Over the past few code cycles, the Building Energy Efficiency Standards have doubled in size. In addition to gains in energy efficiency, there has been an increase in complexity. This complexity gives way to opportunity and options for compliance. The Prescriptive Approach and Performance Approach to energy modeling are two different techniques used to demonstrate compliance with Title 24 energy standards. Each technique has its own advantages and disadvantages, and it is up to each project team to decide which one will suit them better.
The Prescriptive Approach is the simpler method. If all minimum requirements are met, the project meets code. The Prescriptive Approach does have a major disadvantage: it limits flexibility and eliminates the option for tradeoff benefits of energy improvements that are in the design. This can lead to higher construction costs.
On the other hand, an energy model allows for potential flexibility. Not all of the minimum prescriptive requirements need to be met in order to meet energy code compliance. The Performance Approach is more complicated and it requires the architect, energy modeler, and engineers to be in constant communication with each other to select equipment and systems that will satisfy the energy model. However, the added flexibility can enable projects to use more glazing than prescriptively required or forego the need for rigid insulation, as long as the energy model shows that the resulting losses are compensated for with energy efficiency measures. This sort of flexibility can lead to great savings in construction costs.
With the Performance approach, VCA Green has been able to save clients $650k to $1.5 million on construction costs. Contact us to find out more – Moe Fakih, Principal 714-363-4700
Contributing Writer: Albert Luu