N e a r l y Z e r o E n e r g y B u i l d i n g s , S m a r t G r I d s a n d S m a r t C i t i e s
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Background
Net-Nearly Zero Energy Buildings
The recast of the European Directive 2010/31/EU establishes that starting from the end
of 2020 all new buildings will be Nearly Zero Energy Buildings (Nearly ZEBs).
According to this Directive, Nearly Zero-Energy Building means a building that has a
very low energy yearly energy consumption, which can be achieved by both highest
energy efficiency and by energy from renewable sources, which shall be on-site or
nearby.
A relevant international effort on the subject of the Net Zero Energy Buildings (Net ZEBs)
- Net ZEB meaning that the buildings are connected to an energy infrastructure - is
ongoing in the International Energy Agency (IEA), joint
Solar Heating and Cooling
(SHC)
Task 40 and
Energy Conservation in Buildings and Community Systems
(ECBCS)
Annex 52, titled “Towards Net Zero Energy Solar Buildings”. [IEA 2008b] Both from the
theoretical and practical point of view this new “energy paradigm” - or the Net Zero
Energy Building (Net ZEB) balance - might be a revolution for architecture.
The engineering only research taking into account mainly the energy aspects, seems to
be not sufficient to ensure the diffusion of ZEB models: in achieving the ZEB target a
major role will be played by architects and designers, who are amongst the main actors
of this revolutionary change. More precisely, since the form of our buildings and cities
might change radically due to this new energy requirement, the way architects will take
up the challenge of designing ZEBs, is crucial, as architects are highly responsible of the
form of the city and of its symbolic meanings. [Scognamiglio Røstvik 2012]
In a near future, buildings will be designed to need very little energy (passive design
strategies for energy efficiency), and to integrate active surfaces (e. g. PV modules) for
generating energy. This approach requires a new thinking, able to use the energy we
need as an input for design. The energy we use should be seen as a variable able to
relate itself to the form of our buildings (or clusters of buildings, or even cities and
landscapes), instead of being seen as a kind of abstract variable that design cannot deal
with. In the future, design has to consider not only the space we use directly, but also the
space required to provide for electrical and thermal energy from renewable sources: the
surface necessary for placing the energy generation devices (energy footprint).
[Scognamiglio, Ossenbrink, Annunziato 2011]
One of the main consequences of this new condition is that hardly the building’s design
will be carried out without the appropriate consideration of the city context. Often a single
building won’t be able to generate all the energy it needs within its physical boundary,
and as a consequence the Zero Energy balance will have to be achieved on a wider
scale, that considers cluster of buildings as system. To achieve such a condition in the
city context, the way citizens interact with each other is crucial, since the idea of a Net
Zero Energy balance on a cluster of buildings implies also a mutual understanding and
agreement among groups of citizens.
From the morphological point of view, it seems that designing NZEBs at the urban scale
implies to conceive low density areas, in order to leave space enough for placing
renewable energy systems (
on buildings
or
at site
). Nevertheless, such a low density
patterns would be in contrast with the idea of “webness”, where the ability of the city to
connect plays a main role.
In fact, pro and cons of dense and diffuse cities are very well known, and it seems that
dense cities present several advantages (more efficient urban land use, transport and
infrastructure). A first result of these considerations is that buildings might be sized so
that their envelope areas are sufficient to place all the energy generation systems they
need to work. Or, since many European countries present historical cities with a very
dense pattern, it would be reasonable thinking of the city and its peripheral areas as a
