By Michael Flemming and Steve Gross
As of May 2020, the four major counties of the Hawaii have adopted the 2015 International Energy Code (IECC), which marks an important milestone on the pathway to the State’s goal of carbon neutrality by 2045. With the implementation of this new code, there are a few key items for architects, engineers, and builders to keep in mind when beginning new projects:
- Commissioning is now required for most new construction projects
- Two compliance approaches: Prescriptive vs Performance
- Aggressive building envelope requirements
Energy Code Compliance Approach: Prescriptive vs. Performance
The 2015 IECC specifies both a prescriptive and a performance approach for complying with the Standard, with the aim of reducing building energy consumption. The prescriptive approach defines the performance requirement for each regulated building component, such as wall insulation and cooling efficiency rating. The performance approach requires that the proposed building consume no more energy than a prescriptively compliant building.
It’s important to understand the attributes of both methods, as each project is unique and may benefit from one more than the other. One of the more common uses of the performance approach is to overcome the window-to-wall ratio (WWR) restrictions of 30% of the gross wall area. [Using energy modeling software allows the design team to demonstrate code compliance by offsetting the penalty of increasing the WWR with other efficiency measures.
The table below provides a brief summary of the pros and cons of both methods:
In our experience, using detailed energy modeling via the performance method often allows substantial construction cost savings targeting investment in efficiency where it matters most. In particular for the warm climates of Hawaii, properly designed window shading (overhangs, fins, and louvers) is a very cost-effective way to achieve compliance without adhering to the other rigid envelope requirements. The graphic below shows an example of how the performance method allows high WWR designs to comply with the IECC using shading.
Unlike the previous energy code, most new construction projects will require System Commissioning under the 2015 IECC. While previously only LEED projects required commissioning to be completed on building systems, the 2015 IECC calls for lighting controls to be commissioned regardless of the size of the project, while Mechanical and Plumbing systems have the following size criteria:
While the commissioning scope to meet the 2015 IECC is not as intensive as the commissioning scope for LEED, the added requirements for a commissioning plan, functional performance testing and a systems manual have been implemented to ensure that building systems are provided in peak condition.
The goal of any commissioning process is to ensure that the building owner, operators and occupants receive a comfortable and efficient building. Through the commissioning process, the entire project team can confirm that operations meet design expectations from the beginning. This new requirement will allow the entire construction team to ensure that building operators are able to operate their buildings efficiently from the beginning of occupancy and help to reduce the number of call backs during the warranty phase for the entire project team.
Per the 2015 IECC, the commissioning scope can be completed by the registered design professional or an approved agency. While there is not a lot of detail in the code, it’s recommended that a Certified Commissioning Authority (CxA) be utilized for all projects.
There are multiple different certifying agencies for CxAs including:
Regardless of accreditations, it’s most important to select a CxA who has experience in the project and equipment type of the project and can provide added insight into ensuring lasting performance for the project.