upgrade instead relying on instantaneous heating. Rather than use packaged consumer units, bespoke systems were made on site, including plate heat exchangers for hot water and motorised valves for space heating. The plant room is external to Block 2, and relies on Logstor preinsulated pipework to reduce heat loss before entering the building. A combined heat and power system was considered but rejected due to the lack of communal space around the block. Despite the problems with the flats, such as single-glazed windows and a total absence of insulation, residents were nervous at the prospect of change. “The residents were unsure of the work; they were worried about having to move out, but they’re all happy now,” Clifford says. The 12 unoccupied bedsits on the ground floor are now six occupied one-bed apartments, with their internal layout reversed, thus providing a south facing elevation in living areas in order to enhance solar gain. There are a further six one-bed apartments upstairs. Scale was also an issue with the job, but not an entirely negative one: “Quite often the reforms we’ve done before would have been done in [small] lots, broken into packages, whereas with this we were able to it as a [single] job with one contractor,” Clifford says. Kevin Enright, quantity surveyor at main contractor K&J Townmore Construction, downplays the difference between this job and any other, at least from the contractor’s point of view: there was a job to be done; and it was done. “It was much the same, straight-up,” he says. “The spec was sent out and we had to work with that spec.” The question of scale, however, did come into play: “It would be, at that level, a new thing for us. We’d have done elements such as mechanical and electrical and so on, but there was never a whole approach before and airtightness was one of the bigger tasks done. It was a high detail job.” “I have no reservations [about working to the low energy specification]. I won’t say it was an easy job, but it was doable to the specifications laid out,” he says. ““The central thing was the
external envelope.” The addition of external insulation was one of the main changes—after all, this was a housing block with no insulation whatsoever before. A Parex Lanko system comprising 100mm expanded polystyrene with a mineral render finish was applied externally, while the cavity walls were pumped with polystyrene bead, a combination which brings the walls into the realm of passive house specs, with a U-value of 0.17. Meanwhile, 300mm of mineral wool was installed in the attics, bringing the U-value down to 0.18. Double-glazed alu-wood composite windows and doors with an overall U-value of 1.4 replaced the previous aluminium single glazing throughout the block. To prevent cold bridging, the windows were bracketed out from the blockwork, to form a continuous thermal layer with the external insulation. The second phase of the project — retrofit of the main block at Rochestown House to the Enerphit standard — is expected to be completed by early 2016.
SELECTED PROJECT DETAILS Client: Dún Laoghaire-Rathdown County Council Architect: Dún Laoghaire-Rathdown County Council Architects’ Department Main contractor: K&J Townmore Construction M&E engineering: Ramsay Cox & Associates Mechanical contractor: Grade Mechanical External insulation contactor: SF Plastering Airtightness testing: Stroma Technology Building energy rating: IHER Energy Services Windows & doors: Aluwood Ventilation: Aereco External insulation system: Tradecraft Building Products Ltd Airtightness products: Ecological Building Systems Condensing boilers: Worcester Bosch
Want to know more? The digital version of this magazine includes access to exclusive galleries of architectural drawings. The digital magazine is available to subscribers on www.passive.ie
PROJECT OVERVIEW: Building type: 503 sq m two-storey sheltered housing scheme, originally 18 units (6 one-bed and 12 bedsits), post refurbishment 12 one-bed apartments Location: Sallynoggin, Co Dublin Completion date: December 2013 Budget: €761,000 BER Before: Five units across both blocks 1 & 2 tested prior to retrofit. Four of these rated G and one rated F. After: BERs ranging from B2 (120 kWh/m2/yr) to C1 (171 kWh/m2/yr) Airtightness (at 50 Pascals) After: three of twelve units were tested after retrofit, achieving results of 2.74, 2.86 & 2.92 m3/hr/m2 Walls Before: concrete block walls with empty 100mm cavity. U-value: 1.0 W/m2K After: Parex Lanko external insulation system to existing walls, comprising 100mm platinum EPS insulation and mineral render finish externally, along with 100mm blown bead insulation into existing cavity. U-value: 0.17 Roof Before: sloped with mineral wool insulation: Roof slates to sloped areas externally. 150mm mineral wool insulation on the flat between roof joists and a combination of suspended ceiling tiles or plasterboard ceiling internally. U-value: 0.33 After: with added mineral wool insulation: Roof slates to sloped areas, 300mm mineral wool insulation on the flat between roof joists, and a combination of suspended ceiling tiles or plasterboard ceiling internally. U-value: 0.18 Windows & doors Before: single-glazed, aluminium New double-glazed windows: Viking alu-clad timber windows and doors. Overall U-value: 1.4 Heating system Before: oil district heating for the full block, each apt with its own hot water cylinder. After: Gas district heating fed by 89.7% efficient Worcester Bosch condensing gas boiler, instantaneous (plate heat exchanger to the units), no hot water storage. Ventilation Before: no ventilation system. Reliant on infiltration, chimney and opening of windows for air changes / holes in walls. After: Aereco demand-controlled ventilation to each unit. Humidity sensitive wall-vents to prevent heat loss associated with over-ventilation.
(below and p75) before and after photos highlight the transformation of the social housing block. As there was no insulation at all before, one of the main changes was the addition of Parex Lanko EPS external insulation with mineral render finish. New double-glazed timber windows and doors also replaced the existing single-glazed units
ph+ 77