This new home built in West Cork, built for Breda Cooney and Pierre Rousoux, achieves an impressive standard for ecological building. The house is A-rated, airtight and very energy efficient. In addition it is built with ecological materials that are made in Ireland. To achieve such remarkable results they employed Tim O’Donovan of Sustainable Building Services as their main contractor. Once they had made the decision to build, Breda and Pierre started to learn all they could about U-values, BERs and the language of green building. They considered a number of different building methods including concrete and poroton blocks, before deciding to use timber frame. The plan was to have the most energy efficient home possible but also for it to feel as natural as possible. Breda decided “I like the whole feel and vibe of wood.”
The timber used in the building was Irish timber supplied by the Murray Timber Group, a member of the Forestry Stewardship Council (FSC), which certifies forests that are sustainably managed. O’Donovan also specified OSB board from Smartply for the construction. As Smartply is a division of Coilte, all its timber is sourced from Irish forests, and the company has full FSC chain of custody certification. Clonoe Timber was the supplier for the open-web floor truss system that was used for the building’s first floor. It is designed to span wide areas and reduce the need for load bearing walls. Manufacturer ITW Alpine says their truss system abolishes joist shrinkage and twisting, which can cause cracked ceilings and squeaky floors.
O’Donovan used Siga wind-tightness membranes on the outside of the timber frame system, with the Siga airtightness system on the inside. The wind-tight system stops the wind from penetrating from the outside, while the airtight system seals the inside of the building. O’Donovan achieved a very impressive result of 0.26 air changes per hour. Most of the remaining leakage was through the sliding doors. Mark Shirley of 2eva.ie, who carried out the airtightness test pointed out: “in my experience sliding doors and sash windows just never seal, they’re just not airtight.”
With this high level of airtightness, it was very important for the building to have a suitable ventilation system. The couple opted for a heat recovery ventilation unit. The system has a constant airflow, which is set via the controller. ‘Wet’ rooms such as bathrooms and kitchens have humidity-controlled extract grilles that automatically remove more air as humidity increases, enabling a location-specific rise in the rate of ventilation. O’Donovan also installed six square metres of Gasokol TopSol solar panels, supplied by Universal Solar.
The project required that O’Donovan demolish the existing structure on the site before building the new one. All concrete from the building was thrown into a mobile crusher, which produced concrete chips for use as surfaces around the house. “We had perfectly good recycled concrete that we could use, so why not use it?” he says. He installed Ecostar slates for the roof which are produced from post-industrial recycled rubber and plastic.
Breda says she hired O’Donovan because he was offering to do the entire project, everything from the foundations through to fitting the kitchens. She was very pleased with how he managed the project and praised his attention to detail: “The eye for detail that he has is really good, and he really understood what we were trying to achieve,” she says. “The number of people that came to me and said I can’t believe your site, it is so clean, it is unbelievable. And that is Tim, meticulous to the last detail.”
O’Donovan originally received his training in airtightness and low energy building from SIGA in Switzerland. He then trained his construction workers and sub-contractors in the principles of low energy quality building. Since then his company Sustainable Building Services have worked on a number of low energy projects. When asked the secret of his success O’Donovan replied: “The advice I would give to anyone trying to achieve airtightness on site is attention to detail”.