Initial house specification: air system, sensors, Lindner Doppelboden + Plafotherm ceiling

- 01: H13 HEPA whole-house air filtration, MVHR, duct design, pressure management - 02: Sensor placement, automation logic, Home Assistant integration, wiring - 03: Baufritz builder coordination, construction checkpoints, timeline - 04: Lindner NORTEC Doppelboden with WOODline parquet + Plafotherm AirHybrid radiant ceiling - Build system: tsx + marked + puppeteer, renders Mermaid diagrams to PDF
2026-03-08 18:58:22 +00:00
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--- a/specs/01-air-system-spec.md
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+# Air System Specification
+
+## 1. Design Philosophy
+
+In a well-sealed Baufritz home, 100% of incoming air passes through the ventilation system. The goal is to engineer indoor air that is **measurably superior to outdoor air** across every parameter — not merely acceptable, but actively health-positive.
+
+**Target: Whole-house H13 HEPA filtration (ISO Class 7–8 equivalent), with full control over particulates, gases, humidity, CO₂, and pressure.**
+
+---
+
+## 2. Filter Cascade — Corrected Sequence
+
+The filter stages are ordered so that **every upstream stage's potential contaminants are caught by the next downstream stage**. The H13 HEPA is always the final particle barrier before air enters the living space.
+
+```mermaid
+flowchart TD
+    A["Outdoor Air Intake\n weather-protected, north-facing preferred"] --> B
+    B["Stage 1: G4/M5 Pre-filter\nCoarse particles, pollen, insects"] --> C
+    C["Stage 2: F7 Intermediate Filter\nFine dust, mold spores"] --> D
+    D["Stage 3: Activated Carbon\nVOC, NO2, ozone removal"] --> E
+    E["Stage 4: H13 HEPA - FINAL BARRIER\n99.95% efficiency at 0.3um\nCatches everything incl. carbon fines"] --> F
+    F["MVHR Unit\nCounterflow heat recovery 80-95%"] --> G
+    G["Steam Humidifier\nelectrode or resistive, inherently sterile"] --> H
+    H["Motorized Zone Dampers"] --> I
+    I["Room Distribution"]
+
+    style E fill:#1a5e1a,color:#fff,stroke:#0d3d0d
+    style D fill:#4a4a00,color:#fff,stroke:#333
+    style F fill:#1a3d5e,color:#fff,stroke:#0d2840
+```
+
+### 2.1 Stage Details
+
+| Stage | Filter Class | Function | Face Velocity | Initial ΔP | Change Interval |
+|-------|-------------|----------|---------------|------------|-----------------|
+| 1 | G4 / M5 | Coarse protection — pollen, insects, large dust | < 2.5 m/s | 30–50 Pa | Every 3 months |
+| 2 | F7 (ePM2.5 ≥ 65%) | Fine particulates, mold spores, extends H13 life | < 2.0 m/s | 40–60 Pa | Every 6 months |
+| 3 | Activated Carbon | VOC, NO₂, ozone adsorption | < 1.5 m/s | 30–50 Pa | Every 12 months |
+| 4 | H13 HEPA | Final barrier — 99.95% @ MPPS (0.3 µm) | **< 1.0 m/s** | 80–150 Pa | Every 12–18 months |
+
+### 2.2 Critical Design Rules
+
+- **Carbon BEFORE HEPA**: Carbon filters shed microscopic activated carbon fines. The H13 HEPA downstream catches these. Never reverse this order.
+- **Face velocity across H13 panels must stay below 1.0–1.5 m/s**: This requires filter housings 2–4× larger than the duct cross-section. At low face velocity, pressure drop drops to 80–100 Pa initial, noise disappears, and filter life doubles.
+- **Filter housing must accommodate 600×600 mm panel filters** (or larger) — not inline cylindrical filters.
+- **Differential pressure sensors across each stage**: Electronic, connected to Home Assistant. Change filters based on actual loading, not calendar time. Spring pollen will load pre-filters in weeks.
+
+---
+
+## 3. Exhaust Side Filtration
+
+The exhaust path also requires filtration to protect the MVHR heat exchanger:
+
+```mermaid
+flowchart LR
+    R["All Rooms\n(except kitchen)"] --> EF["F9 Exhaust Filter\nProtects heat exchanger"]
+    EF --> MVHR["MVHR Exhaust Side"]
+    MVHR --> OUT["Outdoor Exhaust"]
+
+    K["Kitchen"] --> KE["Dedicated Kitchen Exhaust\nNEVER recirculated into MVHR"]
+    KE --> KOUT["Separate Outdoor Exhaust"]
+
+    style K fill:#8b0000,color:#fff
+    style KE fill:#8b0000,color:#fff
+```
+
+- **Minimum F9 on exhaust** before the MVHR heat exchanger
+- **Kitchen exhaust is entirely separate** — cooking aerosols, grease particles, and combustion byproducts must never enter the MVHR system
+- Kitchen hood: ducted directly outside through a dedicated penetration with backdraft damper
+
+---
+
+## 4. MVHR Unit Requirements
+
+For whole-house H13, the MVHR must handle significantly higher system pressure than standard residential units.
+
+### 4.1 Minimum Specifications
+
+| Parameter | Requirement |
+|-----------|-------------|
+| Available static pressure | ≥ 450 Pa (preferably ≥ 500 Pa) |
+| Airflow capacity | ≥ 400 m³/h (for ~150–200 m² at 0.8 ACH) |
+| Heat recovery efficiency | ≥ 85% (counterflow plate, no enthalpy wheel) |
+| Fan type | EC (electronically commutated), variable speed |
+| Filter bay | External filter box connection, or large internal bay |
+| Controls | KNX or Modbus interface for building automation |
+| Noise at rated flow | ≤ 35 dB(A) at 1 m |
+
+### 4.2 Recommended Units
+
+| Unit | Max Static Pressure | H13 Support | Notes |
+|------|---------------------|-------------|-------|
+| Drexel & Weiss aerosilent | ~600 Pa | Native options | Austrian, Passivhaus standard |
+| Swegon CASA R5 | ~600 Pa+ | Via external box | Semi-commercial, bridges residential/commercial |
+| Zehnder ComfoAir Q600 | ~500 Pa | Via external box | Largest residential Zehnder, KNX native |
+| Paul Novus 450 | ~450 Pa | Via external box | Very quiet, excellent German engineering |
+| Hoval HomeVent FR | ~500 Pa | Via external box | Commercial-grade residential |
+
+**Recommendation**: Drexel & Weiss aerosilent or Swegon CASA — both designed for the pressure demands of H13 whole-house filtration.
+
+---
+
+## 5. Humidification
+
+### 5.1 Requirements
+
+| Parameter | Target |
+|-----------|--------|
+| Relative humidity | 40–60% year-round |
+| Humidifier type | **Steam ONLY** (electrode or resistive) |
+| Position | Downstream of MVHR, in supply duct |
+| Control | Hygrostat per zone, integrated with central controller |
+
+### 5.2 Why Steam Only
+
+Since the H13 HEPA is the final particle barrier upstream of the MVHR, anything added to the airstream after the HEPA must be inherently sterile:
+
+- **Steam humidifiers**: Water boiled to 100°C — output is sterile vapor, no mineral dust, no biofilm
+- **Ultrasonic**: Creates aerosols containing dissolved minerals and bacteria from reservoir — **PROHIBITED**
+- **Evaporative (unsterilized)**: Biofilm grows on wetted media within days — **PROHIBITED**
+
+**Recommended brands**: Condair, Hygromatik — industrial-grade steam humidifiers designed for duct integration, commonly used in German clean rooms and hospitals.
+
+### 5.3 Dehumidification
+
+In summer, dehumidification is handled by:
+- The MVHR cooling bypass (partial)
+- Optional: small split heat pump unit on the supply duct, or dedicated dehumidifier in the technical room
+- Target: never exceed 60% RH at any surface
+
+---
+
+## 6. Duct Design
+
+### 6.1 Velocity Requirements
+
+| Duct Section | Max Velocity | Typical Diameter |
+|-------------|-------------|-----------------|
+| Main supply/extract trunk | ≤ 2.0 m/s | 200–250 mm round |
+| Branch ducts to rooms | ≤ 1.5 m/s | 125–160 mm round |
+| Final connection to diffuser | ≤ 1.0 m/s | 100–125 mm round |
+
+At 0.8 ACH for 150 m² with 3 m ceilings = **~360 m³/h airflow**. Main duct at 2.0 m/s → ~250 cm² cross section → **200 mm round duct minimum**.
+
+### 6.2 Material and Sealing
+
+- **Rigid steel or aluminum ducts throughout** — no semi-rigid flex (adds resistance, collects contamination)
+- **Exception**: final 0.5 m connection to each diffuser may use flex for vibration isolation
+- **All joints sealed with mastic** (not just tape) — Passivhaus duct leakage class
+- **Pressure-tested after installation** before walls are closed
+
+### 6.3 Duct Routing
+
+Must be coordinated with Baufritz at structural design stage:
+- Duct runs in ceilings and walls need to be planned and boxed in
+- Dedicated vertical risers for multi-story distribution
+- No ducts in exterior walls (condensation risk, thermal bridge)
+- Acoustic silencers at MVHR outlets and before each room diffuser
+- **Ground floor alternative**: branch ducts may route through the Lindner NORTEC Doppelboden cavity (see 04-flooring-ceiling-spec Section 6). Supply air may be distributed via Plafotherm AirHybrid ceiling panels (see 04-flooring-ceiling-spec Section 5), potentially replacing conventional wall/ceiling diffusers
+
+---
+
+## 7. Pressure Management
+
+| Parameter | Target |
+|-----------|--------|
+| House pressure vs. outside | **+3 to +5 Pa** (slight positive) |
+| Supply vs. exhaust airflow | Supply 5–10% greater than exhaust |
+| Kitchen exhaust compensation | Dedicated make-up air or interlock with MVHR boost |
+
+Positive pressure ensures:
+- All infiltration passes through the filter stack
+- Radon and soil gases cannot infiltrate from below
+- Garage pollutants cannot enter (garage must be entirely pressure-separated)
+
+---
+
+## 8. Air Quality Targets
+
+| Parameter | Target | Danger Threshold |
+|-----------|--------|-----------------|
+| PM2.5 | < 5 µg/m³ | > 15 µg/m³ |
+| PM10 | < 10 µg/m³ | > 25 µg/m³ |
+| CO₂ | < 800 ppm | > 1000 ppm |
+| TVOC | < 200 µg/m³ | > 500 µg/m³ |
+| Relative Humidity | 40–60% | < 30% or > 70% |
+| Radon | < 100 Bq/m³ | > 300 Bq/m³ |
+| Temperature uniformity | ± 1.5°C between rooms | > 3°C delta |
+| Formaldehyde | < 30 µg/m³ | > 100 µg/m³ |
+
+---
+
+## 9. Estimated Filter Costs (Annual)
+
+| Stage | Interval | Cost per Change | Annual Cost |
+|-------|----------|----------------|-------------|
+| G4/M5 pre-filter | 3 months | 10–20 EUR | 40–80 EUR |
+| F7 intermediate | 6 months | 20–40 EUR | 40–80 EUR |
+| Activated carbon | 12 months | 50–100 EUR | 50–100 EUR |
+| H13 HEPA panels | 12–18 months | 80–200 EUR per panel | 80–200 EUR |
+| **Total** | | | **210–460 EUR/year** |
+
+This is the cost of breathing clean air. For context, this is less than a monthly gym membership.
--- a/specs/02-sensor-automation-spec.md
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+# Sensor & Automation Specification
+
+## 1. Control Architecture
+
+The air system is managed by a layered control architecture: local sensors feed data to a central controller, which modulates the MVHR, dampers, and humidifier. Home Assistant provides monitoring, logging, alerting, and override capability.
+
+```mermaid
+flowchart TD
+    subgraph Sensors["Room Sensors (per zone)"]
+        CO2["CO₂ Sensor"]
+        VOC["TVOC Sensor"]
+        PM["PM2.5 / PM10 Sensor"]
+        TH["Temperature + Humidity"]
+        RN["Radon Monitor\n(ground floor only)"]
+    end
+
+    subgraph FilterSensors["Filter Monitoring"]
+        DP1["ΔP Sensor: Pre-filter"]
+        DP2["ΔP Sensor: F7"]
+        DP3["ΔP Sensor: Carbon"]
+        DP4["ΔP Sensor: H13 HEPA"]
+        DP5["ΔP Sensor: Exhaust F9"]
+    end
+
+    subgraph Controller["Central Controller"]
+        KNX["KNX / Modbus Bus"]
+        HA["Home Assistant"]
+    end
+
+    subgraph Actuators["Actuators"]
+        MVHR["MVHR Fan Speed"]
+        DAMP["Zone Dampers"]
+        HUM["Steam Humidifier"]
+        DEHUM["Dehumidifier"]
+    end
+
+    Sensors --> KNX
+    FilterSensors --> KNX
+    KNX --> HA
+    HA --> Actuators
+
+    style HA fill:#1a5e5e,color:#fff
+    style KNX fill:#1a3d5e,color:#fff
+```
+
+---
+
+## 2. Room Sensor Placement
+
+Every occupied room requires a sensor unit. The following table defines sensor requirements per zone:
+
+| Zone | CO₂ | TVOC | PM2.5 | Temp/RH | Radon | Notes |
+|------|-----|------|-------|---------|-------|-------|
+| Master Bedroom | Yes | Yes | Yes | Yes | No | Priority zone — sleep quality |
+| Leo's Room | Yes | Yes | Yes | Yes | No | Priority zone — child health |
+| Living Room | Yes | Yes | Yes | Yes | No | Largest volume, main gathering |
+| Kitchen | Yes | No | No | Yes | No | Separate exhaust system |
+| Office / Study | Yes | Yes | Yes | Yes | No | Cognitive performance critical |
+| Bathroom(s) | No | No | No | Yes | No | Humidity control priority |
+| Basement / Ground Floor | Yes | No | No | Yes | Yes | Radon monitoring mandatory |
+| Technical Room | No | No | No | Yes | No | Equipment monitoring |
+
+### 2.1 Sensor Mounting Guidelines
+
+- **CO₂ sensors**: Mount at breathing height (1.2–1.5 m), away from windows, doors, and supply diffusers. CO₂ reading at the diffuser is outdoor air, not room air.
+- **PM sensors**: Mount away from direct airflow paths — measure room air, not supply air.
+- **Temperature/Humidity**: Away from direct sunlight, heat sources, and exterior walls. **With radiant ceiling heating and raised floor, mount sensors at 1.2–1.5 m wall height** — away from both the heated ceiling surface above and the floor surface below (see 04-flooring-ceiling-spec Section 9.1).
+- **Radon monitors**: Ground floor / basement only, placed in the lowest habitable room, away from windows and doors.
+
+---
+
+## 3. Sensor Hardware Recommendations
+
+### 3.1 Multi-Sensor Units
+
+| Sensor | Recommended Model | Protocol | Parameters | Notes |
+|--------|-------------------|----------|------------|-------|
+| CO₂ + Temp + RH | Aqara TVOC Air Quality Monitor or Senseair S8 (custom) | Zigbee / UART | CO₂, T, RH | NDIR sensor, ±30 ppm accuracy |
+| TVOC | SGP41 (Sensirion) | I²C | TVOC, NOx index | Requires 24h conditioning |
+| PM2.5/PM10 | Sensirion SPS30 | I²C / UART | PM1.0, PM2.5, PM4, PM10 | Laser-based, long-life fan |
+| Radon | Airthings Wave Plus or RadonEye RD200 | BLE / WiFi | Radon (Bq/m³) | Continuous, hourly updates |
+
+### 3.2 Filter Differential Pressure Sensors
+
+| Sensor | Recommended Model | Range | Output |
+|--------|-------------------|-------|--------|
+| ΔP across each filter stage | Sensirion SDP810 or Dwyer MS-111 | 0–500 Pa | I²C / 4-20mA |
+
+One sensor per filter stage (5 total: G4, F7, Carbon, H13, Exhaust F9). Alerts when pressure drop exceeds threshold indicating filter loading.
+
+### 3.3 Outdoor Reference Station
+
+An outdoor sensor station provides baseline comparison:
+- PM2.5 / PM10 (verify filtration effectiveness)
+- Temperature + Humidity (MVHR efficiency calculation)
+- Air pressure (positive pressure verification)
+
+---
+
+## 4. Automation Logic
+
+### 4.1 Demand-Controlled Ventilation (DCV)
+
+The MVHR operates in demand mode, modulating airflow based on sensor readings:
+
+```mermaid
+flowchart TD
+    CO2{"CO₂ Level?"} -->|"< 600 ppm"| LOW["Minimum Flow\n0.5 ACH"]
+    CO2 -->|"600–800 ppm"| MED["Standard Flow\n0.8 ACH"]
+    CO2 -->|"800–1000 ppm"| HIGH["Boost Flow\n1.0 ACH"]
+    CO2 -->|"> 1000 ppm"| MAX["Maximum Flow\n1.2+ ACH"]
+
+    VOC{"TVOC Level?"} -->|"> 500 µg/m³"| PURGE["Purge Mode\nMax flow + alert"]
+    PM{"PM2.5 Indoor?"} -->|"> 15 µg/m³"| CHECK["Check Filters\nAlert if ΔP normal"]
+
+    style MAX fill:#8b0000,color:#fff
+    style PURGE fill:#8b0000,color:#fff
+```
+
+### 4.2 Humidity Control
+
+```mermaid
+flowchart TD
+    RH{"Room RH?"} -->|"< 35%"| HUMON["Activate Steam Humidifier"]
+    RH -->|"35–40%"| HUMLOW["Low Steam Output"]
+    RH -->|"40–60%"| OKAY["Optimal — No Action"]
+    RH -->|"60–65%"| DEHUMLOW["Reduce Humidifier / Light Dehumid"]
+    RH -->|"> 65%"| DEHUMON["Active Dehumidification + Alert"]
+
+    style HUMON fill:#1a5e5e,color:#fff
+    style DEHUMON fill:#8b0000,color:#fff
+```
+
+### 4.3 Filter Maintenance Alerts
+
+| Condition | Action |
+|-----------|--------|
+| ΔP across any stage > 1.5× initial value | Warning: filter loading, plan change |
+| ΔP across any stage > 2.0× initial value | Critical: change filter immediately |
+| ΔP drops suddenly | Warning: possible filter seal failure |
+| Indoor PM2.5 > outdoor PM2.5 | Critical: filter bypass or seal failure |
+
+### 4.4 Night Mode (Bedrooms)
+
+- Between 22:00–07:00, bedroom zones get priority airflow
+- CO₂ target tightened to < 600 ppm (sleep quality)
+- Fan speed profile optimized for minimum noise
+- Living room / kitchen dampers partially closed to redirect airflow
+
+### 4.5 Cooking Mode
+
+- Kitchen hood activation triggers:
+  - Kitchen zone damper closes (prevents pulling kitchen air into MVHR)
+  - Dedicated kitchen exhaust activates
+  - MVHR boost mode engages to compensate for exhaust pressure
+  - 30-minute timer to return to normal after cooking ends
+
+---
+
+## 5. Home Assistant Integration
+
+### 5.1 Dashboard Elements
+
+| Widget | Data Source | Purpose |
+|--------|-----------|---------|
+| Air Quality Index (per room) | CO₂ + PM2.5 + TVOC composite | At-a-glance air quality |
+| Filter Status (5 stages) | ΔP sensors | Remaining filter life % |
+| MVHR Status | MVHR controller | Fan speed, mode, heat recovery % |
+| Humidity Map | Room RH sensors | Whole-house humidity overview |
+| Radon Trend | Radon monitor | 24h / 7d / 30d trends |
+| Indoor vs. Outdoor | Outdoor station vs. indoor | Filtration effectiveness proof |
+| Energy Dashboard | MVHR + humidifier power | Running cost tracking |
+| Ceiling Heating/Cooling | Manifold actuators + surface temp | Per-zone heating/cooling status |
+| Ceiling Surface Temp | Embedded ceiling sensors | Condensation risk indicator (vs. dewpoint) |
+| Floor Surface Temp | Embedded floor sensors (if cooling) | Comfort limit monitoring |
+
+### 5.2 Alerting
+
+| Alert Level | Channel | Examples |
+|-------------|---------|----------|
+| Info | Dashboard notification | Filter approaching change interval |
+| Warning | Push notification | CO₂ > 1000 ppm, RH > 65% |
+| Critical | Push + audible alarm | Filter failure, PM2.5 spike, radon > 300 Bq/m³ |
+
+### 5.3 Data Logging
+
+All sensor data logged to InfluxDB via Home Assistant for long-term trend analysis:
+- 1-minute resolution for CO₂, PM, TVOC
+- 5-minute resolution for temperature, humidity
+- 1-hour resolution for radon
+- Retention: minimum 2 years
+
+---
+
+## 6. Communication Protocols
+
+```mermaid
+flowchart LR
+    subgraph Field["Field Level"]
+        S1["Room Sensors\n(Zigbee / WiFi)"]
+        S2["ΔP Sensors\n(I²C / 4-20mA)"]
+        S3["Outdoor Station\n(WiFi)"]
+    end
+
+    subgraph Bus["Bus Level"]
+        KNX["KNX Bus\n(MVHR, Dampers, Humidifier)"]
+        ZB["Zigbee Coordinator\n(Room Sensors)"]
+    end
+
+    subgraph Server["Server Level"]
+        HA["Home Assistant\n+ InfluxDB"]
+    end
+
+    S1 --> ZB
+    S2 --> KNX
+    S3 --> HA
+    ZB --> HA
+    KNX --> HA
+    HA --> KNX
+
+    style HA fill:#1a5e5e,color:#fff
+```
+
+- **KNX**: Primary bus for MVHR control, motorized dampers, humidifier — wired, deterministic, reliable
+- **Zigbee**: Room sensor network — mesh, low power, well-supported in Home Assistant
+- **WiFi**: Outdoor station, radon monitors — direct to Home Assistant
+- **InfluxDB**: Time-series database for long-term data retention and Grafana dashboards
+
+---
+
+## 7. Wiring Requirements for Baufritz
+
+The following must be specified at construction stage:
+
+| Item | Quantity | Location | Cable |
+|------|----------|----------|-------|
+| KNX bus cable | 1 run per zone | All zones + technical room | KNX TP (green, 2×2×0.8mm) |
+| 230V outlet for room sensor | 1 per room | At sensor mounting point | Standard NYM |
+| Cat6 network drop | 1 per room | Near sensor location | Cat6a shielded |
+| Dedicated circuit: MVHR | 1 | Technical room | 3×2.5mm² |
+| Dedicated circuit: humidifier | 1 | Technical room | 3×2.5mm² (steam = high draw) |
+| ΔP sensor cable runs | 5 | Filter housing to technical room | 4-wire shielded |
+| Outdoor sensor power + data | 1 | North-facing exterior | Weatherproof outlet + Cat6 |
+| Ceiling surface temp sensors | 1 per zone | Embedded in Plafotherm panels | 4-wire shielded |
+| Floor surface temp sensors | 2-3 per zone | On/in parquet surface | 4-wire shielded |
+
+**Note**: On the ground floor, KNX bus cable and Cat6 runs can be routed through the Lindner NORTEC Doppelboden cavity instead of wall chases, simplifying installation (see 04-flooring-ceiling-spec Section 6.1).
--- a/specs/03-baufritz-coordination-spec.md
+++ b/specs/03-baufritz-coordination-spec.md
@@ -0,0 +1,274 @@
+# Baufritz Builder Coordination Specification
+
+## 1. Overview
+
+This document specifies requirements that must be communicated to and coordinated with Baufritz during the design and construction phases. Baufritz builds with excellent low-emission materials (no formaldehyde, no synthetic glues, tested for 300+ pollutants) and designs for airtight envelopes — this is the ideal foundation for our clean air system.
+
+**The air system is not a retrofit. It must be designed into the structure from the beginning.**
+
+---
+
+## 2. Technical Room Requirements
+
+A dedicated technical room is required for the air handling equipment. This is not a utility cupboard — it needs standing access for filter changes and equipment maintenance.
+
+### 2.1 Minimum Specifications
+
+| Parameter | Requirement |
+|-----------|-------------|
+| Floor area | 4–6 m² minimum (ideally 6–8 m²) |
+| Ceiling height | ≥ 2.4 m |
+| Access | Full-width door (≥ 900 mm), no obstructions |
+| Floor | Waterproof, drainable (steam humidifier condensate) |
+| Electrical | 3× dedicated 230V/16A circuits (MVHR, humidifier, controls) |
+| Lighting | Bright, shadow-free (filter inspection) |
+| Location | Central in building footprint (minimizes duct runs) |
+| Noise isolation | Sound-insulated walls/door (MVHR generates 35–45 dB) |
+
+### 2.2 Equipment Layout
+
+```mermaid
+block-beta
+    columns 3
+
+    block:row1:3
+        A["G4/M5\nPre-filter\nHousing"] B["F7\nIntermediate\nHousing"] C["Activated\nCarbon\nHousing"]
+    end
+
+    block:row2:3
+        D["H13 HEPA\nCassette Bank\n(600×600mm panels)"] space:1 E["MVHR Unit\n(Drexel & Weiss\nor Swegon)"]
+    end
+
+    block:row3:3
+        F["Steam\nHumidifier\n(Condair/Hygromatik)"] G["Control\nPanel\n(KNX Gateway)"] H["Supply\nDuct\nManifold"]
+    end
+
+    style D fill:#1a5e1a,color:#fff
+    style E fill:#1a3d5e,color:#fff
+    style F fill:#1a5e5e,color:#fff
+```
+
+**All filter housings must be accessible from the front** with tool-free opening for filter changes. Minimum 800 mm clearance in front of each housing.
+
+---
+
+## 3. Duct Routing Requirements
+
+### 3.1 Design Principles
+
+| Requirement | Detail |
+|------------|--------|
+| Duct material | Rigid galvanized steel or aluminum — **no semi-rigid flex** |
+| Exception | Final 0.5 m to each diffuser: flex for vibration isolation |
+| Sealing | All joints mastic-sealed (not tape only) |
+| Testing | Pressure-tested to Passivhaus duct leakage class after installation |
+| Velocity: main trunk | ≤ 2.0 m/s |
+| Velocity: branches | ≤ 1.5 m/s |
+| Velocity: diffuser connection | ≤ 1.0 m/s |
+| Main trunk diameter | 200–250 mm round (or equivalent rectangular) |
+| Branch diameter | 125–160 mm round |
+
+### 3.2 Routing Constraints
+
+- **No ducts in exterior walls** — condensation risk and thermal bridging
+- **Dedicated vertical risers** for multi-story distribution — coordinate with structural plan
+- **Acoustic silencers** at MVHR outlets and before each room diffuser
+- **Inspection/cleaning access points** at all bends > 45° and every 6 m of straight run
+- **Fire dampers** at all floor/wall penetrations per DIN 4102
+
+### 3.3 Duct Space Requirements
+
+```mermaid
+flowchart TD
+    subgraph Ground["Ground Floor Ceiling Void"]
+        GT["Main Supply Trunk\n200–250mm"]
+        GB1["Branch: Living Room\n160mm"]
+        GB2["Branch: Kitchen\n125mm (exhaust only)"]
+        GB3["Branch: Office\n125mm"]
+    end
+
+    subgraph Upper["Upper Floor Ceiling Void"]
+        UT["Main Supply Trunk\n200mm"]
+        UB1["Branch: Master Bedroom\n160mm"]
+        UB2["Branch: Leo's Room\n125mm"]
+        UB3["Branch: Bathroom(s)\n100mm"]
+    end
+
+    TR["Technical Room"] --> GT
+    TR --> UT
+
+    style TR fill:#1a3d5e,color:#fff
+```
+
+**Baufritz must allocate ceiling void depth of ≥ 300 mm** in areas where main ducts run, or provide dedicated duct boxing. This must be shown on construction drawings.
+
+**Note**: The ceiling void is shared with the Lindner Plafotherm radiant ceiling system (see 04-flooring-ceiling-spec Section 4). On the ground floor, branch supply ducts may route through the raised floor cavity instead (see 04-flooring-ceiling-spec Section 6), potentially reducing ceiling void requirements. However, the main supply trunk and Plafotherm pipes still require adequate ceiling void depth. **Floor-to-floor structural height must be ≥ 3000 mm** to accommodate both the raised floor and ceiling system while maintaining ≥ 2500 mm usable room height (see 04-flooring-ceiling-spec Section 2).
+
+---
+
+## 4. Building Envelope Requirements
+
+### 4.1 Airtightness
+
+| Parameter | Requirement |
+|-----------|-------------|
+| Blower door test (n50) | ≤ 0.6 ACH (Passivhaus standard) |
+| Target | 0.3 ACH if achievable |
+| Testing | Blower door test during construction (before interior finishing) AND after completion |
+
+Baufritz typically achieves excellent airtightness. This is critical — the air system only works if 100% of air passes through the filter stack. Every uncontrolled leak bypasses the entire system.
+
+### 4.2 Radon Protection
+
+| Item | Specification |
+|------|--------------|
+| Radon membrane | Continuous radon-proof membrane at foundation/ground slab |
+| Membrane type | HDPE or bituminous, radon-tested per DIN/ISO |
+| Sealing | All penetrations (pipes, cables) sealed with radon-rated sealant |
+| Sub-slab ventilation | Provision for passive sub-slab depressurization (can be activated later if needed) |
+| Monitoring | Radon sensor in lowest habitable room, connected to Home Assistant |
+
+**Note**: The Bremen/Grasberg area is generally low radon risk per BfS (Federal Office for Radiation Protection) maps, but radon protection is inexpensive at construction stage and expensive to retrofit. Specify it regardless.
+
+**Raised floor compatibility**: The Lindner NORTEC Doppelboden pedestal system must be anchored with adhesive bonding only — no mechanical fixings that penetrate the radon membrane. Verify adhesive compatibility with the membrane material (see 04-flooring-ceiling-spec Section 7.5).
+
+### 4.3 Thermal Bridge Prevention
+
+Baufritz excels at thermal-bridge-free construction. Verify:
+- No thermal bridges at window reveals, sills, lintels
+- No thermal bridges at floor/wall junctions
+- No thermal bridges at balcony connections (if any)
+- Surface temperatures never below dewpoint at any point (prevents condensation → mold)
+
+---
+
+## 5. MVHR Specification for Baufritz
+
+### 5.1 Unit Selection
+
+Specify to Baufritz that the MVHR unit must meet:
+
+| Parameter | Minimum | Preferred |
+|-----------|---------|-----------|
+| Available static pressure | 450 Pa | ≥ 500 Pa |
+| Airflow capacity | 400 m³/h | 450 m³/h |
+| Heat recovery | 85% | ≥ 90% |
+| Fan motor | EC variable speed | EC variable speed |
+| Bypass | Summer bypass with motorized flap | Automatic |
+| Controls interface | Modbus | KNX native |
+| External filter box | Compatible | Designed for |
+
+### 5.2 Baufritz-Typical vs. Our Requirements
+
+Baufritz typically installs standard residential MVHR units (e.g., Zehnder ComfoAir Q350, Paul Novus 300). These are excellent units but designed for F7/F9 filtration with ~200–250 Pa system pressure.
+
+**Our H13 whole-house requirement means upgrading to a higher-pressure unit.** This must be specified early because:
+- The MVHR unit dimensions affect technical room layout
+- Higher-pressure units may have different duct connection sizes
+- Electrical requirements may differ (larger EC motors)
+- Noise characteristics change — sound insulation may need upgrading
+
+---
+
+## 6. Garage Separation
+
+If the house includes an attached garage:
+
+| Requirement | Detail |
+|------------|--------|
+| Pressure separation | Garage at negative pressure relative to house |
+| No shared air volume | No door directly from garage to conditioned space without airlock |
+| Separate exhaust | Garage has its own exhaust fan with timer/CO sensor |
+| Sealing | All wall/ceiling penetrations between garage and house fully sealed |
+| CO sensor | In garage, interlocked with garage exhaust fan |
+
+**Garage exhaust fumes (CO, NOx, PM, benzene) are extremely hazardous. Zero tolerance for garage air entering the conditioned space.**
+
+---
+
+## 7. Kitchen Exhaust Specification
+
+| Requirement | Detail |
+|------------|--------|
+| Type | Ducted to outside — NOT recirculating |
+| Backdraft damper | Motorized, closes when hood is off |
+| Duct material | Stainless steel or galvanized (grease-rated) |
+| Interlock | Activates MVHR boost mode for make-up air |
+| Separation | Never connected to the MVHR system |
+| Fire safety | Fire damper at wall penetration |
+
+---
+
+## 8. Electrical & Wiring Coordination
+
+### 8.1 Technical Room Electrical
+
+| Circuit | Rating | Purpose |
+|---------|--------|---------|
+| MVHR dedicated | 230V / 16A | MVHR unit power |
+| Humidifier dedicated | 230V / 16A (or 400V / 3-phase) | Steam humidifier (high wattage) |
+| Controls | 230V / 10A | KNX power supply, gateway, sensors |
+| Backup/spare | 230V / 16A | Future expansion |
+
+### 8.2 Building-Wide Wiring
+
+| Item | Specification |
+|------|--------------|
+| KNX bus cable | To every zone (MVHR dampers, sensors) |
+| Cat6a shielded | To every room (sensor data, future-proofing) |
+| 230V at sensor points | USB power for sensor units |
+| Outdoor sensor cable | Weatherproof, north wall |
+| ΔP sensor cabling | 5× runs from filter housing to control panel |
+
+**All wiring for the air system must be specified on Baufritz's electrical plan before wall construction begins.** Retrofit wiring in a sealed timber-frame house is extremely difficult and expensive.
+
+---
+
+## 9. Construction Phase Checkpoints
+
+### 9.1 During Construction
+
+| Phase | Checkpoint |
+|-------|-----------|
+| Foundation | Radon membrane installed and sealed at all penetrations |
+| Framing | Duct routing voids verified, vertical risers in place |
+| Framing | Ceiling void dimensions verified for Plafotherm + MVHR trunk |
+| Pre-close | First blower door test (target ≤ 0.6 n50) |
+| Pre-close | All duct runs installed, mastic-sealed, pressure-tested |
+| Pre-close | All KNX/Cat6 wiring installed and tested |
+| Interior finishing | Plafotherm ceiling suspension and panels installed |
+| Interior finishing | Ceiling heating circuit pressure-tested |
+| Interior finishing | Raised floor pedestals installed, subfloor leveling verified |
+| Interior finishing | Under-floor services (ducts, wiring) installed and pressure-tested |
+| Interior finishing | Floor panels and WOODline parquet tiles installed |
+| Interior finishing | Verify no ducts compressed or kinked by finishing work |
+| Completion | Final blower door test |
+| Completion | Commission MVHR, set airflows, balance dampers / AirHybrid panels |
+| Completion | Commission ceiling heating/cooling, verify surface temperatures |
+| Completion | Commission sensors, verify readings, connect to Home Assistant |
+
+### 9.2 Commissioning Verification
+
+| Test | Acceptance Criteria |
+|------|-------------------|
+| Blower door (n50) | ≤ 0.6 ACH |
+| Duct leakage | Passivhaus class |
+| Room-by-room airflow | Within ±10% of design spec |
+| House positive pressure | +3 to +5 Pa vs. outside |
+| CO₂ decay test | < 800 ppm within 30 min of occupancy end |
+| PM2.5 indoor vs. outdoor | Indoor < 10% of outdoor |
+| Noise at diffusers | < 25 dB(A) per diffuser |
+
+---
+
+## 10. Timeline Integration
+
+| Baufritz Phase | Air System Action | Lindner Floor/Ceiling Action |
+|----------------|-------------------|------------------------------|
+| Initial design | Specify MVHR unit, technical room size, duct routing | Confirm raised floor + Plafotherm, specify cavity heights and floor-to-floor height (≥ 3000 mm) |
+| Detailed planning | Approve duct routing on drawings, specify all penetrations | Lindner layout drawings for floor and ceiling, coordinate with MVHR plan |
+| Pre-fabrication | Confirm radon membrane spec, duct void dimensions | Verify subfloor level tolerance and ceiling anchor points in prefab panels |
+| Factory build | Verify duct voids in prefab wall/floor panels | No impact (Lindner systems installed on-site) |
+| On-site assembly | Supervise duct installation, first blower door test | Install ceiling system, then floor pedestals and cavity services |
+| Finishing | Sensor wiring, diffuser installation | Parquet tile installation, floor and ceiling commissioning |
+| Handover | Full commissioning, sensor calibration, HA setup | Heating/cooling commissioning, AirHybrid airflow verification |
--- a/specs/04-flooring-ceiling-spec.md
+++ b/specs/04-flooring-ceiling-spec.md
@@ -0,0 +1,514 @@
+# Flooring & Ceiling Specification — Lindner Raised Floor + Radiant Ceiling
+
+## 1. Design Philosophy
+
+This house uses a **dual Lindner system**: a raised floor (Doppelboden) below and radiant ceiling panels above. Together they replace traditional screed, radiators, and conventional ceiling finishes with a fully integrated, modular, dry-construction approach.
+
+- **Raised floor** = services distribution layer. The cavity beneath the panels routes MVHR branch ducts, KNX bus cable, Cat6 data, electrical wiring, and plumbing — all accessible by lifting individual tiles.
+- **Radiant ceiling** = heating, cooling, and ventilation air distribution. Lindner Plafotherm AirHybrid panels combine radiant water-based climate control with MVHR supply air distribution through ceiling perforations.
+- **No wet trades**: Both systems are dry-installed — no screed, no drying time. Ideal for Baufritz timber-frame prefabrication.
+- **Lifetime maintainability**: Every component is demountable. A pipe leak, a rewiring job, or a technology upgrade requires lifting tiles or removing ceiling panels — not demolition.
+
+**The raised floor is not a cosmetic choice. It is a services distribution layer that provides lifetime maintainability. The radiant ceiling is not a luxury — it is the most responsive, furniture-independent, and efficient way to heat and cool a sealed, high-performance home.**
+
+---
+
+## 2. Room Height Budget
+
+Both systems consume vertical space. The usable clear room height must be carefully planned with Baufritz at the structural design stage.
+
+```mermaid
+flowchart TD
+    A["Structural Ceiling Deck\n~200 mm timber construction"] --> B
+    B["Plafotherm Suspension\n30-70 mm substructure"] --> C
+    C["Plafotherm Ceiling Panel\n30-50 mm radiant panel + pipes"] --> D
+    D["USABLE ROOM HEIGHT\nTarget: 2500 mm minimum"] --> E
+    E["WOODline Parquet\n4 mm solid wood"] --> F
+    F["CaSO4 Floor Panel\n40-44 mm calcium sulphate"] --> G
+    G["Services Cavity\n80-200 mm depending on floor"] --> H
+    H["Floor Pedestals\nadjustable steel"] --> I
+    I["Structural Floor Deck / Slab\n+ Radon membrane below"]
+
+    style D fill:#1a5e1a,color:#fff,stroke:#0d3d0d
+    style C fill:#8b0000,color:#fff
+    style F fill:#1a3d5e,color:#fff
+```
+
+### 2.1 Height Calculation
+
+| Layer | Ground Floor | Upper Floor | Notes |
+|-------|-------------|-------------|-------|
+| Structural floor-to-floor height | **3000-3200 mm** | **3000-3200 mm** | Baufritz to specify; must be ≥ 3000 mm |
+| Structural deck (floor + ceiling) | -200 mm | -200 mm | Timber joists + sheathing |
+| Ceiling system (Plafotherm + suspension) | -80 to -120 mm | -80 to -120 mm | Depends on product variant |
+| Raised floor (cavity + panel + parquet) | -200 to -250 mm | -130 to -170 mm | Ground floor deeper for MVHR ducts |
+| **Usable clear height** | **2430-2720 mm** | **2510-2790 mm** | Target ≥ 2500 mm |
+
+### 2.2 Recommendation
+
+**Baufritz structural floor-to-floor height must be ≥ 3000 mm**, preferably 3100-3200 mm, to guarantee ≥ 2500 mm usable room height on all floors after both Lindner systems are installed. This must be specified at the initial design stage — it cannot be changed after prefabrication begins.
+
+---
+
+## 3. Raised Floor — Lindner NORTEC Doppelboden
+
+### 3.1 System Overview
+
+Since heating is provided by the ceiling system, the raised floor uses **standard NORTEC Doppelboden panels** (not the "comfort" variant with integrated heating pipes). The Doppelboden (raised floor) system uses individually removable modular panels on height-adjustable pedestals — any panel can be lifted at any time for full access to the services cavity below. This is the key advantage over Hohlboden (hollow floor) systems, which form a continuous layer with limited access.
+
+| Parameter | Value |
+|-----------|-------|
+| Product | Lindner NORTEC (Doppelboden / raised access floor) |
+| Panel material | Fibre-reinforced calcium sulphate (CaSO4), up to 100% recycled |
+| Panel dimensions | 600 x 600 mm |
+| Panel thickness | 40-44 mm |
+| Load class | 3-6 (per EN 13213) |
+| Point load capacity | 3-7 kN (depending on class) |
+| Fire class | A1 non-combustible (EN 13501-1) |
+| Fire resistance | F30 (DIN 4102-2) |
+| Weight | 41-55 kg/m2 |
+| Sustainability | Cradle to Cradle Silver certified |
+
+### 3.2 Pedestal System
+
+| Parameter | Value |
+|-----------|-------|
+| Type | Type S or Type SWH120 |
+| Material | Galvanized steel, chrome(VI)-free, zinc-whisker-free |
+| Height adjustment | Infinitely adjustable, 40-2000 mm |
+| Grid spacing | 600 x 600 mm |
+| Anchoring | **Adhesive bonding only** — no mechanical fixings through radon membrane |
+| Approximate quantity | ~8 pedestals per m2 |
+
+### 3.3 Cavity Height Selection
+
+| Zone | Cavity Height | Services Routed | Justification |
+|------|--------------|-----------------|---------------|
+| Ground floor living areas | 200 mm | MVHR branch ducts (125-160 mm) + KNX + electrical | Must accommodate duct diameter + clearance |
+| Ground floor kitchen | 200 mm | MVHR exhaust branch + electrical + plumbing | Kitchen exhaust duct routing |
+| Ground floor office | 150-200 mm | MVHR branch + KNX + Cat6 + electrical | Data-heavy zone |
+| Upper floor bedrooms | 100-120 mm | KNX + Cat6 + electrical only | No MVHR ducts (routed in ceiling void) |
+| Upper floor bathrooms | 100-120 mm | Electrical + plumbing waste | Waterproof membrane above panels |
+| Technical room | 150 mm | Electrical + plumbing connections | Higher load class (Class 5) |
+
+### 3.4 Surface Finish — NORTEC WOODline Parquet
+
+| Parameter | Value |
+|-----------|-------|
+| Product | Lindner NORTEC WOODline |
+| Material | Solid wood parquet, factory-bonded to panel |
+| Dimensions | 600 x 600 x 4 mm |
+| Wood species | Oak, Smoked Oak, Ash Eco, Bamboo Light, Steamed Bamboo |
+| Design patterns | 16+ patterns (herringbone, mosaic, 2-strip, geometric, etc.) |
+| Certification | PEFC certified |
+| Joint type | Near-invisible joints with color-matched edge bands |
+| Edge protection | Edge bands extend to parquet top — prevents moisture penetration |
+
+#### Surface Treatment Options
+
+| Treatment | Description | Slip Resistance | Best For |
+|-----------|-------------|-----------------|----------|
+| Lacquered | 6-layer UV curing, matte finish | R9, Class 6 durability | Living areas, kitchen, hallways |
+| Oiled | Hard wax oil, 2 applications, matte | R9 | Bedrooms, office |
+| Sanded | Pre-sanded, requires on-site coating | N/A | **Not recommended** — on-site coating introduces VOCs into sealed envelope |
+
+**Recommendation**: Lacquered Oak for main living areas (durability, low maintenance). Oiled Oak for bedrooms (natural feel). **Avoid sanded finish** — on-site coating releases VOCs that conflict with the air quality targets in 01-air-system-spec Section 8 (formaldehyde target < 30 ug/m3).
+
+---
+
+## 4. Ceiling Heating/Cooling — Lindner Plafotherm
+
+### 4.1 Product Selection
+
+| Product | Type | Key Feature | Residential Suitability |
+|---------|------|-------------|------------------------|
+| **Plafotherm AirHybrid** | Hybrid radiant + ventilation | Combines heating/cooling with MVHR supply air distribution | **Recommended** — eliminates separate diffusers |
+| Plafotherm GK HEKDA | Plasterboard radiant ceiling | Seamless plastered finish, residential aesthetic | Good alternative for rooms without MVHR supply |
+| Plafotherm E 210 | Hook-on metal ceiling | Clean metal panel look, butt joints | Modern aesthetic option |
+| Plafotherm B 100 | Post cap metal ceiling | Cost-effective, visible linear joints | Budget option |
+
+**Primary recommendation: Plafotherm AirHybrid** for all rooms with MVHR supply air. Plafotherm GK HEKDA for bathrooms and rooms where a seamless plastered ceiling is preferred.
+
+### 4.2 Heating/Cooling Performance
+
+| Parameter | Standard Radiant | AirHybrid (2x air exchange) | AirHybrid (6x air exchange) |
+|-----------|-----------------|---------------------------|---------------------------|
+| Heating output (at 15K delta-T) | 123 W/m2 | 149 W/m2 | 161 W/m2 |
+| Cooling output (at 10K delta-T) | - | 137 W/m2 | 159 W/m2 |
+| Standard (EN 14037 / EN 14240) | EN 14037 | EN 14037 / EN 14240 | EN 14037 / EN 14240 |
+
+**For context**: A Passivhaus-level Baufritz home has a peak heating demand of approximately 10-15 W/m2. Even the standard radiant panel at 123 W/m2 provides **8-12x the required capacity**. This means only a fraction of the ceiling area needs to be active at any time, or flow temperatures can be very low (maximizing heat pump COP).
+
+### 4.3 Pipe Specifications
+
+| Parameter | Value |
+|-----------|-------|
+| Connection hoses | PlafoTube PK |
+| Nominal width | DN 13 |
+| Press coupling | 12 mm brass fittings |
+| Pressure rating | 16 bar |
+| Flow temperature (heating) | 30-35 C design (low-temp for heat pump efficiency) |
+| Flow temperature (cooling) | 16-18 C (must stay above dewpoint) |
+
+### 4.4 System Depth
+
+| Component | Depth |
+|-----------|-------|
+| Panel (Plafotherm B/E) | 30-50 mm |
+| Suspension substructure | 30-70 mm |
+| **Total system depth** | **60-120 mm** |
+
+The exact depth depends on the chosen product variant and must be confirmed with Lindner for the specific ceiling type. The AirHybrid variant may require slightly more depth for the ventilation hood on the rear side.
+
+### 4.5 Advantages Over Floor Heating
+
+| Aspect | Ceiling Heating | Floor Heating |
+|--------|----------------|---------------|
+| Response time | Fast — low thermal inertia | Slow — 5+ hours typical |
+| Heat output | ~175 W/m2 max | ~65 W/m2 limited by covering |
+| Furniture impact | Zero — completely unobstructed | Significant — rugs and furniture reduce output |
+| Floor covering freedom | Any covering, any time | Covering thermal resistance limits options |
+| Dust circulation | None — radiant, no convection | Minimal but present |
+| Cooling capability | Excellent — natural convection aids cooling from above | Limited — cool air at floor stays at floor |
+| Relative cost | ~50% of floor system cost | Baseline |
+
+---
+
+## 5. MVHR Integration via AirHybrid Ceiling
+
+### 5.1 Supply Air Distribution
+
+The Plafotherm AirHybrid integrates MVHR supply air distribution directly into the ceiling panels:
+
+- Ventilation hood mounted on the rear (upper) side of the panel — invisible from below
+- Supply air distributed through **panel perforations and induction outlets**
+- Even air distribution without perceptible drafts
+- **Replaces conventional wall/ceiling diffusers** in rooms where AirHybrid is installed
+
+This means the MVHR supply air is tempered by the radiant ceiling before entering the room — pre-heated in winter, pre-cooled in summer. No cold-air draft sensation.
+
+### 5.2 Revised Air System Architecture
+
+```mermaid
+flowchart TD
+    MVHR["MVHR Unit\nH13 HEPA filtered supply"] --> TRUNK["Main Supply Trunk\nin ceiling void"]
+    TRUNK --> AH1["AirHybrid Panels\nLiving Room"]
+    TRUNK --> AH2["AirHybrid Panels\nBedrooms"]
+    TRUNK --> AH3["AirHybrid Panels\nOffice"]
+    TRUNK --> BATH["Conventional Diffuser\nBathrooms"]
+
+    HP["Heat Pump"] --> MAN["Heating/Cooling Manifold"]
+    MAN --> P1["Plafotherm Pipes\nLiving Room"]
+    MAN --> P2["Plafotherm Pipes\nBedrooms"]
+    MAN --> P3["Plafotherm Pipes\nOffice"]
+    MAN --> P4["Plafotherm Pipes\nBathrooms"]
+
+    EX1["Exhaust Grilles\nall rooms"] --> EXDUCT["Exhaust Ducts\nin floor cavity or walls"]
+    EXDUCT --> MVHR
+
+    style MVHR fill:#1a3d5e,color:#fff
+    style HP fill:#8b0000,color:#fff
+    style AH1 fill:#1a5e5e,color:#fff
+    style AH2 fill:#1a5e5e,color:#fff
+    style AH3 fill:#1a5e5e,color:#fff
+```
+
+### 5.3 Humidity Control for Cooling Mode
+
+**Critical requirement**: When the ceiling operates in cooling mode, the ceiling surface temperature drops. If it falls below the room air dewpoint, condensation forms on the panels.
+
+- The MVHR system must control absolute humidity of supply air (see 01-air-system-spec Section 5, steam humidifier / dehumidification)
+- Ceiling surface temperature sensors must be installed (see Section 9.3)
+- Automated interlock: if ceiling surface temperature approaches dewpoint within 2K, reduce cooling water flow or activate dehumidification
+- Cooling water flow temperature must never go below 16 C without verified dewpoint margin
+
+### 5.4 MVHR Duct Routing Revision
+
+With AirHybrid ceiling integration, the duct routing changes:
+
+| Duct Function | Routing Location | Notes |
+|--------------|-----------------|-------|
+| Main supply trunk | Ceiling void (alongside Plafotherm pipes) | Shared space — coordinate routing |
+| Supply branches | Via AirHybrid ceiling panels | No separate diffusers needed |
+| Main exhaust trunk | Ceiling void or floor cavity | Depends on building layout |
+| Exhaust branches | Floor cavity (ground floor) or wall ducts | Exhaust grilles at low level preferred |
+| Kitchen exhaust | Dedicated separate stack | Never through MVHR — unchanged |
+
+---
+
+## 6. Floor Cavity Services Integration
+
+### 6.1 Ground Floor
+
+The ground floor raised floor cavity (200 mm) accommodates:
+
+- **MVHR exhaust branch ducts** (125-160 mm diameter, rigid steel/aluminum per 01-air-system-spec Section 6.2)
+- **KNX bus cable** to all room zones
+- **Cat6a shielded data** to all rooms
+- **Electrical wiring** (standard NYM cable)
+- **Plumbing** (where floor-level connections are needed)
+
+**Constraints**:
+- Ducts must be rigid steel/aluminum — no semi-rigid flex except final 0.5 m
+- All duct joints mastic-sealed
+- Minimum 20 mm clearance between ducts and other services
+- No main trunk ducts in the floor cavity — trunk stays in ceiling void. Only branch ducts
+
+### 6.2 Upper Floor
+
+The upper floor cavity (100-120 mm) accommodates only:
+- KNX, Cat6, and electrical wiring
+- MVHR ducts route in the ceiling void between floors (same void as Plafotherm)
+
+### 6.3 Airtightness
+
+The floor cavity must not compromise the house's +3 to +5 Pa positive pressure (see 01-air-system-spec Section 7):
+
+- **Panel joints**: sealed with Lindner's standard gasket system
+- **Perimeter**: sealed to walls with compressible airtight tape
+- **Service penetrations**: all pipe/cable entries through panels sealed with airtight grommets
+- **Cavity is NOT ventilated**: it is a sealed, conditioned space
+- **Ducts are individual sealed runs**: the cavity itself is not used as an air plenum
+
+---
+
+## 7. Structural and Load Considerations
+
+### 7.1 Floor Load Classes
+
+| Zone | Minimum Load Class | Point Load | Justification |
+|------|-------------------|------------|---------------|
+| Living areas | Class 3 | 3 kN | Residential furniture, foot traffic |
+| Kitchen | Class 4 | 4 kN | Heavy appliances |
+| Technical room | Class 5 | 5 kN | MVHR unit, humidifier, control cabinets |
+| Bathrooms | Class 3 | 3 kN | With waterproofing layer above panels |
+| Hallways / stairs landing | Class 3 | 3 kN | Standard residential |
+
+### 7.2 Ceiling Suspension Load
+
+- Plafotherm system weight: approximately 14-16 kg/m2 (without fixtures)
+- Baufritz ceiling deck (timber joists + sheathing) must support this additional suspended load
+- Verify with Baufritz structural engineer — this is within normal limits for timber-frame construction
+
+### 7.3 Combined Dead Load
+
+| Component | Load (kg/m2) |
+|-----------|-------------|
+| Raised floor (panels + pedestals) | 41-55 |
+| Parquet finish | ~4 |
+| Ceiling system (Plafotherm + suspension) | 14-16 |
+| **Total additional dead load per floor** | **59-75** |
+
+Baufritz structural engineer must verify that the timber floor deck supports this additional dead load plus the design live load (1.5-2.0 kN/m2 residential per DIN EN 1991-1-1).
+
+### 7.4 Bathroom Considerations
+
+- Calcium sulphate panels are **not inherently waterproof**
+- Bathrooms require a **waterproof membrane above the panels** (liquid-applied or sheet membrane)
+- Confirm with Lindner whether moisture-resistant panel variants are available
+- Pedestal corrosion: galvanized steel pedestals tolerate occasional moisture but are not rated for continuous wet conditions
+- Floor drains penetrate through panels — connections sealed with waterproof flanges
+- Ceiling panels in bathrooms: use moisture-resistant Plafotherm variant or Plafotherm GK with moisture-rated plasterboard
+
+### 7.5 Pedestal Anchoring
+
+- Pedestals bonded to structural subfloor with **adhesive only**
+- **No mechanical fixings through the radon membrane** (see 03-baufritz-coordination-spec Section 4.2)
+- Verify adhesive compatibility with radon membrane material (HDPE or bituminous)
+- Adhesive must maintain bond under the combined dead load + live load
+
+---
+
+## 8. Acoustic Performance
+
+### 8.1 Floor Acoustics
+
+| Parameter | Target |
+|-----------|--------|
+| Impact sound improvement (delta Lw) | >= 20 dB |
+| Airborne sound insulation (Rw, between floors) | >= 50 dB |
+
+- Calcium sulphate panels on rubber-damped pedestals provide acoustic decoupling from the structural floor
+- Verify Lindner's acoustic data sheets for the specific pedestal type and cavity height
+- Additional acoustic mat between pedestal base plate and subfloor if required to meet targets
+
+### 8.2 Ceiling Acoustics
+
+- Plafotherm panels provide additional acoustic absorption depending on panel type
+- Plafotherm GK HEKDA (plasterboard) offers good mid-frequency absorption
+- Metal panels (B/E series) may require acoustic fleece backing for absorption
+- Verify weighted sound absorption coefficient (alpha-w) with Lindner
+
+### 8.3 MVHR Noise in Shared Voids
+
+- Ducts in ceiling void and floor cavity can transmit fan noise between rooms
+- **Acoustic silencers required** at trunk-to-branch junctions and before each distribution point
+- Target at all distribution points: **< 25 dB(A)** (same as 03-baufritz-coordination-spec Section 9.2)
+- The AirHybrid panel perforations provide some natural sound attenuation — verify with Lindner acoustic data
+
+---
+
+## 9. Sensor Placement Considerations
+
+### 9.1 Temperature and Humidity Sensors
+
+With both a heated ceiling above and a raised floor below, the room air temperature gradient is different from conventional construction:
+
+- **Mount sensors at 1.2-1.5 m wall height** — the midpoint of the room where occupants experience the air
+- **Away from the heated ceiling**: ceiling surface may be 25-35 C — sensors near the ceiling would read high
+- **Away from the raised floor surface**: floor will be at room temperature (no floor heating), but directly above floor diffusers could be cooler
+- **Away from exterior walls**: radiant asymmetry near windows affects readings
+- Cross-reference: 02-sensor-automation-spec Section 2.1
+
+### 9.2 Floor Surface Temperature Sensor
+
+If floor cooling is used in summer (optional — primary cooling is from ceiling):
+- Embedded sensors in or on the parquet surface, 2-3 per zone
+- Floor surface must not exceed 29 C (DIN EN 1264 comfort limit for habitable rooms) or drop below dewpoint in cooling mode
+
+### 9.3 Ceiling Surface Temperature Sensor
+
+**Critical for condensation prevention in cooling mode**:
+
+- Embedded sensors on or in the Plafotherm panels, minimum 1 per zone
+- Connected to KNX / Home Assistant
+- Automated interlock: if ceiling surface temperature approaches room dewpoint within 2K, the system must either reduce cooling water flow or activate dehumidification
+- Cross-reference: 02-sensor-automation-spec Section 5.1 (add condensation risk indicator to dashboard)
+
+### 9.4 Radon Monitoring
+
+- Room-level radon sensor on ground floor (per 02-sensor-automation-spec Section 2)
+- **Additional**: one radon sensor with sampling port into the floor cavity itself — early warning of radon membrane breach
+- If cavity radon levels rise while room levels remain normal, the membrane and cavity sealing are working; if room levels rise, investigate immediately
+
+---
+
+## 10. Heating/Cooling Control
+
+### 10.1 Zone Control Architecture
+
+| Component | Specification |
+|-----------|--------------|
+| Flow control | Thermal actuator on manifold, per room/zone |
+| Manifold location | Technical room or dedicated riser closet |
+| Control bus | KNX |
+| Room input | Room thermostat (1.2-1.5 m) + ceiling surface temp sensor |
+| Flow temperature (heating) | 30-35 C (outdoor-temperature compensated) |
+| Flow temperature (cooling) | 16-18 C (dewpoint-guarded) |
+| Return temperature | 25-28 C (heating), 18-20 C (cooling) |
+
+### 10.2 Home Assistant Integration
+
+- Ceiling heating/cooling zones visible on dashboard alongside air quality data
+- Floor surface temperature displayed per zone (if floor cooling used)
+- **Condensation risk indicator**: calculated from ceiling surface temp vs. room dewpoint
+- Night mode: reduce ceiling temperature setpoint by 2 C (cross-ref 02-sensor-automation-spec Section 4.4)
+- Summer cooling: activate when outdoor temp > 26 C and indoor temp > 24 C
+- Interlock: dehumidification activates automatically when cooling mode is active
+
+### 10.3 Condensation Prevention
+
+```mermaid
+flowchart TD
+    MODE{"Operating Mode?"} -->|Heating| HEAT["Normal Heating\nFlow temp 30-35C"]
+    MODE -->|Cooling| COOL["Cooling Active\nFlow temp 16-18C"]
+    MODE -->|Off| OFF["Standby"]
+
+    COOL --> DEW{"Ceiling Surface\nvs. Dewpoint?"}
+    DEW -->|"> 3K margin"| OK["Safe - Continue Cooling"]
+    DEW -->|"2-3K margin"| WARN["Warning\nReduce cooling flow"]
+    DEW -->|"< 2K margin"| STOP["STOP Cooling\nActivate dehumidification\nAlert via Home Assistant"]
+
+    style STOP fill:#8b0000,color:#fff
+    style WARN fill:#4a4a00,color:#fff
+    style OK fill:#1a5e1a,color:#fff
+```
+
+---
+
+## 11. Installation Sequence and Baufritz Coordination
+
+### 11.1 Pre-Installation Requirements
+
+| Prerequisite | Detail |
+|-------------|--------|
+| Radon membrane | Installed, sealed, and tested at all penetrations |
+| Structural subfloor | Level to +/- 2 mm per 2 m (Lindner pedestal tolerance) |
+| Structural ceiling deck | Installed with suspension anchor points |
+| Heating manifold | Location fixed, main pipe runs to floor/ceiling entry points |
+| MVHR trunk duct | Installed in ceiling void, branch points identified |
+| Electrical rough-in | Floor-level junction boxes and ceiling-level feeds planned |
+
+### 11.2 Installation Sequence
+
+```mermaid
+flowchart TD
+    A["1. Install ceiling suspension\nsubstructure from structural deck"] --> B
+    B["2. Route Plafotherm heating pipes\nin ceiling void"] --> C
+    C["3. Install Plafotherm panels\nonto suspension"] --> D
+    D["4. Pressure-test ceiling circuit"] --> E
+    E["5. Install floor pedestals\non adhesive pads"] --> F
+    F["6. Route services in floor cavity\nMVHR ducts, KNX, Cat6, electrical"] --> G
+    G["7. Pressure-test MVHR ducts\nin floor cavity"] --> H
+    H["8. Install CaSO4 floor panels\non pedestals"] --> I
+    I["9. Seal panel joints and perimeter"] --> J
+    J["10. Install WOODline parquet tiles"] --> K
+    K["11. Commission heating/cooling\nverify surface temperatures"] --> L
+    L["12. Commission MVHR AirHybrid\nverify airflow at ceiling panels"]
+
+    style D fill:#1a5e1a,color:#fff
+    style G fill:#1a5e1a,color:#fff
+    style K fill:#1a5e5e,color:#fff
+    style L fill:#1a5e5e,color:#fff
+```
+
+**Key checkpoints** (green/teal in diagram):
+- Step 4: Ceiling heating circuit pressure test — must pass before panels are closed
+- Step 7: Floor cavity MVHR duct pressure test — must pass before panels are installed
+- Step 11: Heating/cooling commissioning — verify surface temperatures per zone
+- Step 12: MVHR AirHybrid commissioning — verify supply airflow through ceiling panels
+
+### 11.3 Timeline Integration with Baufritz
+
+| Baufritz Phase | Lindner Floor Action | Lindner Ceiling Action |
+|----------------|---------------------|----------------------|
+| Initial design | Confirm raised floor, specify cavity heights | Confirm Plafotherm variant, specify system depth |
+| Detailed planning | Lindner layout drawings, coordinate with MVHR exhaust | Lindner layout drawings, coordinate with MVHR supply |
+| Pre-fabrication | Verify subfloor level tolerance in prefab panels | Verify ceiling anchor points in prefab panels |
+| Factory build | No impact (floor installed on-site) | No impact (ceiling installed on-site) |
+| On-site assembly | After structure complete | After structure, before floor |
+| Finishing | Parquet tile installation | Final panel fitting |
+| Handover | Floor inspection, service access verification | Heating/cooling commissioning, AirHybrid airflow test |
+
+### 11.4 Lindner Coordination
+
+Both floor and ceiling are from the same supplier — coordinate as a single package:
+
+- **Combined layout drawings**: floor panel grid, ceiling panel grid, and services routing in a single coordinated plan
+- **Shared manifold design**: heating/cooling manifold serves ceiling circuits (and optionally floor circuits if future floor heating is desired)
+- **Single procurement**: order floor and ceiling systems together — potential cost advantage and guaranteed compatibility
+- **Lead time**: Lindner products are project-manufactured — typically **6-8 weeks** from order. Layout drawings must be finalized before ordering.
+
+---
+
+## 12. Cost and Material Quantities
+
+### 12.1 Estimated Quantities (for ~175 m2 per floor)
+
+| Item | Quantity (approx.) | Unit |
+|------|-------------------|------|
+| NORTEC Doppelboden panels | ~490 | 600x600 mm panels per floor |
+| WOODline parquet tiles | ~490 | 600x600x4 mm tiles per floor |
+| Pedestals (Type S/SWH120) | ~1,400 | Per floor (~8/m2) |
+| Plafotherm ceiling panels | ~350-450 | Per floor (varies by panel size) |
+| Ceiling suspension profiles | As per Lindner layout | Metres |
+| PlafoTube heating pipe | ~1,200-1,800 m | Per floor (depends on coverage %) |
+| Manifold stations | 1-2 per floor | |
+
+### 12.2 Lead Times and Ordering
+
+- Lindner products are **project-manufactured** — not off-the-shelf
+- Lead time: typically **6-8 weeks** from confirmed order
+- Layout drawings must be finalized and approved before ordering
+- Panels are manufactured to the specific floor plan — changes after manufacturing are costly
+- **Coordinate ordering with Baufritz on-site assembly schedule** — panels must arrive after structure is weathertight but before interior finishing begins