Ben Richard Hughes

A numerical investigation into the feasibility of integrating green building technologies into row houses in the Middle East

A traditional row house was re-designed to be adapted to the hot and arid climate of the Middle East. The vernacular design features include a number of cooling devices such as an open courtyard, wind towers and heat-storing building materials to reduce overheating during the summer months. This paper reports on the results of a computational fluid dynamics (CFD) modelling study of the performance of a wind tower incorporated into the row house to replace the traditional ventilation devices. The study investigated the ways in which the resulting natural air flows in the house operated using the ANSYS Fluent CFD tool to develop a numerical model of an optimized wind tower system. Achieved ventilation rates and temperature distribution inside the structure were investigated. The results demonstrated that the proposed wind tower configuration was able to increase the average indoor air velocity by 63%. An improved airflow distribution is observed inside the modified row housing model.

Integration and application of passive cooling within a wind tower for hot climates

Increasing emphasis on reducing energy consumption has raised public awareness of renewable energy resources, particularly the integration of passive systems in buildings such as wind towers. In hot conditions where there is a relatively low difference between internal and external temperatures, the cooling capabilities of wind towers, which depend mainly on their structural design and material, are inadequate. Therefore, it is essential to cool the air in order to improve the indoor thermal comfort. The aim of this work was to incorporate heat transfer devices (HTDs) in a wind tower, highlighting the potential to achieve minimal restriction in the airflow stream while ensuring maximum contact time, thus optimizing the cooling duty of the device. Computational fluid dynamics (CFD) modeling and wind tunnel testing were conducted to investigate the performance of proposed system. Results have indicated that the average indoor air speed was reduced by 28% to 52% following the integration of the HTD. Furthermore, the study concluded that the proposed cooling system was capable of reducing the air temperatures by up to 12 K, depending on the configuration and operating conditions.

Computational analysis of dynamic architecture

Dynamic architecture is a term devised for a new generation of off-grid high-rise structures that rotate. The proposed structures contain wind turbines between floors which are used to generate the power to rotate the floors and for consumption by residents. This study analyses the capabilities of this system in comparison with the standard vertical arrangement of a wind turbine. A performance analysis of the WinWind 3.0 MW wind turbine is performed. Data from the Dubai Meteorological Services were collected and analysed in conjunction with the performance analysis of this wind turbine. Furthermore computational fluid dynamic modelling was carried out and analysed for comparison. The results demonstrated that the standard horizontal orientation of a wind turbine yielded 80 per cent more power. The proposed horizontal orientation requires 46 turbines to generate enough power to sustain the consumption of the building.

A numerical investigation into the feasibility of a passive-assisted natural ventilation stack device

Various commercially available natural ventilation devices supply fresh air without mechanical assistance. These devices offer a low-energy alternative to mechanical air handling units. However, they often cannot satisfy recommended ventilation rates due to their dependence on both macro- and microclimate wind speeds. This work examines the feasibility of achieving the recommended fresh air delivery rates without impacting on the device energy requirements. A numerical investigation is carried out using a standard passive stack device geometry combined with a simulated low-powered axial fan. The investigation shows that a low-induced pressure of 20 Pa is enough to satisfy the legislative requirements. Depending on the macroclimate conditions, this induced pressure could be generated from a commercially available solar-powered system. As the fan system is only used in periods of low external wind velocities (1 m/s), it is termed a passive-assisted stack.

Passive pre-cooling potential for reducing building air-conditioning loads in hot climates

The passive airside cooling capability of heat pipes operating under high-temperature natural ventilation airstreams was investigated in this study. Pure water was used as the internal working fluid to ensure the system remained sustainable in its operation. The physical domain included 19 cylindrical copper heat pipes assembled in a systematic vertical arrangement. Using the monthly temperature data of Doha, Qatar, as a case-study reference, the efficiency of the heat pipe model was analyzed at fixed inlet air velocities of 1 and 2.3 m/s. At a source temperature of 314 K, the results showed a maximum temperature reduction of 3.8 K for an external air velocity of 1 m/s. A cooling load of 976 W was achieved, indicating a heat pipe effectiveness of 6.4% when the velocity was increased to 2.3 m/s. Wind tunnel experimental testing was conducted to validate the findings. A good correlation was observed between the two techniques with error variations of 10% for velocity and 28% for temperature. The present work identified the potential of sustainable pre-cooling using heat pipes in natural ventilation airstreams for regions with hot and dry climatic conditions. The concept is currently under intellectual property protection (GB1321709.6).

Thermal comfort investigation of an outdoor air-conditioned area in a hot and arid environment

Thermal comfort in hot and arid outdoor environments is an industrial challenging field. An outdoor air-conditioned area was designed and built to host sport and social events during summers 2014 and 2015 in Qatar. This article presents a thermal comfort analysis of the outdoor air-conditioned area using computational fluid dynamics, on-site spectators surveys, and on-spot climatic measurements. The study utilized computational fluid dynamics to develop a thermal comfort model of the outdoor air-conditioned area to predict the thermal comfort of the occupants. Five different thermal comfort indices; mean comfort vote, cooling power index, wet-bulb globe temperature index, Humidex, discomfort index, were utilized to assess the thermal comfort of spectators within the conditioned space. The indices utilized different on site measurements of meteorological data and on-site interviews. In comparison to the mean comfort vote of the sampled survey, all thermal comfort indices underestimated the actual thermal comfort percentage except the wet-bulb globe temperature index that overestimated the comfort percentage. The computational fluid dynamics results reasonably predicted most of the thermal comfort indices values. The computational fluid dynamics results overestimated the comfort percentage of mean comfort vote, wet-bulb globe temperature index, and discomfort index, while the thermal comfort percentage was underestimated as indicated by the cooling power index, and Humidex.

A study of the impact of individual thermal control on user comfort in the workplace: Norwegian cellular vs. British open plan offices

ABSTRACT In modern offices, user control is being replaced by centrally operated thermal systems, and in Scandinavia, personal offices by open plan layouts. This study examined the impact of user control on thermal comfort and satisfaction. It compared a workplace, which was designed entirely based on individual control over the thermal environment, to an environment that limited thermal control was provided as a secondary option for fine-tuning: Norwegian cellular and British open plan offices. The Norwegian approach provided each user with control over a window, door, blinds, heating and cooling as the main thermal control system. In contrast, the British practice provided a uniform thermal environment with limited openable windows and blinds to refine the thermal environment for occupants seated around the perimeter of the building. Field studies of thermal comfort were applied to measure users’ perception of thermal environment, empirical building performance and thermal control. The results showed a 30% higher satisfaction and 18% higher comfort level in the Norwegian offices compared to the British practices. However, the energy consumption of the Norwegian case studies was much higher compared to the British ones. A balance is required between energy efficiency and user thermal comfort in the workplace.

Computational analysis to factor wind into the design of an architectural environment

The effect of wind distribution on the architectural domain of the Bahrain Trade Centre was numerically analysed using computational fluid dynamics (CFD). Using the numerical data, the power generation potential of the building-integrated wind turbines was determined in response to the prevailing wind direction. The three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations along with the momentum and continuity equations were solved for obtaining the velocity and pressure field. Simulating a reference wind speed of 6m/s, the findings from the study quantified an estimate power generation of 6.4kW indicating a capacity factor of 2.9% for the benchmark model. At the windward side of the building, it was observed that the layers of turbulence intensified in inverse proportion to the height of the building with an average value of 0.45 J/kg.The air velocity was found to gradually increase in direct proportion to the elevation with the turbine located at higher altitude receiving maximum exposure to incoming wind. This work highlighted the potential of using advanced computational fluid dynamics in order to factor wind into the design of any architectural environment.

Performance Investigation of a Commercial Wind Catcher with Horizontally-arranged Heat Transfer Devices (HHTD).

The aim of this study was to conduct numerical Computational Fluid Dynamics (CFD) and experimental analysis of the performance of a wind catcher with Horizontally-arranged Heat Transfer Devices (HHTD) for hot climate conditions. A detailed experimental prototype was created using 3D printing and tested in a closed-loop low speed wind tunnel. An accurate geometrical representation of the wind tunnel test setup was recreated in the numerical modeling. The airflow supply velocity was measured and compared with the numerical data and good correlation was observed. Flow visualisation testing was conducted to analyse the airflow within the device and also inside the ventilated space. The results of the numerical analysis showed that the wind catcher with HHTD was capable of reducing the air temperature by up to 12 K within the micro-climate depending on the outdoor conditions. The technology presented here is subject to a UK patent application (1321709.6).

Wind tunnel and numerical data on the ventilation performance of windcatcher with wing wall

The data presented in this article were the basis for the study reported in the research articles entitled “Evaluation of a two-sided windcatcher integrated with wing wall (as a new design) and comparison with a conventional windcatcher” (P. Nejat, J.K. Calautit, M.Z.A. Majid, B.R. Hughes, I. Zeynali, F. Jomehzadeh, 2016) [1] which presents the effect of wing wall on the air flow distribution under using the windcatchers as a natural ventilation equipment. Here, we detail the wind tunnel testing and numerical set-up used for obtaining the data on ventilation rates and indoor airflow distribution inside a test room with a two-sided windcatcher and wing wall. Three models were integrated with wing wall angled at 30°, 45° and 60° and another windcatcher was a conventional two-sided device. The computer-aided design (CAD) three-dimensional geometries which were produced using Solid Edge modeler are also included in the data article.