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A variable air volume (VAV) air handling system can significantly reduce fan power under partial load conditions. The focus of this study is developing a modeling program to predict the potential energy saving by the secondary HVAC system strategies. Comprehensive steady-state models are established to describe the energy performance of different control strategies for secondary HVAC systems. With building loads, minimum fresh air flow rate, pressure losses, supply air temperature control, dampers control and coil characteristic as inputs, the objectives were to develop a simulation model to evaluate performance of an air handling system. The potential energy savings of constant air volume (CAV) and VAV strategies are investigated in a representative residential building. The simulation results show that about 13% of electrical power can be saved by the proposed VAV strategy in respect of the CAV. Also, life cycle cost analysis is applied on the considered system. It is found that VAV system is not economically good for the considered building because of low electricity price in Iran. Finally, a sensitivity analysis was conducted to demonstrate how the electricity price affects the economic performance of the VAV system. [ABSTRACT FROM AUTHOR]

Considering the magnitude of energy loss in Iran’s buildings, development of energy saving and energy optimization methods appears to be essential. To date, many energy saving methods, such as energy auditing, have been developed in this area, though none of them enjoyed high accuracy and efficiency. Optimization methods aided by energy modeling are the most useful tools for energy saving as well as energy loss reduction. In this study, a new model has been developed based on mathematical equations of mass and energy balance between different parts of a building and its surrounding area. Generally, this model integrates two methods of load and heating, ventilation and air conditioning modeling. Furthermore, the presented model allows for simulation of energy-efficient scenarios and their optimization based on life cycle cost analysis method. In this part, capabilities of the model have been closely analyzed based on historical records of existing models. The relations covering boundary conditions at external–internal surfaces; energy equations for building systems; interzone airflow and infiltration; heating, ventilation, and air conditioning models and economic models; and their optimization method and possible solutions have been explained in detail. Complete details about the application of this model for the XYZ case study building will be given in the second part of this article. [ABSTRACT FROM PUBLISHER]

Introduction of perpetual pavement in the late 1990s provided the possibility of constructing a pavement with higher initial investment expenditure but lower maintenance and user costs. Life cycle cost (LCC) of a facility is the sum of all one-time and recurring costs over the full life span of that facility. As for highways, it includes agency costs (initial construction and maintenance costs), user costs (vehicle operation and time value costs), social costs (environmental costs) and salvage value at the end of pavement design life which is considered as a negative cost. This study compares the LCC of highways with conventional and perpetual pavements to figure out which system is economically preferred in various traffic and weather conditions for Iranian highways. Results of the study show that perpetual pavement construction can save LCC of pavements in the range of 4–20%. [ABSTRACT FROM AUTHOR]