Title 24: Performance vs. Prescriptive Approach to Compliance
Title 24 of the Building Standards Code in California is an energy efficiency standard which is used to make sure that buildings are efficient with their energy use. It is used not only for the design and construction of new buildings but also for new additions or alterations on existing buildings. This code is updated roughly every three years, and the latest installment of the code went into effect January 1, 2017. It is important to make sure that your building is operating in accordance with the code, since your local enforcement agencies may check whether your building does indeed comply with the new updated code. But while it is important to verify that your building complies with title 24 of the building code, many are confused about how to exactly go about achieving this compliance. There are two methods which you can use to verify this compliance: the Title 24 prescriptive method and Title 24 performance method. In this article, we will give a short overview of the difference between the two approaches, as well as the advantages and disadvantages of each.
The title 24 prescriptive method is known to be the simplest, most straight-forward way to meet the requirements of title 24. This is considered to be the simplest method because with this approach all you need to do is verify that each individual aspect of the building meets the prescribed energy requirements as clearly dictated by the code. That is, with this method you simply go through each aspect of the building, one at a time, verifying that that aspect is not below the minimum or above the maximum level prescribed by the title 24 code. This is the simplest approach since there are no complicated calculations which need to be done, but only a basic verification of each individual component of the building. On the downside, the prescriptive method is the least flexible of the two. There are no trade-offs of energy consumption, meaning that even though one component of the building might meet the criteria by a wide margin, you are not rewarded for this. Because of this, while the prescriptive method might be the easiest to use, it may end up resulting in the highest overall construction costs.
The title 24 performance method is the more complicated method, yet is also the more flexible and may ultimately save you the most in construction costs. This method is assisted by computers which calculate complicated energy trade-offs. Rather than checking each component of a building individually, as does the prescriptive method, the performance method considers the energy consumption of the entire building at once, and uses a complicated calculation to find the most cost effective method of satisfying the title 24 code. The performance method, while being more complicated than the prescriptive method, is more flexible since it allows the energy consumption of the building to adapt in order to find the most overall cost effective strategy. Because of this, the performance method, while being the more complicated of the two, ultimately ends up providing the least construction costs overall.