NatVent™ is a seven nation pan-European project which aims to reduce primary energy consumption (and consequently C02 emissions) in buildings by providing solutions to barriers which prevent the uptake of natural ventilation and low-energy cooling in countries with moderate and cold climates. It also aims to encourage and accelerate the use of natural ventilation and 'smart' controls as the main design option in new-designs and major refurbishments of office-type buildings.
A buoyancy-capture principle is firstly revisited as the most important fluid dynamics mechanism in kitchen range hoods. A recent new derivation of the capture efficiency of a kitchen range hood, which eliminates the inconsistencies and inadequacies of existing derivations, shows that the capture efficiency equals the ratio of capture flow rate to total plume flow rate in a confined space. The result is applied here, together with the buoyancy-capture principle, to derive a simple formula for determining capture efficiency.
Currently one of the most rapidly growing areas receiving attention is energy efficiency in buildings. In this context naturally ventilated buildings are an inevitable design solution. This paper reports preliminary observations of a project aimed at investigating pollution levels within these type of buildings. Due to the difficulty of predicting and controlling the amount of suspended particles entering naturally ventilated buildings an understanding of the type of pollutants, their size and their composition is necessary.
This paper describes the results of a computational fluid dynamics study to assess the air freshness and percentage of dissatisfied people due to air quality in a partitioned office with different supply air diffusers. The numerical model involves the finite-volume approach of solving governing equations for mass and momentum, assuming that the buoyancy effects are negligibly small in comparison to the inertial effects. The k-s two-equation model of turbulence is used to predict the turbulence transport of flow properties.
Fungal spore content in dust accumulated in air ducts was investigated in 24 mechanically ventilated single-family houses of which 15 had also a central air heating system. Dust was collected from the ducts simultaneously with cleaning of the ventilation systems. Besides spore concentrations and flora of culturable fungi, total fungal spore concentrations were determined in dust samples by the aqueous two phase technique and spore counting with epifluorescence microscopy.
With environmental issues (such as high energy costs for air-conditioning and related C02 emissions and global warming) in mind, designers are increasingly considering natural ventilation as the primary design option. Naturally ventilated office buildings can typically consume less than half the delivered energy consumed in air-conditioned buildings representing cost-effective energy savings of the order of 20-30%.
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