Spain's Husos Architects was commissioned by a doctor to renovate his Madrid apartment that he shares with his heat-sensitive bulldog. In response, the firm created a new layout that promotes ventilation and, it says, keeps the home comfortable year-round without air-conditioning. The project also added some neat features like a "sleeping capsule" and greywater recycling.

The apartment's interior measures 46 sq m (495 sq ft) and its layout has been carefully arranged to maximize the ventilation inside with operable windows. The center of the home is taken up by an open living area, a kitchen and a dining area, with the bathroom off to one side.

A good chunk of the available floorspace is taken up by a new wood-lined area that hosts a dressing-room, store room, and the main bedroom, as well as the sleeping capsule and shelving.

"Since Jaime's work hours are very variable, he catches up on sleep after night shifts by taking long naps during the day," explains Husos Architects. "Therefore, instead of focusing on the bedroom as the only place to rest, we created a capsule-periscope for taking siestas in the living room as an alternative to the bedroom."

The sleeping capsule also serves as a place to hang out and its door can be closed to create a projection screen for watching movies. The "periscope" is an arrangement of mirrors that lets the owner lie back and see the view of the tree-lined street outside behind him.

Elsewhere in the home is a small indoor garden, which the firm says also helps to maintain a cool interior temperature. The garden is irrigated by greywater.

"One important aspect of the apartment's passive cooling design is a vertical edible garden on the west-facing balcony," says Husos Architects. "The vegetation helps prevent the home from overheating in summer and generally functions as a thermal cushion, cooling the interior and avoiding the use of air conditioning.

"Madrid and its surrounding area suffer from a serious lack of water, which is progressively worsening as temperatures rise, so with the help of agronomists and programmers, we designed a system to recycle greywater from the shower to irrigate tomatoes, herbs and other plants in the vegetable garden."

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