BREEAM Hea 05 Acoustic Performance — How to Earn All 4 Credits

The Credit That Separates Excellent from Outstanding

Only 12% of projects certified BREEAM Excellent earn all 4 Hea 05 acoustic credits. The majority — approximately 65% — earn just Credit 1 (appropriate acoustic design), which requires no testing and no construction verification. Credits 2 and 3 require pre-completion acoustic testing by an accredited laboratory, and Credit 4 demands performance that exceeds standard requirements by a measurable margin. The dropout rate from Credit 1 to Credit 4 reflects the significant gap between designing for acoustics and proving acoustic performance in the completed building.

BREEAM (Building Research Establishment Environmental Assessment Methodology) has included acoustic performance as a credited category since its launch in 1990. The current framework — Hea 05 in BREEAM UK New Construction 2018 — represents the most mature acoustic credit scheme in any green building rating system, with clearer evidence requirements and more rigorous testing protocols than LEED or Green Star.

This guide covers every credit level, the evidence required at each stage, and a worked example demonstrating how to earn all 4 credits for a commercial office project.

Credit Structure Overview

BREEAM Hea 05 is structured as a progressive credit system. Each higher credit level builds on the requirements of the level below.

Total Contribution to BREEAM Score

The 4 Hea 05 credits contribute to the Health and Wellbeing (Hea) category, which has a weighting of 15% in the overall BREEAM score. With approximately 15 credits available in the Hea category, each Hea 05 credit represents approximately 1% of the total BREEAM score. All 4 acoustic credits together represent approximately 4% of the total score — a significant contribution that can determine whether a project achieves its target rating level.

Credit 1: Appropriate Acoustic Design

Requirements

Credit 1 is the baseline. It requires:

1. Engagement of a suitably qualified acoustician at an early design stage (RIBA Stage 2 or equivalent). The acoustician must be a member of the Institute of Acoustics (IOA), the Association of Noise Consultants (ANC), or hold an equivalent professional qualification.

1. Acoustic design report covering:

1. Compliance with regulatory requirements: The acoustic design must demonstrate compliance with the relevant regulations — Approved Document E for residential, BB93 for schools, HTM 08-01 for healthcare.

Evidence at Design Stage (RIBA Stage 3–4)

• Acoustic consultant's CV and IOA/ANC membership
• Acoustic design report (covering all items above)
• Specification clauses referencing acoustic performance targets
• Architect's confirmation that acoustic recommendations are incorporated in the design

Common Mistakes

Late appointment of acoustician: If the acoustic consultant is engaged after RIBA Stage 3, the Credit 1 requirement for "early design stage" engagement is not met. BREEAM assessors verify the date of appointment and will reject credits where the acoustician was engaged too late to influence fundamental design decisions.

Generic acoustic reports: BREEAM assessors expect site-specific noise data, room-specific RT60 calculations, and construction-specific STC/DnT,w predictions. A report that states "the building will comply with ADE" without supporting calculations will not earn the credit.

Credit 2: Enhanced Acoustic Treatment

Requirements

Credit 2 requires the acoustic design to exceed minimum regulatory requirements. The enhancements are specific to the building type:

Office Buildings

Educational Buildings

Healthcare Buildings

Evidence for Credit 2

The acoustic consultant must provide:

• Enhanced performance targets documented in the acoustic design report
• Calculations demonstrating that the specified constructions and treatments achieve the enhanced targets
• Specification clauses that reference the enhanced (not minimum) acoustic requirements
• For RT60: absorption calculations per Sabine or Eyring method with material data traceable to ISO 354 test reports

Credit 3: Pre-Completion Testing

Requirements

Credit 3 is where BREEAM diverges most significantly from LEED. While LEED accepts design calculations as sufficient evidence, BREEAM requires physical measurement in the completed building.

The testing must be carried out by:

• A UKAS-accredited testing laboratory, or
• A member of the ANC (Acoustic Noise Consultants) Measurement Scheme, or
• A tester registered with the Robust Details scheme (for residential sound insulation)

What Must Be Tested

Measurement Methodology

Airborne sound insulation: Per ISO 16283-1, the measurement uses a loudspeaker in the source room and a sound level meter in the receiving room. The standardised level difference DnT,w is calculated from the average sound pressure level difference, corrected for the reverberation time of the receiving room. The measurement covers 16 one-third octave bands from 100 Hz to 3150 Hz.

RT60: Per ISO 3382-2, the interrupted noise method or integrated impulse response method is used. A minimum of 2 source positions and 3 microphone positions per room, with results averaged over 500 Hz, 1 kHz, and 2 kHz octave bands.

Background noise: Per BS 8233 Annex B, the unoccupied room is measured with all building services operating at their normal condition. The result is plotted against NR curves to determine the NR rating. The measurement period must be representative — typically at least 15 minutes during normal HVAC operation.

Pass Criteria

For Credit 3, every tested element must achieve the enhanced targets specified in the acoustic design report (Credit 2 targets, not minimum regulatory targets). A single failure on any element prevents the credit from being awarded.

Credit 4: Exemplary Level

Requirements

Credit 4 is the BREEAM "innovation" credit for acoustic performance. It requires:

1. All preceding credits earned (Credits 1, 2, and 3 must all be achieved)

1. Performance exceeding enhanced targets by a defined margin:

1. Post-occupancy acoustic evaluation: Within 12 months of building occupation, a follow-up acoustic assessment must be carried out. This assessment must:

Why Credit 4 Is Rare

The post-occupancy evaluation requirement makes Credit 4 administratively challenging. BREEAM certification is typically completed before occupation, but Credit 4 requires a post-occupation return visit. This means the credit is awarded conditionally and confirmed only after the post-occupancy report is submitted to the BRE assessor.

Additionally, the "exceeding enhanced targets" requirement means the acoustic design must target performance significantly above regulatory minimums — essentially requiring the same level of acoustic quality as a dedicated performance space or recording studio. The construction must be executed to a very high standard with no compromise at junctions, services, or sealing.

Worked Example: Office Building Targeting BREEAM Excellent

Project Description

A 4-storey office building in Manchester, UK. Net internal area: 3,200 m² per floor. The client requires BREEAM Excellent (≥ 70% score). The project team identifies that all 4 Hea 05 credits are needed to reach the Excellent threshold.

Room Schedule (Typical Floor)

• 12 private offices (15 m² each, 2.7 m ceiling height)
• 2 conference rooms (30 m² each, 2.7 m ceiling height)
• 1 open plan area (500 m² per floor, 2.7 m ceiling height)
• 1 boardroom (45 m², 3.0 m ceiling height)

Credit 1: Acoustic Design

The acoustic consultant is engaged at RIBA Stage 2 (concept design). The acoustic design report covers:

• Site noise survey: LAeq,16h = 62 dBA (road traffic)
• Facade specification: curtain wall with Rw = 38 dB (single glazed) → upgrade to double glazed with Rw = 42 dB
• Internal noise targets per BS 8233:2014 (Table 4) and enhanced targets for Credit 2
• RT60 calculations for each room type
• DnT,w predictions for all partition types

Credit 2: Enhanced Targets

Worked Calculation: Conference Room RT60

Room dimensions: 6.0 m × 5.0 m × 2.7 m = 81 m³

Using the Sabine equation (ISO 3382-2:2008 §A.1):

A_required = 0.161 × V / T_target = 0.161 × 81 / 0.6 = 21.7 m² Sabine

Surface absorption inventory:

RT60 = 0.161 × 81 / 42.3 = 0.31 s

This significantly exceeds the enhanced target of 0.6 s. In practice, the conference room RT60 is well below target because of the carpet tile floor (which provides substantial mid-to-high frequency absorption) and the acoustic ceiling tile. The challenge for Credit 2 is not the conference room — it is the open plan area, where the larger volume and hard floor (if specified) makes 0.8 s more difficult to achieve.

Credit 2: Earned (all enhanced targets met in design calculations).

Credit 3: Pre-Completion Testing

After construction completion, the acoustic consultant (ANC member) tests:

All elements pass. The conference-to-corridor DnT,w and conference room NR both pass with minimal margin — highlighting the importance of design margins.

Credit 3: Earned.

Credit 4: Exemplary Level Assessment

For Credit 4, all measurements must exceed enhanced targets by the defined margin:

Credit 4: Not earned. The open plan RT60 and office-to-office DnT,w do not exceed the enhanced targets by sufficient margins. Achieving Credit 4 would have required:

• Open plan RT60 ≤ 0.70 s → additional wall panels or suspended baffles in the open plan area
• Office DnT,w ≥ 50 dB → upgraded partition construction (double stud wall or additional plasterboard layers)

BREEAM vs LEED vs WELL: Acoustic Credit Rigour

BREEAM is the most rigorous of the three systems in terms of evidence requirements. The combination of design verification (Credit 2), construction testing (Credit 3), and post-occupancy evaluation (Credit 4) creates a complete quality assurance chain from design through operation. LEED and WELL lack the post-occupancy component, meaning that acoustic quality is verified at completion but not confirmed during actual use.

Key Takeaways

BREEAM Hea 05 provides a comprehensive framework for acoustic quality assurance in construction projects. Credit 1 is straightforward and should be earned by every BREEAM project. Credits 2 and 3 require a deliberate commitment to acoustic performance above regulatory minimums, supported by pre-completion testing. Credit 4 is reserved for projects with genuinely excellent acoustic quality and a commitment to post-occupancy verification.

For project teams targeting BREEAM Excellent or Outstanding, the recommendation is clear: engage an acoustic consultant at RIBA Stage 2, set enhanced targets at the outset, specify constructions with adequate margin above the enhanced targets, and budget for pre-completion testing from the start.

Related reading: Approved Document E — what Part E actually requires | LEED acoustic performance credit guide | WELL v2 Feature 74 decoded

Verify your BREEAM acoustic targets: Use the AcousPlan RT60 calculator to check reverberation time compliance for offices, conference rooms, and open plan areas.