Delvin is a small town in Co. Westmeath. The house occupies a burgage plot running back from the main street, and the project included a two-storey detached masonry former bank building of c.1800 addressing the street, a detached stone outbuilding at the rear of the plot, and a single storey rear extension with an asbestos tile roof. Performance in a building of this kind is not a single number applied evenly. Each of the three fabrics carries a different limit, and the strategy was to respect and compliment them. The two masonry elements — rubble stone, retained on its existing foundations, underpinned, and chemically dampproofed at 150mm above external ground — were insulated internally to 0.27 W/m²K. The new work placed between them, occupying 120 of the 217m² of the completed dwelling, was built to carry the load

 

the stone could not: a full-fill 150mm insulated cavity wall at 0.17 W/m²K over a ground floor of 150mm poured EPS ballast [BEPS] by Base Therm with 25mm perimeter insulation at 0.16 W/m²K. A 440mm rising wall sits centrally on the foundations, tanked with a bituminous waterproofing barrier over primer, with a thermal block at the perimeter wall. The floor build-up is a radon membrane at minimum 150mm laps over sand blinding on compacted hardcore, a 150mm structural slab, insulation, then screed carrying underfloor heating with oak herringbone glued to it. Where external ground stands higher than the finished floor, an aco drain and a 100mm land drain take the water away before it reaches the wall. Against the retained masonry a breather membrane keeps the junction open to vapour. Assessed under DEAP 4.1.0 as a Major Renovation of an existing dwelling, the completed house achieved an A1 rating [primary energy 0.52 kWh/m²/yr; 2.81 kgCO₂/m²/yr] A total of 22 solar panels with optimiser’s form part of the 9,5KW solar system along with a 10Kw Huawei battery. After powering the Electric Vehicle, the annual running cost of the house is between €200 & €300, with most months being in credit.

 

A large 6000 Litre rainwater harvesting tank is submerged in the rear garden and assists with flushing toilets and irrigating the three quarters of an acre site.

 

Glazing is comprised of triple-glazed aluclad and uPVC units at 0.70–0.79 W/m²K, doors at 0.82–0.84, concentrated to the south-east and south-west across the new elevations. Heating is a single air-towater heat pump serving two zones with weather compensation, underfloor at ground level and radiators above. Ventilation is demand-controlled mechanical.

 

The central modern extension successfully links the two historic buildings, while being subservient and complimentary. The new volume extends deep in the plot and the floor slab steps down, holding the stone at either end. The function of the original building on the main street has changed function over the years from a bank to a shop and now a living room. The new spatial arrangement makes for comfortable living in an urban environment, with density returned to an occupied town-centre site rather than taken from greenfield.