In recent years, developers have turned their attention to what was once the most overlooked and underutilised space on a building: the rooftop.

Historically reserved for plant space and kept well out of the public eye, resort-style rooftop amenity is now rarely excluded from qualifying new luxury residences, and for good reason. 

The 2016 ABS Housing and Population Census showed that in just 25 years, occupied apartments in Australia had risen by 78%. Of those apartment types, 38% were high rise apartments of four or more storey blocks. 

Populations, urban density, and residential city towers are all on the rise, as are private, landscaped garden rooftops complete with alfresco dining areas, sparkling lap pools, wellness hubs and stunning views. 

As populations in high-density urban areas are more likely to be limited in green space and ecologically diverse environments, it is these residents who are set to benefit most from rooftop spaces in which to unwind, reset and entertain guests.

Advantages to the development of green rooftop amenity, in particular, are numerous and well documented (NSW Government). At a glance, green rooftops can be engineered to: 

1. Utilise natural resources to run building services 
2. Add value and liveability to high-density apartments 
3. Provide functional, interactive design features 
4. Improve sustainability ratings 
5. Provide multi-use, public recreational space 
6. Block out street noise 
7. Help cool the air and promote natural airflow 
8. Insulate a building and help save on energy bills 
9. Accommodate community gardens and water features 
10. Provide a place for native animals and plants to live and feed.

Studies show a well-planned rooftop can provide significant uplift in occupant health and wellbeing, not to mention sustainability outcomes. 

This is especially true when the focus is on biophilic design philosophies or biophilia. 

What is biophilia? 

By definition, biophilia in architectural design is about connecting with, rather than imitating nature. Therefore, biophilia is about creating an interplay between the built and natural environment that sparks meaningful connection. 

Biophilia is the term coined by the Harvard naturalist Dr Edward O. Wilson to describe what he saw as humanity's 'innate and genetically determined affinity of human beings with the natural world.' 

In other words, humans are drawn to connect with nature, and we are happier and healthier when we do. 

Numerous studies link environmental immersion to physical and cognitive health benefits, longer life expectancy, improved life quality and work productivity. 

In fact, the Council on Tall Buildings and Urban Habitat (CTBUH), posits that 'healing and recovery are enhanced in environments that engage with their natural surroundings.' 

Healthy individuals contribute to enriched communities, and enriched communities contribute to higher standards of living, better economies, and more sustainable futures. 

This positively geared cycle has sparked a new interest in biophilic design that puts a higher standard of living at the fore. As a result, many new high-rise residential developments feature functional, cohesive green spaces as key aspects of the design:

• One Central Park, NSW 
• Oxley and Stirling, QLD 
• 38 Westbury Street, St. Kilda, VIC

If rooftops really are one of the most critical spaces for maximising high-rise residential development potential, it raises an important question. 

Q: How can we efficiently optimise rooftop functionality and design, without compromising critical services?

Because, while rooftop use has changed, our need for plant space has not. 

We've outlined the main considerations for rooftop plant alternatives below. 

Mechanical Plant 

Architects and mechanical engineers are known for their disagreements, yet this love-hate relationship has inspired some of the most important innovations in mechanical plant design. 

Mechanical plant services and biophilic design can co-exist if the analysis is completed early in the design process.

Neuron's software can run multiple design scenarios quickly, delivering accurate services design options to minimise plant space in one of the most valuable spaces on new buildings. 

Hydraulic Plant 

Recycled rainwater processes for high-density buildings often look like this: 

1. collect water from the roof, 
2. drain water to a basement tank 
3. use energy to filter water 
4. use energy to pump the water (sometimes back to the roof). 

Tanks, solar hot water and gas boilers are the most common hydraulic engineering considerations on rooftops. Configurations largely depend on the project size and location.

However, there are multiple ways to develop a cohesive interplay of rooftop green areas and water storage, bearing in mind that: 

• rooftop shading structures can be engineered to retain water, either around cores or above a column, for gardening, water features and cleaning purposes. 
• open rooftop spaces will naturally capture rainwater and support community gardens. 

Electrical Considerations, i.e. Solar 

While covering the entire rooftop in solar PV may appeal to the embedded network provider, creating a holistic approach to rooftops guarantees liveability alongside sustainability. 

Integrating smart solar PV solutions provides an opportunity for all stakeholders to: 

• reduce common area electrical costs through a balanced offset of PV cells 
• protect residents utilising the rooftop from northern and western sun exposure 

As technology improves, facade integrated solar PV will become more prevalent, allowing design flexibility throughout the building and in future uses. 

Conclusion 

Despite the myriad benefits of green rooftop spaces, the outdated notion of 'plant goes on the roof' lives on. 

Fortunately, Neuron can efficiently and accurately test the impact of various rooftop design scenarios to ensure all of the needs of a development and its occupants are finely balanced. 

We are here to provide alternatives early in the design process for you, your development, its future residents, their communities, and our planet. 

Ready for a demo? Contact our NSW Engineering Lead, Steven Cassells at steve@neuron.build or visit www.neuron.build to run a free pilot project through our software!