A genetic algorithm technique is used to design an HVAC air duct system with minimum life-cycle cost. The approach has the capability to incorporate standard (discrete) duct sizes, variable time-of-day operating conditions and variable time-of-day utility rates. An example is used to illustrate these capabilities and results are compared to those obtained using weighted average flow rates and utility rates to show the life-cycle cost savings possible using this genetic algorithm methodology.

Part I of this paper discussed the theoretical considerations of creating a nonlinear black box model. In P art II, the constraints on the nonlinear model imposed by the application are discussed followed by presentation of the model structure, training method, input selection, and input transformation. The test results of applying the proposed model with the selected features to five test buildings are discussed next. One of the test buildings (Zachry Engineering C enter) selected for this study was also used in a previous study as a p art of energy prediction competition (Haber!

A building energy management system (BEMS) generally monitors and manages energy usage in commercial buildings. With the ability to monitor a plant and to recall the collected data at a later time, actual building energy performance can be measured and compared with the expected performance. The comparison will help in detecting possible abnormalities with the building energy usage and in identifying opportunities to optimize the building energy performance. In order to predict expected building energy performance, a reasonably accurate building energy model is needed.

High outdoor ventilation air requirements can lead to significant increases in building energy use, thermal discomfort, indoor air quality problems, and litigation. Engineers often avoid ground-source heat pumps because of the perception that there are no acceptable methods for conditioning the ventilation air. However, this difficulty is currently a problem with all types of heating and cooling systems. Decisions may be based on system performance at design conditions without regard to seasonal energy consumption.

Angle factors between a human body and rectangular planes are calculated by a numerical model. The method presented in this paper which predicts the thermal radiation field in a space, is based on a numerical integration method proposed in a previous paper. To confirm the validity of the calculated results, predicted angle factors for both standing and seated persons are compared with those from experiments. It was found that the predicted figures matched well with those from experiments except those between the human body and the front floor.

A series of experiments was carried out to study the effect of temperature and humidity on the perception of indoor air quality. The study included both laboratory and controlled field experiments using an untrained sensory panel to judge the air quality at different levels of temperature and humidity. Facial and whole-body exposure for a short term (up to 20 minutes) was used in the laboratory study, and long-term whole-body exposure (up to 4. 6 hours) was used in the field study. The study found a significant impact of temperature and humidity on the perception of indoor air quality.

Relations between indoor neutral temperatures and outdoor temperatures are currently proposed as an "adaptive standard" to supplement ASHRAE Standard 55-1992. They rest on the 1998 ASHRAE database. Humphreys and Nicol drew attention to the depression of the regression coefficient by measurement and formulaic error in thermal comfort indices. This paper applies their suggested correction, and improves the precision of the relations. Comparison is made with similar relations from earlier data. The relation for unheated, naturally ventilated buildings has remained unchanged.