English

Compact ventilation appliances appeared on the market for solar passive houses. They include a heat pump to transfer heat from ventilation exhaust air to fresh air and/or domestic hot water. This article describes such systems and gives information about a model for simulating the operation and performance of such appliances which was developped to be used in the TRNSYS software environment.

This article compares the requirements for mechanical ventilation systems in the new German regulation on energy savings (EnEV 2002) with those contained in the previous regulation (named WSchV 1995). It also gives information about the way to test and certify mechanical ventilation components according to this new regulation.

Ventilation systems designed for a constant air volume (CAV) provide fresh air in office buildings. It means that very often huge amounts of energy can be wasted on ventilating empty offices. A simple analysis of the profitability of Demand Controlled Ventilation (DCV) has been performed on a reference office building in Norway.

The aim of that study was to develop a fuzzy controller for naturally ventilated buildings. This paper describes the process of designing a supervisory control to provide thermal comfort and adequate air distribution inside a single-sided naturally ventilated test room.

Maintenance of air-conditioning systems is acknowledged as an important means to run HVAC-systems properly. Although several maintenance programs and standards exist, not many systems are maintained in a proper way. Most standards and programs are not concerned with the indoor environment, they are only concerned with repair and failure-response of system components. Just now, some new guidelines come out in Europe, which contains first definition of cleanliness.

Thermal comfort variables were measured in Singapore mechanically ventilated classrooms. In parallel the cccupants filled questionnaires on their perception of the indoor climate. The results showed that ASHRAE Standard 55 was not applicable in free-running buildings in the tropics. The study showed that generally cool thermal sensations were more readily accepted by the classroom occupants than warm thermal sensations.

Variable Air Volume system use VAV boxes that serve open areas for five or more occupants, each zone is controlled with a single space temperature sensor. But VAV zone control strategies remained the same for the last years, so the designers have to consider that system : it provides a high quality environment for occupants, it permits the use of a smaller air-distribution system that is low cost and does not compromise building comfort or operating efficiency.

A contaminated supply air system may have an adverse effect on indoor air quality. The aim of that study was to evaluate the effectiveness of different protective actions in achieving a clean supply air duct system on the one hand and to find out the location in the ductwork where most of the duct is accumulated. Measurements were made and presented in tables.
It appears that dust accumulation can be partly avoided by ducts protection during the whole of the construction transportation and storage phases and that no ducts with residual oil on the inner surface should be used.

In air-based systems, ducts deliver heat and cool air to conditioned spaces. Taking extra time to properly seal ducts during the installation along with repairing and patching leaks in HVAC duct systems will save cooling, heating and fan energy. With aerosol-sealing technology higher performance ducts in new and existing buildings potentially exist.

Air quality in conditioned spaces can be improved even in humid locations, in Florida. A field experiment in a Florida school confirmed that the use of a dual-path air-distribution system with low temperature air can maintain lower and more comfortable humidity levels.
Furthermore, that system coupled with a thermal energy storage (TES) keeps energy use as low as possible, and makes costs savings.