Kallista
Project Overview
Kallista is one of the most technically and creatively demanding projects I have worked on. It was designed during my time as a lead designer and Passive House consultant at Maxa Design, where I worked under director Sven Maxa from 2012 to 2015.
The project involved navigating seven overlapping planning overlays, pioneering a construction method developed specifically for an inaccessible rainforest site, and achieving Passive House performance in a cold, heavily shaded environment where conventional sustainability strategies could not apply.
The home was commissioned by Ann and Allan. Ann is an artist and sculptor whose sensibility shaped every curve and surface of the project. Allan is a retired civil engineer with a lifetime’s experience designing and constructing refineries and major infrastructure, who owner-built the home with characteristic precision and commitment.
They had previously built two homes as owner-builders, one of them on a complex rainforest site in the Blue Mountains, and they brought that experience and confidence to what became an extraordinarily ambitious undertaking.
The completed home received a Commendation for Best Energy Efficient Design (Residential) and a Commendation for Excellence in Use of Steel at the Building Designers Association of Victoria Awards in 2018. It has been published in Sanctuary Magazine, The Age Domain and the Herald Sun, and featured in Better Homes and Gardens.
This project is gratefully featured with the kind permission of Sven Maxa of Maxa Design. The full project profile is available at maxadesign.com.au. A full acknowledgement and acceditation details are here.
Project Details
- Location: Kallista, Dandenong Ranges, Victoria
- Project Type: New Home, Remote Rainforest Site
- Standard: Passive House Principles Throughout
- Construction: Prefabricated curved LVL ribs, longitudinal LVL beams, curved plywood and corrugated steel envelope. Cast Reinforced Concrete Piers and Steel Framed Substructure with Timber Infill. Â
- Site: Steep gradient, 1.5 acres, BAL 29, mountain ash rainforest
- Planning Overlays: Seven including BAL 29, Green Wedge A, Erosion Management Overlay, Significant Landscape Overlay
- Services: Rainwater harvesting and recirculation for fire suppression, worm farm waste treatment system, heat recovery ventilation, heat pump hot water and space conditioning
- Completed: 2018
- Owner-Builder: Allan
- Structural Engineer: Rob Nestic, STFAB/TGA Engineers
- Design Practice: Maxa Design
- Lead Designer and Passive House Consultant: Niall O Healaithe
- Awards: BDAV Commendation, Best Energy Efficient Design 2018; BDAV Commendation, Excellence in Use of Steel 2018
- Published: Sanctuary Magazine Issue 45, The Age Domain, Herald Sun, Better Homes and Gardens
- Photography by Sunpath, Featured with permission of Maxa Design
- Video by Bell Real Estate Olinda
Log Inn
A charred fallen log on the site became the genesis of the entire design. Lying diagonally across the slope, spanning between three high points of ground, touching the earth lightly at only those points, it had a minimal footprint, allowed water and animals to pass freely beneath it, and belonged completely to its environment. It was not a precedent to reference but a model to follow.
The completed home is a single-level elliptical volume elevated above the steep site on prefabricated structural ribs, projecting across the slope in the same way the fallen trunk had done. The curved form prevents leaf litter accumulation on the roof and supports ember shedding as required under the site’s BAL 29 bushfire attack level rating. The elevated structure creates clear space beneath the building, allows vegetation to continue growing around and beneath it, and reduces ground disturbance to the minimum required for the concrete piers and below-ground services.
From within, sweeping views of the mountain ash forest are visible through generous triple-glazed windows. The grey gums and Victorian ash trees that the council required be protected are present in every outlook, framed and celebrated.
Ann and Allan
Ann and Allan are the kind of clients who make an architect’s work genuinely meaningful.
Ann’s sculptural sensibility is present in every curve of the building, in the warmth of the interior materials and in the quality of attention brought to every detail.
Allan’s engineering rigour and his willingness to take on the extraordinary challenge of owner-building a project of this complexity is something I have rarely seen matched. He managed a construction process that required coordinating specialist fabricators, engineers, tradespeople and suppliers across a remote and difficult site with the same precision he had applied to major civil infrastructure throughout his career.
Visiting the completed home and spending time with Ann and Allan in a space we had worked so hard together to realise was one of the defining experiences of my early years in Melbourne. I am grateful to them both for the trust they placed in me at a point in my career when I was still establishing myself in a new country.
Construction Method
Prefabricated Curved LVL Structure
The inaccessible nature of the site, accessible only via an unpaved track down a 15-degree slope through dense rainforest, ruled out conventional construction methods requiring large vehicles and heavy equipment on site for extended periods. The solution was developed collaboratively between myself, structural engineer Rob Nestic of STFAB/TGA Engineers, and owner-builder Allan, whose civil engineering experience proved invaluable in developing a construction sequence that worked within these extreme constraints.
The structural system uses curved ribs of laminated veneer lumber (LVL), fabricated off-site by Rob Nestic’s team. Each rib is formed from curved sections of LVL laminated together to create the elliptical cross-section profile, analogous to the ribs of a boat hull or the sections of a bent spine. Longitudinal LVL Beams and noggins space the ribs apart and provide rigidity, and curved plywood sheeting applied to the full envelope provides both structural diaphragm action and the airtight layer required for Passive House performance.
The design uses two constant radii: one for the top and base of the ellipse and one for the sides. This geometric simplicity, developed with Rob to make fabrication as efficient as possible, means every rib of each type is identical, allowing batch fabrication in a factory and delivery to site on standard trucks. Every component was sized to be carried and lifted by two people, eliminating the need for cranes or heavy lifting equipment on the slope.
Construction Method
The construction sequence was carefully planned to minimise site disturbance and allow rapid lock-up before the cold rainforest winter. A minimum clearing zone was established. Below-ground tanks and systems were installed first within the building footprint. Bored concrete piers were then drilled and poured, extending above ground level. Steel beams spanned between the piers, allowing a level deck platform to be created by infilling between beam webs with timber members and sheeting, minimising the need for scaffolding on the slope.
All subsequent structure was achieved in timber. The prefabricated LVL ribs were lifted by hand into position and fixed to the deck and to each other through the longitudinal noggins. The curved plywood envelope was applied progressively, with the gutter and pier lines forming seamless transitions between the two radius curves. Triple glazing and all mechanical systems were installed within the completed shell.
The result is a building that arrived on site in manageable components, was assembled by hand with minimal ground disturbance, and was locked up and weathertight within a construction programme that respected both the environmental sensitivity of the site and the constraints of a remote rainforest winter.
Concepts and Design Process
Seven Overlays and One Fallen Tree
The site presented what might politely be described as a comprehensive set of constraints. Seven planning overlays applied simultaneously: BAL 29 bushfire attack level, Green Wedge A zoning, Erosion Management Overlay, Significant Landscape Overlay, and requirements for land capability assessment, vegetation protection and environmental significance. Council required the established mountain ash and grey gum trees to be retained. The 15-degree slope, the unpaved access track and the dense overhead canopy that limited both solar access and construction vehicle movement completed the picture.
Most sites have one or two difficult constraints. This site had seven operating simultaneously in partial conflict with each other. The vegetation protection overlay required trees to be retained; the bushfire overlay required the landscape to be managed for fire risk. The slope required an elevated structure; the erosion management overlay required minimal ground disturbance. Meeting all seven simultaneously required a design solution that was not a compromise between them but a response that turned each constraint into a generative force.
The fallen mountain ash trunk lying across the slope provided that solution. Its elevated form addressed the slope and the erosion requirements. Its minimal footprint addressed the vegetation protection requirements. Its curved form addressed the bushfire requirements. Its quality of spanning lightly between points of contact addressed the geotechnical uncertainty. It was not a metaphor applied to a conventional design; it was a direct model for how a building on this site could exist.
Passive House Features
A heat recovery ventilation system, heat pump hot water and space conditioning were selected and sized based on the PHPP outcomes.
This was one of the first projects in Australia to apply Passive House principles, and none existed in a rainforest environment of this type. It demonstrated that the standard’s methodology, when rigorously applied, could deliver comfort and performance in conditions where passive solar strategies were simply not available.
Achieving Passive House performance in a heavily shaded, cold and damp rainforest environment required a fundamentally different approach from our typical sunny north-facing projects. The dense overhead canopy limited solar gain to a fraction of what would normally be relied upon. The cold wet winters created significant condensation risk. The BAL 29 rating constrained glazing areas and required fire-resistant detailing at every envelope junction.
A heat recovery ventilation system providing constant filtered fresh air throughout the home and recovering warmth from exhaust air. In a damp rainforest environment prone to condensation, the controlled ventilation of a sealed Passive House envelope is particularly valuable, eliminating the moisture accumulation that affects conventionally ventilated buildings in this climate.
Read our full guide to Passive House / Passivhaus here.
Off-Grid Systems & Sustainability
The performance measures include:
A prefabricated LVL and curved plywood envelope providing continuous insulation and an airtight shell, with every junction and penetration detailed to eliminate air leakage and thermal bridging. The curved geometry required specific airtightness detailing at the rib-to-plywood connections and at the gutter transitions between the two radius curves.
Triple-glazed windows selected and positioned based on PHPP modelling, balanced against the BAL 29 constraints on glazing area and specification. The orientation and shading analysis for a heavily canopied rainforest site required a different approach from standard Passive House solar gain optimisation, with the PHPP used to verify that the envelope performance was sufficient to compensate for the reduced solar contribution.
A rainwater harvesting and recirculation system serving both domestic water supply and fire sprinklers integrated into the roof structure, a dual-purpose solution that addressed both the site’s off-grid water requirement and the BAL 29 fire suppression requirements simultaneously.
An underground bushfire shelter was also installed as a place of last resort.
A worm farm waste treatment system appropriate for the remote location with no access to mains sewerage, selected for its low maintenance requirements and environmental compatibility with the rainforest setting.
The project received a BDAV Commendation for Best Energy Efficient Design (Residential) in 2018, recognising both the performance outcomes and the ingenuity of the approach that achieved them within one of the most constrained sites on which a Passive House has been designed in Australia.
A Note on This Project and an Acknowledgement
Kallista was designed during my time as a lead designer at Maxa Design, where I worked under director Sven Maxa from 2012 to 2015. It is featured here with Sven’s generous permission and I am grateful to him for it.
I arrived in Melbourne in 2012 having left a practice I had co-founded in Dublin where I had spent six years designing residential and small commercial projects. The global financial crisis and the Irish banking collapse had made continuing practice in Ireland impossible, and the decision to emigrate with my partner was one made from necessity as much as aspiration. Starting again in a new country, without a local professional network, without Australian registration, and without the portfolio of local projects that clients and employers look for, was not straightforward.
As many of the fellow immigrants to this country understand, you give up so much when you leave your home, but you also gain so much when you are fortunate enough to make Victoria your new home.
Sven gave me my first real opportunity in Melbourne. He hired me based on my portfolio and my evident commitment to sustainable architecture at a point when some practices would have hesitated over my unfamiliar credentials and Irish registration. He promoted me to lead designer, trusted me with ambitious projects, and gave me the creative freedom that allowed me to grow quickly and to produce work I am genuinely proud of. He encouraged me to pursue my Passive House Designer qualification and supported my study. He later encouraged me to register as a building designer and to re-register as an architect in Victoria so I could establish my own practice.
Beyond the professional opportunity, Sven and his wife Dawn and their family and my colleagues Alex, Lauren, Simone and Katrina welcomed me warmly at a time when I was far from home and still finding my feet in a new city and a new country. That warmth and generosity meant more than I can adequately express.
Sven is not only a skilled practitioner but a long-term advocate for sustainable design and a passionate spokesperson for Passive House principles in Australia. His practice Maxa Design continues to produce distinguished work from their studio in Blackburn. I recommend them without reservation to anyone whose project does not suit my own practice’s focus, and I consider Sven a colleague, a mentor and a gentleman.
Maxa Design can be found at maxadesign.com.au.
This project remains the intellectual property of Maxa Design. Images and content are reproduced here for portfolio reference purposes with the permission of the director.
“Our house is lovely to live in and we thank you for your creative genius”
Ann & Allan, Kallista 2019
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