Sustainability is quite the buzz word among hotels, with brands eschewing small bottles of toiletries for refillable ones, guests asked to reconsider the standard practice of washing sheets and towels daily and water-saving low-flow showers and toilets. But one hotel in Spain is going even further.

Amid the Miramón forest in San Sebastián , Arima Hotel is aiming for eco-friendliness . “Arima” means “soul” in Basque, and the property, a member of the Small Luxury Hotels of the World, is the first hotel in Spain and the largest in Europe to hold the Passivhaus Certification, a German standard focused exclusively on high energy-efficiency of buildings to minimize the need for energy. Maintaining this certification means that the hotel consumes 70% less energy than one built with conventional criteria. In other words, had Arima been built with regular construction, the amount of CO2 it would have emitted in a year would have needed to be absorbed by all the trees in Retiro Park in Madrid just to offset the effects.

This is all accomplished with thick thermal insulation, triple-glazed windows whose chambers are filled with argon gas, wood joinery and completely airtight enclosures without unwanted air filtration - a practice that does double duty by also making the building better insulated from sound. All spaces have a mechanical ventilation system with permanent heat recovery at a very low speed, which combined with correct regulation and special filters translates to optimal air quality for health, restfulness and comfort .

Beyond the clean and highly-efficient energy systems, the Arima is eco-friendly in other ways. Among them are the use of sulfate-free toiletries in rooms, a menu that uses locally-grown ingredients and separated recycling bins throughout the property.

For more information on Arima Hotel’s sustainability efforts and to book a room, visit their website .