Windows are where we often look to improve the energy performance in old homes. But don't rip out those old sashes yet. A field study in Vermont suggests that "remove and replace" is not necessarily the way to go when it comes to old windows.
This paper presents an investigation into natural ventilation in the field of computational fluid dynamics using in particular rather rough mesh cells. The CFD results were then compared to the wind tunnel results obtained by Gouin at the Centre Scientifique et Technique du Batiment ( CSI'B) in Nantes. The role of eaves, and that of window configuration on windward and leeward sides of buildings was also investigated to search for a better interior airflow.
The energy statistics of OECD Countries shows that between 30-50% of primary energy is consumed in non-industrial buildings (i.e. in dwellings, offices, hospitals, schools etc.) Of this, as much as 50% is dissipated from the building in the departing air stream. As buildings become more thermally efficient, the proportion of energy loss (either heating or cooling losses) associated with ventilation and air infiltration is expected to become the dominant thermal loss mechanism. Additional losses may be associated with the energy needed to operate mechanical ventilation systems.
The authors' previous analysis of dynamic insulation is extended to include the inner and outer air film resistances with the objective of modelling the variation in surface temperature with air flow. The boundary condition that comes closest to predicting the variation of the surface temperature with air flow is one which assumes that the conduction heat flux at the wall surface, rather than the net heat flux, is equal to the flux incident on the wall from global environmental temperature, T.;.
This paper is concerned with the numerical modelling and investigation of the performance of air curtains employed to reduce air flow and heat transfer across open doors and between conditioned and unconditioned spaces. It has been found that the model based on a commercial Computational Fluid Dynamics software package can successfully predict the critical velocities and efficiencies of air curtains and the influence of external parameters such as wind speed.
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