Engineering Principles

"Compound Curved Sandwich Shell Structures" (c2s3™ for short)

DomeShells c2s3™ Technology combines two fundamental engineering concepts - the structural qualities of the compound curved shell, and the structural qualities of the sandwich panel.

Strength of the Compound Curve

In compound curved structures, the strength of the arch is magnified because energy forces are distributed both downwards and sideways. The eggshell provides a simple illustration of this principle. Try crushing an egg by placing its ends between your palms and pressing hard. You’re more likely to hurt your hands than crush the shell.

Like the eggshell, DomeShells take advantage of the inherent strength of the compound curve. The gravitational stresses in the overhead section are distributed out and around, enabling the building to be self-supporting without the need for beams, walls or columns.

Sample of the shell panel - A core of polyurethane foam sandwiched between two Glass Fibre Reinforced Concrete structural skins.

Strength of the Sandwich Panel

The second element of c2s3™ Technology is the ‘sandwich’ panel which is both lightweight and extremely strong.

The basic principle of sandwich construction is to separate two load-bearing skins with a lightweight core material. In a sandwich panel under load, one skin is under compression while the other is in tension. The further apart the skins are, the greater the stiffness of the panel.

Thermal Performance and Energy Efficiency

The core of the sandwich panel is a structural, close celled polyurethane foam which is one of the most efficient insulating materials available. Closed cell polyurethane is reported to be up to 97% efficient compared to some traditional systems which can be as low as 35% efficient. The minimum core thickness of 60mm (for DomeShells from 4.0m to 10.0m diameter) represents R Value R3.0 under the Australian Value Code.

The following independent expert assessment was recently commissioned to demonstrate the thermal performance features of a typical home under New South Wales latest regulations addressing thermal performance.

Simulation Assessment by Dr Peter Lyons (PhD Physics, M.ASHRAE).

Dr Peter Lyons is an active committee member of the U.S. National Fenestration Rating Council (NFRC) and ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) NFRC Accredited International Trainer. This assessment has been certified by ABSA Certificate No. 73976671

Typical Example - Byron Bay Home, Australia
Local Authority Requirement	Actual values
BASIX Annual Energy Load Targets	150m2 (conditioned floor area)
(Max. Load) for dwelling -	3, interconnected, dome home
Climate Zone: 10

Cooling (L&S):	82.6 MJ m2/yr	40.2 MJ m2/yr
Heating:	63.1 MJ m2/yr	56.2 MJ m2/yr
Total Cooling & Heating	145.7 MJ m2/yr	96.4 MJ m2/yr

A saving of 49.3 MJ m2/yr above the Australian Energy Efficiency target.