| summary |
In this dissertation, developments in the field of building performance evaluation tools are
described. The subject of these tools is the thermal interaction of building structure and
heating and ventilating system. The employed technique is computer simulation of the
integrated, dynamic system comprising the occupants, the building and its heating and
ventilating system.
With respect to buildings and the heating and ventilating systems which service them, the
practical objective is ensuring thermal comfort while using an optimum amount of fuel.
While defining the optimum had to be left for other workers, the issue of thermal comfort is
addressed here.
The conventional theory of thermal comfort in conditions characteristic for dwellings and
offices assumes steady-state conditions. Yet thermal conditions in buildings are seldom
steady, due to the thermal interaction between building structure, climate, occupancy, and
auxiliary systems. A literature rewiew is presented regarding work on thermal comfort
specifically undertaken to examine what fluctuations in indoor climate may be acceptable.
From the results, assessment criteria are defined.
Although its potentials reach beyond the area of Computer Aided Building Design, a
description is given of building and plant energy simulation within the context of the CABD
field of technology. Following an account of the present state-of-the-art, the choice for
starting from an existing energy simulation environment (ESPR) is justified. The main
development areas of this software platform - within the present context - are identified as:
fluid flow simulation, plant simulation, and their integration with the building side of the
overall problem domain.
In the field of fluid flow simulation, a fluid flow network simulation module is described.
The module is based on the mass balance approach, and may be operated either in standalone
mode or from within the integrated building and plant energy simulation system. The
program is capable of predicting pressures and mass flows in a user-defined building / plant
network comprising nodes (ie building zones, plant components, etc) and connections (ie air
leakages, fans, pipes, ducts, etc), when subjected to flow control (eg thermostatic valves) and
/ or to transient boundary conditions (eg due to wind).
The modelling and simulation techniques employed to predict the dynamic behaviour of the
heating and ventilating system, are elaborated. The simultaneous approach of the plant and
its associated control is described. The present work involved extensions to the ESPR energy
simulation environment with respect to robustness of the program, and with respect to
additional plant simulation features, supported plant component models and control features.
The coupling of fluid flow, plant side energy and mass, and building side energy simulation
into one integrated program is described. It is this "modular-simultaneous" technique for the
simulation of combined heat and fluid flow in a building / plant context, which enables an
integral approach of the thermal interaction of building structure and heating and ventilating
system. A multi stage verification and validation methodology is described, and its applicability to
the present work is demonstrated by a number of examples addressing each successive step
of the methodology.
A number of imaginary and real world case studies are described to demonstrate application
of the present work both in a modelling orientated context and in a building engineering
context.
Then the general conclusions of the present work are summarized. Next and finally, there are
recommendations towards possible future work in the areas of: theory, user interface,
software structure, application, and technology transfer. |
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