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Programy a algoritmy numerické matematiky 13,
Praha 2006
Uncertainties in measurement of thermal technical
characteristics of building insulations
Stanislav Štastník, Jirí Vala, Hana Kmínová Brno
University of Technology, Faculty of Civil
Engineering e-mail vala.j_at_fce.vutbr.cz
1. Modelling of heat propagation in buildings 2.
Basic thermal technical characteristics and their
measurements 3. Fourier analysis of heat transfer
in the new testing equipment 4. Deterministic
approach identification of material
characteristics 5. Non-deterministic approach
analysis of uncertainties
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• Thermal stability by technical standards
• nearly constant temperature T(t) in time t in the
  interior of a building, independent of
  quasi-periodic (day and year) climatic cycles
• very slow changes of time derivatives of T(t),
• minimization of energy consumption by heating (in
  winter) and air conditioning (in summer)

• Physical processes in porous materials
  (conservation laws for mass,
  momentum and energy)
• heat conduction, convection and radiation
  (Fourier equation)
• partially irreversible propagation of moisture in
  various phases (as air humidity, liquid water and
  ice), eventually of other contaminants
• compressible viscous air flow in rooms and
  through walls, roofs, etc. (Navier-Stokes
  equations)

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• Classification of thermal technical
  characteristics
• of the heat conduction
• of the heat convection
• of the heat radiation
• of the pore space and its availability for air,
  moisture and contaminants
• of the air flow in rooms, walls, roofs, etc.

• Heat conduction characteristics ?
  dT/dt ? d2T/dx 2
• material density ?
• heat conduction factor ? thermal insulation
• thermal capacity (specific heat) c thermal
  accumulation
• ? ?c

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• Classical approach to measurements ? dT/dt ?
  d2T/dx 2
• of ? easy (mass / volume)
• of ? from standard experiments with the
  stationary heat transfer
• of c using various calorimeters (contact with
  water needed, danger of mismatched results caused
  by humidity in pores)

• New approach to measurements
• of both ? and ? from a similar experiment as in
  b), but with the non-stationary heat transfer
• advanced numerical analysis needed for
  simultaneous identification of both
  characteristics

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New equipment in practice
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Example of a cost function F (?,?) for the new
insulation layer, based on the wood waste
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Thank you for your attention. All question and
remarks are welcome.