Energy Saving Potential in Hot and Dry Climate by Adjusting Building Fabrications and Application of Dew Point Cooler




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De Montfort University


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Peer reviewed


This research is to tackle the electricity crises in Kurdistan, as a primary objective, and minimize emissions and global warming effects; this research investigates the potential for the reduction of energy consumption through the use of advanced cooling systems of residential buildings in Kurdistan (Northern Iraq). The objectives are achieved by applying a set of building interventions to existing building fabrications to act as a guide for new residential buildings, and by replacing conventional split air conditioners with newly developed indirect evaporative dew point air-conditioning systems. A review of residential buildings and their energy-related parameters, and the conventional cooling systems commonly used in hot and dry climates was conducted, in particular, the split air-conditioner. Two different residential buildings, a house and a low-rise multi-flat building, were selected as case studies in Erbil, the capital city of Kurdistan. A critical review of the case studies is presented covering the state of the area, climate conditions, energy and water demands, change in building typologies over time, and most prevalent cooling systems. The required cooling loads are the core of the research as the ultimate aim is to minimize the cooling load by detailing the optimum building fabrication, then choosing an efficient air conditioning system. The cooling load was investigated and calculated by using realistic occupancy-based cooling schedules and two software (DesignBuilder and EnergyPlus). The procedure included modelling the case study buildings with the DesignBuilder based on the building data from the contractors, followed by transferring the baseline model to the EnergyPlus for further and faster dynamic simulation purposes, then calculating the hourly cooling load for the case studies in Erbil. The most effective and optimum building parameters were identified. To gain further energy savings, the conventional widespread split air conditioner was replaced with the new dew point evaporative air-conditioner that is more efficient in hot and dry climate such as Erbil. A MATLAB simulation model was used to predict the feasibility of the use of such systems in Erbil’s climate. The simulated model was optimized to determine a suitable size and the water consumption of the system. The simulation shows that the energy consumption due to the cooling systems represents 78-79% of all energy consumed in residential buildings and that the hollow clay blocks and a suspended ceiling each allow for a considerable reduction in cooling load. Three centimetres of insulation represents the optimum thickness in terms of the balance between the cost of the insulation with increasing thickness and energy savings. The percentage of energy saving that could be achieved by adjusting the building fabrication could reach 26.8% and combining this with the dew point system yields savings of up to 90.8%. These high energy savings reflect the effectiveness of the new dew point cooler. An economic analysis was undertaken to verify and calculate the energy savings that could be achieved by adjusting the buildings and replacing the conventional split air-conditioner with the dew point cooling system. By replacing the conventional split air conditioner with the dew point cooler, the base models were found to have a Pay Back Time (PBT) that could be as low as 2.4 years. The environmental effects of the changes were analysed in term of reductions in annual CO2 emissions, it could be reduced up to 7.2 tons. With the newly developed dew point evaporative cooler, the supply temperature could be lowered to near the inlet air dew point temperature by 65-70%. A model of the dew point cooler was developed based on the building’s cooling load for the sizing purposes, and the effect of building fabrics on the sizing of the dew point heat exchanger per conditioned floor area was determined. It is also predicting the energy and water consumption per floor area of any building in arid climate for both conventional and dew point air conditioner with the effects of the building fabrics. Estimation of energy savings and CO2 production was given. The figure could be used by the decision-makers in local government to update the current building code based on the results presented for the future buildings and retrofit the existing buildings. In addition, it could be used as a reference for other climate applications as a function of building cooling load.





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