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
two-dimensionalnumerical 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 so-called convective
heat balance model as well as the response factor
method developed. The air flow balance is solved in a
quasi steady-statecondition, 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 |
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Qualification | Doctor Degree |
Awarding Institution |
|
Supervisors/Advisors |
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Award date | 26 Apr 1993 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-4252-5 |
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