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On sale now – a stocktake of low-carbon options for retail centres

Retail By Binaya Karki, Associate, Building Services – 01 November 2021

Marrickville Metro Shopping Centre
Computer generated image of the front entrance of a large retail centre in the evening, illuminated from the inside

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Binaya Karki in middle of a park with blurred trees and grass background

Binaya Karki

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Retail centres are complex built ecosystems. They typically occupy large land footprints and have an insatiable thirst for power and water. Add to this the tenancy and consumer waste, and you have a unique sustainability challenge.

But there is hope. We are finding a shift from asset owners to embrace low-carbon approaches. The real opportunity for retail centres is to utilise all the tools in the sustainable design and building services kit including fabric, building systems, operations, energy and even mobility.

In effect, a retail centre done well is proof for the public that net zero is achievable right now and on scale, using available technologies.

Driving this shift are two considerations. One is the momentum by retail centre portfolio owners to achieve verified carbon neutrality. Vicinity Centres, for example, has a target of net zero by 2030. They hold one of Australia’s largest retail portfolios, including a substantial number of regional centres with SME retail tenants. They are not alone. Asset owners and operators in this sector have an appetite for finding ways to decarbonise operations and shrink environmental footprints while also improving operational cost-effectiveness.

Many tenants are also starting to pursue the ESD agenda. Large anchor tenants such as Coles, Woolworths and others are adopting net zero and waste reduction targets with publicly stated ambitions. The flow-on effect to smaller tenants is evident with an increased awareness about the opportunities to include energy-efficiency – and potential zero carbon aspirations – in their own approach.

Because retail centres are complex assets, one of the over-arching considerations from an engineering design perspective is to make the solutions as simple as possible. This applies to both new centres such as Stockland’s Birtinya, and to the refurbishment, upgrade and expansion of existing retail centres, such as our recent work on the Marrickville Metro project.

Passive Design is one approach we have been incorporating with clients for over a decade. This approach looks at aspects such as orientation, building fabric, strategic shading for summer and insulation.

Natural ventilation or mixed-mode ventilation is the alternative to conventional approaches of designing a big box with big air conditioning systems. It improves indoor air quality as well as lowering energy use. The use of modelling here is key. Engineering modelling helps ensure the laws of physics to provide part of the cooling and airflow at minimal cost. We used this to great effect at the Marrickville project where we modelled the principles of thermal stratification in combination with a massive fan.

Instead of a typical consultancy approach of sizing mechanical plant for peak load – which means a massive energy-guzzling chiller – we start by getting the passive design right and then design for energy efficiency based on the annual energy use. This has significant compounding benefits.
It means we can use multiple, smaller chillers and – in combination with building automation systems experts – configure comfort levels and HVAC operations for when it is most needed, instead of a 24/7 default operation.

When air starts to cool down outside towards sunset, increased outdoor air intake tempered by the HVAC system will use less energy than operating the HVAC at the same set point and recycling indoor air.

One of the major advantages retail centres have from a design perspective, is having a large roof to floorspace ratio. So unlike a tower-type building, there is significant roof space available for solar PV.

An integrated thinking approach can combine solar PV with providing shade for rooftop parking – so the panels provide a more comfortable parking environment and help power the centre. This also resolves one of the common problems for retail around providing sufficient parking for customers.

This can also be taken one step further towards low-carbon mobility by providing EV charging spaces powered by the centre’s own solar generation. Where feasible, this is an initiative we are introducing more often on our projects. We believe the next evolution of this trend will be provision of EV share car spaces and charging facilities so fewer people generate fuel emissions as part of their retail experience.

We are already designing all our retail projects to be future-ready for EVs by incorporating the means to connect the charging infrastructure. It’s a similar situation with renewable energy storage batteries. We ensure they can be connected when the time comes that the asset owner is ready to procure them.

The remaining piece of the net zero retail picture is removing gas from the equation. This remains a challenge particularly for food and beverage tenants: there remains a false perception that food cooked via induction is different. –In fact, food is less likely to be over-cooked, as induction provides more instantaneous temperature control than gas.

Where gas has traditionally been used for other purposes such as hot water and space heating are effectively being phased out by more efficient, cheaper electric solutions.

The key to parcelling up all the energy-efficiency, renewable and passive measures in one functional, cost-effective and customer-centric asset is holistic thinking. We have something of an advantage in this respect as our disciplines including mechanical, lighting, electrical, hydraulic, acoustic and ESD all work within a collective digital model. We are all speaking the same language – and net zero is the goal we are all striving towards.

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