De Kroeven-development process

Originally the owner of the social houses planned a renovation that would extend the economic lifespan of the houses by 10 years. Occupants did not agree with this and wanted a lifetime of 25 years with special attention to energy reduction measures. Consequently, the owner asked an architect to make a renovation plan for two pilot houses in which all the ingredients of a passive house concept were incorporated.

This would result in a lifespan extension of 40 -50 years. Based on the experience gained with the two pilots some alterations have been made aimed at reducing the amount of thermal bridges and improvement of airtightness. Due to ever increasing demand from occupants, the planning phase of the project took about 10 years. The owner has not chosen one main contractor responsible for the whole project but several secondary contractors. In this situation the owner has the lead and is responsible for quality of renovation and secondary contractors have a responsibility for problem solving.

This approach has its risks for the owner being responsible for the renovation results. By dividing the project into clusters of houses to be renovated one after the other the owner was able to monitor the quality of the work and to improve it in the following clusters.

In the end the purpose of the renovation was to drastically improve the energy performance of the existing houses from the present level (Dutch energy performance labels F and G) to A++. The owner expects a maximum energy cost reduction of €65 per month based on a yearly reduction of natural gas consumption of 1000-1500m3 compared with the present situation. Each house cost €130,000 to renovate. These costs are relatively high because of the long planning period, advice and development costs. If the renovation had been planned at a natural moment of planned maintenance, total costs would have been €90,000-96,000 (incl VAT) for a house in a row.

The calculated energy reduction costs per month will be €65 per household. The monthly rent has been raised by the same amount ensuring that monthly housing costs would not be higher after renovation. If the energy reduction proved to be lower than expected, the owner guaranteed to compensate this for 5 years. If savings rise in the future due to higher energy prices this will benefit the occupants.