Lecture-4-c-control_strategies_Compatibility_Mode_ -...

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12/3/2008 1 4 th International Conference On Energy Research & Development Kuwait, 17-19 November 2008 Discussion Panel, 17 November 2008 Energ & Climate Change Perspecti es from the Region 12/3/2008 Nesreen Ghaddar Energy Efficiency in HVAC Systems: Optimal Control Strategies for Multi-zone and Hybrid Air-conditioning Systems Energy & Climate Change: Perspectives from the Region Sponsored by the United Nations Environment Programme (UNEP) Introduction (1) ± Building in general consume 35-50% of total electrical energy consumption. ± In the summer, the HVAC (Heating, Ventilation, and Air conditioning) systems of buildings and facilities represent 60-70 % of peak load. ± Improving HVAC systems performance becomes an important element for mitigating building energy consumption. ± Advanced control strategies that establish optimal operation mode and set points can be implemented to improve HVAC performance while providing the desired indoor comfort and environment quality at minimum cost. 12/3/2008 4 th International Conference On Energy Research & Development Kuwait, 17-19 November 2008 Introduction (2) ± Optimal control strategies are the guidelines for the HVAC system to follow as an operational plan. These strategies vary according to the building nature, the dynamic load, the HVAC system components, and the outdoor conditions. ± In a conditioned spaces, overcooling is not uncommon in conventional system applications because supply temperature is set at a fixed value irrespective of the humidity, occupancy, and air velocity (fan) in the room. ± Fresh air for ventilation for indoor air quality is normally supplied at constant rate which causes unnecessarily low CO2 concentration in periods when the space is not occupied. 12/3/2008 4 th International Conference On Energy Research & Development Kuwait, 17-19 November 2008 Introduction (3) ± Research in HVAC systems design and development has resulted in major advancements in enhancing these systems thermal performance/efficiency and reducing their electrical energy consumption. ± However, more energy savings can be achieved with implementation of better control of HVAC system operation. 12/3/2008 The Third International Green Conference - Vasteras, Sweden
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12/3/2008 2 ¾ Practiced Control Strategies of Conventional HVAC in Lebanon Constant Air Volume where the control is achieved by controlling the supply air temperature for all the spaces within a zone. ± Draw backs ² The amount of fresh air is kept constant irrespective of occupancy schedule. ² CAV may lead to thermal discomfort when load profile of various zones served by same AHU is different while supply air temperature is the same. ² Cost of the fan power is constant through the whole operation. ² Energy could be saved if the supply air temperature is higher.
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This note was uploaded on 02/07/2011 for the course MECH 673 taught by Professor Drnesreenghaddar during the Fall '09 term at American University of Beirut.

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Lecture-4-c-control_strategies_Compatibility_Mode_ -...

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