The natural light-flooded kitchen area, complete with bamboo worktops and salvaged timber flooring

Secondly, further insulation was specified that was compatible with the existing structure, notably, 70 millimetres of external insulation from Kingspan added to the front of the dwelling.

Daly explained that this was in part a spatial issue as the alternative, dry lining, would have reduced the useable floorspace, but also that external insulation is better at reducing thermal bridging: “You’re going above the [upper] floors and down into the ground, so there are no gaps in the insulation,” he said.

Building work, handled by McGlynn Construction, started in October 2007 and was complete by April 2008.

“It was a sizeable enough job,” said Denis McGlynn, “a medium-to-big renovation in relation to Dublin.

“Aside from the two storey extension to the side, we removed the back wall and created an open plan space downstairs. We’re very happy with how it worked out. The timber construction of the walls was new to us – most timber-frame houses still have a block-work leaf.

“The main emphasis was very much on insulation. After that the building was sealed with a Pro Clima membrane and tape on the inside. It was then battened on the inside – the services run through that cavity, which was filled with 60 millimetres of rock wool,” said McGlynn.

Fireplaces were also sealed in order to prevent heat loss.

Triple glazed N-Tech windows from NorDan, supplied by the Dublin Door Store, replaced the existing double glazed units to the front. High performance double glazed units were used to the rear on the ground floor where the entire wall is glazed.

Nordan’s John McMenamy told Construct Ireland: “N-Tech is a range of windows. There are two types, low-energy and passive standard. This house used the passive standard windows.”

N-Tech passive standard windows have a u-value of 0.7 W/m2 K for the entire unit and are triple glazed and argon-filled. Nordan tend not to use Krypton because although it achieves a lower u-value, it is high in embodied energy.

The triple glazing is a major factor in lowering the u-value: “1.6 would be a good u-value on a typical Irish window,” said McMenamy. “The lowest we can go with double glazing is 1.2. We do that with a thermal break in the frame.”

The windows in Catherine Cleary’s house are made from PEFC-certified Nordic pine: “We have a full chain of custody,” said McMenamy. They achieve an A-rating from the British Fenestration Rating Council.

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The house’s primary space heating system is a condensing gas boiler. Cleary considered other options such as a ground-source heat pump and biomass but found the capital costs of the former too high and access a problem for the latter, so she made the decision to put the money into lowering the heating demand by increasing insulation.

Nevertheless, Patrick Daly points out that the gas system achieves 92 per cent efficiency, adding, “the insulation standards should mean the boiler is being called on very little.”

Daly’s assertion is backed-up by Cleary’s experiences so far: “We could have put in the Rolls Royce of heating systems but if the house wasn’t insulated properly it wouldn’t make sense. We’ve [only] used about six hours of heat since we moved in,” she said.

The gas boiler is joined by solar water heating in the form of 40 vacuum tubes, with an expected output of 1,600 kilowatt hours per annum.