Danish participation in IEA ECBCS Annex 55
Energy retrofit of existing buildings fulfils a very important ambition in the energy policy. However, if not done properly, energy retrofit may incur a risk that the desired energy target will not be achieved, and moreover it may lead to partial or complete building failure, or to impaired function of the building, e.g. with respect to air tightness, thermal resistance and moisture performance of the building envelope structure. Successful renovation depends on parameters such as climatic load , material properties, retrofit approa ch, workmanship, etc., and each of these parameters varies according to its stochastic nature. The project facilitates Danish participation and subtask leadership in an International Energy Agency (lEA) project Probability Assessment of Performance and Cost (RAP-RETRO)". The project is Annex 55 in lEA's Energy Conservation in Buildings and Community Systems research programme (ECBCS). The lEA project will develop design methods to support realization of robust retrofitting of buildings in order to obtain low energy consumption and low life cycle costs , while controlling risk levels for performance failure. The project will accomplish these goals by work in the following areas: Subtask I: Gathering of stochastic data; Subtask 2: Probabilistic tools; Subtask 3: Framework and case studies; Subtask 4: Practice and Guidelines
Specific objectives in the Annex have been to:
• Develop and validate probabilistic tools for energy, life cycle costs and functional performance
• Apply and demonstrate probabilistic methods in connection with real case studies.
• Develop guidelines that can be used by practitioners when assessing renovation techniques.
The Annex has dealt with analyzes of energy renovated building envelopes such as various forms of re-insulation systems, e.g. for facades and attics. The case studies have focused on residential buildings.
Energy related performance criteria such as U-values and airtightness have been studied with the methodologies developed in the project. There have also been studies of durability and hygrothermal properties such as resistance to frost damage, fungal attacks and algae growth, and the significance on life-cycle costs.
Subtask 1 Gathering of stochastic data collected a large amount of data with information about their random distribution. Data are presented and discussed regarding material properties, air tightness and ventilation, indoor loads and outdoor climate.
Subtask 2 Probabilistic tools is a subtask where methods have been developed to assess the energy and hygrothermal performance of renovated buildings, taking into account the spread in the required input variables. The subtask also looked to sensitivity analyzes and meta-modeling, which is a way to limit the number of required simulations when many variations of the variable to be tested. Finally, the methods were used to undertake economic analysis with uncertainties.
Subtask 3 Framework and case studies set out proposals for a method for practitioners on how to work with probabilistic design tools. This sub-task also collected information on the case studies that formed basis for the development and testing of the various tools and methodologies.
Subtask 4 Practice and Guidelines gathered information about design rules and practices from the participating countries, and developed guidelines for use of probabilistic data, the tools and the framework that from the other subtasks.
In connection with the working meetings in the project, there have usually been sessions where project participants met local experts and / or practitioners from the local building practices. Latest in Lund, November 2013, a seminar was arranged for people from construction practice who got a lecture entitled "How do we design and realize robust retrofitting with low energy demand and lifecycle costs, while controlling risk levels of performance failure?". Finally, the results of Annex 55 are expected to be presented at a session held in conjunction with Nordic Symposium on Building Physics in Lund, June 2014.
In summary it can be concluded that the project has represented a significant activity of promoting a development which makes it possible to use state-of -the-art tools for energy and hygrothermal analysis of buildings to be renovated in such a way that the random uncertainty in the analyzes can be considered by the professionals who are expected to use the tools and methods in practice.
Key figures
Category
Participants
| Partner | Subsidy | Auto financing |
|---|---|---|
| Danmarks Tekniske Universitet (DTU) | 0,43 mio. DKK | 0,08 mio. DKK |
