(Sole24ore)
Only in Sweden there are more than ninety thousand. Not to mention Canada, and Swiss cantons where almost a house in five has a geothermal heat pump plant. In practice this is conceptually simple air-conditioning systems, and tested for decades: a circuit of fluid (even simple acqua) si affonda nel terreno, e la pompa di calore (un frigorifero bidirezionale) vi trasferisce il caldo estivo e lo preleva in inverno. Bastano pochi gradi di differenza tra la temperatura ambiente e quella che viene dai tubi del geoscambio e la pompa di calore è in grado di moltiplicarla per tre o persino per sette, per ogni unità elettrica necessaria al suo funzionamento.
Pannelli radianti nella casa, d'inverno arriva acqua a 30 gradi, d'estate anche a 15. Per un'edificio a involucro ben isolato i risparmi possono raggiungere il 40-50% sulle bollette tradizionali. Con circa 15mila euro di investimento, una pompa di calore e due pozzi con sonde di geoscambio (in pratica tubi di polietilene a U affondati per un centinaio di metri) una house of 300 square meters can be heated by this technology, largely renewable. And men know, not only in Switzerland but also in Bolzano and Trentino, Italian tread of this emerging market. Who field in front of a free (and a house suitable for renovation) can even make use of the tax deduction of 55 percent.
"Italy, however, suffered a heavy delay in geothermal heat pumps - notes Sergio Chiesa del CNR, author of a recent study for the Cesi Research - representing only 8% of the Italian geothermal. Yet today this is today, globally, one of the most dynamic sectors in renewable energy. " "The focus so far has focused sull'elettrico renewable energy - said Gianni Silvestrini, president of the Kyoto Club - but the heat must go to four or five times what we have now. And geothermal heat pumps can make a major contribution. "
Yet something starts to move, and not just on small residential scale. Tread, for two years now, is Ikea, the first geothermal heat pump system in Corsico (304 probes) and now with that of Parma (213 probes), considered the largest in Europe. In front of the shopping center in Parma, what is now a yard full of tubes and small wells will become tomorrow's hardened parking for visitors. A reservoir of thermal energy, invisible and underground. "A tank, subtract the heat of summer to the circles and put it in the ground for the winter and do the reverse - explains Luca Tirillo of GroundHeat Systems, -: polyethylene pipes carry water only. The drilling was done in safety, with cylindrical steel jacket and special cement. The risk, in fact, is to alter the balance of the groundwater aquifer. "
The construction of a field of geothermal heat pump, in fact, is not something trivial. "A Corsico, we were faced with a highly polluted ground water first - said Sergio Giuseppini, designer of geothermal systems Ikea - if we had not drilled safely the risk of being put in communication with deeper groundwater and clean. A disaster, and the local administration would never have given permission. "
Corsico But now it works. As Parma has cost more than € 2 million, but has a savings target of 56% (approximately 200 thousand € / year) and then a return period of ten years. "So far, the data of the summer - said Giuseppini - Corsico is confirming expectations, with peaks slightly higher." And then, for Ikea, will be the turn of the shopping centers of Turin and Rimini, "where we will put heat pump efficiency even higher, given that technology is moving very quickly."
Il dato nuovo, però, è che simili impianti, di taglia medio grande, «cominciano a interessare direttamente i costruttori edili – osserva Tirillò – e per un motivo preciso. Un complesso residenziale a basse emissioni passa in categoria A, e può valere anche 500 euro in più per metro quadro. Un impianto di geoscambio centrale invece aggiunge, su ampie dimensioni, poche decine di euro in più di costi unitari».
È quanto si sta avviando in almeno due progetti: a Roma e nel Canavese. «Noi cominceremo ad aprile, su un lotto di 92 ettari a Roma Nord-Ovest, di cui 45 destinati a parco – spiega Barbara Mezzaroma, a.d. di Mezzaroma Energia, del gruppo Impreme – con a first batch of one thousand apartments, all serviced by a field of geothermal heat pump (about 200 geosonde) and a system of heat pumps for at least one third of air conditioning, and 40% with biomass boilers, most small wind. "
the same "Ninsola in San Francesco al Campo. "Five houses - says Giovanni Miccoli GV Construction - High thermal insulation and underfloor heating with a geothermal heat pump central park of 22 probes, water at 22 degrees in summer and hot water directly produced by the heat pump." Barbara is an enthusiastic Mezzaroma building zero-emission - "Many competitors said that we waste time when we started our first project home Kyoto ' - But today is also an economic forecast states: "Each of our apartment with zero emissions can also mean less than 900 euro per year, an installment loan. And even if, in class A +, cost us 15% more than we sell them at the same price today. In this way the customer base will gain about twenty years. It seems a good proposal for a housing market is still as of today. "
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