Abstract
Numerical methods have been introduced for the thermal
analysis of airleakages in building components and in
buildings as a whole. Numericalmethods at the structure
level are developed on the basis of physical
modelling derived from the balance equations of coupled
heat and airtransfer in building structures. The study
focuses on crack and filtrationflows. The numerical
formulation of the model equations is based on the
finite difference method and the reliability of the
twodimensionalnumerical methods developed at the
structural level have beenexperimentally confirmed.
For energy analyses of buildings, an application
of the response factor method for leaky structures, which
takes intoaccount the thermal coupling of transmission
heat flows and the convectionheat flows of air leakages,
is also introduced. A simulation procedure for
the simultaneous solution of air flow and heat balances
is elaborated. Inthis procedure the heat balance of a
building is solvedby means of the socalled convective
heat balance model as well as the response factor
method developed. The air flow balance is solved in a
quasi steadystatecondition, using the MOVECOMP program
as a basis.
In the analyses at the structure level, the thermal
interactions of structures
and leakage air flows in some typical air leakage cases
are examined. The
dependence of heat transfer (the heat recovery effect) on
the leakage air
flow rate, the length and location of the leakage path,
the dimensions and
thermal property values of the structure and on the heat
transfer
coefficients of the surfaces are analysed numerically.
The numerical
analyses made on the building level are used to study the
annual
interactions between the airtightness of the building
envelope, air leakages
and heating energy consumption. A single family house
with a mechanical
exhaust ventilation system was chosen for the case
studied. According to
analyses, it is evident that both the omission of the
heat recovery effect of
infiltrating/exfiltrating air and using the constant
exfiltrating airflow rate
tend to overestimate the calculated heating load compared
with the actual
heating load. Finally, thermal analyses are carried out
on a house with so
called dynamic walls.
Original language  English 

Qualification  Doctor Degree 
Awarding Institution 

Supervisors/Advisors 

Award date  26 Apr 1993 
Place of Publication  Espoo 
Publisher  
Print ISBNs  9513842525 
Publication status  Published  1993 
MoE publication type  G4 Doctoral dissertation (monograph) 
Keywords
 thermal analysis
 coupling (process)
 building components
 building envelope
 structures
 buildings
 energy consumption
 heat transmission
 air tightnes
 heat transfer
 air low
 leakage
 development
 numerical analysis
 computer programs
 simulation
 convection
 models
 theses
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Virtanen, M. (1993). Thermal coupling of leakage air and heat flows in buildings and in building components: Development and application of numerical methods: Dissertation. VTT Technical Research Centre of Finland.