John Kaiser Calautit

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.

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.

Wind tunnel data of the analysis of heat pipe and wind catcher technology for the built environment.

The data presented in this article were the basis for the study reported in the research articles entitled ‘Climate responsive behaviour heat pipe technology for enhanced passive airside cooling’ by Chaudhry and Hughes [10] which presents the passive airside cooling capability of heat pipes in response to gradually varying external temperatures and related to the research article “CFD and wind tunnel study of the performance of a uni-directional wind catcher with heat transfer devices” by Calautit and Hughes [1] which compares the ventilation performance of a standard roof mounted wind catcher and wind catcher incorporating the heat pipe technology. Here, we detail the wind tunnel test set-up and inflow conditions and the methodologies for the transient heat pipe experiment and analysis of the integration of heat pipes within the control domain of a wind catcher design.

Does a neutral thermal sensation determine thermal comfort

The neutral thermal sensation (neither cold, nor hot) is widely used through the application of the ASHRAE seven-point thermal sensation scale to assess thermal comfort. This study investigated the application of the neutral thermal sensation and it questions the reliability of any study that solely relies on neutral thermal sensation. Although thermal-neutrality has already been questioned, still most thermal comfort studies only use this measure to assess thermal comfort of the occupants. In this study, the connection of the occupant’s thermal comfort with thermal-neutrality was investigated in two separate contexts of Norwegian and British offices. Overall, the thermal environment of four office buildings was evaluated and 313 responses (three times a day) to thermal sensation, thermal preference, comfort, and satisfaction were recorded. The results suggested that 36% of the occupants did not want to feel neutral and they considered thermal sensations other than neutral as their comfort condition. Also, in order to feel comfortable, respondents reported wanting to feel different thermal sensations at different times of the day suggesting that occupant desire for thermal comfort conditions may not be as steady as anticipated. This study recommends that other measures are required to assess human thermal comfort, such as thermal preference. Practical application: This study questions the application of neutral thermal sensation as the measure of thermal comfort. The findings indicate that occupant may consider other sensations than neutral as comfortable. This finding directly questions the standard comfort zone (e.g. ASHRAE Standard 55) as well as the optimum temperature, as many occupants required different thermal sensations at different times of the day to feel comfortable. These findings suggest that a steady indoor thermal environment does not guarantee thermal comfort and variations in the room temperature, which can be controlled by the occupant, need to be considered as part of the building design.

CFD Simulation of Integrating Solar Roads in Urban Canyon

A 3-D computational modelling analysis of a road pavement solar collector (RPSC) system was used in two different macro domains; a standard urban canyon domain and a flat domain (no buildings). The computational model was developed in ANSYS Fluent to consider the temperature effects of solar radiation and radiative exchange between canyon air and surfaces. Good agreement was observed with average error 4.19% validated from the previous CFD model. The simulation of 21st June at 13:00 demonstrated the RPSC system in the urban canyon domain performed 36.08% more effectively in thermal collection with 27.11% more surface temperature reduction as compared to its performance in the flat domain.

Data on the natural ventilation performance of windcatcher with anti-short-circuit device (ASCD)

This article presents the datasets which were the results of the study explained in the research paper ‘Anti-short-circuit device: a new solution for short-circuiting in windcatcher and improvement of natural ventilation performance’ (P. Nejat, J.K. Calautit, M.Z. Abd. Majid, B.R. Hughes, F. Jomehzadeh, 2016) [1] which introduces a new technique to reduce or prevent short-circuiting in a two-sided windcatcher and also lowers the indoor CO2 concentration and improve the ventilation distribution. Here, we provide details of the numerical modeling set-up and data collection method to facilitate reproducibility. The datasets includes indoor airflow, ventilation rates and CO2 concentration data at several points in the flow field. The CAD geometry of the windcatcher models are also included.