Australia is great at delivering conditioned air. But our bodies don’t experience comfort as airflow and kilowatts, they read it as calm, even, radiant warmth. That’s the idea I wanted to explore with Ozge Fettahlioglu, someone who treats thermal experience as a first-class design layer, not an afterthought.
Ozge is the founder of Cocoplum Wellness Design, a global interior design studio specialising in biophilic design, neuroarchitecture, and modular construction for high-end residential and hospitality projects. Known as Madame Cocoplum, Ozge is a keynote speaker, a board member of Biophilic Cities Australia, and a leading voice in wellness-driven design. Her mission is simple and bold: create spaces that heal, inspire, and elevate everyday living.
In our conversation we look into the physiology of how people actually feel rooms. We talk radiant warmth as nature’s default, the nervous system as your toughest client, and the practical detailing that makes stone, timber, and touchpoints read as quietly sun-warmed on purpose.
Giovanna: Ozge, let’s start bluntly. Most Australian homes chase comfort with fans, ducts, and bigger compressors. You argue the body reads comfort differently, almost pre-cognitively. What does the body “notice” before the architect thinks they’ve designed comfort?
Ozge: The body measures before the mind admires. Thermoreceptors in the skin report to the hypothalamus within a heartbeat. If warmth arrives as steady and even radiation, like sun-warmed stone, the nervous system drops into a parasympathetic state: calmer heart rate, easier breathing, clearer focus. That happens long before anyone notices the staircase detail or the chandelier.
Giovanna: You use the phrase “thermal biophilia” – not standard spec language. Translate it for a drawing set: where does it live in a plan, a section, a schedule?
Ozge: Think of it as a design layer that sits with light, materiality, and acoustics. In plan: where bodies dwell (such as lounges, work zones, spa suites) should have surfaces that hold and release heat gently such as timber or stone. In section: prioritize radiant exchange to people, not air volume. In schedules: call up finishes and systems that create sun-like, quiet warmth: radiant floors, low air movement, and materials with thermal inertia.
Giovanna: Many here in Australia default to “air first” thinking. Give me a rule-of-thumb shift when choosing radiant.
Ozge: Ask: “Do I want to heat air, or people?” Radiant warms bodies and surfaces directly, so you can sustain comfort at lower air temperatures with less sensory noise. The research (Karmann et al. and long-horizon reviews in Building and Environment) consistently shows this effect: lower set-point air temperatures for the same or better comfort because radiant exchange is doing the heavy lifting.
Giovanna: Lower air temperatures are a nice line in a brochure. What does that feel like in a lobby, a living room or a guest suite?
Ozge: Quieter, steadier, and more trustworthy. No “whoosh,” no hot-then-cold swings. Surfaces read as naturally warm, like stepping onto sun-touched timber. People feel cocooned without the energy penalty or the micro-drafts that make them fidget.
Giovanna: Let’s talk brains, not brochures. You cite work from Energy and Buildings on physiological stability. How does that matter to an architect planning a wellness retreat or a focus space in a school?
Ozge: Radiant systems, especially when paired with good control, stabilise skin temperatures and heart-rate variability. That stability supports attention and calm. In practice: fewer temperature “events” across a day. For a retreat, that’s deeper rest. For a classroom or office, it’s better sustained focus.
Giovanna: Australian reality check. We design for mixed modes, for cost, for construction speed. Where does radiant warmth win without asking the client to rebuild their budget?
Ozge: Three places:
Sensory-critical zones, meaning reception, treatment rooms, premium suites etc. where first impressions and quiet matter.
Contact-rich areas where bare feet meet floors: bathrooms, bedrooms, spas, wellness studios, living zones.
Spaces with high finish value, such as stone or engineered timber, which want to be gently warm, not blasted by air.
Giovanna: In previous articles of your, you romanticise stone that “remembers” sunlight. Beautiful but give me a detailing note that honours that poetry.
Ozge: Keep the heat source close to the touch layer and distribute it evenly. Avoid point-hot coils under “cold spot” materials. Aim for broad, ribbon-like emitters or hydronic plates that deliver uniform surface temperature. The sensation you’re designing is evenness.
Giovanna: Architects here will ask: how do I brief controls, so the space feels like sunshine, not a thermostat war?
Ozge: Specify gentle ramps, not aggressive set-point chasing. Use surface temperature limits appropriate to the finish and pair with low-movement background air. The goal is a stable radiant backdrop; air is the fine-tune, not the headline act.
Giovanna: Where have you seen radiant warmth misunderstood or misapplied?
Ozge: When it’s treated as a luxury add-on rather than a primary sensory layer. If it’s value-engineered late, you end up with patches of heat, uneven floors, and frustrated users. Integrate it at concept stage with lighting and acoustics, that’s where it belongs.
Giovanna: Let’s push beyond residential comfort. What can thermal biophilia do for brand experience in hospitality or wellness?
Ozge: It builds trust. People can’t articulate why a room feels safe and restorative, but they return to it. Radiant warmth is legible to the nervous system as “nature-like.” That’s a brand asset as real as your material palette: calmer guests, longer dwell, better reviews.
Giovanna: Final challenge. Finish this sentence for Australian project teams: “If we can design for what the eye sees…”
