Striking Solar Equinox Passive House Aligns With the Sun in Bulgaria

Aligning buildings with the sun is an ancient technique, but it's high time we do it more often. This coastal home in Kavarna, Bulgaria, is oriented and designed to match perfectly the angle of the sun at the summer equinox. Designed by <a href="http://www.bignatov.com/" target="_blank">Ignatov Architects</a> and completed last year, the <a href="http://inhabitat.com/ignatov-architects-super-efficient-solar-equinox-passivhaus-tracks-the-sun/" target="_blank">Solar Equinox Home</a> is tucked snuggly into is sloped site and makes the most of the free energy given off by the sun. A super tight envelope and energy efficient design also gives this home <a href="http://inhabitat.com/tag/passive-house/">Passive House</a> status, allowing it to use 90% less energy than a similar home without all the upgrades.

Taking cues from the home's hilly site, <a href="http://www.bignatov.com/" target="_blank">Ignatov Architects</a> came up with a plan that fit in with the surroundings and took advantage of the seaside views.

The home is built into the hillside and oriented due south to make the most of the sun and the constant temps of the earth.

A green roof wraps up and over the top of the 2-story home and adds additional lawn space as well as insulation.

A super tight and insulated envelope minimizes energy loss and works to maintain a comfortable climate indoors.

The front wall of triple-paned glass is inverted to perfectly match the angle of the sun on the <a href="http://en.wikipedia.org/wiki/Summer_solstice" target="_blank">solstice</a> at that location. This means no sun at all gets into the house in the middle of the summer.

Conversely, at the winter equinox the low sun angle hits the middle of the swimming pool on the patio and bounces into the house to provide additional daylighting.

The home also features a roof oculus that allows a ray of light to shine into the house to act as a annual calendar marking the progression of the days throughout the seasons.

Besides the <a href="http://inhabitat.com/tag/green-roof" target="_blank">green roof</a> and passive house design standards, the home also works to recover rainwater.

A small bio-active wastewater treatment unit turns waste into dry bio-compost and irrigation water.

A natural ventilation and recovery system along with rooftop solar panels provide passive heating and cooling. If extra heat is needed, a ground source heat pump provides it and the solar hot water panels provide extra heating for the pool.

Local labor and materials were provided used exclusively to lower costs and emissions associated with transportation. The 5,543 sq ft home was completed in 2012.

The upper floor plan.

The lower floor plan.