Critical global issues of energy use, resource depletion, and land use are forcing the academia and professionals to re-evaluate design and construction processes, and look to more resource efficient practices. Designing carbon-neutral plus-energy buildings with active, passive or hybrid means of achieving thermal comfort requires a thorough understanding of micro-climatic site conditions, building occupancy, psychrometrics, physics, and the availability of renewable resources. This is why new legislation and increasing market demands are changing and driving the education, the profession and developers to create measureable low-carbon buildings worldwide. While it may be unrealistic to completely move away from the current high-exergy active methods for climate control, considering passive means of low-exergy-heating, cooling and ventilation are becoming increasingly critical. Present HVAC systems have already achieved relatively high thermal efficiencies as defined by the first law of thermodynamics. However, according to the second law of thermodynamics, there is an urgent need to increase low-exergy efficiencies by changing high-exergy consuming HVAC sources to passive low-exergy systems.
