Iea ebc energy in Buildings and Community Proposal for a new iea ecbcs‐Annex

3 – Definition of the Long-Term Requirements for Building Components & Systems

Task leader: BBRI, ARCELIK, CSTB

In this Annex, the approach will start from the building & system needs to move towards materials requirements through components optimisation. Therefore, it is not intended to develop new materials and then to seek applications but rather to develop new products using existing materials (VIP, Aerogel, GFP) in order to meet the need of buildings and systems.

Hence, the objective of this task is twofold:

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  to define the application areas of SIM. Among these applications, are external insulation, load bearing insulation product for floorings, prefabricated façade panels, façade components, water tanks and appliances as illustrated in Figure 6.
  
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  to describe the conditions of the intended use of the products. Indeed, it’s clear that the requested performance of the SIM will strongly depend on the temperature, humidity and load conditions.
  

Figure 6: Some SIM Application Domains and on-site or in-use conditions

3.1: Conditions of use on-site and definition of Long Term Requirement (LTR)

The challenge of this subtask will be to define the use conditions on-site of the implemented SIM.

In Figure 6, a few examples of building applications are presented.

Local conditions on site: Temperature, Humidity, Wind pressure, Load … ?



Other Application?

Figure 6: Some Building Applications (modified from Porextherm : www.bau-vip.de )

To give an order of magnitude of life span, it could be assumed that the life span could vary from 10 years for household appliances, 15 for water tanks, 50 for building envelope. According to the ETA (European Technical Agreement) the assumed working life is 50 years for most building materials.

This task will also provide a framework for the ageing tests in laboratories. For each application, the use conditions on-site will be clearly defined, especially the temperature, the humidity and the mechanical constrains. These working life conditions such as Temperature, Humidity, Pressure, and Load will be used to define the ageing test in laboratories.

For building applications, storage, handling and implementation requirements will be also described.

3. 2: Performance on-site during the working life

For building envelope applications, this task will be carried out in conjunction with the Annex 58 devoted to the “Reliable Building Energy Performance Characterisation based on Full Scale Dynamic Measurement” (http://www.kuleuven.be/bwf/projects/annex58/index.htm )

For building applications, special attention will be paid to:

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  Thermal Performance such as Uvalue, including thermal bridge
  
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  Heat, Air and Moisture Transfer Air & Water Tightness
  
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  High temperature & Low temperature (condensation & freezing risk), especially for façade applications
  
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  Fire & Acoustic performance
  
• 
  …
  

For systems, the performance requirements will be defined during this Annex.

4 – Performance of Materials & Components measured in Laboratories.

Task leaders: CHALMERS & FIW

The work to be done in this task is to define and precisely describe the methods of characterisation which will be used to provide accurate data for end-users like engineers, architects and constructors.

4.1: Methods of Characterization & Modelling Tools at the Material scale

As their structure and microstructure are completely different, SIM cannot be compared directly to traditional insulating materials. In particular, meso and nano-porous materials used to develop SIM are characterized by a high specific area (m²/g) and narrow pores (below 1 µm) which make them very sensitive to gas adsorption and condensation, especially with water molecules if they did not undergo an hydrophobic treatment.

Therefore, the methods of characterization must be adapted and even in some cases; new methods have to be developed to measure microstructural, hygro-thermal and mechanical properties of materials and barrier films as:

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  Porosity & specific area
  
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  Gas adsorption, desorption , especially water vapor
  
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  Thermal conductivity versus moisture content and temperature
  
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  Permeation through barrier films
  
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  Compressive strain
  
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  Dimensional stability under defined conditions of temperature and humidity
  
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  Deformation under defined pressure, thermal and hygroscopic stresses
  
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  Tensile strength
  
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  Bending
  
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  …
  

In parallel, modeling methods to describe heat, moisture and air transfer through meso – nano-porous materials and film will be developed (adsorption/desorption models, diffusion models, freezing-thawing …).

Modeling of heat transfer at the nano-scale could help us to develop new cheaper nano-porous materials using percolation principle and mixing components.

Modeling of mechanical behavior of nano-porous granular materials will be also investigated. In particular, nanoporous materials can be considered as granular packing, similar to soils. This approach could be an important contribution of this annex.

Of course, a few methods will be common to all SIM but due to their structural difference between them some specific methods will be analyzed.

4.2: Methods of Characterization & Modelling Tools at Component scale

At the component scale, additional characterizations are needed as in general panels or rolls are sold by manufacturers. Hence, a lot of question must be solved at the component scale such as:

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  First of all, storage on-site, handling and fastening
  
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  U-value including thermal bridge due to panel assembling and fastening
  
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  Airtightness, air and vapor barrier
  
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  Fire characteristics; for example do we need to protect SIM by a covering board as it is done for Expanded Polystyrene with plasterboard for internal insulation.
  
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  Acoustic properties; for example, do we need to couple SIM with and other materials to reach acoustic performance in a room.
  

Common and specific modelling methods will be also developed at the component scale in order to understand the impact of SIM on the performance of wall, roof and floors an even the whole envelope with regards mainly to thermal insulation, airtightness and risk of condensation.