Sustainable by design 2050

An initiative of the UIA

Velux model home 2020




Velux Sunlighthouse

Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
Velux Sunlighthouse
HEIN-TROY Architects, Vienna
Kaspar Greber Holz- und Wohnbau GmbH, Bezau, Merz Kley Partner ZT GmbH, Dornbirn, Donau University Krems, IBO GmbH (Austrian Institute for building biology and -ecology) , Vienna
Western Europe - Austria - Pressbaum / Vienna
Climate Zone
Design status
Date of completion
Site area (m²)
Footprint (m²)
GFA (m²)
NFA (m²)
Gross Volume (GV) (m³)
Building Costs
700000 EUR
Building Costs / m² GFA
Building Costs / m² NFA
Building Costs / m³ GV
Primary Energy (kWh/m²a)
Heating Energy (kWh/m²a)
Cooling / Heating-System

Heating-System with support of a heating pump, solar panels and a ventilating device with heat exchange

Use of renewable ressources - low tech
natural cross ventilation, solar chimneys, use of high thermal mass
Use of renewable ressources - high tech
solar heating, photovoltaics, heating pump, geothermal energy use, energy recuperation, energy storage, thermal building mass activation, other
Renewable, recycled, recyclable and innovative materials

All materials were evaluated by their ecological qualities and CO2 bilance before being
authorized to use: locally grown and processed wood, blast-furnace-slag concrete, sheep wool,
flax and recycled cellulose.

Key Sustainability aspects
solar building integration, vernacular building strategies, accessability for disabled, renewable building materials, recycling and reuse, ecological building materials, innovative bulding materials, integrated planning process, participation of users in planning process, use of innovative design tools, plus energy design
Sustainability rated
Social and ethical responsibility

The Sunlighthouse is the first CO2-neutral single-family-house in Austria. It was completed end of 2010. The project was launched about two years ago by the Velux company as a part of their Pan European experiment, the so called model home 2020 project. The goal is to develop, build and monitor a house as a prototype following the highest approach to progressive and sustainable building and living.
The challenge of the Austrian model home was to create a house that taps the full potential of the plot on one hand and to develop an energy and ecology concept to erase the ecological footprint of the house within the next thirty years on the other hand. What distinguishes this project from many ambitious preceding projects is the need and wish to combine minimized numerical values for energy efficiency with ambitious architecture.
In the end the goal was accomplished. The Sunlighthouse will produce more energy than the transport, building and using (!) of the house over 30 years consumes.

Ressource efficiency and environmental impact

The energy concept of the building was developed in collaboration with the Danube University of Krems. The building equipment includes a high performing heat pump, 48 m2 photovoltaic roof panels, 9 m2 thermal solar panels for hot water and a controlled air system with heat recovery. The heat insulation of the shell surface of the house is optimized and the windows fulfil passive house requirements. A (in Austria) so far disregarded demand was to obtain a maximum of daylight to lower the energy consume for artificial light. The roof and facade windows were strategically positioned to provide stunning views, to maximize passive solar energy, to enable optimal, natural ventilation during summer time and to minimize the thermal losses during winter time. Like the outside planking, the interior fitting is made of spruce wood. All materials had to be evaluated by their ecological qualities before they were authorized to use by the Austrian Institute for Construction Biology and Ecology.

Economic lifecycle perfomance

The house was financed by the Velux company to show new ideas of design and development of houses in relationship to sustainable architecture.
As the plot was very difficult to till it was relatively cheap to buy. Now after we showed the way how to deal perfectly with this site the value rose automatically.
This year the house will be sold to a private owner who allows our clients to operate a comprehensive monitoring for a period of two years to compare all the calculated and simulated results.

Contextual performance and impact

Fortunately the clients had chosen an anything but ideal plot for the Austrian model home. It is a slender and long piece of land that declines towards a beautiful (but shading) wood with high trees in the Southeast, flanked by a dense hedge in the Northeast, a high wall in the Southwest and two close situated neighbouring houses on both. A design concept that uses a maximum of the potential had to be more than a lip service, if the ambitious targets were supposed to be accomplished.