Stephan Ott

Life cycle assessment of wood construction according to the normative standards

AbstractThis study demonstrates life cycle assessment (LCA) on a reference wooden building according to the latest normative standards: EN 15978, EN 15804 and EN 16485. Global warming potential and primary energy balance over the reference building were assessed in a case study. Through the assessment, the application of the standards was studied. In addition, possible points for development in the standards, especially concerning wood products and wood construction, were discussed from a practical perspective. The lack of proper data is a critical issue in conducting the assessment in compliance with the standards. Since LCA is a data-intensive method, the preparation of data for the building assessment according to the standard is certainly required. This paper also raises questions about the life cycle modules defined in the standards and the importance of the communication system used for the assessment results. It would be of importance to develop the communication system in such a way as to stimulate environmental consciousness in society. In order to develop a relevant communication system, further discussion and case studies would be important and feedback from such practices should be incorporated into the development of the guideline for the assessment.

Greenhouse gas emission from construction stage of wooden buildings

Abstract This study reports on a detailed investigation into the greenhouse gas emissions associated with the construction process of multistory wooden buildings relative to the other life cycle stages: the material production and operation stages. The results showed that the construction stage accounts for 20–30% of the initial embodied emissions and 6–10% of the total emission of the included life cycle stages. Especially the transport process of building components seems to have higher potential to mitigate the emissions than the actual construction work. In addition, the emissions from different construction systems were studied based on the reference buildings. Although definitive conclusion would be difficult to be drawn from this study alone due to the small sample size and the assumptions made, prefabrication work seems to be a more efficient construction method compared to on-site work for wooden buildings.

Recycling and End-of-Life Scenarios for Timber Structures

In consideration of sustainable buildings, closing life cycle loops becomes more and more important. Up to now reuse and recycling is taken rarely into account in building processes. With rising consumption of wood for energetic use recycling of material becomes more important.

Wind driven rain and moisture safety of tall timber houses – Evaluation of simulation methods

Abstract The research work presented here belongs to a transnational project which aims at the development of a moisture risk analysis method used for tall timber facades. The major interest covers heat, air and moisture simulation of wind-driven rain-(WDR) exposed multi-story timber-based building envelopes (over their entire cross-section). While available moisture-safety concepts are often rule based with limited performance-oriented parts and are limited to small-scale housing, further exploration involves exposure of tall facades. State-of-the-art research compiles WDR examinations and available field and laboratory data as well as monitoring and simulation results. That is followed by evaluations of simulation methods at a best practice wall cross-section with the aim of examining the sensitivity and uncertainty of different parameters in relation to outdoor climate. This approach is chosen to discern the complex relations between exposure and vulnerability and the number of different facade detailing. The findings hold a categorization model of facade cross-sections that is used for risk analysis to describe moisture impact and reaction of functional layer groups. Furthermore, all WDR models and measured data show a high level of uncertainty and simulation results are strongly dependent on that input. An additional consideration of deficiencies and WDR penetration into the core layer of the facade shows only vague results of moisture accumulation. Under these circumstances failure modes of structural members are hard to determine. Therefore, this research is ongoing with a focus on more suitable exposure parameters and calibration of simulation methods for tall timber facades.

The Multifunctional TES-Façade Joint

In comparison to a demolition of existing buildings with severe technical deficits, usually the retrofitting of buildings is more effective in order to prepare them for low energy consumption and new necessities as communication and media connection or HVAC-installation (Heat, Ventilation and Air-Conditioning). Prefabricated retrofit solutions are developed throughout Europe to enable higher levels of industrialization in building envelope modernization and hence additionally improvements in energy efficiency. Five years of experience and a reasonable number of demonstrations done with timber-based element system (TES) facades show tendencies for best-practice building construction.

A Case Study for End of Life Reuse and Recycling Survey Methodologies： The Hollentalanger Cottage

Up to now, reuse and recycling of existing buildings have not been examined widely. This paper discusses the theories, methods and practicalities of buildings’ end of life with a main focus on planning and managing reuse and recycling of existing buildings. Our aim is the realistic modelling of theoretical scenarios for end of life based on a case study. The methods of building survey, material classification and documentation for reuse, recycling and disposal of existing constructions are presented. Investigations and calculations were done on an existing cottage in the Alps. The ecologically most beneficial disposal phase of the old wooden hut is our main objective. Critical questions arise from the quality of the material and how it can be extracted, separated and balanced in an appropriate way. A systematic survey of the building by inspection of constructions and materials in iterative steps allows a detailed material balance with condition and property information. This information is crucial for scenarios and material flow analysis of demolished and rebuilt building in environmental system analysis. For future planning, the reuse and recycling of existing buildings should be integrated quite early in the planning process so that we can use the materials in the best way.