Buildings, which are in fact ecosystems (living and inanimate organisms interacting together), are nowadays conceived and operated on the base of energy assessments underpinned by the first law of thermodynamics, and design strategies work towards energy conservation. Different approaches, based on the second law of thermodynamics, exist in research; they use the thermodynamic function called exergy - a measure of energy quality obtained from the combination of first and second law - and their scope is still centred on conservation strategies, optimised through irreversibility reduction. However, irreversibility plays a key role in nature, as entropy production dictates the direction and modality of all processes and real phenomena are actually irreversible. The main problem related to the forefront of high-efficiency buildings is their high cost and complexity, which contrast stridently with the needs of the largest part of the built environment: effective low-budget sustainable solutions, easy to raise and control by non-specialised users. This research, through a pragmatic methodology, mixes practi- cal experiences from low-budget construction sites with concepts from the relatively new discipline of non-equilibrium thermodynamics, and proposes an alternative energy design approach based on the second law of thermodynamics. Thinking of buildings as evolving ecosystems, their ability to perceive and exploit useful gradients can be enhanced through a deeper understanding of the role of irrevers- ibility as the driving force of spontaneous processes, and imperfection as an intrinsic characteristic of architecture.
buildings, exergy, irreversibility, low-cost, spontaneous processes.
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