Altherm ICF helps housing development achieve NZEB

THE CLIENT Capcon Building

Cluain Dara Estate is a low-density residential development of 106 houses, located in Derrinturn, County Kildare. Twenty-four homes in Phase One were completed in 2006; however, following the economic downturn of that period, the subsequent phases were put on hold. In 2018 Capcon Building were engaged to complete Phases 2 and 3 – but they faced a challenge.

THE CHALLENGE Improving BER C to A2

Although it would have been possible to “get away with” delivering C-rated homes, the developer Alder Homes (formerly Landport) recognised that home-buyers were demanding better energy efficiencies. They tasked Capcon Building with improving the BER rating from High C to A-rated, within the constraints of the existing planning



We talked with Robert Finn, Construction Director of Capcon Building about the difficulties his team faced in working with planning that dated back to 2006.

We were constrained within the existing planning but challenged to produce best in class, A-rated homes. To complicate matters, some units were partially complete but still needed to achieve A-ratings. We changed the existing build methodology to convert the units from the outdated building regulations to the new standard of BCAR.

THE WORK Using ICF to Achieve NZEB

The team at Capcon Building deployed further innovations in the third phase to obtain full NZEB compliance for the next phase of 22 houses. These innovations included employing the Altherm ICF build process alongside air-to-water heat pumps and heat recovery systems which brought them well within the threshold for achieving NZEB and BER rating of A2.

We asked Robert why he decided on the Altherm ICF system for the building project. Robert said:

We had been looking at modern methods of construction; ways to make the site work more efficiently, and cleaner. Obviously, we also needed to make sure that we complied with current and future building regs. In the end though the biggest factor was speed of build. The mindset change of bringing a house from greenfield to sealed envelope within 2 weeks really made up our mind on the product.

Robert was enthusiastic about how the utilisation of ICF improved programme time.

Without a shadow of a doubt, it improved our programme time. We were a lot quicker into first fix - carpentry, mechanical and electrical, which takes the weather out of the equation more quickly. Once we're indoors, it helps us speed up the finishing process of each unit. The airtightness of the ICF means it cuts down on the airtightness finishes internally - like your battoning out of walls, sand and cement finish on external walls and filling around opes (openings).

CAVITY CLOSERS

Robert was also very impressed with the proprietary Altherm cavity closers that are used in conjunction with the ICF blocks minimise thermal bridging. Using cavity closers around the window and door openings ensures that heat loss is minimal and typically a very low thermal bridging factor of 0.04 is delivered. It’s a vital step in achieving an overall u-value of below <0.18.


COMPARISON WITH OTHER CONSTRUCTION METHODS

In previous builds, Capcon Building used a twin-wall blockwork construction method. Shifting to ICF has several advantages, according to Robert:

You end up with a masonry built home, far more quickly and far tidier as well. Safety on site has improved greatly. As the blocks are much lighter, there are less onerous works on the labour force. We don't need mixers, sand, cement, bags of cement, water supply etc. so the site is much cleaner. Also, the resulting dimensions of the building are much more accurate - much closer to the Revit modelling we are now using. It means we can bulk order doors, windows and external plastering materials. It allows us to plan ahead, with budgeting and buying power with our supply chain.

RESULTS Recognised for Excellence

The industry has recognised Capcon Building’s achievement with Cluain Dara Estate as an example of construction excellence, with particular reference to achieving an A2 rating within the existing 2006 planning. Capcon Building and the Cluan Dara development have been nominated for both an Irish Building and Design award in late 2019 and an ICE Award in 2020.



Capcon Building is currently well underway with construction of 22 more properties in Ballintine Park in Allen, County Kildare. It’s their second development using Altherm ICF and the team are again seeing the benefits of the construction method.

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