The Story of Ireland’s first “Zero Carbon Emissions Concrete House”
Introduction
In order to show the potential for concrete homes to achieve the highest standards in energy efficiency and indeed, sustainability the Irish Concrete Federation made a commitment to the then Minister for the Environment, Heritage & Local Government, Mr. John Gormley T.D to build a Zero Carbon Emissions concrete house in Ireland. Construction on this ambitious project has now been completed. The house has achieved the double target of zero carbon emissions from ongoing operational use and an A1 Building Energy Rating. This means that there will be a zero carbon footprint from the energy used for space heating, lighting, hot water supply, ventilation and any motive power used to provide same as well as achieving all the other requirements of national building regulations.
As you can see this is a spectacular project located in the heart of Ireland. The house was constructed as the family home of Micheál O’Dowd of O’Dowd Landscaping Ltd in Mount Temple, near Moate in Co Westmeath. The aerial photograph above shows the southern face of the house.
Background
Micheál’s initial intention was to design a 370 square metre, four bedroom house on a six acre site and to achieve passive house standard but that changed at the detailed design stage to the achievement of an A1 Building Energy Rating and Ireland’s first zero carbon emissions concrete home.
“When I met with the Irish Concrete Federation they asked me to think about taking the build to zero carbon level” says Micheál. “I started researching it and realised that it wasn’t going to take that much more to achieve this standard, taking into account the longer term benefits it will have”
Why Concrete?
The Westmeath home is Ireland’s first concrete house built to the exacting zero carbon emissions standard. As concrete construction had already been used for Ireland's first passive house we, at ICF, were determined to achieve the even more exacting standards of Zero Carbon Emissions and A1 Building Energy Rating.
“I wanted to be ahead of what will be required under future Building Regulations and I feel that the approach that I’m taking with this house will yield significant cost savings in the long term with no heating and little or no electricity bills” says Micheál. “I put a lot of time and energy into researching the various different building options that were available and concrete block construction came out on top for me for a number of reasons. It is a durable, speedy and cost effective way to build"
Air-tightness, high thermal mass and good insulation are three of the main characteristics of the house. "The concrete block walls are my radiators" says Micheal. "I decided on using concrete blocks long before I met with the Irish Concrete Federation because blocks have thermal mass and regulate temperature within the house – they store heat during the day and release it at night. Additionally, the concrete first floor stops noise travelling throughout the house. Concrete blocks also gave me more flexibility in constructing the house”.
The house has been constructed using a solid single leaf 215mm masonry wall - essentially a “concrete block on the flat” with external Aerobord Platinum insulation and solid internal walls on both levels. There is a concrete intermediate floor - in this case a 100mm wide slab with a 125mm structural screed. The entire structure sits on a raft foundation, itself underlain by insulation, which acted as the formwork for pouring of the raft.
Passive Solar Gain
Micheál decided to locate the house using freedom of orientation to achieve maximum solar gain. “The south face of the house with increased glazed areas makes best use of light as all habitable rooms substantially face in that direction”. Halls and washrooms are located on the north side where reduced glazing levels minimise the potential for heat loss. With the house designed to have maximum hours of light in all living areas, the risk of overheating has been anticipated and reduced by the use of overhangs which limits the impact of peak sun periods.
Heat recovery ventilation units and the effective use of renewable energy technologies such as solar water panels and wind power are key components of the house, along with other environmental features such as rainwater harvesting. The house has a sealed log burning unit which distributes hot air around the house in winter in conjunction with the heat recovery unit.
Energy Performance
The house was originally designed to achieve the PHI target of 15 kWh/m2/yr for space heating alone. This is achieved in part by a target U-value of 0.1 W/m2K for walls, floors and roof (the ground floor of the house has, in fact, exceeded that target, posting a U-value of 0.09 W/m2K. There is a target overall U-value of 0.7 W/m2K for external windows and doors, and by minimising thermal bridging heat loss with a y-value <0.04 W/m2K. Indeed, they-value actually achieved is 0.034W/m2K.
For Further Information on the Insulation and U and Y-values please click here
ICF Member Companies Supporting the Build
The Irish Concrete Federation has been providing project management advice to the zero carbon emissions house project and member companies of the ICF have made a significant contribution to the build by supplying ready mixed concrete and concrete blocks (Cemex), concrete lintels (Killeshal Precast), concrete first floor (Flood Flooring), concrete slates (Condron Concrete), external render (CPI), concrete rainwater catchment and foul water treatment systems (Shay Murtagh Precast) and cement for on-site mixing of mortars (Irish Cement).
Visits to the Zero Carbon Emissions House
Since the completion of the Zero Carbon Emissions House, the ICF have held a number of open visits to the house for stakeholder groups, including construction professionals and students. Groups ranging in size from 5 to 30 can be catered for. Please register your interest in participating on one of these visits by clicking here. Please indicate your background or profession when registering and we will revert to you as soon as possible.
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