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df81ec R. Bishop 2025-04-03 18:34:47 1 
## **Smoke Ventilation & AOV Systems**
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Smoke ventilation systems, including **Automatic Opening Vent (AOV)** systems, are critical life safety measures designed to remove smoke and heat from buildings during a fire. In the UK, these systems are regulated by **Approved Document B (ADB)** of the Building Regulations and supported by standards such as **BS EN 12101-2**.
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### **Purpose of Smoke Ventilation Systems**
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- Maintain clear escape routes for safe evacuation.
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- Assist firefighters by improving visibility and reducing smoke temperature.
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- Limit smoke spread and heat build-up within buildings.
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- Protect property and structural integrity.
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### **Main Types of Smoke Ventilation Systems**
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#### 1. **Natural Smoke Ventilation Systems**
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**How it works:**
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Utilizes the natural buoyancy of hot smoke to rise and exit through automatically controlled openings like roof vents, windows, or louvres.
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**Pros:**
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- Lower installation and maintenance costs.
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- No moving parts like fans, less risk of mechanical failure.
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- Energy efficient.
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**Cons:**
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- Relies on effective natural airflow and building design.
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- Less control compared to mechanical systems.
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- Limited performance in large or complex layouts.
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#### 2. **Mechanical Smoke Ventilation Systems (MSVS)**
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**How it works:**
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Uses powered fans and ducts to extract smoke from common areas, typically via a dedicated shaft or riser system.
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**Pros:**
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- Suitable for tall or complex buildings (e.g., multi-storey residential).
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- Provides controlled, consistent smoke extraction.
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- Effective even in low wind or pressurised environments.
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**Cons:**
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- Higher cost and design complexity.
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- Requires backup power (often UPS or generator).
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- Regular specialist maintenance needed.
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#### 3. **Automatic Opening Vent (AOV) Systems**
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**How it works:**
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Connected to smoke detectors or fire alarm systems, AOVs automatically open designated vents (rooflights, windows, doors) when smoke is detected.
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**Pros:**
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- Fast automatic response to fire events.
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- Complies with Part B of Building Regs.
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- Widely used in stairwells, lobbies, and corridors.
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**Cons:**
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- May need integration with fire alarm or BMS systems.
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- Can be affected by obstructions or poor installation.
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- Requires regular function tests and inspections.
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### **Common Applications in the UK**
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- **Apartment block stairwells & lobbies** (to maintain smoke-free escape routes).
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- **Commercial/industrial buildings** (to reduce risk to life and property).
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- **Schools, shopping centres & care homes** (to support safe evacuation).
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- **Underground car parks** (mechanical systems typically used).
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### **Relevant UK Regulations & Standards**
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| **Document / Standard** | **Purpose** |
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|--------------------------|-------------|
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| **Approved Document B (Fire Safety)** | Legal guidance for designing smoke control systems in new and existing buildings. |
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| **BS EN 12101-2** | Specifies requirements for natural smoke and heat exhaust ventilators (NSHEVs). |
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| **BS 9999 / BS 9991** | Fire safety design guidance for commercial and residential buildings, respectively. |
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### **Maintenance & Testing Overview**
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To comply with regulations, AOV and smoke ventilation systems must be inspected and maintained regularly by competent persons. Testing typically includes:
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| **Test Type** | **Frequency** | **Details** |
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|---------------------------|-----------------------|-------------|
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| **Weekly Visual Check** | Weekly | Ensure vents are unobstructed and visually inspect control panels. |
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| **Monthly Functional Test** | Monthly | Simulate fire/smoke trigger to confirm vent operation. |
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| **Six-Monthly Service** | Every 6 months | Engineer-inspected test of full system operation, including sensors and controls. |
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| **Annual Certification** | Annually | Full system test with documentation for fire safety compliance. |
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> 🔧 A maintenance logbook should be kept on-site detailing all inspections, test results, and any remedial actions taken.
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### **Key Components of AOV Systems**
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- **Smoke Detectors** – Trigger vents when smoke is detected.
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- **Control Panels (AOV Controllers)** – Manage activation logic and power distribution.
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- **Actuators/Motors** – Open vents, windows, or rooflights.
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- **Manual Override Switches** – Allow fire services or staff to trigger vents if needed.
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- **Power Supply** – Often includes battery backup or mains-fed supply with failover.
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### **Common System Layouts (Example)**
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- **Stairwell Smoke Ventilation:** A single roof vent opens on fire signal to keep the stairwell clear.
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- **Lobby Ventilation (with shaft):** A vent on each floor opens along with a roof-mounted extract point.
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- **Mechanical Shaft System:** Central fan extracts smoke via ducts from each floor; often includes dampers and fire-rated enclosures.