Alternatives to Active HVAC Systems

The global energy scenario has undergone a drastic change in the last two decades. Due to ever growing demand and shortage of supply, the cost of fossil fuel (coal, oil and natural gas) is increasing day by day. Increasing consumption has led to environmental pollution resulting in global warming and ozone layer depletion. Consequently, the era of fossil fuel is gradually coming to an end and the attention is focused on the conservation of energy and search for renewable sources of energy, which are environmentally benign. Buildings are major consumers of energy insofar as their construction, operation and maintenance are concerned. It is estimated that almost 50% of the global energy demand is due to buildings with active HVAC equipment being the highest contributor. Thus, the energy conscious architecture has evolved to address these issues. It involves the use of eco-friendly and less energy intensive building materials, incorporation of passive cooling techniques in building design and integration of renewable energy technologies. Passive cooling methods maximize the efficiency of the building envelope by minimizing heat gain from the external environment and facilitate cooling by air movement, ventilation, night cooling, evaporation, desiccant dehumidification and earth coupling to name a few. All these techniques require little or no input of electrical energy. Even when these alternatives cannot avoid the use of compressive cooling systems completely, their role can optimize the energy consumption and the peak electric load. This 6-hour Quick Book will introduce you to the passive cooling systems and is intended to be used as guidelines to choose technologies that are suitable to different situations. This course is aimed at students, mechanical engineers, architects, facility managers, environmentalists, energy auditors and anyone who wants a basic understanding of cooling systems. Learning Objective Following completion of the course readers will: -Explain the factors having greatest impact on summer cooling loads; -Understand the mechanisms of heat gain control by intervening solar radiation, vegetation, ventilation and internal heat gains; -Explain the principles of natural ventilation design in night cooling; -List the design factors for stack and wind driven ventilation; -Explain the basic principles of direct and indirect evaporative cooling systems; -Understand the factors affecting evaporation rate and cooling; -Understand the principles of desiccant cooling and dehumidification; -Describe the performance of an absorption chiller system v/s vapor compression cycle; -Understand various radiant cooling strategies; -Understand the fundamentals of direct ground cooling systems and geothermal heat pumps.