Sunlighthouse is Austria’s first carbon-neutral single-family house. Nestled in a wooded, mountainous region, the home’s sloping roof and architectural elements take full advantage of the sun to ensure maximum solar energy.

Sunlighthouse aims to keep energy consumption to a minimum without sacrificing the family’s comfort or standard of living. With its ultra-efficient brine heat pump for heating, thermal solar collectors for hot water, photovoltaic (PV) solar cell system for electricity, and energy-efficient household appliances, the house is powered exclusively by renewable energy.

The home’s PV solar cells and solar collectors actually generate more energy than the house uses. This means that after 30 years the home will have generated as much clean energy as was created in its construction, making it truly carbon neutral



Sunlighthouse takes advantage of sunlight to provide its residents with optimal conditions for their health and well-being. Researchers at Danube University Krems evaluated the home’s daylight levels and found that it has an average daylight factor of at least five percent in all living spaces.

The roof and façade windows were all strategically placed to provide stunning views, maximum passive solar heat gain and natural ventilation. These many windows ensure daylight levels are balanced throughout the home’s two storeys. In fact, Sunlighthouse’s total window area is equal to 42 percent of its floor area, so very little artificial light is needed during the day.

Automated, intelligent control of the home’s windows is the primary source of ventilation in spring, summer and autumn. In the winter, however, Sunlighthouse uses a mechanical ventilation system with heat recovery. The home uses no energy for cooling, but the stack effect of the windows, night cooling and awning blinds on the windows ensure Sunlighthouse has a comfortable indoor climate throughout the warm summer months.


Juri Troy’s architectural design is a direct response to the home’s surroundings. Sunlighthouse is located on a steep, partially-shaded slope and faces southeast towards the Vienna woods. The nearby mountains cast dramatic shadows over the valley, so the living area features high roof windows that bring light to the centre of the room.

The kitchen and dining areas face southwest and feature numerous roof and façade windows, all positioned to provide amazing views and maximum passive solar energy gain. And besides providing an unusually high level of daylight, the windows also act as a central design element in home.

The home’s design was the result of a competition between nine up-and-coming Austrian architects, and the winner was Hein-Troy Architekten. VELUX Austria is monitoring the project along with our partners at Danube University Krems and the Institute for Healthy and Ecological Building (IBO). Sunlighthouse is the recipient of the Austrian State Prize for Environment and Energy Technologies.

Hein-Troy architects won fourth prize for the project Sunlighthouse in the international architecture award organized by Fiandre entitled Active Architecture. Read more at

In February 2010 Sunlighthouse, won the Austrian National Awarfd or environment & energy technology 2010 in the category “special awards”. The award was given for the outstanding innovative content, the degree of novelty and market potential and/or for the already achieved market position.

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