Building Code:

The City has adopted the 2012 International Building Code (IBC) and International Residential Code (IRC), as incorporated into the Revised Ordinances of Honolulu (ROH) Chapter 16.

The 2012 IBC requires new construction to be designed with one foot freeboard above current Base Flood Elevation (BFE) in hazardous flood zones. The 2012 IRC limits impervious surfaces of some residential developments to 75 percent of the total lot area. The 2018 IBC is anticipated to be adopted in 2021. It contains additional provisions for resilience.

Flood Hazard Areas:

Following adoption of the 2012 IBC, amendments to ROH Chapter 21A are forthcoming to reflect changes in the requirements for designing buildings in flood hazard areas.

Plumbing Code:

The City is proposing updates to the Plumbing Code (ROH Chapter 19) that would allow more applications for on-site water reuse for residential and commercial properties.

Rules Related to Water Quality:

The 2018 update incorporates requirements for low impact development (LID), green infrastructure, and source control best management practices (BMPs). Other updates are underway or expected to be formalized into updated City codes and regulations within the next one to five years.

Special Management Area and Shoreline Setbacks:

A working group is preparing updates to regulations of the Shoreline Setbacks (ROH Chapter 23) and Special Management Area (ROH Chapter 25) to incorporate State-identified Sea Level Rise Exposure Areas (SLR-XAs) and improved mapping.

Climate Adaptation Strategy:

Action 28 of the City’s Resilience Strategy calls for the preparation of an O‘ahu Climate Adaptation Strategy, which the City has initiated. The Strategy is expected to include policy guidance and a recommended framework for approaching adaptation islandwide. However, it will not recommend specific adaptation strategies at a regional or neighborhood scale. Regional or neighborhood scale adaptation strategies will need to continue to be developed through community, special district, and functional plans. For more information, see www.climatereadyoahu.org.

Climate Resilience Design Guidelines:

Action 14 of the City’s Resilience Strategy calls for the City to establish Future Conditions Climate Resilience Design Guidelines that incorporate forward-looking climate change data and provide specifications to inform the design of City and private facilities and infrastructure (essentially expanding on this document).

Stormwater Utility:

In accordance with Action 31 of the City’s Resilience Strategy, the City is exploring the formation of a stormwater utility. This would establish fees for impervious surfaces and further incentivize the use of green infrastructure, LID, and water conservation in new development and redevelopment. For more information, see www.stormwaterutilityoahu.org.

Urban Tree Canopy:

In accordance with Action 33 of the City’s Resilience Strategy, the City is establishing policies and practices that improve the management of trees to mitigate increasing temperatures resulting from climate change. Mayor’s Directive 20-14 (2020) requires City departments and agencies to consider climate change mitigation and environmental benefits of a healthy urban tree canopy when making decisions that affect city trees. This policy requires the protection of trees that pose no threat to safety and do not undermine an essential government function, as well as planting more trees to expand urban canopy.

A TOD Street Tree Plan is under development. This plan will provide guidance for street tree type selection to maximize canopy and streetscape coherency in the TOD neighborhoods.

How to make buildings and sites more resilient?

International, national, and local best practices and tools that can be used to make buildings and sites more resilient are highlighted on the document section pages. These practices and tools are presented in four categories:

A: Understanding Applicable Hazards

B: Managing Stormwater

C: Design for Flooding and Sea Level Rise

D: Mitigating Extreme Heat

In addition, resilient design best practices are shown and documented for three urban building typologies:

1: Tower and Podium

2: Mid-Rise Building

3: Low-Rise Walk-up

(Back to Climate Adaptation)