Apartment buildings and residential flat buildings in NSW generally need BASIX as part of the residential approval pathway. These projects can be more complex than single dwellings or townhouse rows because the assessment may need to include many apartments, different dwelling types, common areas, central services, lifts, shared gardens, car parks, pools, spas and building-wide energy and water systems.
BASIX covers water, energy use and thermal performance for NSW residential development. For residential flat buildings, the BASIX project type guidance asks users to enter the number of residential flat buildings and, for each building, the number of dwellings or apartments and the number of storeys. This means the assessment needs a clear understanding of the building structure before it can be prepared accurately. NSW Planning Portal
Apartments and residential flat buildings in NSW generally require BASIX. The assessment needs to account for each apartment, dwelling type, thermal performance, glazing, insulation, water commitments, energy systems, common areas, lifts, shared gardens and central systems such as central hot water, central heating, central cooling or central water tanks.
Apartment projects usually sit within the BASIX multi dwelling assessment environment rather than the single dwelling pathway. NSW Planning explains that the BASIX multi dwelling section is designed for larger residential developments, especially unit blocks with common areas such as car parks, lifts and shared gardens that can require significant amounts of water and energy. NSW Planning Portal
This makes apartment BASIX more detailed than a simple dwelling assessment. The assessor may need to review individual apartments, repeating apartment types, common corridors, shared services, car park ventilation, central systems and site-wide water and energy commitments. The BASIX Certificate should reflect the actual approval drawings and the way the building will operate.
Townhouses and residential flat buildings can both involve multiple dwellings, but they are not always assessed in the same way. Townhouses usually have ground level access for each dwelling and may include shared or private open spaces. Residential flat buildings usually include apartments stacked across storeys, with shared access, common circulation and building-wide services.
This distinction matters because apartment buildings can include common areas and central systems that are not present in a row of townhouses. Lifts, car parks, central hot water, central cooling, central heating, mechanical ventilation and shared water systems may all need to be considered in the BASIX assessment.
BASIX assesses water, energy use and thermal performance. In apartment buildings, those categories can apply at both the individual apartment level and the building-wide level. Each apartment may have different glazing, orientation, floor level, shading and thermal performance. The building may also have shared services that use water or energy.
The assessment may need to include:
Common areas can use significant water and energy in apartment developments. NSW Planning states that the BASIX multi dwelling section is designed for larger residential developments, especially unit blocks with common areas such as car parks, lifts and shared gardens. These features can influence the overall BASIX outcome and should be documented clearly. NSW Planning Portal
For example, common garden irrigation may affect water commitments. Lifts and car park ventilation may affect energy use. Shared pools and spas may affect both water and energy. These systems are part of the building’s performance, not just background infrastructure.
Central systems are common in apartment buildings. NSW Planning describes a central system or facility as a system or facility that services more than one dwelling. BASIX assesses energy used by central systems and common areas in multi dwelling developments, including central hot water, central cooling, central heating, alternative energy sources, lifts, pools, spas and other measures. NSW Planning Portal
If an apartment project includes central hot water, central heating or central cooling, the assessor needs enough information to describe the system accurately. This may include the fuel source, plant type, distribution, dwelling allocation and whether the system serves apartments, common areas or both.
Central water tanks can also be relevant in apartment projects. NSW Planning explains that a central water tank can be used in a multi unit development to supply water to common area uses, such as landscaping, car washing bays or cooling towers, or to more than one dwelling for private garden watering, toilet flushing or laundry. A central tank can collect rainwater or stormwater. NSW Planning Portal
These water systems need careful coordination. The assessor may need to know tank capacity, catchment area, common area uses, private dwelling uses and whether water is supplied to irrigation, toilets, laundry, cooling towers or other nominated uses.
Thermal performance can vary significantly between apartments in the same building. A ground floor apartment, middle apartment, corner apartment and top floor apartment may all have different exposure, glazing, roof conditions, shared walls and shading. Apartments on different elevations may also have different solar heat gain and cooling risks.
The BASIX thermal performance section aims to ensure thermal performance for dwelling occupants, reduce emissions from artificial heating and cooling and manage peak demand for cooling and heating. This means the apartment model or thermal assessment should reflect the actual building geometry, window exposure and construction assumptions. NSW Planning Portal
Ventilation can be more complex in apartment buildings because individual dwellings may use natural ventilation, individual fans, ducted systems or central ducted systems. NSW Planning states that for individual dwellings in a multi dwelling development, BASIX recognises options such as no mechanical ventilation, individual fans, individual fans ducted to facade or roof, central ducted systems and individual fans into central ducting with variable speed drive arrangements. NSW Planning Portal
This information is important because ventilation systems can affect energy use and documentation. The design team should confirm how bathrooms, laundries, kitchens, apartments and common areas are ventilated before the BASIX assessment is finalised.
Apartment BASIX delays often happen when the project information is not clear enough to assess each apartment and shared system properly. Common issues include:
For apartment and residential flat building BASIX assessments, the assessor needs enough information to understand both the apartments and the building-wide systems. Clear schedules are especially helpful because large residential projects often have repeated apartment types and shared services.
Useful documents and details include:
Certified Energy prepares BASIX Certificates and NatHERS assessments for apartment and residential flat building projects across NSW. Our team can review the plans, confirm the likely BASIX pathway, identify missing information and coordinate the assessment across individual apartments, common areas and central systems.
This is especially useful for residential flat buildings, apartment blocks, mixed apartment types, projects with central services, developments with lifts or car parks and larger residential projects where water, energy and thermal performance need to be coordinated before lodgement.
Send your apartment plans to Certified Energy and our team can review the BASIX pathway, missing information and central system requirements.
Request a ReviewYes. BASIX applies to new residential developments in NSW, including apartments and residential flat buildings. The BASIX assessment may need to include each apartment, common areas, central services, lifts, shared gardens and other building-wide systems.
The NSW Planning Portal project type guidance says users enter the number of residential flat buildings and, for each building, the number of dwellings or apartments and the number of storeys.
Common areas that can affect apartment BASIX include car parks, lifts, shared gardens, pools, spas, plant rooms, central hot water, central heating, central cooling, alternative energy systems and common area lighting or ventilation.
An assessor usually needs the project address, site plan, apartment floor plans, dwelling schedules, elevations, sections, roof plan, window details, construction and insulation details, common area information, central systems, lifts, hot water, rainwater, solar, pools, spas and any shared infrastructure details.