September 15, 2021

Understanding the impact of Washington State's Clean Buildings Act

The Washington State Clean Buildings Act provides operational energy performance requirements for existing buildings. New buildings above 50,000 square feet in size that are currently in development also need to meet CBA energy performance targets and so also must be designed to meet CBA criteria.

The goal of the Clean Buildings Act, aka HB 1257 or Washington Administrative Code (WAC 194-50), is to reduce energy consumption in existing buildings greater than 50,000 sf.

The compliance schedule for the CBA is based on building size, as follows:

• Buildings over 220,000 gross square feet: June 1, 2026

• Buildings between 90,001 – 220,000 gross square feet: June 1, 2027

• Buildings between 50,000 – 90,000 gross square feet: June 1, 2028

Owners and facility managers of existing buildings must begin planning now for compliance with CBA or face penalties for non-compliance. By the same token, the owners and the design teams of new buildings above 50,000 SF must also plan and design buildings such that when the buildings are constructed and operational, they also will comply with the CBA.

CBA compliance criteria requires buildings meet an annual Energy Use Intensity (EUI) target that is based on the building type. EUI is calculated by totaling annual energy used on-site – converted into thousands of British Thermal Units (Btus) - and dividing by the gross square feet of the building. The Clean Buildings Act includes lookup tables that list the EUI target for each building type with an adjustment methodology for higher than typical weekly hours of operation or for mixed-use buildings with more than one occupancy type.

For new buildings, aka ‘recently built' – meaning any building with a permit date of July 1, 2016, or later and therefore permitted under one of the recent, more stringent energy codes - the EUI target is reduced by 15% relative to values in the lookup tables.

For buildings whose operational EUI does not comply with the EUI target, steps need to be taken in the form of re-commissioning, energy audits, and implementation of energy efficiency measures as needed to reduce energy consumption sufficiently for the building to comply. These steps generally require some capital expenditure. For this reason, new buildings now in development should be designed to meet the EUI target from when they are first placed in operation. Otherwise, if the building is found then to not be in compliance it will trigger additional costs for the owner.

Owners and design teams that have designed buildings to achieve an aggressive operational EUI or Zero Net Energy understand how the design process differs from what has been the industry business-as-usual. The act creatively requires the same approach be brought into designing all large new buildings in the State of Washington.

The process of designing a building to an EUI target requires two main ingredients:

1. An integrated design process, and

2. Incorporating building energy simulation (BES) as a design tool.

Integrated design is a highly collaborative design process and is generally a necessary step toward achieving a high-performance building design that can meet an EUI target when the building is operational. It relies upon a multidisciplinary project team whose members make decisions together. It is ideally employed through the entire delivery of a project, from earliest predesign through construction and into the occupancy (aka, performance verification) phase. Integrated design enables better outcomes for owners without necessarily increasing the overall project cost.

BES is a critical design tool used on high performance building projects. It utilizes computer simulation software to estimate the annual energy use for a building design. BES helps the design team answer questions such as:

a) How is energy being consumed? Or what is the breakdown of energy “end-uses” such as heating, cooling, fans, interior lighting, and miscellaneous equipment/plug loads.

b) How effective are different energy efficiency measures at reducing estimated energy use?

c) Do proposed energy efficiency measures make financial sense?

d) What energy efficiency measures, bundled together, enable the building to achieve the EUI target?

As building energy codes have become more stringent, the contribution of miscellaneous equipment/ plug loads to the overall building's energy consumption has increased. For this reason, energy analysts are now working with project teams to more carefully account for the power use of all miscellaneous equipment that is anticipated to be plugged into wall receptacles, including computers, printers, coffee machines, dishwashers, refrigerators, imaging equipment, and other “process” equipment. Call it the “big spreadsheet” part of the BES process.

This increase level of detail is necessary when designing for an operational EUI target because we need the energy model to - within a safety margin - “predict” the energy use of the building. So, the building is generally designed to exceed prescriptive code requirements based on the EUI target required during operation.

BES then, is something that is required early in design to first validate an EUI target and then to help identify and optimize design strategies throughout the design process, mitigating the risk that a new building will not comply with the act.

BES is also an important tool during the post-occupancy measurement and verification phase. The BES ‘as designed energy model' is calibrated to be an ‘as-built energy model' at this time. Once calibrated, the BES energy model can be used in conjunction with energy meter data to spot and diagnose operational anomalies, enabling the optimization of building energy use. This hedges risk with regards demonstrating CBA compliance and reduces energy operational costs.

Key Takeaways

• The Clean BuildingS Act is a standard for both existing and new buildings.

• Owners and their project teams need to design new buildings to meet the acts required EUI target to future proof their development against penalties or expenses associated with exceeding the EUI target.

• Designing to achieve an operational EUI target is not something new, it is done for buildings targeting ultra-low energy use or Zero Net Energy.

• Designing to an EUI target requires an integrated design process and the use of BES as a design tool throughout the design process and then on into operation.