Living in a tree house in Torino (Italy): combining adaptation and mitigation measures to improve comfort

Torino has experienced rising maximum temperatures (about +2C over 60 years, per ARPA Piemonte) and increasing heatwaves (4 in summer 2017 alone); under RCP4.5, summer discomfort days are projected to double by 2011-2040 and triple by 2041-2070 versus 1971-2000, with tropical days rising from 2 (1971-2000) to a projected 21 by 2041-2070.

Increase building resilience to heatwaves and temperature extremes through thermal insulation, while reducing energy demand for heating and cooling, exploiting adaptation-mitigation synergies.

The 63-apartment '25 Verde' building integrates over 150 trees and plants into a cor-ten steel façade structure, uses deciduous species for seasonal shading, high-thermal-mass construction (35cm floor slabs, thick brick walls, continuous exterior insulation), a green roof (60-100cm soil layer), and geothermal heat pumps connected to groundwater wells for heating/cooling with individual-unit metering.

Construction cost was about EUR 2,500/m2, roughly double the approximately EUR 1,200/m2 standard-building average; the greenery alone accounted for 10-15% of total cost (versus 3-5% typically). Apartments sold quickly: 55% within two days of launch and 90% during construction, at an average sale price of about EUR 5,500/m2, some EUR 500/m2 above the area average at the time.

The building has no direct CO2 emissions (geothermal heat pumps provide heating and cooling) and is reported to contribute less to the local urban heat-island effect than surrounding buildings. Residents reported valuing the added comfort, natural light, sun protection and noise insulation. The developer received tax discounts during licensing and experienced no construction delays.