. To inform relevant building policies, two bottom-up building stock modelling approach: 1) archetype-based and 2) Building-by-building have been developed. This paper presents the main characteristics and applications of these two approaches and evaluates and compares their ability to support policy making. Because of lower data requirements and computational cost, archetype-based modelling approaches are still the mainstream approach to stock-level energy modelling, life cycle assessment, and indoor environmental quality assessment. Building-by-building approaches can better capture the heterogeneous characteristics of each building and are emerging due to the development of data acquisition and computational techniques. The model uncertainties exist in both models which may affect the reliability of outputs, while stochastic archetype models and timeless digital twin model have the potential to address the issue. System dynamics modelling approach can describe and address the dynamics and complexity of often-conflicting policies and achieve co-benefit of multiple policy objectives.

The built environment has been a significant contributor to global carbon emissions. It, therefore, has a vital role to play in the reduction efforts of future climate change. While the design of buildings may determine future energy use for cooling, heating, and lighting during the operational stage of the building, this study aims to observe the effect of the building design on the operational as well as the whole-life carbon emissions. Past studies have focused on either the operational carbon or the embodied carbon of a building. Using a cradle-to-grave assessment of a typical UK supermarket, this study explores the relationship between embodied carbon and operational carbon. Additionally, it examines the effects of the variables between three approved construction methods of the same design on the whole life of carbon. These methods are a steel structural frame and cladding panel external wall, steel frame and poroton walls, precast concrete and glulam frame and precast concrete walls. The findings of this research will contribute to mitigation strategies for the environmental impacts of supermarket building construction whilst providing a framework for future assessment of the whole-life carbon of supermarket buildings.