In buildings, favorable growing conditions for mold fungi can occur and cause fungusinfestation. The danger for the occupants of dwellings lies in the spreading of pathogensthrough microorganisms. Mold fungi can occur not only on the surface of external walls, butalso inside construction parts. A prerequisite for preventing mold fungus is the knowledge ofthe transient building physical boundary conditions under which fungus growth takes place.The decisive parameters of influence like temperature, humidity and substrate have to beavailable over a certain period of time simultaneously.
The energy consumption of a building is evaluated by neglecting the heat loss which can occur when the air passes through the envelope. However, recent studies showed that air leakage plays asignificant role by affecting the thermal performances of walls and the energy consumption. Moststudies have focused on the quantification of air leakage flows through the building shell, withoutaddressing the problem of the heat exchange between this airflow and the construction materials asthe air passes through the envelope.
This paper presents the results of a field study conducted on 8 houses (out of a set of 31) owned and managed by a French social housing public leasing company. The central objective of our investigation was to evaluate and characterize the envelope leakage of these houses in order to propose and prioritize rehabilitation scenarios. For this, envelope leakage measurements were performed together with infrared thermography measurements.
In moderate climates, adventitious ventilation helps in keeping the water vapor balance in a building under control. This does not hold in hot and humid climates, where the outside air is a moisture source. Adventitious ventilation should be avoided in such climates and intended ventilation flows must be dried before entering the space. Anyhow, could adventitious ventilation also generate moisture problems in moderate climates? To get an answer, a reference case was analyzed with the air leakage distributed over facades and roof.
Buildings leak water and air : it is normal and impossible to avoid. So the architect and HVAC engineer's goal should be to recognize the concept of building air leakage and account for it in :- quantifying leakage- reducing it if excessive- controlling leakage by managing air pressures with the HVAC system.The aim of this article is to discuss the methods for measuring and expressing leakage and to report the results of a cas study, San Carlos Park elementary school in Fort Myers, Florida.
Effective weather resistive barriers (WRB) perform important functions in retarding waterentry into walls and in controlling water vapor movement as well as the amount of energyattributed to air leakage (Burnett, 2000; Weston et al 2001). Recognizing this, a public andprivate sector research consortium was established to develop reliable and precise methodsfor evaluating their performance.This paper, third in a series, provides an overview of the most significant results obtainedduring the consortium work.
Many energy codes require that ductwork installed outside of the conditioned space be sealed. Prescriptive codes have no performance standard for what constitutes an acceptable level of duct sealing. Testing and anecdotal evidence indicate that many new homes have extensive leaks on both the supply and return sides of the heating system. A field study of 29 recently built homes was conducted in the Spokane, Washington, area. Systems were visually inspected; all defects were
Leakage data for ducted air terminal connections are reported. The leakage flow rate generally varied from 1% to 8% of the total approach flow rate. Leakage was found to increase with the increase in the static pressure adjacent to the terminal for the unsealed condition. With marginal sealing of rigid ducts, leakage was found to be less than half that of the unsealed connection. The use of drawbands to mount air terminals to flexible ducts can reduce leakage at the collar to virtually
An experimental study was conducted to estimate the leakage through air terminal connections to rigid duct and flexible duct. Air terminals from three different manufacturers were tested under different sealing conditions, namely, unsealed, marginally sealed, and fully sealed. Diffusers and supply grilles were tested in a blow-through test setup, whereas return grilles were tested in a draw-through test setup. The experimental procedure and data reduction are described.
A model for air flow inside ducts with leakages has been established from the equations governing the variation of total pressure and velocity along the duct. It was found that duct performance could be expressed as a function of two dimensionless constants, allowing the calculation of the required total pressure and velocity in the duct.
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