This study is an analysis of the advantages of two ventilation systems (exhaust mechanical ventilation, balanced mechanical ventilation with heat recovery) using the Negative Index approach, which is affected by life cycle cost and environmental impact. The balanced system appears to be a better choice (less environmental impact, better indoor air quality) even if its life cycle cost is higher.
The study was to evaluate energy use of ventilation system with supply in corridors and exhaust in wet rooms. The field test protocol was to measure energy use one day with corridor supply ventilation on, one day off, for a range of different outdoor temperatures in winter. When corridor supply is on, the internal pressure changes (although always negative) and infiltrations are modified.
This study is a part of the Finnish contribution to the HYBVENT project (Annex 35 of IEA). Two 'hybrid' ventilation concepts designed for northern climates were evaluated for a 4300 m2 office building in Helsinki : one of them is low pressure mechanical exhaust with CO2-controlled air inlets ; the other uses mechanical air supply through coils and two parallel exhaust circuit with and without fan and heat recovery. They were compared with conventional systems in Finland (mechanical supply and exhaust with constant or variable air volume).
A multizone air flows simulation code (IDA MAE) was used to evaluate a hybrid ventilation system (passive stack with assisting fans) in a Swedish school (9350 m2 - 20 classrooms), in the framework of the HYBVENT project (Annex 35 of IEA). Simulation was operated with 18 zones. Results show the sensitivity of air flows to changes in wind speed and direction.
The risk of contaminant deposition (10 microns particles) on an operating room surgical site is evaluated for different ventilation systems - conventional, laminar, non-aspirating, displacement -, using airflow modeling and particle tracking methodologies. Results show that laminar flows are the most appropriate to avoid particles deposition.
The market evolution of domestic exhaust air heat pumps since 1979 in Sweden is described. Some information is also given about the German market. Technologies of different exhaust air heat pumps systems are shown and results of several monitoring projects in Sweden are summarized : they show for houses built in the 1980's an electricity consumption of 90 to 130 kWh/m2/year (including domestic hot water and household electricity), depending on the thermal characteristics of the building envelope. The energy savings thanks to the exhaust air heat pump are about 30%.
An examination was conducted of thirty single family homes with either high or low house-dust mite allergen levels in mattress dust, with regard to ventilation, thermal climate, and air quality. High concentrations were associated with the difference in absolute humidity between indoor and outdoor air, also with low air change rates, especially in the bedroom. The research found no correlation between concentrations of TVOC or formaldehyde in bedroom air and HDM allergen concentration.
Describes a cross sectional study carried out on 2678 employees in 41 office buildings in March 1991 aimed at examining the role of sick building syndrome symptoms. Concludes that the risk of the studied symptoms is related to the type of ventilation in the existing office building stock. Suggests that future studies should concentrate on the typical function problems and specific causes connected with the high-risk ventilation systems.
Based on the literature and our long-term investigations on indoor environment, the heat source patterns (distribution, location, size, etc) have a predominant effect on temperature efficiency as well as ventilation effectiveness. Although the heat sources of ventilated rooms are various and complicated in engineering practices, some typical characteristics still exist in common.
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