Celcius
Celcius is a minimalist heating and cooling installation located in Switzerland, designed by Salla Vallotton for ECAL‘s diploma project. Buildings consume nearly 40% of global energy, with heating and cooling systems driving this demand in opposite seasons while remaining architecturally invisible. This project challenges that disconnection by returning to a pre-industrial logic: thermal mass as both spatial element and environmental mediator. Rather than separating winter heating from summer cooling through distinct mechanical systems, the installation uses terracotta’s material properties to create a hybrid device that stores and radiates warmth in cold months while providing evaporative cooling when temperatures rise.
The choice of terracotta reaches beyond nostalgia for traditional masonry stoves. Its porosity allows water absorption for evaporative cooling, while its thermal mass stores heat efficiently without the carbon footprint of modern HVAC infrastructure. Unlike contemporary heating systems hidden within walls or dispersed through ductwork, this system occupies physical space deliberately. The terracotta elements become architectural features rather than concealed utilities, making energy use visible and legible within daily life.
This visibility carries cultural significance. Pre-industrial heating was never purely functional – massive tile stoves in Alpine regions served as gathering points, their warmth structuring domestic routines and social interaction. By contrast, centralized heating systems operate autonomously, their thermostatic control divorcing occupants from seasonal rhythms and energy consumption. The terracotta installation restores this relationship, requiring engagement with material behavior: understanding how porous clay absorbs moisture, how thermal mass releases stored warmth gradually, how placement affects heat distribution.
The system operates through seasonal inversion. During winter, the terracotta mass absorbs heat from a minimal source – potentially solar gain or a small heating element – then radiates it slowly across hours. The material’s thermal inertia prevents the temperature spikes and drops common to forced-air systems, creating stable ambient warmth. In summer, the same porosity that makes terracotta effective for heat storage enables evaporative cooling. Water drawn into the clay structure evaporates slowly, pulling heat from surrounding air through phase change rather than mechanical refrigeration.