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No description available.

The project aims to improve the modelling of moisture transfers at internal surfaces by linking the finite volumes representing the Heat, Air and Moisture (HAM) and Computational Fluid Dynamics (CFD) domains. Conflation of both models facilitates the detailed study of moisture flow as it impacts on indoor air quality and occupant health. The thesis lays down the conceptual framework for the subsequent development of an indoor air quality analytical tool. The work thus improves the modelling of construction feature risk assessment, for example, moisture absorption and desorption at the internal fabric surfaces in as much as it relates to indoor air quality. Through such an improvement, an indoor air quality analytical tool for the prediction of time-varying temperature/humidity conditions at specific locations within the building is enabled and subsequently these conditions may be related to the likely occurrence of mould. Humidity in indoor spaces is one of the most important factors in the determination of indoor air quality. High indoor humidity is a major contributor to the accumulation of moisture in the building envelope. This often results in dampness within the building envelope and subsequent health-related problems for the occcupants. Moderation of the indoor relative humidity, temperature and moisture content of the indoor air amongst others is a pre-requisite for a healthy building because it affects the perception of indoor air quality, thermal comfort, occupant health (asthma, respiratory illness, etc), building durability, material emission and energy consumption. Excessively high relative humidity promotes the growth of moulds and mildew on building surfaces. The basis for the envisaged conflation evolves around the boundary layer theory as it pertains to the velocity, thermal and concentration profiles associated with flow parallel to a flat surface, a phenomenon which is recognised as being similar in nature to buoyancy-driven convective heat transfer within building enclosures (White 1988). Within the framework of modelling of indoor air flows, the conflated modelling approach is very much dependent upon the treatment of the internal surface convection, for example, in the conflation of HAM and CFO models. This is referred to as the pivot point for the handshaking between HAM and CFO modelling domains. Within the framework of this project, the pivot point refers to the treatment of surface convection mass transfer at the internal surface to facilitate the hand shaking between HAM and CFO modelling domains. The two-time step coupling approach based on the loose coupling algorithm is adapted for the conflation. The technique involves a process whereby the HAM and CFO models are processed independently but exchange information at the interface at every time-step. The numerical method for the solution of the Navier-Stokes equations is based on the co-located grid arrangement, whereby all flow variables are defined in the centre of the grid cells. The transport equations are integrated for each grid cell and the Gauss Theorem applied to yield an integral over the cell face. These cell face integrals are then approximated using interpolation of the cell centred data. For the resolution of flow in the near-wall regime, the Low-Reynolds number k-ε turbulence model is used. A configuration mechanism with a rules-based moisture control algorithm to facilitate the handshaking of the HAM and CFO domains is presented. Methods for the solution of problems due to moisture migration across the interface, which are effected through variation of the convective mass transfer coefficient, hm, through variation of the standard k-ε turbulence model, namely the lowReynolds number model with its embedded wall damping functions and through adjustment of the source terms of governing transport equations of the CFO and HAM models are also discussed.

The extensive use of air conditioning for indoor cooling in offices and large commercial buildings in Kuwait represents a major part of the power and electricity consumption in that country. The main objective of this research was to investigate ice and chilled water cool thermal storage technologies and operating strategies for air conditioning. This was motivated by the extreme climatic conditions in Kuwait and the necessity to reduce both maximum power demand and energy consumption whilst being economically feasible. This work represents the first such study undertaken. In Kuwait approximately 45% of the total annual exported electrical energy is consumed solely by air conditioning systems as a result of the very high ambient temperatures occurring between March and October. Furthermore, it was estimated air conditioning systems represent about 62% of the peak electrical load. To assess the potential of cool thermal storage, the air conditioning system for an existing clinic building, representing a typical medium size building in Kuwait, was designed with and without a cool thermal storage system. The results demonstrate that internal ice-on-coil and chilled water storage systems are suitable storage technologies that can be implemented in Kuwait. The cooling demand of the clinic building was first estimated using the ESP-r building energy simulation program, following which the different components in the air conditioning systems were sized including chiller, storage tanks, pumps, air handling units for conventional, ice and chilled water storage air conditioning systems operating with load levelling, 50% demand limiting and full storage strategies. The heat gains by different auxiliary components in the air conditioning systems were estimated and the final cooling demand profiles were developed. For each air conditioning design, the power and energy consumption for the design day condition and over the whole year were calculated and analysed. Furthermore, the life cycle costs were determined based on the estimated capital, maintenance, operating costs and a financial analysis was carried out. For the Kuwaiti climate, the results demonstrate ice and chilled water storage systems can reduced the maximum power consumption during the day time when the electricity demand is high and largest reduction in the maximum power achieved full storage strategy. However, the energy consumption of ice storage system operating with 50% demand limiting and full strategies were found were found to be higher than the conventional air conditioning system. Nevertheless, the energy consumption in the ice storage system with a load levelling operating strategy was slightly lower. Chilled water storage system was found to be unlike ice storage system, the energy consumption in all operating strategies improved over the conventional system. Based on the estimated life cycle cost using the actual operating costs for both the government and user, it was established that for the government, ice storage operating with load levelling strategy and all other strategies of the chilled water storage systems would be more economical than conventional systems. However, for the user, load levelling ice storage, load levelling chilled water storage, and 50% demand limiting chilled water storage systems would be more cost effective. Out of all alternatives, chilled water storage system with a load levelling strategy was found to be the most cost effective for the climate of Kuwait and for similar climates of Kuwait. Although, the outcome from this research work can not be generalised however, the method of sizing and energy and economic analysis, which was discussed in this thesis can be generalised and followed to evaluate the impact of cool thermal storage systems on energy performance and economy of the air conditioning systems.

This study is set out to confirm the phenomenon commented on by Hassan Fathy (1986) that the temperature difference between courtyards has a role in the promotion of convective cooling through transitional spaces in a multiple-courtyards building in semi and regions. The transitional spaces situated between courtyards are identified with specific titles such as Takhtabüsh in the Egypt; and Tablinum in a Roman Domus. However, despite the historic significance of these spaces, most studies have mainly focused on the climatic performance of buildings with a single courtyard. Empirical and numerical study has not been conducted on the nature of this phenomenon. In order to confirm this conjecture, this thesis is set out to conduct fieldwork and theoretical investigation. This thesis is a single case study of the Casa de Pilatos in Seville, Spain. The case study is used to develop a methodology for analysis of multiple-courtyard phenomenon. Field measurement and mathematical models are used to determine the drivers for yard-to-yard airflows. The fieldwork uses data logging equipment to record dry bulb temperatures, relative humidity, and air velocity through the transitional spaces. The amount of cooling attributed to yard-to-yard flows and implication to cooling requirements in a contemporary environment are evaluated. Adaptive criteria of Nicol and Humphrey (2001)'and Brager and de Dear (2001) are used to predict the thermal comfort of subjects. The drivers are determined through analysis of buoyancy `stack' forces and local wind regime. The building mass introduces three hours delay with up to 2.5kW or 36W/m2 variation in heat balance in the transitional spaces by 15: 00h. The calculated volume flow rates through the transitional space are 5.3m3/s (equivalent to 5kW or 71 W/m2 in convective cooling) at 15: 00h. The DBT in the gardens are up to 11 k below the WBT. It is shown that multiple-courtyards phenomenon is a robust strategy accommodating a large variation in temperatures. The study confirms that temperature difference is the driver for convective flows through transitional spaces. This study presents an opportunity to investigate the applicability of this concept in the contemporary context. Findings of this study have direct application in the reduction of cooling energy in widely used courtyard concept in semi and regions.

Fossil fuels are the major sources of electrical power generation in the world. Among all fossil fuels, oil is considered as the most sought-after fuel. The burden on countries that provide subsidized electricity produced from oil-fired power plants is noteworthy. Kuwait is a notable example of these countries. Electricity in Kuwait is heavily consumed by residential air conditioning, which comprises 60% of the total electricity generated at peak times on a hot summer day. From this perspective, residential air conditioning in Kuwait was selected to undergo further investigation regarding low energy air conditioning choices. Three solutions to control the rapid growth of demand for electricity by residential air conditioning are examined. The first solution investigated assesses the orientation and grouping of houses in Kuwait in order to examine their effect on cooling load and electrical energy consumption for future houses. Four residential cases were developed; each case comprises six typical houses. The cases identified are: (1) single block facing east-west, (2) single block facing north-south, (3) double block facing east-west and (4) double block facing north-south. Cooling loads are calculated using the DesignBuilder building thermal simulation software. Case (2) is found to have the smallest cooling load, and case (1) the largest. The estimated savings from applying case (2) compared to the average of the four cases for the future houses planned to be built by the government by the year 2016 (i.e. approximately 20,000 houses) are found to be approximately .US 33 million of power system capital costs, 15 GWh per year of electrical energy consumption and 11 kilotons per year of CO2 emissions. In the second solution, a lifecycle cost analysis is performed to evaluate the economic feasibilities of electricity driven chilled water system compared to predominant air conditioning system in Kuwaiti houses which is Packaged- Direct Expansion. The study considers the total cash paid by the consumer and the total cash paid by the government, since electricity is subsidized in Kuwait. The study finds that the chilled water system is not cost-effective for consumers due to high installation cost. However, a chilled water system would be cost-effective for the government because it consumes 40%less electrical energy than Packaged-DX. So, the study suggests subsidising the installation of chilled water systems so that the installation cost to the consumer is the same as for Packaged-DX systems. In the third solution, the study examines the viability of a single-effect LiBr absorption chiller driven by steam extracted from the steam turbine in the configuration of a combined cycle power plant (CCPP). The analysis shows that CCPP with absorption chiller yields less net electrical power available to utility grid compared to similar CCPP giving electricity to the grid and to Direct-Expansion air conditioning systems for the same cooling requirements. The reasons for that are the reduction in steam turbine power output resulted from steam extraction, and the amount of electrical energy required to operate the configuration of CCPP with absorption chiller.