But they couldn't be more different. So, which is the best, and which stands the best chance of being successful?

The Eco-Igloo is a project by Willy Brinksma and Kees de Kraker. Their house, which at present can be seen at an exhibition in the north of Holland, looks like a huge glass igloo with a steel frame that is simply joined by bolts. The glass - which naturally lets in the warmth of the sun - is super-insulating.

Thanks to an ingenious system of heat exchangers no energy is needed to heat or cool the house. An impressive 74 square metres of solar panels provide more electricity than the building uses. As soon as all the exhibitions and fairs are over, it won't be long before Ms Brinksma and Mr De Kraker can move into their Eco-Igloo.

"It takes us five days to take down the house and seven days to rebuild it. Of course this makes a huge difference to the building time, man hours, transport and digging pits for foundations."

 The Eco-Igloo

Floating on Styrofoam

The construction of the Eco-Igloo is so light that it can float on a simple Styrofoam foundation. This is useful in areas where there is a high risk of flooding or in places where space is needed to store water: you simply let your house float on it. And finally, at around 450,000 euros for 300 square metres of living space, it is relatively cheap by West European standards.

However, a sustainable house doesn't have to look so eccentric. At a new housing estate in the town of Leusden the Energy+ house has been built, a project by Innoconstruct and the owner Johannes Out. It is a nice, spacious house, built in the popular 1930s style and it is just as energy efficient as the Eco-Igloo.

Concrete-filled Styrofoam

But here, the high tech solutions are concealed by a traditional finish. The walls are made of hollow Styrofoam blocks that are filled with concrete. They are super-insulating, strong and can be finished off with ordinary brick or plaster. Mr Out says the house is so energy efficient that only 12 solar panels and a small wind turbine are required.

"We use very little electricity; all the equipment needed to heat and ventilate the house is very energy efficient. We have also made all the household appliances and lighting as energy efficient as possible. The washing machine, the dryer, everything uses as little electricity as possible."

Mr Out and his girlfriend use so little energy that they have a surplus of electricity, which they use to charge their electric car.

Spaceship

The Energy+ house, with its traditional features, might stand the best chance of being succesful. However, we shouldn't dismiss the futuristic Eco-Igloo. It may resemble a spaceship but, as Willy Brinksma enthusiastically tells us, there are more advantages than being energy efficient, light and quick to build:

"As you see, there is glass all around, so you have a panoramic view."

It looks like there are two winners here. The Eco-Igloo because of the courage it takes to set aside all architectural traditions and start again from scratch. And the Energy+ house because the concept fits better in a normal housing estate.

Thijs Westerbeek van Eerten
Radio Netherlands