The most efficient ventilation system would only operate on demand, when ventilation was "needed". Running the ventilation system all the time at a low flow rate, a rate sufficient to match the ASHRAE recommended 0.35 ACH is a crude control approach to an optimum system. Conditions in a house are not constant. On average, a constant flow rate ventilation system will work reasonably well and certainly is simple, but there are more energy efficient approaches, and users tend to shut down systems that run constantly.
A supervisory control scheme for a sensor based demand-controlled ventilation system is described in this paper. The strategy based on neural network models is used to diagnose the measurement faults of outdoor and supply air flow sensors, and makes the fault-tolerant control of outdoor air flow when faults occur. Tests using that dynamic system simulation have been conducted to validate the strategy.
Ventilation airflow rates and internal air distribution were measured in four poultry slaughter plants (250 to 775 workers), equipped with negative pressure ventilation systems (exhaust flow rate from 7.1 to 27.4 m3/s - no air intakes - supply air entering through various openings). Results lead the authors to recommend the installation of diffusers for makeup air supply, changes in the organisation of rooms to avoid contamination of one by the other and regular maintenance and cleaning of ventilation components.
The Ajust'Air concept makes it possible to adjust between the entry loss of fresh air and the extraction of tainted air in the locality following the ventilation requirements marked by the carbon gas parameter.
The ventilation system of a community hospital deteriorated progressively over a period of years until it no longer met regulatory guidelines. The publicly funded military facility hospital asked for funding for repairs but they were not available. The funding request was met when an increase in infections was identified and high-risk operations had to be curtailed. The problems were solved entirely when the new ventilation system was in place.
Many buildings in Austria experience poor indoor climate states and critical states of their construction. Possible causes of the high moisture content of indoor air might be bad ventilation or high moisture content of the buildings because of rising damp or weathering. Retrofitting is needed to increase indoor climate comfort levels. It is essential when designing the retrofitting to understand and predict the influences of different actions on the building's indoor climate and behaviour.
Mould, wet insulation, wet or weakened wood or premature aging of roof coverings often leads to the addition of extra ventilation in attics at time of renovation. The study develops a protocol to determine the effects, surveys several occupied buildings to establish why the ventilation was added, and establishes a base to analyse the effect of the installation.
In large buildings, pollutants may be emitted locally and discontinuously what can result in time dependent heterogeneous pollutant concentration fields. Efficient ventilation solutions should provide the right amount of fresh air at the right place so as to minimise energy cost and discomfort. In this paper, a new ventilation strategy is developed. It is divided in several phases. First, pollution sources are identified with a minimisation technique and then the time dependent pollutant concentration is predicted.
A large part of the housing stock in the Netherlands is ventilated badly. Exhaust systems do not work according to building standards. Bad design, bad maintenance and deterioration give a reduction in exhaust volumes of more than 50 %. Home owners and tenants compensate with extra cross-ventilation, but often the results is poor. The National Union of Tenants and the Research Institute OTB cooperated in the design of a quality assessment tool, to evaluate the provisions for ventilation in housing. The tool is a checklist for the quality of ventilation services in the house.