The Loop Equation Design Method has been proposed for sizing ventilation airflow components of natural and hybrid ventilation systems. While the loop design method has been demonstrated on a limited basis, the method has been automated in order to better evaluate its reliability under a more controlled, i.e., less error-prone, environment. This paper describes a computer program that implements the Loop Equation Design Method of sizing the openings of naturally ventilated buildings.

Air infiltration through revolving doors may have significant impact on the heating load of commercial and institutional spaces, and may create discomfort to people. This paper modifies a 40-year old model by Schutrum et al. (1961), composed of two components:
(1) estimation of air exchange between one segment of the revolving door and the indoor/outdoor,
(2) estimation of net air infiltration rate.

Convective air circulation occurring through wall layers is frequently observed in building envelopes. Significant thermal coupling can take place between the incoming cold/warm air and the wall structure, thereby modifying the thermal performances of the envelope. This paper presents an unsteady threedimensional numerical heat and air transfer model, which was developed to

The hygrothermal behavior of a building component exposed to weather is an important aspect of the overall performance of a building. Today the hygric transport phenomena through a building envelope are well understood and a realistic assessment of all relevant effects can be carried out by one of the numerous models and computer programs, that have been developed in different countries over the last years. The calculation of the hygrothermal performance of a part of the envelope is state-of-the-art, but until now, the total behaviour of the actual whole building is not accounted for.

Air supply diffusers used in air-conditioning systems can be classified as ceiling diffusers, sidewall diffusers, floor diffusers, jet nozzles, and low velocity displacement diffusers. Fixed or adjustable slats are usually used to control airflow directions.

With the advancement of technology, and with the widespread availability of simulation tools, we are forced to consider which simulation tool would be appropriate for a particular problem. The seemingly trivial decision is in reality not very easy to make. And this leads to the practice of using the most sophisticated tool available for every problem. The levels of resolution and complexity are directly related to the accuracy of the simulation and to the total cost of the simulation process. A simple tool may be cheaper, but there is a high risk of inaccuracy.

The Norwegian Building Research Institute (NBI) has completed a study of the performance of balanced residential ventilation systems with heat recovery (HRVs) in Norway. The study involved both a national questionnaire survey and thorough laboratory tests of 10 HRVs on the market. The overall conclusion is that balanced ventilation with heat recovery provides very good air quality, and has a payback time of 4~6 years for the most profitable systems despite Norways cheap hydropower (0.09 /kWh in 2002).

This paper will address the shortcomings of typical heat balance-based HVAC design and analysis software when applied to thermal displacement ventilation (TDV) system design. The performance characteristics of thermal displacement systems that lead to inaccurate calculations from heat balancebased programs are discussed. Finally, the paper presents an approach for estimating the performance of TDV systems using existing heat-based calculation tools that responds to most of the significant differences between overhead mixing systems and thermal displacement systems.

During the last 20 years, the humidity sensitive ventilation system evolved to products increasingly simplified thus standardised. At Aereco, there were 5 generations of extract units, each modification of product was due to a change in the acceptation criteria. In many countries, systems with variable airflows are accepted and recognised ; regulations moved. In other countries, the orthodoxy of the constant airflow of an air change per hour remains in force for simplifying reasons or by ignorance of the real interest.

This paper presents the development of a simulation tool based on the Matlab computational environment for building temperature performance analysis with automatic control. The simulation tool contains mathematical models for buildings, HVAC (Heating, Ventilation and Air Conditioning) systems, sensors, weather data and control algorithms. The building mathematical model is described in terms of statespace variables, with a lumped approach for the room air governing equations energy and mass balances. In this context, the simulation tool structure and components are explained.