Page 16 - The future of the metro booklet
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Encounter                                                                                                           Encounter

      In praise of voids                                                      TEXT                                             between the                      the very concept                  → How could

                                                                                                                               underground and
                                                                                                                                                                of air circulation.
                                                                                                                                                                                                  geothermics
                                                                              Eric Senabre
                                                                                                                               the overground,                                                    influence the
                                                                                                                               couldn’t it?                  P.R. We do not yet fully unders-     future metro?
                                                                                                                                                             tand  how  the  virus  circulates.
                                                                                                                           P.R.   Vegetation  needs  certain   Studies  show  that  if  Milan  has   I think that geothermics could be
                                                                                                                           qualities  of  air,  light  and  mois-  been  so  severely  affected,  it  is   used widely to cool down the air
                                                                                                                                                             due to the air pollution. The virus
                                                                                                                           ture.  That creates a degree of   attaches itself to fine particulate   blown into the metro, acting as
                                                                                                                           technical dependence which can    matter. In the metro, we should   an earth-to-air heat exchanger. If
                                                                                                                           be  hard  to  control.  Take  irriga-  certainly expect the virus to cir-  outdoor  air  was  blown  directly
                                                                                                                           tion, for a start. And the conse-  culate  more  actively,  using  the   into the metro tunnels during a
                                            → When we think                   → Quite so.                                  quences would be more psycho-     high density of fine particulates.   heatwave,  it  would  be  stifling.
                                            of architecture,                  And how do you                               logical than anything else. It    The  solution  might  be  to  dilute   But  if you  blew  the  air  through
                                                                                                                                                                                              heat exchanger coils, it would be
                                            we think                          consider the voids                           takes 300 trees to compensate     this  concentration,  just  as  we   cooled. Of course, it is a bit com-
                                                                                                                           the average person’s annual car-
                                            spontaneously of                  created by spaces                            bon  footprint.  A  few  shrubs   can  attenuate  pollution  above   plicated to make the air move
                                            materials, masses,                in the metro, in                             won’t do much for the thousands   ground level.                    naturally but it is possible.  The
                                            surfaces and solids.              terms of climatic                            of  people  in  the  metro.  They      → You mentioned             upper  sections  of  a  solar  chim-
                                            But your vision                   comfort and                                  won’t be much use as air freshe-     the cool                      ney are black. They get hot and
                                            focusses on voids.                energy efficiency?                           ners, or at least no better than a   temperatures                  create an updraft. Such thermal
                                                                                                                                                                                              chimneys could replace mecha-
                                            What does                                                                      pool or a fountain.                  of Renaissance                nical ventilation.

                                            the void stand                P.R.  In Paris, you just need to go 5                → What else                      churches.
                                            for, in your                  metres  underground,  to  reach                      could be done                    Could we pursue
                                            approach?                     the mean annual temperature of                       to make the
                                                                          the  town,  between  11°  and                                                         this line of thought,
                                                                          12°C. It’s a bit like the wine cel-                  metro more                       to reconsider
                                        Philippe Rahm  The first duty of an   lars in Reims where they mature                  resilient, or at
                                        architect, which we tend to for-  champagne. Renaissance churches                      least a bit nicer?               the materials used
                                        get, is to create a space, a void   have a thermal value too, just like                                                 for the metro?
                                        where it does not rain when it is   Roman basilicas. Today, the me-                P.R.  First and foremost, the qua-
                                        raining  outside,  which  has  less   tro is primarily functional. Tubes           lity of the air and the light. The   Yes,  these  are  major  questions
                                        sunshine when there is too much   joining  one  station  to  another.              lighting  devices  in  the  metro   about  emissivity  and  effusivity.
                                        outside. We take portions of the   But it might be worth endowing                  emit  standard  spectra  of  light.   Highly  emissive  material  oppo-
                                        world  and  its  atmosphere,  and   it with an ‘urban’ value, like the             However,  we  ought  to  choose   site  us  would  absorb  our  heat,
                                        we  transform  them  so  that  the   semi-underground  shopping                    them  to  satisfy  the  metabolic   because  it  would  be  constantly
                                        climate  inside  is  acceptable  to   malls in Canada. This thermal va-            needs of travellers, and we could   cooled by the earth at 11°C. In
                                        people.  External  walls  are  built   lue could take on a public role. In         even adjust them to suit the time   the metro, everything we touch
                                        to  delimit this  void. It  interests   winter,  there  is  a  huge  loss  of      of  day.  For  instance,  we  could   should  made  of  highly  effusive
                                        me to tell myself “this void is not   heat from the metro. We ought                make the lights go yellow in the   material,  and  the  materials  op-
                                        something neutral. It is a mate-  to recover the air coming out of                 evening,  to  respect  circadian   posite us should be highly emis-
       The Swiss architect              rial in itself”. We can adjust the   metro station entrances, to stop              rhythms. The quality of air is still   sive.
       Philippe Rahm advocates          real parameters of this material,   it from going to waste.                        quite hard to control. Intrinsically,
                                                                                                                           these two notions could become
       a form of architecture           in  terms  of  temperature,  humi-                                                 aesthetic  considerations.  Light
                                        dity and quality of air, quantity of
       that features physiology         light,  radiation.  There  is  also  a   → Do you think                            and air could create the beauty
       and meteorology.                 chemical parameter and an elec-       that growing                                 of the metro.
       He has agreed to tell us         tromagnetic one too. Architects       plants in the metro
       about a future metro,            use  bricks,  concrete  and  steel.   could be a good                                  → The problem                                De profundis
       that is in harmony               Why shouldn’t they use air pollu-     way of regulating                                today is that                                The Arsenalna metro station in Kiev had the funny idea of setting up
                                                                                                                                                                            at the top of the valley. Consequently, the metro platforms are 105 meters
       with the natural needs           tion,  temperature  and  the  type    the temperature?                                 the covid-19                                 lower and require a long journey on escalators: between 5 and 10 minutes.
                                        of light? This is how I approach
       of individuals and               my work. I consider the void as a     At least it could                                crisis has                                   Of course, this is not about gratuitous cruelty on the part of the engineers:
       the climate.                     raw material for the architect.       build a link                                     questioned                                   the following station is indeed in the valley, and it would have been a lot
                                                                                                                                                                            more complicated to make it up the hill for the train.


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