The September 2025 acoustic study identified the east-facing Bard HVAC unit associated with the Samish Island BESS as the primary source of noise impacting the adjacent residential property. The study measured sound levels increasing from approximately 41–42 dB(A) ambient conditions to approximately 64 dB(A) during HVAC operation at the property boundary, exceeding applicable daytime and nighttime noise limits by roughly 7 dB and 17 dB respectively. The HVAC system operated in repetitive on/off cycles of approximately two minutes on and two to three minutes off, with operation occurring during approximately 58–60% of the measurement period. The study noted that the cyclical nature of the operation undermined short-term exceedance allowances and confirmed that the impacts were ongoing rather than incidental. Acoustic modeling and analysis were specifically focused on reducing impacts to the neighboring residential property, and the study ultimately concluded that a large sound barrier would be the most effective mitigation measure.

3rd Party Analysis of the September 2025 Sound Study 

Key Takeaways from the Third-Party Acoustical Review

1. The Noise Impacts Are Substantial and Measurable

The review concluded that the BESS HVAC system:

• exceeds daytime noise limits by approximately 7 dB

• exceeds nighttime noise limits by approximately 17 dB

The engineer further stated that:

“this system represents a substantial increase in noise for the neighbor.”

2. The Rural Ambient Environment Significantly Increases Perceptibility

The review emphasized that:

• ambient sound levels near the property line average approximately 40 dBA

• existing noise standards do not fully account for real-world perceptibility in quiet rural environments

This supports the broader concern that even “near compliant” mechanical noise can remain highly intrusive in low-ambient rural settings.

3. The Impacts Are Strongly Tied to Proximity and Orientation

The engineer observed that:

• at approximately 130 feet off-axis, the system met nighttime noise limits

This strongly suggests that:

• the impacts are highly dependent on proximity and directional orientation

• the current placement adjacent to neighboring residential property is a central component of the issue

4. Multiple Mitigation Options Were Technically Available

The review noted that more cost-efficient mitigation approaches were available, including:

• quieter HVAC systems

• split-system HVAC configurations

• relocation

• simpler and lower-cost sound barrier methods

This undermines the notion that the only potential solution involved an excessively expensive engineered wall system.

5. The Recommended Barrier Did Not Require Specialized Construction

The engineer specifically noted that the recommended sound wall:

• did not require CMU or engineered acoustic panels

• could potentially utilize more conventional materials such as:

  • plywood

  • Hardie Board

  • corrugated metal

This suggests that simpler and faster mitigation approaches may have been feasible.

6. Relocation Was Identified as a Viable Technical Solution

The review concluded that, with the current HVAC configuration:

• the unit should be located at least 100 feet from neighboring residences

• additional sound mitigation and orientation considerations would still be necessary

In effect, the review found that achieving code-compliant operation with the existing HVAC system would require substantially greater separation distance and additional mitigation measures. This supports the broader concern that the current siting and configuration adjacent to residential property is a core cause of the problem.

7. Pre-Installation Acoustic Analysis Should Have Occurred

One of the review’s strongest conclusions stated:

“It is prudent that any party installing noise-making equipment… do a noise impact study during design.”

This supports the argument that:

• the impacts were reasonably foreseeable

• acoustical compatibility should have been evaluated prior to installation

• sound analysis should have informed siting and design decisions before the project was constructed