By replacing mineral building materials with biobased building materials, CO2 emissions are minimized. In fact, in biobased materials, CO2 can be stored for a long time, perhaps for several hundred years. As a result, CO2 is extracted from the atmosphere. Studio Marco Vermeulen has calculated that the construction of 1 million homes in a conventional way emits 55 Mton CO2. With the choice of biobased materials, that amount of CO2 release can be avoided and at the same time 45 Mton CO2 can be stored. A difference of 100 Mton! In contrast to costly storage under the North Sea, this form of CO2 storage actually creates value in the form of homes. For almost all building parts there are bio-based alternatives such as wood wool and cellulose for insulation, and hemp fiber and flax as biocomposite elements. But an especially potent material is that of solid timber, for the construction of structural shell - the walls, floors and the roof. This allows the construction industry to play an active role in the fight against climate change.

In the Netherlands, solid timber construction is still in its infancy, but application in Austria and Germany, for example, shows great opportunity for faster construction speed, lower construction costs and better health of construction workers. The PZH has a major building task, but wants to develop it in a sustainable, responsible manner. Timber construction has a positive CO2 effect. However, building is still minimal with wood due to lack of experience and a standard building culture. The province can transition the building culture with this strategy. The use of wood ensures a short construction time because of prefabrication, which has a positive effect on the large demand for housing.

With the solid wood construction method, local, fast-growing wood is glued crosswise to large sheets in different thicknesses under the name cross laminated timber (CLT). From these, building elements can be prefabricated industrially in the desired shape and provided with recesses for doors and pipes. These elements are assembled "dry" at the construction site.

Solid wood elements are easy to replace or adjust, giving these buildings a certain degree of flexibility in use. When a CLT building is no longer adequate, it can easily be dismantled and recycled into low-quality wood products such as veneer, chipboard and insulation material, or ultimately burned into energy in a biomass plant.

Based on the urbanization route map of the Province of South Holland, the majority of the housing assignment, approximately 80%, will be realized in existing urban areas. These housing projects take place near high-quality public transport (HOV) stops. In addition, outdated business parks are being transformed into multifunctional residential areas. Thanks to its low weight, wood is pre-eminently suitable for adding extra floors to existing buildings. The remaining 20% ​​of the houses can be integrated with new forests. This creates attractive residential landscapes that are currently scarce in South Holland. Currently, minerals are being used and the negative effect of this is enormous. By inspiring/ proving that timber construction is feasible in the current market, the entire chain becomes encouraged to work with biobased materials. With this circular housing construction strategy, the serial nature of timber construction for middle class homes can be tested and proven.

Outside the Natura 2000 areas, the Netherlands disposes of at least 140,000 hectares of forest, mostly laid out as a production forest for mining. Here trees can be selectively replaced by young specimens of other species. This provides around 8m3 per hectare of wood per year, but at the same time ecological, landscape and recreational added value in the often monotonous pine forests. In order to be able to make 210,000 homes from Dutch wood in South Holland, an additional 14,500 hectares of new forest are needed. That could provide an impetus for parts of the Netherlands that are struggling with poor soil quality and / or a declining agricultural sector

The development of this circular housing strategy, along with the associated positive changes to the landscape and living environment, requires time and effort. At the same time, we can already begin using proven technology and accelerate the construction of homes with it. To achieve the climate goals and the circular ambition of the province of South Holland, a resolute and integrated approach is crucial.

An important factor for the success of this strategy is approaching it as a chain. We are already in discussions with Staatsbosbeheer about potential collaboration opportunities. The availability of raw materials, the planting of new forests, the processing of timber into prefab CLT elements, assembly at the construction site, and the cascading of residual streams must be organized in an integrated way to realize a circular construction strategy.