59–61 West Street, Balgowlah NSW 2093

1Executive Summary

IGS has been commissioned to assess the proposed development at 59 West Street, Balgowlah NSW 2093 in terms of BASIX compliance. A BASIX Certificate is a regulatory requirement and demonstrates compliance with the NSW Government's sustainability targets; BASIX assessment and certification has been completed for this project (Certificate No. 1858474M).

With the recommendations provided in the BASIX certificate, the development meets and exceeds the minimum requirements for Water Efficiency, Energy Efficiency and Thermal Comfort, as summarised in Table 1.

2Introduction

BASIX is an NSW State planning policy tool which assesses the environmental performance of new residential premises against a range of water, energy and greenhouse-gas-emissions targets. The assessment has three core components: BASIX Thermal Comfort, BASIX Water and BASIX Energy.

The thermal comfort assessment requires that the thermal performance of dwellings is evaluated and measures put in place to ensure annual heating and cooling loads do not exceed pre-defined limits without compromising the occupant's thermal comfort. This assessment uses computer simulation to evaluate the building fabric thermal performance and passive solar design features such as orientation and solar shading.

The energy section evaluates gas (if any) and electrical energy used for heating, cooling, lighting, ventilation and appliances. The BASIX Energy target is a project-specific minimum percentage reduction in greenhouse-gas emissions relative to the NSW benchmark; for this development the target is 61%.

The water assessment takes account of landscaping and stormwater management as well as the water-efficiency performance of fixtures and fittings such as taps and showers. The BASIX Water target is a required percentage reduction in mains (potable) water use against the fixed benchmark of 90,340 L/person/year; for this development (High Water Target Zone) the target is 40%.

Note: this report is a guide to the BASIX certificate. For the full details of the BASIX requirements, please refer to the BASIX certificate.

3Building Description

This BASIX assessment report is prepared by IGS in support of the proposed development at 59 West Street, Balgowlah NSW 2093, comprising a residential development with one level of basement. The development includes the following space types:

• 9 residential apartments, comprising a mixture of 2, 3 and 4 bed apartments
• A residential lobby on ground floor
• 1 level of basement car parking (17 car parks) dedicated to residents

3.1Site & Location

The site is near St Paul's Catholic College, with West Street on the east, Seaview Street on the west and White Street on the south. The site falls within the Northern Beaches Council local government area, and the Lot / Plan is Lot 13, Section 2, Deposited Plan 2072.

3.2Building Summary

3.3Information Used in Review

Our review is based on the architectural drawings by PSI Architects, "DA ISSUE ARCHITECTURAL PLANS — 59-61 WEST STREET BALGOWLAH — REV K", dated 22/07/2026.

4.1Water

The water-efficiency performance of the development has been assessed using the online BASIX Tool. The assessment has considered the common-area and central-system features including the landscape design, plant species, water-catchment areas, rainwater-tank size, and the efficiency of the preferred fixtures and fittings in the dwellings.

The development meets the BASIX Water target of 40% — the required percentage reduction in mains (potable) water use against the fixed benchmark of 90,340 litres/person/year — provided the water commitments in Table 5 are installed. For the requirements necessary to achieve this target, refer to BASIX Certificate No. 1858474M.

4.3Thermal Comfort

The energy simulations demonstrating the thermal comfort compliance of the development have been evaluated using FirstRate5 (Version 5.5.5a (3.21)) software, which is approved under the Thermal Comfort protocol of BASIX since March 2021. This computer simulation of residential developments is used to assess the potential of a residential development to have low heating and cooling energy requirements once operational. This method does not guarantee or warrant performance in the practical world, as it considers a simplified and idealised building.

Thermal Comfort targets are set by the Department of Planning in the form of heating and cooling caps. The building's thermal physics is assessed using thermal-performance simulation tools, equating an expected level of heating and cooling energy per dwelling per annum, expressed in MJ per square metre of floor area. Each dwelling has individual heating and cooling caps, and the development has a weighted-average load; the weighted-average caps are harder to achieve than the individual-unit caps.

The "base-case" building fabric and estimated glazing and thermal-performance requirements are described in Table 7. Note these estimated requirements are based on the construction materials nominated by the architect.

The thermal insulation and glazing performance requirements outlined in this report nominate the estimated minimum BASIX requirements only and do not consider requirements for other disciplines such as acoustics, fire or safety compliance.

Compliance with the minimum BASIX requirements does not warrant thermal comfort. All services consultants and contractors shall design and construct the development to comply with the minimum requirements of the NCC Vol 1 & 2 and NSW Section J requirements.

There were several glazing elements for which sufficient information was not available in the drawing package provided. Where this occurred, we modelled the glazing based on our professional judgement and typical industry practice (e.g. assuming awning, sliding, or fixed windows as appropriate). These assumptions have been identified and are included in Appendix D — Insulation and Glazing Markups for your reference.

4.3.1Assessment basis

The assessment covers all 09 dwellings arranged from Ground Level to Level 03. The drawings confirm 4 dwellings at Ground Level, 2 units each on Level 01 and Level 02 and 1 unit on Level 03. The modelling considers orientation, apartment geometry, exposed walls, floor and roof interfaces, glazing, shading, neighbouring obstructions, corridor exposure, ventilation openings and ceiling-fan assumptions.

The heating and cooling caps applied in this assessment are based on the site being in Climate Zone 56 (Mascot / Sydney Airport).

4.3.5Conclusion

All 09 dwellings remain below the applicable individual heating, cooling and total-load caps. The assessment therefore demonstrates a viable pathway for the current design to satisfy the applicable BASIX and NatHERS thermal-performance requirements. Compliance relies on the specifications and assumptions documented in Section 4.3.

Any change to dwelling layouts, glazing performance or operability, shading, exposed construction, insulation, or the surrounding built form must be referred for NatHERS reassessment before certification.

4.2Energy

The energy performance of the development has been assessed using the online BASIX Tool. The assessment has considered common-area and central-system features including lifts, ventilation and lighting for common areas (corridors, lobbies, car park), centralised domestic hot water, and the efficiency of the preferred lighting and appliances in the dwellings.

The development meets the mandatory BASIX Energy target of 61% provided the energy commitments in Table 6 are installed.

6Summary & Conclusion

The proposed development has been assessed in terms of its ability to conserve water and minimise energy consumption, and its thermal performance (passive and fabric design) will comply with the BASIX thermal comfort requirements.

Subject to the provisions of this report, the proposed development is able to meet the BASIX requirements and is BASIX compliant. For further details, please refer to BASIX Certificate No. 1858474M provided.

5Disclaimer

This report is prepared using the information described above and inputs from other consultants. Whilst IGS has endeavoured to ensure the information used is accurate, no responsibility or liability to any third party is accepted for any loss or damage arising out of the use of this report by any third party. Any third party wishing to act upon any material contained in this report should first contact IGS for detailed advice which will take into account that party's particular requirements.

Computer performance assessment provides an estimate of building performance. This estimate is based on a necessarily simplified and idealised version of the building that does not and cannot fully represent all the intricacies of the building once built; as a result, simulation results only represent an interpretation of the potential performance of the building. Although great care has been taken to prepare this report, IGS does not make any representations or give any warranties or assurances as to the accuracy or completeness of the information contained in the report or that the report is free from errors or omissions. IGS and its employees and agents shall not be liable for any loss arising because of any person using or relying on the report, whether caused by error, negligent act or omission.

Performance of the completed building may be significantly affected by the quality of construction, commissioning, ongoing management of the building, and the way the building is operated, monitored and maintained. Building fabric inputs require verifiable manufacturer data to confirm thermal properties.

This report is intended as a guide to assist with the application of BASIX. It should be read in conjunction with the BASIX certificate and the NCC applicable to the development; specific applications may vary during the design development of the project.

Document Control

Appendices

• Appendix A — BASIX Certificate 1858474M (17 pages)
• Appendix B — NatHERS Certificate YNQXNY4LMK (3 pages)
• Appendix C — Architectural Drawings, PSI Architects Rev K (22 sheets)
• Appendix D — Insulation & Glazing Mark-ups (6 sheets)

Every page of every appendix is reproduced in the Evidence room of this app.