The analysis of enthalpy control strategies and its application in hot and humid climates

Air enthalpy control strategy, or often known as free cooling, has been very effective in conserving building air-conditioning power consumptions-in moderate climatic areas. However, it stands for a challenge on its application in hot and humid areas, such as in Taiwan, where outdoor air enthalpies are constantly high. Three control schemes, namely, those using temperature control (economizer, or T-control), enthalpy control (H-control), and the Modified temperature control (MTcontrol) were studied in this paper.

Techiniques for simultaneous simulation of buildings and mechanical systems in heat balance based energy analysis programs

The current generation of building simulation software is based upon separate building and mechanical system simulations. While separate simulations are adequate for some buildings, there are many configurations which require a simultaneous simulation to completely model the interactions between the building and mechanical systems. Work is underway to develop a new version of the Building Loads Analysis and System Thermodynamics (BLAST) [1] energy analysis program which will simulate buildings and mechanical systems simultaneously.

Simulation in lighting cost analysis

Since methods incorporating the time value of money are the only ones that give an accurate picture of life costs of a system, they are the only methods appropriate for the analysis of building lighting systems. However, these procedures (such as the present worth method) and the algorithms for employing them are not without shortcomings. One problem with traditional methods is that they employ single point estimates as input values and result in a single value that is supposed to represent the present worth of the system.

Simulation and optimization in the real time control of building environmental systems

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.

Rule-based diagnostic method for HVAC fault detection

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.

RESEM: an evaluation tool for energy retrofits in institutional buildings

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.

Promising (and not so promising) developments in energy analysis software

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.

Product models of buildings and their relevance to building simulation

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.

Predictions of thermal comfort and pollutan distributions for a thermostatically-controlled, air-conditioned, partitioned room: numerical results and enhanced graphical presentation

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.

Perturbations in atmospheric density caused by high rise buildings and their effect on astronomical observations: a case study

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.