Described by the architect (who is also the owner) as “a real jigsaw puzzle“, this new residence design in Glen Park, San Francisco is dazzling inside and out. It’s deliciously airy inside, thanks in part to the huge front window and an open floorplan that makes use of every inch of the property’s modest dimensions. Lighting, heating, insulation and building materials are all cutting-edge sustainable. Why aren’t more houses like this? That’s the puzzle here.

Squeezed into a densely-packed corner of Osaka’s urban sprawl, this infill seeks to return to the qualities that traditional Japanese architecture excels at – a delicate use of space, a liberal use of light. Angled windows and multiple skylights flood the house with natural light, and are positioned to present the occupants with greenery or blue sky – no parked cars on view here (ironically, as the property is a former car-park).

One thing you can’t call this house in north London is shy. Standing proud in every sense, 76A Newtington Green Road fits into a gap just 4.8 meters (16ft) wide, hiding reclaimed materials behind an unashamedly modern exterior that dares to be different. We can’t help wondering how the neighbors feel about that…

But when it comes to architecturally bewildering the entire street, it’s hard to beat Atelier Tekuto’s “Reflection of Mineral“. Tiny plot on a street corner – and you want a roofed garage? No problem. By cutting away the front of the building an overhang big enough to shelter a car is created. Since this turns the exterior into a crazy-angled polyhedron, why not continue the theme inside? Health warning: this is not a house you should ever be tipsy in.

Finding a gardened inner-city property in London is a problem. Multiply that by a large figure if it’s a brand new residence. The elegant solution is to pinch an idea or two from those clever green roofing people, and drape ivy over the outside walls. If you’re worried those walls look a little too diaphanous for the British climate, the designers promise a sophisticated 3-stage glazing system that will maintain comfort and privacy – and we’ll have to wait until 2012 to see what they have in mind.

Potential infill sites are often deemed useless for development because there’s something in the way – and that was the dilemma facing architect Chris Cobb with this house in Austin, Texas. What to do with that tree? Cobb decided it was part of the design – and shaped the house to tuck under its branches. Wood cladding, primarily Brazilian Redwood, and dark bamboo flooring keep the house in visual harmony with its century-old neighbor.

Sometimes speedy infills are a grave concern. For cities suffering in the wake of natural disasters, architects buildingstudio have devised this template for affordable, easily-constructed and quickly-built infill housing based on the traditional New Orleans “shotgun” style. A single or double housing unit extends out towards the road, three stories high with the ground floor a communal courtyard. Air is kept moving around via louvred shutters and ceiling fans and freshened with vines and trellises, while renewable energy sources provide heating and hot water.

Is it a house? Is it a garage? Is it finished? Yes, this beautiful and wildly unconventional design from Pine Street in Philadelphia is all of the above. Drive your car into the first floor, and it’ll sink down into the hidden garage, the parking space replaced with a patch of lawn and a potted plant. Inside, the house’s 60-foot depth allows for long, spacious rooms including two guest bedrooms, and two stories of wooden solar shades ensure that open frontage doesn’t give passers-by an embarrassing eyeful.

Tackling the problem of a property that fits a curving street end is Carmarthen Place SE1 on Bermondsey Street, London. No need to worry about consulting the rest of the street, because the owners are the rest of the street, choosing a design they feel works in harmony with the existing listed buildings. Since the area has historically relied on timber cladding and shuttering, they form the backbone (or rather the skin) of these 2-bedroomed homes.

For the people at Dwell Development in Seattle, creating gorgeous sustainably-built infills is all in a day’s work – and their mantra is “we build green because it is the right thing to do”. Check out their galleries of gorgeous exteriors and interiors, and let your imagination go nuts. What would your dream urban infill look like?

Images: Inhabitat, Velux, Mother Nature Network, Moto Designshop (via Inhabitat), Chris Cobb Office of Architecture (via The Contemporist), buildingstudio (via EcoFriend), Bermondsey Street Studio (via greenfab), Atelier Tekuto (via Abitare), Studio Seilern Architects (via Inhabitat) and Dwell Development.