"External Wall Insulation will help improve the Airtightness of your home "
Roughly speaking airtightness is a measure of “draftiness” or air permeability of a house. So airtightness of a building should be measured by how much air leaks or out in a period of time. As we move towards the PassivHaus standard and even tighter future standards, airtighness will be more and more important.
The formal measure is expressed in terms of air leakage in cubic metes per hour per square metre of the dwelling envelope area when the building is subjected to a differential pressure of 50 Pascals (m3/(h.m2)@50Pa). The dwelling envelope area is defined in this context as the total area of all floors, walls and ceilings bordering the dwelling, including elements adjoining other heated or unheated spaces. See the Department of the Environment’s ACD for Air Filtration for more details
The three major ways to lose heat from a house are conduction, radiation and convection. Conduction and radiation are solved by using external wall insulation, this stops the heat penetrating to the outside layers of the walls and escaping. Convection the third method refers to is the transfer of heat by the actual movement of the warmed matter, in this case air. Uncontrolled air leakage increases the amount of heat loss as warm air is displaced through the envelope by colder air from outside. Air leakage of warm damp air through the building structure can also lead to
- · Surface condensation, damaging decorations and enabling mould growth
- · Deterioration of the building fabric caused by interstitial condensation
-
·
Occupant discomfort caused by draughts and cold rooms
Source Department of Environment
The current Irish Building Regulations (Building Regulations 2008 TGD-L (Dwellings)) indicates that reasonable provision for air tightness is to achieve a pressure test result of no worse than 10m3/(h.m2)@50Pa. This is believed to be moving to 3m3/(h.m2)@50Pa when the regs are updated.
Some research ointo airtighness was done during the AVASH project. AVASH stands for ‘Advanced Ventilation Approaches for Social Housing’. It is a project funded by the EU with partners in the UK, Ireland and Denmark.
Interestingly during the AVASH project houses built during the 1950s has a better air tightness than houses built during the last 10 years. (7.92 as opposed to 10.36 m3/(h.m2)@50Pa). This is probably due to the method of construction, the old houses have solid walls which were wet plastered and the new cavity walls have plaster board fitted. During the air tightness test air could be seen leaking in the new housed from light fittings, electrical sockets etc.
.jpg)
Standard concrete blocks, even 100mm solid blocks, let alone hollow blocks, are not airtight as they are highly porous. During an air tightness test you can actually feel air passing through the middle of a block. Naturally External Insulation will help improve Air Tightness. By adding external insulation slabs over the block work as wells as the various layers of adhesive and render will help reduce the passage of air through the block work.
Other sources of air leaks are openings through the outer face, including ‘hole-in-the-wall’ vents, recessed ESB or gas meter boxes, cable and telephone cables, are all highly likely to introduce external air. Properly applied External Insulation, will close the infiltration routes listed above and prevent air entering into the core of building.
Contact us now to learn how your home can benefit from External Wall Insulation.