Eco-flex houses in IJsselstein

People take more care of their direct environment when they are more involved with its design and maintenance. In order to create a sustainable social environment in which people want to live for a long time, it is necessary to provide people with the possibility to develop themselves, both in their own house and in their direct living-environment.

In the Eco-Flex project, the parties involved have sought to create a high-quality living environment and houses that can easily be adapted according to the wishes of the inhabitants. In addition, they have aimed to achieve a healthy indoor and outdoor climate.

Flexible and life-time lasting
Lifetime-lasting building means that the houses are ideally suited to varying lifestyles and circumstances, for example, home-office combination and extended family situations, now and in the future. New inhabitants were given a choice of house type that they wished to buy. They could choose from five types of houses, each with different lay-outs and/or sizes. In addition, the new residents had the opportunity to design their own preferred size and lay-out: only the stairs, the toilet and the location of services were fixed. The flexibility of the houses also includes the adaptability of the floor plans and sizes in a later phase, achieved through the concept of a core building with detachable facades and an innovative floor system.

The 'free floors' around the core give the residents the possibility to create their own floor plans. Use of detachable internal walls makes it easy to change the lay out of the house at any time. Kitchens and bathrooms can be situated almost anywhere in this free space as on each level there are two places to connect fittings to the pipe systems in the core.

To give the inhabitants even more freedom to make their own lay-out, now and in the future, an innovative floor system is used in which all pipes are directly accessible and can be installed in any direction. This floor makes it easy to change functions later. Looking ahead to the longer term, the houses have the possibility to be extended. Foundations for such an extension have been constructed already in the backyard. The rear-facade of the houses is a pre-fabricated element made of wood. In a later phase this element can be detached easily to allow the extension. Afterwards it can simply be re-attached. Future extension of the house will thus use less building materials than normal and because of the re-use of the (pre-fabricated) rear-façade, less building-waste will be produced.

Energy
The houses have natural ventilation. Fresh air will enter directly from outside through air-grates. Part of the fresh air comes in via the core and is heated by the sun. The other part comes directly from outside. Natural ventilation is used to avoid the need for pipes for air-delivery in which bacteria can live and cause negative effects on air quality. The air is removed mechanically through outlet pipes. This heated waste air passes through a heat exchanger and boiler in which the warmth is re-used to heat water for showering and other household tasks. Part of the electricity for this process is delivered by photovoltaic cells on the roof of the core. To reduce energy losses, the houses have been insulated to levels higher than required by the Dutch sustainable building standards.

Healthy Living Environment
The houses are situated on the edge of IJsselstein's new Zenderpark district, in which eventually about 4000 houses will be built. In the immediate vicinity, sufficient possibilities for children of several ages to play are necessary. Near the houses a big playground is built which, especially for older children, is a perfect place to play football and other games. Children of the whole neighbourhood will come and play here.

In front of the14 houses is a gravel basin for the collection of rainwater from the roofs and the street. Around the basin, a play area for the younger children has been planned. While each house has a private front and back garden, the architect and developer decided to reduce the individual backyards slightly in size and create extra public space. The municipality will use this space to create a play facility for the youngest children of the area. Finally, the 14 houses and their surroundings will be enclosed

Conclusions
The process of designing and building preparation teaches us several important lessons. When new, more sustainable building features are included in the design, for example heating techniques or photovoltaic energy, one should be aware of its higher costs. This is especially true in the normal situation in which the developer has to pay the extra costs of these innovations, and is not sure if he will get his investment back.

Prices of houses in the Netherlands are still based on the size of the area upon which they are built, and on the surface area and volume of the house and not on the new techniques included. Buyers are willing to pay a little more for such things but when prices become in their view too high because of these features, they will simply choose for a larger house.

It was striking that, in spite of giving the new residents lots of choice in unusual house lay-outs, almost all chose for a 'typical' family house. Depending on their purchasing power, the buyers chose to have either a larger living room at ground floor-level or an extra bedroom on an upper floor. In the same house they could also have chosen a lay-out allowing them to start a company or live upstairs in a two storey living space with a nice view.

The location, a new area in which lots of young families are to live, is the main reason for these choices. Living environments closer to the centre of cities demand more varied houses and floor plans. Fortunately, these Eco-Flex houses, occupied by people who will change during their lives, and each in another way, can grow and change with their owners.