With House LLP, a Passivhaus-certified structure erected on steep slope in the Collserola mountain range of Barcelona, Spanish firm Alventosa Morell Architects set out to prove that prefabricated housing can make winning architecture. Like a previous Barcelona project by the firm, this home also consists of a series of modular wooden volumes, which give each of the client—two sisters—a living/dining area, two bedrooms, and a bathroom. The home, outfitted with a clean, white and pale wood interior, employs a number of energy-efficient measures, including positioning the house for optimal natural cross-ventilation, creating a green roof to help retain heat in the winter, and adding a thorough system of blinds for light control on the glassy side of house.

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