Comparative Retrofit Scenarios for 20-Storey Tower at Atherton Gardens, Fitzroy

Comparative Retrofit Scenarios for 20-Storey Tower at Atherton Gardens, Fitzroy Authors: C.Barnett, N.Bertram, A.Cattanach, P.Dowling, R.Harding, C.Kelly, W.Young

Contents Background Context // International Context // Sustainability // Social Considerations Methodology // Case 01 // Case 02 // Case 03 Existing Conditions & Design Assumptions // Existing Buildings // Structural Approach // Fire Separation, Access & Egress // Acoustic Requirements // Internal Architectural Fit-out // Upgrades to Public Areas // Environmental Requirements Results of Analysis // Capital Costs // Operating Costs // Embodied Carbon // Construction Time Discussions // Recommendations for Further Work Appendix

2

Background 44 Housing Towers This research project was initiated by a group of interested design practitioners interested in providing some data to inform the debate on how to approach the refurbishment and/or replacement of the ‘Housing Commission towers’ located in inner Melbourne suburbs.

Designed and built in a time of post-war modernist vision and social aims, Melbourne’s 44 housing towers were constructed between 1960 and 1975 and comprised 7,834 apartments - ranging from 27m2 bedsits to 96m2 three-bedroom units. Located on 21 estates, the towers provide homes for some of our most vulnerable populations (low-income, elderly, sick) and account for 10% of the city’s social housing stock.

We have used the Atherton Gardens tower as a case study due to spatial data being available. Whilst acknowledging that every case would need to be evaluated individually, there are ten towers with this same plan, and at 20 storeys with 180 dwellings the building is broadly representative of the average scale of the towers currently slated for demolition.

The intention of this research is not to advocate for one scenario or another, but rather to provide some realistic comparative approaches that could be applied to any of the 44 towers.

3

Context

Context

International Context

Sustainability

Social Considerations

Our public housing towers form part of an international modernist movement to provide high rise public housing throughout the 1950s & 1960s, with many countries now looking at how to best to update this aging building stock. Needing to be updated to current building codes and living standards, European approaches have included the successful retrofitting of existing towers.1 With lower costs and environmental impacts, European case studies such as Lacaton Vassal’s Bordeaux housing have even managed to avoid social upheaval of needing 2 decant residents.

With both architecture and engineering professions and the State Government having policies to transition to zero emission buildings over the next 20 years, the operational energy and carbon embodied in the towers have been considered as an important part of this research. The embodied carbon in the concrete of the towers has been quantified and resultant emission impacts of rebuild and refurbishment options compared.

In comparison to a new building meeting the energy efficiency requirements of our current building codes, the operational energy savings of retrofitting options has also been identified.

While the significant social impacts and costs associated with the relocation of residents from the towers is beyond the scope of this research, strategies that can minimise the need and time to relocate residents are seen to hold great public value - both in avoiding breaking up established communities and avoiding the significant decanting costs involved. The demolition of all the towers and resulting long-term decanting of approximately 10,000 residents into the Melbourne rental market will add further pressure to the housing crisis we are currently facing.

1. Knikkers Estate, Rotterdam, Netherlands - https://divisare.com/projects/370974-hans-van-der-heijden-architect-stefan-muller-knikkers 2. Lacaton Vassal Bordeaux Housing - https://www.archdaily.com/915431/transformation-of-530-dwellings-lacaton-and-vassal-plus-frederic-druot-plus-christophe-hutin-architecture 3. Kings Crescent Estate Phases 1 & 2 - https://www.karakusevic-carson.com/projects/kings-crescent-estate-phases-12

5

Methodology

Methodology Whilst there have been many architectural schemes proposed for these towers with various potential improvements and modifications, this study excludes design as a variable and simply looks at the comparative case of refurbishing versus demolition and rebuild.

The study is not a proposal for a real design or building outcome, but an ‘apples for apples’ comparison that could inform future designs for the towers and/or their replacements.

Case 1

Case 2

Case 3

Demolish and rebuild an equivalent building to current standards, minimum compliance (equivalent to current new social housing construction approach).

Externally: provide seismic strengthening, provide new insulated thermal layer to existing precast facade. Internally: refurbish building and bring up to current regulatory standards, while maximising environmental initiatives that would reduce operational costs for residents.

This scenario would meet the requirements of current market housing.

As per Case 2, but adding fully new external bracing facades with balconies for each apartment. This scenario would meet the requirements of current social housing.

We considered 3 scenarios: Case 1 - Demolish & Rebuild.

Case 2 - Retrofit: Minimal Intervention for Building Code compliance.

Case 3 - Retrofit: Upgraded Intervention to meet requirements of social housing standards.

7

Methodology For each of these cases, we evaluated three key figures: capital cost of construction, operational cost (per annum) and embodied carbon of building works. In addition, we considered the time taken for construction and also possible staging, as this would affect the length of time residents would have to move out for and be housed elsewhere.

Capital Cost

There are many other factors that could be considered, including the direct costs of decanting residents and rental of alternative housing during construction plus indirect costs of relocation including impact on education, health and wellbeing – however these have been excluded from this study and can be referred to elsewhere.3,4 To determine the scope of works required we assessed the existing building spatially and consulted with an experienced team for advice on works required. This advice is high level and would require verification if works were to proceed – however onsite verification of actual building conditions was not feasible within the scope of this project.

Operating Costs

$

The key areas of technical consideration informing the cost plan were: Building Surveyor: access and egress, requirements for fire protection/ fire separation between dwellings Structural engineer: reinforcement of existing structure to meet current requirements for seismic (earthquake) resistance. Overall performance of building and structural principals. Likelihood of concrete cancer and potential rectification.

Operational Carbon

Acoustic engineer: requirements for acoustic separation between dwellings Environmental engineer: requirements for thermal performance of envelope and options for services including heating, cooling and ventilation.

A cost plan was developed for each scenario taking into account the scope of works and analysing the likely construction approach that would be taken by a large-scale commercial builder. A detailed explanation of assumptions for each of the above is included below.

Embodied Carbon

Community Impact

3. OFFICE Barak Beacon Report - https://office.org.au/project/retain-repair-reinvest-barak-beacon-estate/ 4. OFFICE Retain Repair Reinvest: Ascot Vale Estate - https://office.org.au/project/retain-repair-reinvest/

8

Existing Conditions & Design Assumptions

Existing Building The existing building was prefabricated and constructed as a total precast system, with precast slabs supported on precast walls throughout. The walls combine to provide lateral load resistance using predominantly the weight of the building to clamp the walls down. In some of the later towers, the walls are post-tensioned down at the lower floors.

The primary internal and external walls are only 100mm thick in the upper floors, thickening to 150 for levels 7-12 and 175 below this. Secondary internal walls are thinner throughout.

Floors are 125mm thick throughout.

The structure transfers above ground floor to reinforced concrete frames: these“legs” providing the open public spaces predominantly on the wings of the building. Some walls run to ground around the stair and lift cores, plus surrounding the ancillary spaces central to the building. The buildings are piled under these legs and core structures.

The buildings are exposed aggregate and/or painted: it is assumed that the panels have remained dry and hence carbonation of the concrete is not yet critical. The panels should be treated with a specialist cementitious coating to assist with extending their life further against carbonation. This warrants further investigation in the buildings, and it may vary according to the accuracy of production, concrete quality and potential degradation in use.

Floor Plan

Generally it has been assumed that carbonation (or ‘concrete cancer’) is more likely in the external facade due to weather exposure. Hence our approach has been to clad over the facade and encapsulate the panels in Case 2, and to replace the external facade completely in Case 3.

Building Section 10

Structural Approach The buildings have an inherent seismic resistance from their height: the nature of earthquakes possible in Australia captured by the standard AS1170.4 illustrates how much less energy is imparted into buildings with long periods (those that sway slowly). Site specific hazard analysis (PSHA)_using the latest research is likely to show these “code” demands are conservative.

The precast nature of the floors means they have less tying capability as more conventional in situ structures. However the distributed seismic resistance means the demands on the floors to do this tying are small, with the exception of first floor.

The existing building has significant irregularity at the open ground floor, and the change in seismic resistance is particularly critical for the small tying capability of the precast floors. This can be retrofit with supplementary seismic resistance fattening the “legs” and providing tying across the structure in key locations.

This work, carried out at the low level, has little disruption to any refurbishment project above.

Plan Level 0 (Ground Floor)

Showing extent of new strengthening works

Seismic Strengthening Zones Isometric view

11

Design Assumptions Fire Separation, Access & Egress

13-W

The existing building floor-to-floor levels are very tight at 2590mm (compared to say 3000 for contemporary construction). The existing concrete slabs are 125mm thick, leaving 2465mm internally from floor level to underside of slab. This poses some difficulties for compliance as internal minimum ceiling heights of 2400 leave only 65mm for finishes. In addition, the 125mm slabs would not achieve the required 90 minute fire-rating between dwellings in their current state. The consultant team reviewed this condition and noted that a number of the existing buildings were upgraded with fire sprinklers in recent decades (and fire sprinklers are assumed in all 3 cases). By adding 2 layers of 16mm fire-rated plasterboard on 28mm resilient mounts, the distance between fire source and existing concrete reinforcement is increased and the overall FRL between dwellings is increased. Further review by a fire engineer would be required for a performance solution specific to the actual conditions of each building.

14-W

AW

15-W

exterior wall

LIVING

party wall

BEDROOM

exterior wall

structural wall

A-W

Acoustics BATHROOM

In tandem with fire separation, the current construction of single-layer concrete walls and slabs is unlikely to meet current requirements for acoustic separation between dwellings. The above ceiling linings on resilient mounts would improve transmission between floors to achieve compliance, assuming new carpets are installed to all units. An additional acoustic layer has been assumed for party walls between adjacent dwellings on the same floor; this discontinuous layer being offset to one side of the concrete walls to avoid symmetrical acoustic reverberation.

Both the new wall and ceiling linings are able to be absorbed into the refurbished apartment interior layouts.

KITCHEN exterior wall

B-W

C-W

exterior wall

Internal Architectural Fit-out 0

For costing purposes, the interior of each apartment has been assumed as fully refurbished, with all new services, finishes, fittings and joinery within the existing structural shell. In the refurbished cases 2+3, it is assumed that 80% of internal walls will be retained, as these have a structural role for lateral racing of the egg crate concrete structure. The existing walls provide a number of limitations on internal apartment layout, and room functions are assumed to remain as per existing in both case 2 and 3, with additional amenity to living rooms for Case 3 through new balconies.

ENTRY

0.5

2.5 m

Typical Floor Plan

AR1014

1 : 50

SCALE

WEST WING

1 Bed Corner Plan

PROJECT ATHERTON GARDENS STAGE Feasibility - Case Two DATE 7/10/2024

Upgrades to Public Areas Allowance has been made for new lifts and full replacement of service pipe runs for the refurbished cases. Existing fire stairs are spatially compliant, however new stair nosing’s, handrails and indicators would be required and are included. The cost plan also assumes a fully new roof to the existing structure.

Typical Section 12

Environmental Understanding the environmental requirements Case 1 was considered as a brand new building of the same design and scale as the existing building, but aligned with current building code minimum compliance. Energy consumption was estimated based on dynamic 3D thermal simulation of a year’s operation using industry standard software Integrated Environmental Solutions: Virtual Environment (IESVE). Water consumption was estimated in line with the Green Building Council of Australia’s Potable Water Calculator Guide.

Waste generation was calculated based on Sustainability Victoria waste generation rates for multi unit developments. Embodied carbon was estimated based on the Race to Net Zero Carbon report by the Low Carbon Living CRC, Low Carbon Institute and UNSW. Cases 2 and 3 considered an environmental retrofit targeting maximum performance using financially viable initiatives. Initiatives considered included upgrading the facade performance, adding heat recovery ventilation, installing domestic hot water heat pumps, adding a rooftop solar PV system, installing efficient water fixtures and fittings, installing rainwater collection for laundry and toilet flushing, and greywater diversion for subsoil irrigation. Operating costs and carbon were calculated using the same methodology as in Case 1, but including the cumulative impact of all of these initiatives.

Embodied carbon was calculated in Cases 2 and 3 by estimating the equivalent embodied carbon for a new build (in line with the methodology for Case 1), and subtracting materials being retained on site based on the quantity surveyor cost analysis. Some reductions in embodied carbon of new materials were also considered to allow for low carbon material selection where possible.

Inputs used in the calculation of environmental impact and operating costs can be found in appendix.

Net-positive Energy Produces more energy than it consumes

Water Neutral Imports waste water and exports treated water

Zero Waste

Food-positive

Imports and treats organic waste and sends no waste to landfill

Grows food for residents on-site

Zero Waste Construction

Minimise Embodied Carbon

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Results

Capital Cost Total Capital Cost $

Cost Break Down Summary $

Case 1

$140m

Case 2

-30%

$99m

Case 3 -25% $105m

Assumption of capital cost is based standard construction costs supplied by QS consultant.

Cost parameters are provided in the appendix.

15

Capital Cost Breakdown Total Capital Cost $ Case 1

$140m

Case 2

-30%

$99m

Case 3 -25% $105m

Assumption of capital cost is based standard construction costs supplied by QS consultant.

Cost parameters are provided in the appendix.

16

Operations Summary Total Annual Running Cost $

Annual Running Cost Summary $

Case 1

$770,000

Case 2

-70%

$250,000

Case 3 -70% $250,000

Assumption of operational cost is based standard operating costs of multi-residential buildings. Cost parameters are provided in the appendix.

17

Operations Breakdown Total Annual Running Cost $ Case 1

$770,000

Case 2

-70%

$250,000

Case 3 -70% $250,000

Assumption of operational cost is based standard operating costs of multi-residential buildings. Cost parameters are provided in the appendix.

18

Embodied Carbon Summary Total Embodied Carbon tCO2

Embodied Carbon Summary tCO2

Case 1

47,000 tCO2

Case 2

-34%

30,000 tCO2

Case 3 -36% 31,000 tCO2

Embodied carbon was estimated based on the Race to Net Zero Carbon report by the Low Carbon Living CRC, Low Carbon Institute and UNSW.

19

Embodied Carbon Breakdown Total Embodied Carbon tCO2 Case 1

47,000 tCO2

Case 2

-34%

30,000 tCO2

Case 3 -36% 31,000 tCO2

Embodied carbon was estimated based on the Race to Net Zero Carbon report by the Low Carbon Living CRC, Low Carbon Institute and UNSW.

20

Construction Time Construction Time & Life Expectancy Cases Case 1

25 Months

Case 2

20 Months

Case 3

22 Months

Construction time is estimated based on the standard time frames required for each case scope.

21

Summary Summary of our analysis across all three cases

Capital Cost

$ Operating Costs Community Impact

Case 1

Case 2

~ $140,000,000

~ $99,000,000 (-30%)

~ $105,000,000 (-25%)

~ $770,000 per annum

~ $250,000 (-70%) per annum

~ $250,000 (-70%) per annum

25 months

20 months (-20%)

Case 3

22 months (-12%)

All tenants move out and are relocated

Staged resident relocation possible floor by floor in sync with works

Staged resident relocation possible floor by floor in sync with works

Operational Carbon

1,700 tonnes per annum

270 tonnes (-84%) per annum

270 tonnes (-84%) per annum

Embodied Carbon

47,000 tCO2

30,000 tCO2 (-34%)

31,000 tCO2 (-36%)

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Results Summary These results demonstrate that retrofitting options can achieve substantial savings across both capital and operational costs in comparison to a new build of the same floor area and configuration.

There are also significant reductions in embodied carbon. The overall time taken for construction of retrofit options is marginally less than new build, however the real benefits are in the ability to stage construction level by level (or in groups of levels) which would allow existing residents to be relocated for a much shorter period of time. The reduced impact on existing communities, and the ability for residents to stay connected to existing networks of support and maintain coherence of social bonds should be a major consideration for any project on these sites.

The costing results for Case 2 and 3 are quite close, which suggests that the benefits of a new braced façade with additional amenity in the form of balconies for all apartments and larger windows (Case 3) would potentially be the best value-for- money outcome.

ATHERTON GARDENS FITZROY INDICATIVE BUDGET MODELLING

CASE 1

CASE 2

New Building Construction - 21 levels. 9 residences per level (excl Ground).

Total Floor Area 20,977m2. 56.2m bldg height. Façade area = 13,175m2 including 3,246m2 of windows. Approx internal wall area 30,000m2. Concrete roof, 4 no. lifts

30th July 2024

20,977 20,977

Gross Floor Area (m2)

Elemental Cost Centre DEMOLITION/STRIP OUT

$ 7,866,375

$

375.00

Full strip out and demolition of entire structure and substructure and external services infrastructure (7 months) Assumes significant piled foundation system to 20m depth, plus ground level slabs/beams ,column pads and core pits

SUBSTRUCTURE

2,460,000

117.27

COLUMNS

2,412,355

115.00

UPPER FLOORS

17,523,625

835.37

20,977 20,977

Gross Floor Area (m2) Commentary

$/m2 FECA

CASE 3

Retains entire building structure and solid internal walls (30%), and also retains and clads existing facade. Windows are replaced. Refurbishment is to all 21 levels. 9 residences per level (excl Ground). Total Floor Area 20,977m2.

56.2m bldg height. Façade area = 13,175m2 including 3,246m2 of windows.

Approx internal wall area 30,000m2. Concrete roof, 4 no. lifts (2 in existing shaft, 2 in new)

Retains entire building structure and solid internal walls (30%), but replaces entire facade. Refurbishment is to all 21 levels. 9 residences per level (excl Ground). Total Floor Area 20,977m2. 56.2m bldg height. Façade area = 13,175m2 including 3,246m2 of windows. Approx internal wall area 30,000m2.

Concrete roof, 4 no. lifts (2 in existing shaft, 2 in new) 20,977 20,977

Gross Floor Area (m2) Commentary

$/m2 FECA

$

Commentary

$/m2 FECA

310.00

Internal strip out only, facades are retained but windows removed (4 months)

7,027,295

335.00

Internal strip out and full façade only (5 months)

183.53

Bored Piers, concrete beams and columns providing seismic bracing some lower elevations

3,850,000

183.53

Bored Piers, concrete beams and columns providing seismic bracing some lower elevations

3,188,504

152.00

No work Treat existing slabs only/level wet areas/some infill

3,188,504

152.00

No work Treat existing slabs only/level wet areas/some infill. Excludes balcony

6,502,870 3,850,000 -

-

STAIRCASES

1,890,000

90.10

1,050,000

50.05

Updrade works only to 2 No. stairs (fire rating)

1,050,000

50.05

Updrade works only to 2 No. stairs (fire rating)

ROOF

1,080,150

51.49

1,080,150

51.49

Assumes new roof and plant space

1,080,150

51.49

Assumes new roof and plant space

EXTERNAL WALLS - SOLID/PANEL SYSTEM

7,843,910

373.93

5,560,240

265.06

Cladding over retained façade only

7,843,910

373.93

New Facade

EXTERNAL WALLS - WINDOWS

5,031,300

239.85

5,193,600

247.59

5,193,600

247.59

INTERNAL WALLS

12,750,000

607.81

3,450,000

164.47

New Windows/labour intensive 80% existing internal walls retained (80% x 30,000 = 24,000m2)- see WF also

3,450,000

164.47

New Windows/labour intensive 80% existing internal walls retained (80% x 30,000 = 24,000m2)- see WF also

DOORS AND HARDWARE

1,534,000

73.13

1,534,000

73.13

73.13

7,605,750

362.58

4,296,000

204.80

All new One side of existing/retained walls only (30,000m2 x 80% = 24,000m2)

1,534,000

WALL FINISHES

4,296,000

204.80

All new One side of existing/retained walls only (30,000m2 x 80% = 24,000m2)

FLOOR FINISHES

2,664,079

127.00

3,020,688

144.00

Includes floor levelling/prep

3,020,688

144.00

Includes floor levelling/prep

CEILING FINISHES

3,272,412

156.00

2,894,826

138.00

Lining exists soffits only

2,894,826

138.00

Lining exists soffits only

FITMENTS/JOINERY

3,080,000

146.83

146.83

3,080,000

146.83

HYDRAULICS AND DRAINAGE

3,200,000

152.55

3,085,000

147.07

Additional BWIC

3,085,000

147.07

Additional BWIC

MECHANICAL SERVICES

3,600,000

171.62

3,960,000

188.78

Additional BWIC

3,960,000

188.78

Additional BWIC

FIRE PROTECTION

3,062,642

146.00

10 risers, SWV to 180 residences, sanitary fixtures (5 per residence) Split Unit per residence, bathroom/kitchen exhaust only. Not full Heat Pump System Full residential sprinkler and detection system/panels

3,080,000

3,335,343

159.00

Additional BWIC

3,335,343

159.00

Additional BWIC

ELECTRICAL SERVICES

9,229,880

440.00

Includes main board (excludes external)

10,110,914

482.00

Additional BWIC

10,110,914

482.00

Additional BWIC

SECURITY

1,573,275

75.00

Main Lobby and lift access only with CCTV

1,678,160

80.00

1,678,160

80.00

4 No. - core walls part of Internal Walls

4,228,000

COMMUNICATIONS - (EXCL EQUIPMENT)

1,363,505

TRANSPORTATION SERVICES

3,040,000

65.00 144.92

1,783,045

85.00 201.55

1,783,045 Includes new core walls (for 2 of 4 lifts)

85.00

4,228,000

201.55

SPECIALIST SERVICES

Excluded

Excluded

Excluded

LOOSE FURNITURE AND AV EQUIPMENT

Excluded

Excluded

Excluded

102,083,258

4,866

DESIGN FINALISATION RISK

6,124,995

291.99

CONTRACTORS PRELIMINARIES ETC

24,887,898

1186.44

6% (New Build) Tower Crane, Jump Form, 18 month contract duration (23%)

5,323,846

253.79

4% Tier 2 Contractor

138,419,998

6,599

CONTRACTORS MARGIN

NETT BUILDING WORKS

Say Excludes: Hazardous Materials Repair of retained concrete structure (concrete cancer) Seismic upgrade of retained structural elements External Works and Services Infrastructure Loose Furniture and Equipment Cost Escalation Consultants Fees and Authorities Charges Construction Contingencies

$6,600/m2 GFA RISK NIL NIL NIL

100%

72,881,340

3,474

5,830,507

277.95

16,135,929

769.22

8% Slight programme reduction 20 month overall in lieu of 23 (20.5%)

4,031,030

192.16

4.25% Tier 2 Contractor

98,878,806

4,714

Say

$4,720/m2 GFA RISK POSSIBLE LIKELY

HIGH COST NEEDS VERIFICATION ALLOWANCE INCLUDED

71.43%

75,689,435

3,608

7,568,944

360.82

17,067,968

813.65

10% full new façade/existing structure Slight programme reduction 20 month overall in lieu of 23 (20.5%)

4,263,870

203.26

4.25% Tier 2 Contractor

104,590,216

4,986

Say

75.56%

$4,990/m2 GFA RISK POSSIBLE LIKELY

ALLOWANCE INCLUDED NEEDS VERIFICATION HIGH COST

HIGH COST ALL OPTIONS

HIGH COST ALL OPTIONS

EXCL ALL OPTIONS

EXCL ALL OPTIONS

ADD 3.5% PER ANNUM

ADD 3.5% PER ANNUM

ADD 3.5% PER ANNUM

10%-12% X Construction

11%-13% X Construction

11%-13% X Construction

ADD 10%

ADD 10%

ADD 6%

Includes new core walls (for 2 of 4 lifts)

HIGH COST ALL OPTIONS EXCL ALL OPTIONS

WILDE AND WOOLLARD

23

Community Impact Understanding the impact on residents across cases Cases Case 1

All tenants are vacated and relocated for 25 months.

Case 2 & 3

Staged relocation possible, floor by floor in sync with proposed work schedule.

24

Discussions

Key Findings Summary of key findings for Atherton Gardens

~$35-41 million reduction in capital cost (-25-30%)

~$500,000 per annum reduction in operating costs (-70%)

Includes earthquake upgrade

Opportunity to retain residents through construction programming

34-36% reduction in embodied carbon

26

44 Typologies Identifying the opportunity of how it impacts all 44 buildings

27

Opportunity Identifying the impacts across all 44 buildings (based on Case 3)

~$1.5 Billion reduction in capital cost (-25%)

~$22 Million per annum reduction in operating costs (-70%)

62,920 tonnes per annum reduction in operational carbon (-84%)

~27,000 residents homes are restored

748,000 tCO2 reduction in embodied carbon (-36%)

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Recommendations for Further Work Retrofitting options for the towers should be properly investigated and solutions that could be applied across multiple sites properly designed and costed. Individual sites should then be assessed to see if retrofitting options, along with additional medium density infill buildings, may be able to provide less disruptive and lower cost solutions to the redevelopment of our public housing estates.

This study is not intended as a stand-alone solution to the future of Melbourne’s Housing Commission estates; however it provides evidence to assist with retrofit of the existing towers as one of a number of strategies for increasing housing numbers and urban design amenity on these important public sites. A range of medium-rise infill buildings and substantial landscape design specific to each site would be required to augment refurbished existing towers, in consultation with existing residents and communities.

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Appendix

Cost Parameters ATHERTON GARDENS FITZROY INDICATIVE BUDGET MODELLING

CASE 1

CASE 2

New Building Construction - 21 levels. 9 residences per level (excl Ground).

Total Floor Area 20,977m2. 56.2m bldg height. Façade area = 13,175m2 including 3,246m2 of windows. Approx internal wall area 30,000m2. Concrete roof, 4 no. lifts

30th July 2024

20,977 20,977

Gross Floor Area (m2)

Elemental Cost Centre DEMOLITION/STRIP OUT

$ 7,866,375

Retains entire building structure and solid internal walls (30%), and also retains and clads existing facade. Windows are replaced. Refurbishment is to all 21 levels. 9 residences per level (excl Ground). Total Floor Area 20,977m2.

56.2m bldg height. Façade area = 13,175m2 including 3,246m2 of windows.

Approx internal wall area 30,000m2. Concrete roof, 4 no. lifts (2 in existing shaft, 2 in new) 20,977 20,977

Gross Floor Area (m2) Commentary

$/m2 FECA

CASE 3

$

Retains entire building structure and solid internal walls (30%), but replaces entire facade. Refurbishment is to all 21 levels. 9 residences per level (excl Ground). Total Floor Area 20,977m2. 56.2m bldg height. Façade area = 13,175m2 including 3,246m2 of windows. Approx internal wall area 30,000m2.

Concrete roof, 4 no. lifts (2 in existing shaft, 2 in new) 20,977 20,977

Gross Floor Area (m2) Commentary

$/m2 FECA

$

Commentary

$/m2 FECA

375.00

Full strip out and demolition of entire structure and substructure and external services infrastructure (7 months)

6,502,870

310.00

Internal strip out only, facades are retained but windows removed (4 months)

7,027,295

335.00

Internal strip out and full façade only (5 months)

Assumes significant piled foundation system to 20m depth, plus ground level slabs/beams ,column pads and core pits

3,850,000

183.53

Bored Piers, concrete beams and columns providing seismic bracing some lower elevations

3,850,000

183.53

Bored Piers, concrete beams and columns providing seismic bracing some lower elevations

152.00

No work Treat existing slabs only/level wet areas/some infill

3,188,504

152.00

No work Treat existing slabs only/level wet areas/some infill. Excludes balcony

SUBSTRUCTURE

2,460,000

117.27

COLUMNS

2,412,355

115.00

UPPER FLOORS

17,523,625

835.37

3,188,504

-

STAIRCASES

1,890,000

90.10

1,050,000

50.05

Updrade works only to 2 No. stairs (fire rating)

1,050,000

50.05

Updrade works only to 2 No. stairs (fire rating)

ROOF

1,080,150

51.49

1,080,150

51.49

Assumes new roof and plant space

1,080,150

51.49

Assumes new roof and plant space

EXTERNAL WALLS - SOLID/PANEL SYSTEM

7,843,910

373.93

5,560,240

265.06

Cladding over retained façade only

7,843,910

373.93

New Facade

EXTERNAL WALLS - WINDOWS

5,031,300

239.85

5,193,600

247.59

5,193,600

247.59

INTERNAL WALLS

12,750,000

607.81

3,450,000

164.47

New Windows/labour intensive 80% existing internal walls retained (80% x 30,000 = 24,000m2)- see WF also

3,450,000

164.47

New Windows/labour intensive 80% existing internal walls retained (80% x 30,000 = 24,000m2)- see WF also

DOORS AND HARDWARE

1,534,000

73.13

1,534,000

73.13

1,534,000

73.13

WALL FINISHES

7,605,750

362.58

4,296,000

204.80

All new One side of existing/retained walls only (30,000m2 x 80% = 24,000m2)

4,296,000

204.80

All new One side of existing/retained walls only (30,000m2 x 80% = 24,000m2)

FLOOR FINISHES

2,664,079

127.00

3,020,688

144.00

Includes floor levelling/prep

3,020,688

144.00

Includes floor levelling/prep

CEILING FINISHES

3,272,412

156.00

2,894,826

138.00

Lining exists soffits only

2,894,826

138.00

Lining exists soffits only

FITMENTS/JOINERY

3,080,000

146.83

3,080,000

146.83

3,080,000

146.83

HYDRAULICS AND DRAINAGE

3,200,000

152.55

3,085,000

147.07

Additional BWIC

3,085,000

147.07

Additional BWIC

MECHANICAL SERVICES

3,600,000

171.62

3,960,000

188.78

Additional BWIC

3,960,000

188.78

Additional BWIC

FIRE PROTECTION

3,062,642

146.00

10 risers, SWV to 180 residences, sanitary fixtures (5 per residence) Split Unit per residence, bathroom/kitchen exhaust only. Not full Heat Pump System Full residential sprinkler and detection system/panels

3,335,343

159.00

Additional BWIC

3,335,343

159.00

Additional BWIC

ELECTRICAL SERVICES

9,229,880

440.00

Includes main board (excludes external)

10,110,914

482.00

Additional BWIC

10,110,914

482.00

Additional BWIC

SECURITY

1,573,275

75.00

Main Lobby and lift access only with CCTV

1,678,160

80.00

1,678,160

80.00

COMMUNICATIONS - (EXCL EQUIPMENT)

1,363,505

65.00

1,783,045

85.00

1,783,045

85.00

TRANSPORTATION SERVICES

3,040,000

144.92

4,228,000

201.55

4,228,000

201.55

4 No. - core walls part of Internal Walls

Includes new core walls (for 2 of 4 lifts)

SPECIALIST SERVICES

Excluded

Excluded

Excluded

LOOSE FURNITURE AND AV EQUIPMENT

Excluded

Excluded

Excluded

102,083,258

4,866

DESIGN FINALISATION RISK

6,124,995

291.99

CONTRACTORS PRELIMINARIES ETC

24,887,898

CONTRACTORS MARGIN

5,323,846 138,419,998

6,599

NETT BUILDING WORKS

Say Excludes: Hazardous Materials Repair of retained concrete structure (concrete cancer) Seismic upgrade of retained structural elements External Works and Services Infrastructure Loose Furniture and Equipment Cost Escalation Consultants Fees and Authorities Charges Construction Contingencies

72,881,340

3,474

5,830,507

277.95

1186.44

6% (New Build) Tower Crane, Jump Form, 18 month contract duration (23%)

16,135,929

253.79

4% Tier 2 Contractor

4,031,030 98,878,806

4,714

100%

Say

75,689,435

3,608

7,568,944

360.82

769.22

8% Slight programme reduction 20 month overall in lieu of 23 (20.5%)

17,067,968

813.65

10% full new façade/existing structure Slight programme reduction 20 month overall in lieu of 23 (20.5%)

192.16

4.25% Tier 2 Contractor

4,263,870

203.26

4.25% Tier 2 Contractor

104,590,216

4,986

$4,720/m2 GFA RISK POSSIBLE LIKELY

71.43%

$6,600/m2 GFA RISK NIL NIL NIL

ALLOWANCE INCLUDED NEEDS VERIFICATION HIGH COST

HIGH COST ALL OPTIONS

HIGH COST ALL OPTIONS

EXCL ALL OPTIONS

EXCL ALL OPTIONS

EXCL ALL OPTIONS

ADD 3.5% PER ANNUM

ADD 3.5% PER ANNUM

ADD 3.5% PER ANNUM

10%-12% X Construction

11%-13% X Construction

11%-13% X Construction

ADD 6%

ADD 10%

ADD 10%

WILDE AND WOOLLARD

Includes new core walls (for 2 of 4 lifts)

Say

75.56%

$4,990/m2 GFA RISK POSSIBLE LIKELY

ALLOWANCE INCLUDED NEEDS VERIFICATION HIGH COST

HIGH COST ALL OPTIONS

31

Comparative Retrofit Scenarios for 20-Storey Tower at Atherton Gardens, Fitzroy

www.findinginfinity.com

Authors: C.Barnett, N.Bertram, A.Cattanach, P.Dowling, R.Harding, C.Kelly, W.Young