The CoNZEBs team has completed the activity on the identification of potential cost reductions in the design and construction processes. The scientific partners and the housing organisations assessed the cost related to the design and planning phase according to the specific conditions applying in the participant countries (Germany, Denmark, Italy and Slovenia). Also the temporal development of construction costs for the main categories was investigated.
After having identified common boundary conditions, the stakeholder involvement was the second step. Designers, planners, construction companies, contractors and social housing companies were invited to express their view about the current status of the design and construction process, and the identification of most promising solutions for cost reduction. Some of the main topics were:
- Awareness about and experience with the design and planning of NZEBs.
- Method of calculating the costs for design and planning.
- Experience and impact of the long-term maintenance costs.
- Magnitude and causes for cost variations in respect to the planned costs.
- Internal process to reduce construction costs.
- Solutions to reduce design and planning costs.
- Solutions to reduce overall construction costs (to be tailored at national level).
Close to 100 questionnaires and interviews were collected, and the results presented and discussed.
As final step, exemplary solutions for the cost reduction in the design and construction process were identified. The design and construction process is complex and has many boundary conditions that make a systematic identification of cost reduction solutions impossible; instead cost optimisation solutions should be explored and pursued in each construction project. For these reasons some exemplary cases, referring to the main areas, were presented and discussed:
- Impact of specific building envelope and energy system technologies including the use of large blocks and monoblock windows
- Impact of specific design solutions including external staircases
- Impact of innovative project management systems like Building Information Modelling (BIM)
The full report is available here.
CoNZEBs is analysing the design and construction processes of multi-family houses in the four participating countries in order to identify cost reduction potentials. Aspects to be taken into account are the timing, the actors involved and the requirements to meet. Assessed cost saving strategies will include pre-fabrication, using local resources nearby the building site and information technology solutions such as BIM instruments.
The results will be documented in a public report “Assessment and proposal for cost-reduction in the design and construction process”.