Practicing engineers need an integrated building, HVAC and control simulation tool for optimum
HVAC design and retrofit. Various tools are available to the researchers, but these are not appropriate
for the consulting engineer. To provide the engineer with a tool which can be used for
typical HVAC projects, new models for building, HVAC and control simulation are introduced and
integrated in a user-friendly, quick-to-use tool.
The new thermal model for buildings is based on a transfer matrix description of the heat transfer
through the building shell. It makes provision for the various heat flow paths that make up the
overall heat flow through the building structure.
The model has been extensively verified with one hundred and three case studies. These case
studies were conducted on a variety of buildings, ranging from a 4m2 bathroom, to a 7755 m2
factory building. Eight of the case studies were conducted independently in the Negev Desert in
The thermal model is also used in a program that was custom-made for the AGREMENT Board
(certification board for the thermal performance of new low-cost housing projects). Extensions to
the standard tool were introduced to predict the potential for condensation on the various surfaces.
Standard user patterns were incorporated in the program so that all the buildings are evaluated on
the same basis.
In the second part of this study the implementation of integrated simulation is discussed. A solution
algorithm, based on the Tarjan depth first-search algorithm, was implemented. This ensures
that the minimum number of variables are identified. A quasi-Newton solution algorithm is used
to solve the resultant simultaneous equations.
Various extensions to the HVAC and control models and simulation originally suggested by Rousseau
 were implemented. Firstly, the steady-state models were extended by using a simplified
time-constant approach to emulate the dynamic response of the equipment. Secondly, a C02 model
for the building zone was implemented. Thirdly, the partload performance of particular equipment
Further extensions to the simulation tool were implemented so that energy management strategies
could be simulated. A detailed discussion of the implications of the energy management systems
was given and the benefits of using these strategies were clearly illustrated, in this study.
Finally, the simulation tool was verified by three case studies. The buildings used for the verification
ranged from a five-storeyed office and laboratory building, to a domestic dwelling. The energy
consumption and the dynamics of the HVAC systems could be predicted sufficiently accurately to
warrant the use of the tool for future building retrofit studies