Infiltration eats in to your earnings!
Infiltration (commonly called leakage) eats away your earnings and a big chunk at that. Studies show the cost of your home infiltration component may be up to 30% of the total energy bill. What can be done to minimize this?
Where does infiltration occur?
Infiltration can take place through any weakness in the building envelope. In other words it is the air tightness of a building. Infiltration is not intentional and the quantity and the quality of air leaking in or out of your home cannot be controlled.
Contrary to the popular belief the worst culprits are the floors, walls and ceilings. Of course windows, doors, gaps around vents, air ducts, chimney flashings, recessed lighting fixtures, pipes and plumbing etc. too contribute their mite. Though technically not classified under infiltration the moisture ingress to the building due to the high moisture permeability of the building fabric (through microscopic pores, cracks and gaps) ,wind velocity out side, temperature and vapor pressure difference between indoors and outdoors offer energy wastage similar as in air leakage.
Infiltration, exfiltration and Human comfort
The infiltration and the opposite exfiltration not only add to the intentional air intake of a house but also distort the air flow patterns and uniform distribution. Furthermore it brings in pollutants which are designed to be minimized in a building ventilation system. The infiltration air being uncontrollable the heating or cooling too follow suite. The indoor air quality, a hot health topic nowadays, is lowered along with the occupant comfort. Heat recovery device performance too is impaired. The condensation of moisture on the interior walls, furniture and curtaining etc are a nuisance and a burden on your purse.
Notably in the past the issue of infiltration has not been given due consideration in human dwellings though the quantities and thus the adverse effects on older dwellings are considerable.
Can infiltration and exfiltration be eliminated?
The phenomenon takes place through ill fitting floors, ceilings separating heated and unheated spaces, window and door glass panes, sashes and frames. Also poor workmanship in fixing of widow and door frames to walls is another major cause of heat loss. This leads to moisture damages and aggravated situations. Roof and supporting wall air gaps are another place this can occur.
Total elimination is not possible .But minimizing is certainly possible by weather sealing (weather stripping) the flows in building fabric, gaps and cracks. For moisture ingress due to porosity a good vapor barrier must be installed.
Weather Sealing
Use of special rubber beadings for weather-stripping is the most effective. Felt weather stripping is very inefficient in that sense.
Weather sealing of windows and doors can be done from inside or out side of building by using see through PE adhesive tape. It is also effective as a window glass crack temporary sealer.
Butyl and Silicon sealants are widely used now in old or new buildings under construction as these are very effective as sealants while offering flexibility to a lot of variations in temperature and pressure to maintain its integrity. Special tapes are available to seal gaps in flues leaking hot gases.
Moisture barrier
Nowadays most insulation boards and blankets can be obtained with integral vapor barriers. Good wide duct tape (say 65-75mm width) has to be used to close the joints between foil backed insulation. Polymer film vapor barriers too are used for economy but Kraft paper laminate or plain foil vapor barriers offer better performance against vapor permeability. What ever the material used the sealing between each section of moisture barrier section must be made extremely good other wise the whole purpose will be lost.
About the Author:
John Mahoney is a freelance author who writes about various technology realated subjects. For more information about John visit his website www.techstore.ie.
