Lean production of cost optimal wooden nZEB

The paper studies lean construction as a co-operational way of working to achieve nZEB targets and good indoor climate and to find new innovative combinations of building solutions. Main target of this paper is to assess energy efficiency, resource efficiency and economics of lean wooden nZEB compared to traditional wooden apartments. The results are based on lean construction literature survey, interviews and two case studies. According to a case calculation lean production of cost optimal wooden nZEB causes only about 115 /m2 additional investment cost compared to construction, which only fulfils the minimum requirements as defined by building regulations. Annual savings in energy cost is about 8 /m2 as present value. The annual life cycle cost is about 5 /m2 as present value for the calculation period of 30 years. Also resale value and user-value (aesthetic value, thermal comfort, high quality of inner climate and good adjustable lightning) are a little higher compared to the traditional building. Calculations show that the total productivity of lean construction is about 20% better than of basic construction in both assessment cases.