Viewed from the outside, Tralee Town Council’s new housing development in Rath Oraigh looks pretty much like any other. You have sixty-four housing units, plus a Crèche, together with on-street parking and two open green-spaces. The difference is on the inside however. This development stands apart from any other the local authority has built because of the range of energy saving initiatives used in its construction.
Besides a beefed-up insulation spec, Rath Oraigh incorporates ground-source heat pump for space heating, solar panels for hot-water, condensing boilers burning LPG, and a heat recovery ventilation system together with a state-of-the-art district gas distribution system. All told, these initiatives should yield energy savings of between 40% and 55% relative to current building regulations. “This was all new to us,” says John Casey, Clerk of Works with the Town Council. “We have never used them before. The entire project, everything that went into it; the gas, the geothermal, the solar panels, everything was new. In the past, we had always used traditional stoves, solid fuel and back boiler.” Fully occupied since January, project co-ordinator Willie Moynihan of Kerry County Council, working under the auspices of the Kerry Energy Agency, has been monitoring the energy aspects of the development closely over the past six months. So far, he says, things are going well. “It’s been a good education for us, but we’re delighted with the outcome. The scheme consists of one to five bedroom dwellings together with the crèche and three special needs bungalows.
While sizes may vary, the insulation was standard throughout. Kingspan high-density foilback: 50mm underfloor, 25mm around the edges, 60mm in the cavity, together with 270mm of German Knauff insulation between the joists. “The ordinary rollout insulation would have been 250mm,” says John Casey, “but the Knauff needed 270mm to reach the U value…Where the joists go into the blocks, we pointed up around those and siliconed around them then. Years ago they used to leave them open and this was a source of air leakage, now we ensure that they’re sealed.” The windows – Nordic pine from Munster Joinery – feature argon gas filled double glazing with Pilkington K low-E glass.
The council decided to use a single ground source heat pump for space heating in the seven bungalows and creche via a district hear system
When it came to heat sources, geothermal was one of the first options Willie Moynihan checked out. “We were familiar with the heat-pump in a commercial setting. We have one in the Motor Tax Building in Kerry County Council which is working very satisfactorily. This is a 1,200 square metre building which opened in 1999. We were anxious to find out how the heat pump would operate in a domestic building.” The Council decided to use a single ground-source heat-pump for space heating in the seven bungalows and crèche via a district heat system. Heat pumps operate most favourable with under floor heating due to its low temperature requirement. But it’s relatively expensive to install, particularly on first floors, hence the decision to restrict its use to the single-storey buildings. Moreover, Moynihan was anxious not to put all the council’s eggs in one basket.
“It was a major step into the unknown for us,” he says, “but we’re delighted with the outcome…In the Motor Tax Building the heat-pump is timed to operate for three or four hours early in the morning and this provides sufficient heat store in the floor slabs for the remainder of the day. We weren’t sure how that would work in a domestic situation where the heat demands are higher.…At the moment we operate the heat pump for about five hours in the morning, plus a two hour boost in the evening. We’ve installed temporary monitors to look at temperature trends in the houses during the day…So far, so good.”
“We ensured the plumber installed the pipe work (on the underfloor heating) at spacings suitable for flow temperatures of 30-35 degrees. This allows the heat pump to operate at its maximum coefficients of performance (COP).
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