The residential element of Number One Ballsbridge is almost complete, and its 88 top-end apartments are about to set a record for the highest rents in Dublin.

The smallest of its two-bedroom apartments, which cover 96sq m (1,033sq ft), and are on the first to seventh floors, start at €3,850 a month. This outstrips Kennedy Wilson’s new Capital Dock scheme in Dublin’s south docklands, which set a new benchmark last week when its two-bed units were advertised seeking €3,300 a month.

The two-bed apartments in the Ballsbridge complex range up to 140sq m (1,505sq ft), however, and will therefore cost significantly more than the entry-level €3,850 to rent. Three-bed units, which range from 155sq m (1,670sq ft) to 177sq m (1,905sq ft), will cost from €5,500 a month.

Prices increase for penthouses on the eighth and ninth floors. Two-beds start at €5,000 a month for 109sq m (1,175sq ft). Three-bed penthouses, covering 155sq m (1,670sq ft), start at €6,000 a month.

The development’s entry-level two-bed apartments – it has no one-bedroom units – are also likely to set a record as the largest minimum unit sizes in a big Dublin development. The average size of its two- and three-bedroom apartments is 125sq m (1,350sq ft). The biggest unit, the four-bedroom Galileo penthouse, occupies 223sq m (2,400 sq ft) of the ninth floor, along with a private terrace that covers a further 163sq m (1,750sq ft). It is available to rent for €4,750 a week, or about €20,600 a month.

The complex includes 4,645sq m (50,000sq ft) of residents’ amenities, including a spa, gym, swimming pool, business centre, orangery and roof terrace, along with an on-site concierge.

Number One Ballsbridge is located on the controversial former veterinary-college site bought more than five years ago by the Comer Group and the Mayo-based McHale brothers for a reported €22.5 million, 87 per cent less than the €171.5 million paid by Kintene, a company linked to the developer Ray Grehan, during the boom.

The Comers’ decision to opt for a build-to-rent model is in sharp contrast to Chartered Land’s build-to-sell strategy at neighbouring Lansdowne Place. Luke Comer said in 2014 that prices of €1,000 per square foot were conceivable in Ballsbridge. Even though prices at the ultra-luxe Lansdowne Place now well exceed that goal, the Comers have still opted to rent the units.

A key question is whether they will hold the complex as a long-term investment or sell the entire development, including its office and retail elements, as a trophy investment once they prove to investors that renters are willing to pay the record rents for the 88 luxury apartments.

Such a sale would be a major vote of confidence in Ireland’s burgeoning private rental sector, given that capital values would likely have to average about €1.5 million per unit in order to make it an attractive proposition for the Comers compared with selling them individually.