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Wednesday, 01 February 2012 |
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Page 6 of 10
OLS architects in Co Wexford are overseeing an EnerPHit refurbishment of
a two-storey house located in a built up area in Castlebridge, Co
Wexford. The usual challenges are in evidence here; poor orientation,
window distribution and overshading are all issues, mitigated somewhat
by the house’s relatively modest size. While the client wants the refurb
to deliver a comfortable home that’s cheap to heat, he also needs to
address very serious damp issues. Cathal O’Leary of OLS says that the
house is full of mould. “There’s mould all around the perimeter of every
window. Upstairs, there’s mould where the first floor walls meet the
ceilings. The whole place is terrible really. You pull back a chair and
there’s mould growth in the corner.”
OLS’s sub-floor level external insulation is designed to solve the mould problem
The Passive House Institute’s EnerPHit criteria for refurbished
buildings deals specifically with this issue: “Without exception, all
standard sections and connection details must be planned and implemented
so that there is no excessive moisture accumulation on the interior
surfaces or in the building component structure.”
Cathal O’Leary says that the initial thermal bridge and condensation
risk analysis calculations for the house showed that the internal
surface temperature in the mould affected areas was around 10 or 11C.
“The rule of thumb is if the internal temperature drops below 12C, you
have a condensation or dew point, which leads to moisture and mould
growth.” Proposed thermal bridge details will bring those temperatures
up to around 17/18C. This, together with better ventilation and
insulation will combine to provide the right conditions to remove
interstitial and surface condensation that’s causing the problem. “This
house was built in 2002,” says O’Leary. “It’s a shocking indictment of
the housing boom and the supposed good times.”
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