The development potential of 136-142 Walker Street
36 While there were separate objections for 136-140, and for 142 Walker Street, the applicant has considered the three sites in an amalgamated form. This is a sensible approach, since No 142 by itself is significantly short of the minimum allotment size in the LEP. However, the sites are not amalgamated and, as mentioned before, there is a proposal for No 136-140 that has been refused by the council and is on appeal before the Court. In the event, little turns on this, since the tower in the subject proposal does not extend to the part of the site where it adjoins No 142; hence the effect of the tower's setback from the eastern boundary is of minor consequence to the development potential of No 142. The consequence flows to No 136-140.
37 The residential section of the proposal's tower is set back 3.5m from the common boundary with 136-142 Walker Street. Mr Harrison and Ms Higgins have justified this on the basis that the development potential of No 136-142 is five storeys, and those five storeys must be in non-residential use to comply with the requirements of the mixed zone. The lower five storeys of the subject proposal are also commercial. In Mr Harrison's and Ms Higgins' view, a separation of 7m is adequate between two commercial buildings; hence the subject proposal's setback of 3.5m from the eastern boundary is sufficient.
38 Mr Mossemenear told the Court that he considered a much bigger development on 136-142 Walker Street would comply with the requirements of cl 28D and may be acceptable. In his opinion a building on 136-142 could reach a height of RL 103, which means nine storeys on top of a five-storey podium. In Mr Mossemenear's opinion, the shadow cast from such a building would comply with cl 28D(4) providing for minor variation of the overshadowing controls in cl 28D(2).
39 Mr Harrison and Ms Higgins disagreed with Mr Mossemenear on three grounds. First Mr Mossemenear had disregarded the building height plane, second, his model did not meet the requirement that there should be no increase in overshadowing that would reduce the amenity of any dwelling that is outside the North Sydney Centre and falls within the composite shadow area; and, third, he had disregarded the impact on the four heritage items to the north of 142 Walker Street. Mr Harrison and Ms Higgins remained convinced that 136-142 had a potential for a five-storey commercial building only. Mr Mossemenear agreed that he had assumed that the building height plane could be varied.
40 Mr Harrison also told the Court that, even if a building on 136-140 were higher than five storeys, a setback of 3.5m on the subject site would be adequate as long as the setback on 136-140 was at least 6.5m. This is because the logical position for a core containing lift and stairs on 136-140 was on the western part of the site where it adjoins the subject site.
41 Unlike Mr Mossemenear, Mr Harrison and Ms Higgins who based their evidence on theoretical building envelopes, Mr Byrnes based his evidence on the building proposal of 35 storeys on 136-140. This is the proposal that has been refused and for which an appeal has been filed with the Court. Mr Byrnes' evidence included a diagram showing the shadows cast by a building of the same floor plan as the proposal on appeal, but limited to a height of RL 119. The additional shadow falls on the northwest blank wall of the Century building, including two triangular balconies from bedrooms. The shadow affects the ten lower floors. Decreasing the floor plan of the proposed building on 136-140 would decrease the shadow; however, it is unlikely that the shadow could be entirely eliminated because that would leave the floor plan too small to be viable. The diagram suggests, however, that a small decrease in the floor plan would remove the shadow from one of the bedroom balconies.
42 I note that Mr Mossemenear had no difficulty with the concept of varying the building height plane. Mr Byrnes thought the application of the building height plane to this site would be "a travesty". Mr Harrison and Ms Higgins considered it important to apply the building height plane in its strictest form. I note that even a strict application of the building height plane would allow a building to approximately RL 96, on the assumption that it is set back 6.5m from the western boundary and has a depth at the top level of 10m. RL 96 corresponds to level 9 in the subject application.
43 The Court thus has before it widely differing assessments of the development potential of 136-140 Walker Street. Mr Harrison and Ms Higgins consider the potential to be five storeys at about RL 77. Mr Mossemenear, who looked at a larger site amalgamated with No 142, considers the development potential to be about 13 storeys at about RL 103. Mr Byrnes, who advocates a 35-storey building, says that an 18-storey building at RL 119 would pass the test of cl 28D with flying colours.
44 The Court must therefore choose from a range of professional opinions suggesting a height limit from five to 35 storeys. It appears that a building up to RL 96 would certainly be possible on 136-140 Walker Street. Such a building would comply with the building height plane. It would cast a shadow on one bedroom balcony per floor in the Century Plaza building from 1pm to 3pm on three or four lower floors. The impact would be so minor that it would have to be described as negligible or immaterial. It would not be considered as "an increase in overshadowing that would reduce the amenity of any dwelling". It would therefore comply with cl 28D(2)(d) even if that clause were a prohibition, which, as I have stated above, is unlikely to be the case.
45 Three further matters need to be dealt with in relation to the issue of the development potential of 136-140 Walker Street. First is the matter of impact on the four heritage items to the north of 142 Walker Street. Mr Mossemenear agreed that he did not seek advice on the impact of his building envelope on the heritage items. I do not think that this of great moment, given that the minimum development potential that the Court accepted was in relation to a site that excludes 142 Walker Street, so the building envelope is not adjacent to the items and is lower than that accepted by Mr Mossemenear. Second, the evidence shows that at one stage Mr Mossemenear accepted that 136-142 had a potential of only five storeys. I accept that, on further reflection, he changed his mind.
46 Third, I have considered Mr Harrison's evidence that even if a higher building than five storeys were allowed on 136-140 it could live with the subject proposal being set back only 3.5m from the common boundary. This assumption relies on the building on 136-140 being set back twice as much from the common boundary as the subject proposal, and on the lift core being at the western end of the site. This would add constraints on a site that, as we have seen, is already subject to heavy constraints. It would be an unfair constraint that favours the owner of the subject site at the expense of that of No 136-140.
47 The consequence of the above conclusion for the relationship between the subject site and 136-140 Walker Street is that there could be at least five residential floors in the subject proposal that would be directly opposite residential floors on the Walker Street site. This means that along the common boundary where the towers overlap (for 15 to 17m) there should be a separation of 13m, of which 6.5m should occur on the subject site. Mr Mossemenear provided a graphic representation of the required setback. The result is a loss of 7% of floor space on the lower floors, less on the upper floors where the building sets back in any case.