dontDIY's thoughtful Passive house design sees off international competition


April 26, 2012

dontDIY's thoughtful Passive house design has won an international competition to design an ultra-low energy house to be built in Bulgaria (Image: Passive House Bulgaria)

dontDIY's thoughtful Passive house design has won an international competition to design an ultra-low energy house to be built in Bulgaria (Image: Passive House Bulgaria)

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Passive House Bulgaria recently announced the winner of its international competition to design a low-energy domicile to be built in Lozen, a village very close to Sofia. The winning entry, from Bulgarian outfit dontDIY, is not only eye-catching, but also fully compliant with the rigorous, though voluntary, Passive house standard.

Buildings that qualify for the accolade of Passive house (it's not limited to residencies) have been described as "ultra-low energy," as they must fall within strict performance criteria per unit area of the building in respect of heating, cooling and energy consumption. This typically results in drastic energy savings when compared to buildings built to meet (though not exceed) national building codes. Oh, and they must leak no more than 0.6 of the house's total volume in air over the course of an hour. Really, the idea is to build a house that requires so little active heating and cooling, that conventional heating and air conditioning systems are not required.

How have dontDIY done it? Well, with a little help from AEE Asian European Engineering, in a number of ways. Perhaps the most eye-catching technology is the 25-sq m (270-sq ft) photovoltaic array destined for the roof (along with a skylights and a garden), generating an estimated (or perhaps I should say calculated) 2380 kWh of electricity per year. But photovoltaics help you to offset your energy demand. Passive houses are really more about reducing that demand through architectural and other non-mechanized design measures - and such measures are far from lacking in this design.

The south facade has a large window in order to maximize solar heat gains (with east and west facades also generously fenestrated), while the north facade is entirely windowless. The overall windows-to-wall area ratio is under 30 percent, yet all the main rooms have south-facing glazing.

And to prevent over-heating during the summer, the south facade has passive stack ventilation built in, so that warm air escapes through high-level vents, while cool air enters through low-level ones. Needless to say, materials have been selected to minimize heat flow between outside and inside.

The house's second floor has been designed as entirely open plan (fret not, the bathroom is downstairs) in order to optimize natural ventilation - the effectiveness of which supposedly receives an additional kick from the choice of location of the house on the available land.

The sloping roof, which lends the design a somewhat jaunty cross-section, is not the result of mere architectural whimsy. These have been carefully measured up in order to achieve optimal facade-to-volume and facade-to-floor area ratios.

A central stairwell forms a quasi-atrium that allows natural light to penetrate right down to the basement-level, where there's another garden.

This may not have any one single eye-catching gimmick that makes this house stand out, but then truly green design is rarely achievable through any one means alone. Here's hoping dontDIY's house works as well in the flesh as it does in paper. Perhaps one day all houses will be built this way, and the very idea of a passive house will be so familiar and ubiquitous as to become meaningless: we'll just call them houses.

See the picture gallery for some of the competition entries the judges thought warranted an honorable mention.

Source: Passive House Bulgaria, via Treehugger

About the Author
James Holloway James lives in East London where he punctuates endless tea drinking with freelance writing and meteorological angst. Unlocking Every Extend Extra Extreme’s “Master of Extreme” achievement was the fourth proudest moment of his life. All articles by James Holloway

If all the buildings on earth would be based on this concept in the future ..... i can guarantee that one day we all will be able to manage without fossil fuel-based power plants and would be successful in completely depending on the renewable sources of energy like solar,wind and tidal energy...

Siddharth Bhatla

Why so big?

Siddharth, that day is already here. RE already in many places is cheaper that FF or gird power. RE equipment are simple machines that built right last 25-50 yrs.

Homes.building are esp[ecially blessed because they pay retail power costs so the savings is much larger.

In the US PV is now selling retail for $1/wt, in Miami as one example.

And I'm building a 2kw wind gen for production for $2k/kw as other do here in the US.


The hourly air leakage limit on this house seems high (0.6) which I interpret to be 60% of the total volume of the house every hour... which is basically all the doors and windows open.

Did you mean something like 0.6% per hour?


This gets better and better! Small houses, self-sufficient, vapor extractors, solar and wind powered ... all they will need is a patch to grow a garden and raise a few egg-layers ... walla, the self-regulating, self-governing, tax free, horizontal communal living center. All you need then is a school, community gathering place and some sort of ritual to celebrate it all ...

Jansen Estrup

Bedroom on the second floor and bathroom on the first? That seems like a basic design flaw.

Michael Crumpton

There must be a toilet in every bedroom. The shower can be anywhere and a tub is unnecessary. I like the inside growing area. High ceilings (12+feet) are nice. A house was built by RMI in Davis, CA several years ago that needed no heat or cooling. Why is that so rare? If one person can do it, everybody should be able to. RMI shares its tech.


Actually the air exchange is 60% of the volume, however not under normal conditions - the house is pumped with air so that there is 50Pa over-pressure. Anyway you can look here to see how the measurement is done:

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