Alventosa Morell Heats an Entire House in Osona with a Single Pellet Stove

In Seva, a village in the Osona region of Catalonia pressed against the edge of Montseny Natural Park, Alventosa Morell Arquitectes completed a 110 square meter house that needs no cooling system and heats itself with a single pellet stove. That is not a marketing claim or a theoretical energy model. It is the actual performance outcome of a building whose every decision, from siting to section to material selection, serves a bioclimatic logic. GE House, designed by Marc Alventosa and Xavier Morell, is a quiet proof of concept: a small residence that treats sustainability not as an overlay of technology but as the generator of architectural form.

The project sits on a triangular plot with significant slope, bordered by two streets. Rather than reshaping the terrain, the architects surveyed the land and placed the building at its highest, flattest point, minimizing earthworks and preserving existing trees. The resulting form is deceptively simple: a linear sequence of rooms under a pitched timber roof oriented to capture southern sun, with service spaces tucked to the north beneath a flat roof. Between these two roof planes, skylights introduce daylight and drive cross ventilation. The house is legible at a glance, yet everything about it is calibrated.

The Timber Hat and the Ceramic Base

GE House reads from the outside as two distinct registers. A ceramic base, its brickwork reaching only to the window lintel height, gives the ground plane a solid, protective character. Above it floats what the architects describe as a large "hat": a ventilated black-tinted wooden facade topped with black tiles. The gap between ceramic and timber is occupied by generous glazing that opens every main room to the south-facing garden. The result is a building that feels simultaneously grounded and light, anchored to its plot yet lifted off it.

The patterned brick catches dappled light under the tree canopy, and the corrugated black roof plane hovers above, its pitch visible from below as an elegant vaulted timber soffit along the porch. The ceramics were fired with biomass, extending the project's commitment to low-carbon construction into the supply chain itself. Every visible material, from the PEFC-certified pine to the brick, was chosen to minimize embodied energy while aging well in the Catalan climate.

A Diaphanous Section

Inside, the structural system of wooden porticos generates a single diaphanous space that contains the porch, living room, dining area, kitchen, and bedrooms in succession. There are no corridors to speak of. The rooms flow into one another beneath exposed timber ceiling beams, with polished concrete floors providing thermal mass that absorbs winter sun and radiates warmth into the evening hours. The kitchen island, faced in plywood that matches the structural timber, sits beneath a clerestory window that bathes the work surface in natural light.

The inclined porticos do more than hold up the roof. They modulate rhythm and scale within the open plan, creating implied boundaries between living zones without the need for partition walls. Privacy from neighboring houses to the north is handled architecturally: the closed, flat-roofed service volume acts as a buffer, while the main spaces face only the garden and the open landscape to the south.

Passive Systems as Primary Architecture

The bioclimatic strategy here is not supplementary. It is the architecture. South-facing windows are sized to capture low winter sun while remaining shaded by the roof overhang when the sun rides high in summer. Skylights positioned in the gap between the sloping and flat roofs draw warm air upward through the section, generating cross ventilation with the sliding doors on the main facade. Cellulose insulation packed into the envelope reduces heat transfer to the point where a single pellet-burning stove handles the entire heating load.

No mechanical cooling is installed. The architects have designed their way out of the problem entirely, using mass, insulation, ventilation, and shading in concert. In a moment when residential construction increasingly relies on heat pumps and smart home systems to hit energy targets, GE House demonstrates that sectional intelligence and material discipline can achieve the same result with far less complexity.

Material Honesty from Outside In

One of the project's quiet strengths is the continuity between its exterior expression and interior experience. The timber framing visible on the facade reappears inside as exposed structure. Pine covers the ceiling, frames the windows, and lines the walls. The polished concrete floor reads as a continuous ground plane from the hallway through the living spaces, and the light that enters through the south-facing glazing is the same light that warms the thermal mass underfoot. Nothing is concealed behind drywall. What you see is what heats you.

All the wood carries PEFC certification, meaning the timber supply chain is independently verified for sustainable forest management. The ceramics are biomass-fired. The insulation is cellulose. These are not exotic materials. They are conventional, affordable, and locally available. The achievement is not in sourcing rare green products but in deploying ordinary ones with precision.

Plans and Drawings

The site plan and floor plan confirm the linear logic of the house: a rectangular volume placed at the high point of the triangular lot, its long axis oriented east-west to maximize southern exposure. Rooms stack along this axis in a clear sequence, with wet and service spaces consistently pushed to the north edge. The elevation drawing shows the timber framing hovering above the tree line, and the axonometric exploded view is especially revealing. It separates the black roof, timber wall panels, structural portico frames, and concrete foundation into distinct layers, making the construction logic legible at a glance. The physical sectional model, built in layered wood, demonstrates the terraced relationship between the house and its sloping site.

Why This Project Matters

GE House is not a demonstration project or an experimental prototype. It is a modest family home on a modest budget in a small Catalan village. Its significance lies precisely in that ordinariness. The architects did not invent a new system or deploy cutting-edge technology. They applied well-understood bioclimatic principles with enough rigor and spatial intelligence to eliminate the need for mechanical cooling and reduce heating to a single stove. In a construction industry addicted to complexity, that simplicity is radical.

The broader lesson is about where sustainability actually lives in a building. It is not in the product specification sheet or the energy consultant's appendix. It is in the section, in the orientation, in the distance between a window sill and a roof overhang. Alventosa Morell have built a house that proves the most effective sustainable technology is architecture itself.

GE House by Alventosa Morell Arquitectes (Marc Alventosa, Xavier Morell), Seva, Osona, Spain. 110 m². Completed 2020. Photography by Adrià Goula.

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