Raphaël MÉNARD, Architect engineer, professor at EPFL, co-manager of the design office Elioth (Egis Concept)
In the past, in cities, energy came from the ground. In the past, that was before there was gas on all floors and before the electricity fairy was introduced into all rooms. In the past, the fuel for our homes came from the street. It supplied our fireplaces, our stoves, our ovens and sometimes our lighting.
It came to us in different forms: wood, coal, kerosene. Once consumed, the fatal heat went up to the sky; roofs had to incorporate exhaust systems allowing the safe evacuation of this combustion. Today, our built up spaces retain traces of these energy systems, such as Paris and its walls, punctuated by terracotta chimneys. The soil dictated the urban canopy. The ground had to be accessible and ideally flat to facilitate the transport, logistics and delivery of fuel from outside the city. What uses remain? Wood fires have become suspect. Ultimately, unblocked ducts help with natural ventilation in summer. From now on, the city must be resilient to meet all or part of its energy needs. Producing even a tenth of the needs is undoubtedly the guarantee of being able to perform vital functions in the event of a failure in energy distribution. Self-production and micro-networks are our essential safeguards. Due to its human density, stable or growing individual needs, but also the scarcity of external fuels, the city must locally produce a fraction of its energy. Let us not be fooled by the very temporary drop in the price of hydrocarbons: the “counter-shock” is coming… In the future, only flow energies (the sun and its derivatives, and to a lesser extent geothermal energy) will be able to provide a sustainable supply. The city will then have to bring down energy directly from its roofs. So in this case, the sky will dictate the shape. Sunlight needs to be caught horizontally; the chimneys prevent this new relation. The city must shift its shape: its canopy will henceforth have to be homogeneous, soft and regular to effectively bring energy inward. USIs, the speaker recalls, start like
this.