Eco friendly Passive House at Oranmore Co. Galway
Planning permission had already been granted when we were contracted to build this passive house in Oranmore, Co. Galway. This fact made the build particularly challenging. Once you have permission, there’s not much you can do about orientation or glazing, and getting both of these right are very important in passive building. The client’s plans hadn’t ignored the sun however, and with the front just twenty degrees off full south, he had secured permission for a large glazed section on this elevation.
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Insulated Foundation ready |
Alu clad Passiv Haus |
Passive house certified |
The house itself could hardly look less passive. It’s a traditional design, and a traditional build in one way at least; the client was anxious to go with blocks as opposed to timber frame, so we went with a single course, then wrapped this with an external insulation.
A high density insulated foundation system was used to ensure as little heat loss as possible through the foundation, and we also used low carbon concrete. The client was also keen on having a concrete first floor so we had to design the foundation with sufficient density to take that additional weight.
Because our planning permission didn’t have quite as much southern glazing as we’d like, it was important to get the window absolutely right. We choose a Passivhaus certified window from Optiwin. It’s triple glazed, has insulated frames and an aluclad exterior finish. The window frames are made from spruce and they look really well with a painted cream interior.
The roof is a standard cut, onsite roof with cellulose insulation pumped into the attic space.
Our air-tightness result was 0.5 air changes per hour (ACH), which meets the Passivhaus standard with a little to spare, and testifies to the high quality of workmanship that went into the house.
Mechanical heat recovery ventilation (MHRV) is used in all our houses for maximum comfort and to minimize heat loss through ventilation. We design these systems ourselves before a block is laid; when planned correctly, you won’t see any ducts as you walk through the building. Again, when you get the design right, these systems give you a very high level of efficiency and a very low payback period. MHRV is effectively the lungs of your passive house. It’s central to maintaining both clean air and a comfortable, even temperature.
The client chose a condensing oil boiler with an underfloor heating downstairs and in wet areas upstairs.
During last year’s cold snap, ice actually formed on the outside of the building – that’s how little heat escaped, while the client says that he only needed to turn on the heat for twenty minutes every two days.
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Ice/frost formed on the |
cold bridge free or |
10mm of frost, this is proof of how little heat loss there is on these walls |
The key thing about all of these houses is that the floor temperature never falls below nineteen degrees as long as the house is occupied. You’ll only see the temperature drop if the house is empty for a long stretch.
‘It’s a lovely house to live in.’ Says the client. ‘No big fluctuations in temperature, really comfortable. Passive House builders were great to work with, their staff treated everything like it was their own. I couldn’t recommend them more highly.’
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| Front south east view | Full south |
