Number Twenty Nine Fitzwilliam Street is a moderate dwelling, three bays wide, with a frontage of 28 feet, and a depth of nearly 50 feet. The external proportions of the outside of each building are based upon those of a classical column. Window height increases from the basement through to the first floor piano nobile. From that point it decreases as far as the attic storey. Beautiful as these houses were, those of a smaller scale in Fitzwilliam Street were more generic in character than their Merrion Square counterparts, many of which contain fine plasterwork. In Fitzwilliam Street Lower, evidence such as the extensive use of generic plaster moulds in the ceilings points to houses which were built as a type.
This house was first used by the Electricity Supply Board in 1928. The Board had been established the previous year. The building was then used for office purposes until the late 1980s. Number Twenty Nine was one of ten houses on Fitzwilliam Street Lower and on Mount Street Upper restored by the Electricity Supply Board in 1988.
In 1986, prior to refurbishment work commencing, the Irish Architectural Archive in conjunction with the Irish Georgian Society, completed a full survey of numbers 55-62 Mount Street Upper, and 29 and 30 Fitzwilliam Street Lower.
It was the opinion of the archive that the first two buildings on both Mount Street and Fitzwilliam Street were significantly earlier in date than adjoining properties in Mount Street, which they suggested did not appear in contemporary sources until 1834.
This detailed report, found in Number Twenty Nine, a building much altered over time. A number of features, such as the internal fanlight and doors in the ground floor hall, and the internal partition wall in the dining room, were deemed to be Victorian additions and were recommended for removal.