Optimizing structural roof form for life-cycle energy efficiency

• Vaulted roofs can reduce embodied energy by over 40% relative to flat slabs.
• EE savings are equivalent to as much as 35 years’ worth of operational energy.
• Energy saved cumulatively over a 50-year life cycle is close to 25%.
• Savings result from significant reductions in both steel and concrete.
• Segmental and parabolic vault forms provide similar energy savings.

This study evaluates the potential for life-cycle energy savings in buildings through the use of efficient structural roof form. A simulation-based optimization methodology was developed for comparing the energy requirements of reinforced concrete structures based on conventional flat slabs with those employing alternative vaulted spanning elements, in which the required quantities of high embodied-energy materials like steel and cement may be significantly reduced. The modeling framework combines structural and thermal analyses for the respective quantification of embodied and operational energy. It accounts for local conditions influencing material production and transport, code requirements for structural reliability and serviceability, and heating and cooling demands over a 50-year life span. Results clearly show the potential of non-flat structural roof forms to reduce life-cycle energy consumption – with maximum savings of over 40% in embodied energy and of nearly 25% in cumulative life-cycle energy. This model may be implemented from the early design phases for achieving environmentally responsible buildings.