If a system can be characterised by n parameters, each of which may assume 3 independent
states, then the total number of combinations is 3 n. A major problem encountered in the design
of any energy systemmfrom a component such as a boiler, to a system such as a buildingmis
that n is large. A building, for example, is characterised by parameters such as occupancy
level, ventilation rate, degree of insulation, location of thermal capacity, glazing type, extent of
HVAC provision, level of control and type of fuel, to name but a few. Even a relatively low
number of parameters will give rise to a large number of combinations: n = 10 equates to
59,000! In short, energy systems are complex. To pretend otherwise is to design for certain
failure.
Achieving a high quality indoor environment at acceptable cost has always presented a challenge
for the construction industry. With aspects of sustainable development now being added
to the list of requirements, and the growth in the available materials/systems that may be
employed, this challenge is set to become even more formidable.
To add to the designer's problems, determining the merit of one combination over another is
a non-trivial task requiring some means to translate the myriad physical interactions to information
on cost and performance relating to fitness-for-purpose, energy use and environmental
impact. Returning to the previous example: a building comprises several thermodynamic
domains~air movement, radiation exchange, moisture flow, electrical power flow, daylight distribution
etc--each one of which may interact with the others in a non-trivial manner. For
example, the simple act of adjusting the position of a window shading device will have cascading
effects on glare, internal daylight level, artificial lighting requirement, luminaire heat gain
and space cooling, heating and electricity demand. Clearly, the construction industry has some
way to go if it wishes to incorporate a rigorous life cycle ysis into its future design practice.
Given the limitations inherent in traditional design methods, is it surprising that our energy
systems often fail to attain their expected performance? Many buildings stubbornly hover at
around 300 kWh m-Zyr -1, energy conversion and delivery systems operate at substantially less
than their optimum efficiency, and human health and comfort needs are rarely fully satisfied.
Simulation represents a possible solution to the complexity dilemma by enabling comprehensive
and integrated appraisals of design options under realistic operating conditions. In
other words, simulation supports the emulation of future realities at the design stage. It gives
practitioners the ability to appreciate the underlying behaviour of a system and, thereby, to take
judicious steps to improve performance across the range of relevant criteria. To be contentious:
simulation represents a paradigm shift of vast potential. It will give rise to a cheaper, better
and quicker design process. And it will provide outcomes that better match society's aspirations
for sustainable practices, environmental protection and climate change mitigation.
This book addresses the issues underlying the development, proving and use in practice of
building energy simulation. While these issues are covered in a generic manner, the specific
material derives from the ESP-r program, which has been under continuous development over a
twenty five year period with financial support from the UK's Engineering and Physical Science
Research Council and the R&D Framework Programmes of the European Commission. I am
indebted to both organisations and to the many technical reviewers and project officers who
recognised something of value in the ESP-r project
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