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HVAC Coordination Log — MediaVerse B3

Date: 2026-03-04 | Version: v01 ACTIVE | Author: Obai (logged by Claude Opus 4.6)

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System Identification

Parameter	Value
HVAC System	Daikin VRF (Variable Refrigerant Flow)
Previous assumption	Samsung DVM VRF — CORRECTED
Status	System already customized to previous design; main piping/tonnage NOT being changed
Modification scope	"Last mile" ductwork only — final drops, silencers, diffusers

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Communication Thread

Message 1: Obai → HVAC Contractor

Context: Initiating HVAC coordination for MediaVerse acoustic build-out.

Key statements:

• Moving forward with B3 MediaVerse full acoustic build-out
• Taking ceiling back to 3.5 m concrete slab
• Building floating room-within-a-room for VO studio
• Target noise floor: NC-15 (dead silence)
• Existing metal ducts described as "speaking tubes"
• Existing linear slots are a weak point — won't hold isolation

Integration plan proposed by Obai:

1. Cut supply and return lines out in the external buffer spine
2. Install heavy-duty inline acoustic silencers (baffle boxes) right before ducts penetrate control room and VO room walls
3. Inside VO room: drop hard pipe → transition to flexible acoustic ducting → run in S-curve to break line-of-sight sound travel
4. Terminal velocity at diffusers: strictly under 1.5 m/s — most critical requirement (mic sensitivity)

Questions posed to HVAC team:

1. Can we oversize final drops and use expanded acoustic plenum boxes to kill air velocity to 1.5 m/s?
2. What specific inline silencers fit inside 60 cm drop ceiling space?
3. Are existing indoor units hard-mounted to slab? If so, need neoprene vibration isolators under brackets.
4. Can routing be altered to keep all noisy branch lines in east buffer corridor (not crossing live room)?
5. Request: review routing on updated floor plan from Sarah (architect)

Closing: "We have one shot to get this noise floor right."

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Message 2: HVAC Contractor → Obai

Response (3 points):

1. "Division": Didn't understand — asked for clarification
2. System: Confirmed Daikin VRF. Needs complete floor plan to confirm assigned airflow for the area.
3. Modifications: "Difficult to change at this stage" — system already customized to previous design.

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Message 3: Obai → HVAC Contractor (Clarification)

Clarification on point 1:

• NOT removing AC from the area
• Intercepting the duct right before it penetrates the VO room wall
• Break hard pipe → insert silencer box → prevent sound traveling back up the metal

Clarification on points 2 & 3:

• Daikin VRF acknowledged
• Updated floor plan will be sent for airflow verification
• NOT asking to: redesign VRF system, change tonnages, redo main piping
• Only asking to: modify "last mile" of air delivery
• Indoor VRF unit to sit outside critical rooms (in corridor or editing area)
• From there: oversize final drops → expanded acoustic plenum boxes → velocity ≤ 1.5 m/s at diffusers

Key phrase: "If we can just adjust that last stretch of ductwork, we are good."

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Confirmed HVAC Design Parameters

Parameter	Value	Source
HVAC system type	Daikin VRF	HVAC contractor confirmation
Modification scope	Last-mile ductwork only	Obai/HVAC agreement
Indoor unit location	Outside critical rooms (corridor/editing)	Obai specification
Max terminal velocity	≤ 1.5 m/s at diffusers	Obai specification
Silencer type	Inline acoustic baffle boxes	Obai specification
Silencer location	Buffer spine, before wall penetrations	Obai specification
VO room ducting	Flexible acoustic duct, S-curve routing	Obai specification
Vibration isolation	Neoprene isolators under indoor unit brackets	Obai specification (pending confirmation)
Ceiling space for silencers	60 cm (drop ceiling zone)	Obai specification
Preferred branch routing	East buffer corridor (away from live room)	Obai specification (pending feasibility)

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Outstanding Items

• HVAC team to receive updated floor plan (from Sarah)
• HVAC team to confirm assigned airflow (CFM/L/s) for MediaVerse area
• HVAC team to confirm silencer fitment in 60 cm ceiling space
• HVAC team to confirm indoor unit mounting method (hard-mount vs. isolated)
• HVAC team to confirm if branch routing can stay in east corridor
• Joint review meeting to be scheduled after floor plan delivery
• Acoustic consultant (this project) to provide NC budget breakdown per duct run

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Impact on Acoustic Design

Scope Correction: Daikin VRF (not Samsung DVM)

The locked scope (v01) stated Samsung DVM VRF. This is now corrected to Daikin VRF. The acoustic implications are similar (both are VRF systems with indoor fan coil units), but specific noise data sheets will need to reference Daikin models.

Design Implications

1. Indoor unit placement: Must be in non-critical zone (corridor/editing). This affects layout — the unit needs physical space and clearance.
2. Duct penetrations: Each penetration through an acoustically rated wall is a potential flanking path. Silencers at every penetration point are mandatory.
3. S-curve flexible duct: Adds pressure drop. HVAC team must verify that the system can deliver required airflow with the added restriction.
4. 1.5 m/s velocity target: Requires significantly oversized diffusers compared to standard HVAC. Typical commercial diffusers operate at 2.5–4 m/s. We need ~2.5× the face area.
5. Plenum boxes: Must be lined with acoustic insulation (min 50 mm, 60 kg/m³ rockwool) and have internal baffles.

NC Budget Consideration

For NC-15 in the VO room, the HVAC system's contribution must be well below NC-15 (target NC-10 to NC-12 from HVAC alone), leaving margin for background noise from structure-borne vibration and other sources.

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This log is part of the project audit trail. All communications are documented for transparency.