The Science of Round Buildings

    Many consider round buildings to be more comfortable, more energy efficient and even safer.

    Q: I’ve heard there are inherent advantages to having a “round house.” Can you expand on this?

    A: The oldest forms of indigenous shelter were often round. Think of the Southwest American hogan, the Mongolian yurt, the North American teepee and the Greek temenos. Why did our ancestors choose to build round? Because an ovoid shape — like that of eggs, the earth, tree trunks and stones — is what they saw reflected in their natural environment and, as usual, Mother Nature knows best.

    Today, the rounded shape still has great value when it comes to our homes. In fact, there is some interesting science at play that makes round buildings more comfortable, more energy-efficient and even safer. Here’s how.

    Safety. Wind and tsunami waves move naturally around a round building rather than getting caught at and potentially ripping off corners. And a rounded roof avoids “air-planing” — a situation where a strong wind lifts the roof structure up and off the building.

    There are dozens of interconnected points in a round home. These are sites where builders can connect parts of the building together. In the old days, the connecting materials were rope, vine and hides. Modern materials are engineered components — like a center radial steel ring, steel brackets, seismic and hurricane ties, bolts and steel cables. These pieces connect the structural pieces and give the building a unique combination of flexibility and strength — qualities which cause them to be significantly safer in severe conditions like earthquakes, extreme winds and heavy snowfall.

    Strength. The roof structure of a round home incorporates a unique architectural design that has its origins in the mountain steppes of Central Asia. Roof trusses meet in a center ring, producing inward and outward pressure which holds the roof in a state of compression. In modern round buildings using the ancient yurt design, one to three airplane-grade steel cables circle the outer perimeter where the trusses meet the wall and hold the natural outward thrust. Because of this combination of a central compression ring at the top of the roof and the encircling cables, where the roof meets the walls, long roof spans are possible without any internal support system like beams or posts. The interconnected tension in the building goes all the way to the ground and uses gravity and compression to hold it together with incredible strength.

    Efficiency. The natural thermal dynamics of a round space uses no external energy to circulate air. Warm air naturally rises until it reaches the insulated ceiling. It then moves up the domed surface until it reaches the center skylight, which is cooler, and the air reacts by descending to the floor where it moves across to the walls and rises again until it meets the skylight and drops again. This action constantly circulates the air and temperatures in the home, draft free.

    Space. Round buildings use less wall, floor and roof materials to enclose the same square footage as a rectangular structure. Between 15 and 20 percent less material is needed to create the same square-foot building compared to a rectangular design. This creates the possibility for a smaller eco-footprint and more living space for less cost. It also means less surface area in contact with adverse weather conditions, which improves the overall durability and efficiency of the home.

    Sound. The acoustics of a circular space are extraordinary. The curved ceiling both softens and brightens the sound inside the building. The shape also prevents noise from penetrating in from the outside. Sound waves dissipate as they wrap around the building, shielding the interior from loud outside noise.

    Positive energy. Our ancestors also understood another, less measurable, aspect of circular living. Living in a round home provides a balance of looking inward and outward, looking out at the natural environment and surroundings but then coming in again to the self and the heart.

     A 21st-century round home built with modern materials can be a safe, efficient and healthy home of the future with roots in the past. You may want to think round when shopping for or building your next home.
    (this article originally appeared in The Seattle Times, Home Trends)