Spain's Alventosa Morell Arquitectes recently completed work on a prefabricated energy-efficient residence that's located in the Montseny mountain range, to the north-west of Barcelona. Named Casa GG, the home was built in just four months – however this fact belies the impressive effort that went into studying how best to minimize energy-use before construction even began.

Measuring 111 sq m (1,200 sq ft) of usable floor space, the single-story Casa GG is a simple rural dwelling that sits nicely amongst the surrounding trees. Structurally, it comprises six box-shaped wooden modules, which are joined together by an interstitial space. The modules were prefabricated off-site using sustainably-sourced wood, before being delivered by truck and lifted into position by crane.

Inside, the house sports a plain interior finish. A single bathroom, kitchen, and three bedrooms are located within the modules, and the home also sports a dining area, lounge, and garage. The plain wooden walls are broken up in points by large glass windows and doors which make the most of solar heat gain and increase the interior temperature naturally.

Before ground was broken on the project, Alventosa Morell Arquitectes liaised with the Meteorological Service of Catalonia in order to gain detailed information on local weather conditions. With this data in hand, the expected effects of solar heat gain, humidity, and the prevailing wind were all measured, and this went some way to deciding the best orientation for Casa GG, and the number and placement of the windows and glass doors.

The house sports a rainwater catchment system and solar hot water system, while hand-operated aluminum venetian blinds cut down the solar heat gain from the windows in summer months. The entire interior can be heated with just one 1 KW radiator – which in turn need only operate for two hours a day, even in winter. When warmer weather hits, windows are simply opened to make the most of the prevailing cool mountain winds and increase air circulation.

Within the technical notes Alventosa Morell Arquitectes made available to the press lie several references to the Passivhaus standard of energy-efficient homes, though Casa GG itself doesn't appear to actually have received official Passivhaus certification. We're awaiting further information on this point and will let you know.

Either way, Casa GG is certainly an energy-efficient home, and Alventosa Morell Arquitectes states that it requires 76.77 percent less energy to heat when compared with a similarly-sized traditionally-built house in the same area.

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