English

Due to the rapid growth of the country, prototype school buildings in Saudi Arabia were designed with little effort made towards the utilization of the natural resources to improve indoor conditions. Most of the existing school buildings in Riyadh, the capital city of the kingdom of Saudi Arabia, rely on mechanical equipment to cool interior spaces. As a result, these schools have become one of the major energy consumers during the peak time of the day.

The article shows the results of a case study dealing with indoor daylighting concepts and practice. The analysis evaluates the performances of different window options taking into account quantitative and qualitative aspects such as daylight factor, uniformity ratio of illuminance, and daylighting glare index.

Defrosting in supermarket refrigeration systems is normally controlled by a preset time cycle with most display cabinets timed to defrost every 6 hours. It is widely acknowledged that timed defrost may cause a number of unnecessary defrost cycles and this reduces the energy efficiency of refrigeration systems as well as the accuracy of temperature control of the cases.

It has been shown by previous researchers that Artificial Neural Networks (ANNs) not only be used to predict energy more reliably than traditional simulation models and regression techniques but can also from the basis for a predictive controller of thermal systems such as HVAC equipment. This work is directed towards the identification of the important inputs (independent variables) to facilitate on-line prediction and thereby implement refrigeration and HVAC system diagnostics, process control, optimisation and energy management in retail food stores.

In the last years, as fenestration and shading systems have become more complex and sophisticated, a great improvement of thermal and solar-optical performance has been required and as a consequence old methods of characterization have become inadequate. This evolution has yielded the introduction of new lumped parameters and the implementation of more sophisticated calculation models, which allow to evaluate the performance of fenestration and shading systems taking into account a large number of factors, such as the angular dependence of solar heat gain.

This paper compares the results obtained with the simplified sizing methodologies for thermal energy storage components usual in HVAC current practice and those obtained from an optimised procedure based on hourly simulations. The PC version of the building energy analysis programme DOE2.1E was used in energy simulations of a central hospital in Lisbon, as part of an energy audit. The audit enabled the simulation model to be calibrated.

A dynamic model based on physical laws and field measurements has been developed to simulate temperature, humidity and gas concentration in livestock buildings and the emission of ammonia from these buildings. The model consists of several sub models and permits to evaluate different control algorithms for heating and ventilation of livestock buildings. For each control algorithm the dynamic evolution of the resulting inside temperature and humidity are calculated together with the corresponding energy use for the specified heating and ventilation system.

Through this paper we describe the introduction of a comprehensive routine, able to take into account air changes needed for IAQ purposes, in a computer simulation code based on the explicit form of the finite difference method and devoted to the evaluation of the thermal behaviour of multizone buildings. Main characteristic of the routine is the capability of selecting and comparing different international technical standards, like those provided by the ASHRAE, the E.U. guidelines and so on.

For new design approaches the engineers of HVAC systems need tools for estimating energy requirements of different heating systems in advance. The heat losses of buildings can be classified into three fields. These are at first the losses through transmission and ventilation. Further on there are the losses which occur during heat generation (e.g. boiler heat losses). The third field contains the losses occurring at the heat distribution (e.g. pipe heat losses).

This paper presents laboratory and field test results for a new pattern recognition adaptive controller (PRAC) that adjusts the gain and integral of proportional-integral controllers while under closed loop control. The laboratory results demonstrate how PRAC tunes a static pressure control loop with aggressive and sluggish initial conditions. Field test results are presented for a static pressure control loop, supply air temperature control with a heating coil, supply air temperature control with dampers, and supply air temperature control with a cooling coil.