In Europe, the NZEB (Nearly Zero-Energy Building) stands as the future standard for buildings meeting the requirements of the Directive 2010/31 / EU that defines the energy performance to be achieved by the construction sector in particular after 2020. A similar evolution of the legislation in other major industrial countries will induce the same effects on buildings.
While the precise definition of what is a NZEB and of the performance to be achieved, is left to the initiative of each European country, one fact remains valid for all: the targeted consumption level is so low that the consumption of the building will not fall below the threshold without deducting a local renewable energy production.
In this case, a question arises: Is the NZEB the right concept to work on?
Any large scale development of local electricity generation will be accompanied by predictable changes : self-consumption to avoid excessive energy flows on the network, emergence of new balance groups, more local, the storage of a portion of the energy produced etc …
Many pilot projects have shown the interest to mix various types of buildings, corresponding to various activities (housing, shops, offices, medical centers), in the same area as their energy and electric consumption profiles are different. The aggregation of these consumptions provides a more regular load profile than the consumption of a single building, whatever it is. The surplus or the deficit of the production in the area is reduced compared to that of each building ; the balance of the area is facilitated.
Similarly, organizing and managing the local production at the level of a group of buildings allows for economies of scale and a more efficient management. A similar reasoning applies to storage if entities are pooled or larger.
Finally, what about the interest to require local production on a landlocked building, in the shade, which do not allow the installation of photovoltaic panels, nor that, in a few years, of micro wind-turbines. Conversely, specifying a required level of energy production to a group of buildings may open the door to other production technologies such as micro-cogeneration
Many reasons lead us to believe that the performance obligations assigned to NZEB would rather be fixed on broader and most relevant areas than a single building. The acronym NZEB is today, in many minds, already well anchored, triggering the idea that the right nearly zero-energy perimeter to consider is the building itself. So it is today to build the future of buildings by sweeping a notion yet established while having never existed. Like all established notions, it will die hard.
The actors in charge of the global design of the zero- energy perimeter that emerges in these few lines, are more planners (and their advisers) than builders, developers or architects. This may be through the choice of who will bear the responsibility of designing a zero-energy area that we will favour a sound development of future urban energy architectures and of the corresponding regulations.
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