The application of Mixed-Mode ventilation in severe arid climates and its integration with other passive cooling strategies is very challenging. This paper presents a systematic evaluation of the performance of various Mixed-Mode cooling strategies for office buildings with different levels of internal heat gain operated in four cities representative of arid climates. The results of the simulations are evaluated in terms of appropriate thermal comfort criteria and subsequently potential reductions in plant energy consumption so that the most effective strategies for each representative arid city can be identified. The results show that mixed-mode ventilation could save about half of the plant energy consumption compared to common active air-conditioning systems. Savings in plant energy due to the application of mixed-mode strategies that include low energy cooling technologies such as radiant, evaporative and ground cooling could exceed 90%.We conclude that mixed-mode cooling strategies should be able to provide satisfactory indoor environments and can result in highly efficient office building designs and so should be considered for application in arid climates.

a b s t r a c tLighting energy consumption represents a significant percentage of total energy consumption in residential building sector. During the last 20 years, advanced energy-efficient lighting fixtures have been introduced worldwide to conserve the energy consumption in residences. In the Middle East and North Africa (MENA) region, very few studies have been conducted to evaluate the association between the introduced lighting fixtures and the resulted energy savings using valid measurements and verification techniques. This study evaluates the techno-economic impact of replacing new energy efficient lighting in residences in Egypt (a representative MENA region country). A quantitative analysis is applied by tracking the utility bills of 150 residential apartments in Cairo. The average measured power consumption before (1993-1998) and after (2009-2014) installation energy efficient lighting fixtures is analyzed. A building performance simulation model is developed to back the findings. The findings indicate a significant disparity between the estimated savings based on simulation and the real measured savings due to penetration, rebound effect and low quality lamps. Moreover, the findings present an example of quantified benefits of energy efficient lighting, which is very important to inform the decision making of public policy makers, investors and building occupants.

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Consideration of building energy performance in the early stage of the design process is very important to help minimizing energy consumed by the built environment. Therefore, help in minimizing energy crisis problem. Optimization of building form and orientation at the early stage of the design process can save a significant amount of energy consumed by the building. This paper proposes an annual thermal energy performance-based form making (EPBFM) method that generates numerous design configurations and tests their annual thermal energy performance till it reaches an optimal solution. The proposed workflow uses 3d parametric modeling program, energy simulation program, and genetic algorithm. A case study of an open plan office building is used to evaluate the proposed workflow in three different cities with different climates, Cairo, London, and Chicago. Building's contexts were not considered in order to highlight the change of the building form and orientation caused due to the change in climate conditions. Then, Scatterplots were developed to test the impact of each dynamic parameter on thermal energy use intensity (EUI). Compared to the initial square shaped building, optimization results showed that thermal EUI decreased by 22.76%, 29.7%, and 19.2% in Cairo, London, and Chicago, respectively. Manipulation of building area along one axis and each floor area along the other axis proved to have the highest positive impact in decreasing thermal EUI.

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