Some details of the optimization work conducted over the last five years in a high rise office complex are described. The solution of the many nonlinear equations representing the building environmental system in real time necessitates very fast algorithms and complete mapping of the feasible regions. The authors experiments in this area are outlined. Models for a chilled water system and an unusual application to an existing dual duct system are given as examples of a general nonlinear approach.

In a typical computer-based building energy management system (BEMS) for HVAC applications, pertinent variables such as pressure, temperature, fluid flow rate, valve and damper positions and the open/close status of the flow control devices, are measured for control and energy monitoring purposes. In addition to these primary functions, the data from the measurements can also be used to detect the abnormal performance of the HVAC system and possible equipment malfunction.

Lawrence Berkeley Laboratory is developing a PC-based computer tool, the Retrofit Energy Savings Estimation Model (RESEM) which can provide high-quality estimates of energy savings, based on actual pre-and post-retrofit utility bills. Designed to be used by state and regional energy office staff who have little energy modeling expertise and access to only limited information regarding a building and its retrofits, RESEM hides much of its sophistication behind a simple, intuitive interface.

Building energy analysis programs have undergone a slow evolution since arrival over a decade ago. The frequency of use and number of applications for these sophisticated modeling tools seems to have reached a plateau. Changes are underway that may result in renewed vigor in the field. This paper reviews some of the dominant energy analysis issues. Recent thrust areas are examined for the alternative futures they suggest.

Computers are currently used for a large variety of tasks in building design and analysis. Among the basic software types used are 2-D draughting systems, 3-D modelling systems, spreadsheet and database programs, technical calculation and simulation software. One of the major drawbacks in today's situation is that almost every program uses a unique internal representation of the relevant data describing the building to be designed or analyzed. Consequently it is very difficult to exchange data directly between different programs.

An index of local thermal comfort and pollutant distributions have been computed with the TEMPEST computer code, in a transient simulation of an air-conditioned enclosure with an incomplete partition. This complex three-dimensional airconditioning problem included forced ventilation through inlet vents, flow through a partition, remote return air vents, an infiltration source, a pollutant source, and a thermostatically controlled airconditioning system. Five forced ventilation schemes that varied in vent areas and face velocities were simulated.

Proposed construction of high rise buildings near the U. S. Naval Observatory in Washington D.C. caused astronomers to ask what effect the heat released by these buildings would have on their ability to make accurate observations. Models of the thermal performance of the proposed buildings were developed and used to estimate the rate of heat release to the atmosphere.

Collaborative efforts among building simulation researchers in Europe and the US have resulted in wide acceptance of certain features as necessary attributes of future simulation environments. As identified 'in the Energy Kernel System (EKS), the principal features are those of the object-oriented programming (OOP) paradigm, in which a hierarchy of submodels is readily defined and interconnected to form system models of widely varying purpose, solution methodology, and implementation description.

The heat transfer processes occurring in the earth surrounding a building have a substantial effect on the building's energy consumption. During the heating season, for example, heat loss through ground- contact surfaces may be one of the most significant contributors to building heating load. Equipment sizing procedures and building energy analyses must use some method for calculating heat exchange between the building and the surrounding earth if they are to adequately calculate the building heating and cooling loads.

Modellers ands users of simulation softwares need to agree on a standard way to state the physical bases of their models The proposals presented in this paper are not new; they refer to the very classical way of describing thermodynamical systems. The basic piece of this description is the reference volume which may be "crossed" by mass and energy flows and which may also have some (mass and/or energy) "capacity". R-C networks are nothing more than "degenerate" or "simplified" sets of reference volumes.