By Eamonn Ryan
When it comes to designing buildings that consume minimal energy, engineers and architects often look to cutting-edge technology, advanced HVAC systems and solar panels.
Termites construct complex mounds that self-regulate temperature through passive ventilation
Ingeborg Korme | Unsplash
But according to Max Rohr, director of education at Caleffi North America, some of the most inspiring solutions come straight from nature.
In a recent ASHRAE Journal Podcast, Rohr shared his insights on zero energy buildings and the role of biomimicry – learning from natural processes and animals to create more energy-efficient structures. “Animals have evolved to thrive in their environments with minimal energy. If we study them, we can find strategies to reduce the energy footprint of buildings,” Rohr explained.
Biomimicry offers profound lessons for building designers. Rohr explains that animals have evolved to survive and thrive with minimal energy, and humans can learn from these strategies to reduce a building’s energy footprint.
For example:
• Elephants’ ears as natural radiators: The large, vascularised ears of elephants dissipate heat passively. Designers can mimic this principle by creating surfaces that naturally regulate temperature, reducing reliance on mechanical cooling.
• Polar bear insulation: Polar bears maintain warmth in harsh climates with minimal energy expenditure due to their highly insulating fur. This translates directly to building envelopes – well-insulated walls, roofs and windows can drastically reduce heating and cooling loads.
Perhaps the most striking architectural example is the Eastgate Centre in Harare, Zimbabwe, inspired by termite mounds. Termites construct complex mounds that self-regulate temperature through passive ventilation. The Eastgate Centre uses this same principle: as the building warms, hot air rises through chimneys and exits, drawing in cooler air at lower levels. The result is a building that uses up to 35% less energy than comparable structures in the area, without relying on energy-intensive HVAC systems.
The lesson for designers? Observe, understand and adapt the environment rather than fight it. By studying how animals manage heat, conserve energy and regulate their internal environments, architects can develop buildings that are inherently more efficient. This might include optimising natural ventilation paths, enhancing insulation or designing thermal mass that absorbs and releases heat at the right times.
Rohr also shared how this thinking translates to modern hybrid systems, such as the ASHRAE headquarters in Atlanta. By combining radiant hydronic heating and cooling with forced-air ventilation, the design team created a system that responds efficiently to changing occupancy and weather conditions. The building’s envelope was optimised to reduce energy demand from the start – less glass, more insulation and smarter orientation – so that mechanical systems only needed to supplement, not dominate, the building’s energy balance. Solar panels completed the zero energy equation, providing locally sourced renewable energy to offset what little the building consumes.
The lesson is clear: nature is a blueprint for efficiency. Whether it’s mimicking the cooling ears of elephants, the insulation of polar bears, or the self-regulating mounds of termites, Rohr encourages designers to look globally and locally for inspiration. “Adapt your site first. See how animals and nature solve thermal problems and incorporate that thinking before you even turn on a single machine,” he advised.
Biomimicry isn’t just a novelty, it’s a pathway to buildings that consume less energy, provide more comfort, and coexist with the environment rather than fight it. As Rohr puts it, “The cleanest energy is energy unused. If we can design buildings that naturally need less, we can make a real difference.”
BEYOND BIOMIMICRY: MODERN STRATEGIES FOR ZERO ENERGY BUILDINGS
Designing zero energy buildings involves more than mimicking nature. Rohr explains that it also requires a deep understanding of energy terminology, thoughtful system integration and practical trade-offs in building design.
Rohr emphasises the importance of sorting through buzzwords that often confuse stakeholders. Terms like electrification, carbon-neutral, zero emissions and zero energy buildings each have specific meanings:
• Electrification is the shift from direct combustion fuels to electricity, ideally paired with renewable sources.
• Carbon-neutral or decarbonised depends heavily on boundaries – what energy sources count, and where emissions occur.
• Zero emissions refers to a building or system producing as much energy from renewable sources as it consumes.
• Zero energy buildings (ZEBs) minimise energy demand through efficiency and then meet remaining needs with renewable energy.
Rohr notes that efficiency is the foundation: “You can’t just slap a billion solar panels on a leaky, inefficient building and expect it to work. Reduce the energy needed first, then balance the equation with renewable energy.”
THE CHALLENGE OF MODERN ARCHITECTURE
Modern architecture often conflicts with energy efficiency goals. Rohr humorously contrasts two extremes: a glass skyscraper with stunning views but high energy demand, versus an underground cave with constant natural temperature but no sunlight. While the cave is energy-efficient, it’s impractical for most office environments. The takeaway: architecture often drives energy demand, and engineers must innovate to reduce it within realistic design constraints.
Rohr shares lessons from his early experiences in hydronics versus forced-air systems, once considered rival trades. Today, buildings require hybrid approaches, combining radiant heating/cooling and forced-air ventilation. Radiant systems efficiently handle sensible loads, while forced air manages latent loads like humidity.
Standards such as ASHRAE 62.1 (ventilation) and 55 (thermal comfort) provide boundaries that prevent issues like condensation or discomfort, enabling hybrid systems to work in tandem. Additionally, ASHRAE Standard 90.1 guides energy-efficient design for building envelopes and system performance.
