Tools (Computer Programs)

Most of the dynamic building programs have some kind of simple model to consider natural ventilation, but very few allow full multizone airflow and contaminant transport calculations. However, updates of these codes as well as new developments include a multizone ventilation model. Also, a number of programs have been specifically developed for passive cooling applications. The following sections give examples of widely used programs for both the de­tailed multizone models and the simplified single-zone models. Detailed Multizone Programs


ESP-r is a building and plant energy simulation environment based on a numerical approach in which building and plant energy flows and their inter­connections are represented.3’6 In particular, the system is able to integrate heat, air, moisture, daylighting, and power flows, while including special com­ponents such as photovoltaic cells, advanced glazings, and renewable technol­ogies. For advanced lighting applications, ESP-r is able to pass (automatically) its building representation to the RADIANCE daylighting simulation code and receive back, for example, the internal illuminance distribution as an in­put to a user-specified lighting controller.


The multizone airflow model COMIS is adapted as a TRNSYS type, to be used in combination with the TRNSYS Type 56 thermal multizone building model.7 Input is somewhat redundant. Separate input files are necessary for the thermal model and the ventilation model, but not for meteorological and link schedules.


EnergyPlus is a new-generation building energy simulation program that builds on the best features and capabilities of BLAST and DOE-2.s EnergyPlus includes innovative simulation capabilities including time steps of less than an hour, built-in template and external modular-systems simulation module» that are integrated with a heat balance-based zone simulation, and input and out­put data structures tailored to facilitate third-party interface development. Other planned simulation capabilities include multizone airflow Lind clectric power simulation, including photovoltaic systems and fuel cells.


IDA Indoor Climate and Energy (ICE) is a new generation of building per­formance simulation tools.9 The mathematical models are described in terms of equations in a formal language, NMF. Whenever appropriate, models rec­ommended by ASHRAE have been used. Advanced database features support model reuse. Single-Zone Models


LESOCOOL is an easy-to-use computer program for the determination of passive cooling potential by nighttime ventilation.10’11 It is based on a simple combined airflow and thermal model, originally described in Van der Maas and Roulet.12


This code is a product of the pan-European EU-JOULE research project NatVent.13’14 The program is intended to be used in an early stage of the building design process to predict airflow rates and indoor air temperatures. The code is an integrated single-zone model with an airflow model and a ther­mal model. Thermal analysis is made using a solar radiation model and a sim­ple, single-zone room model with fixed geometry, heat transfer coefficients, and a user-defined active mass ratio. Overhangs and solar protection systems are considered.