Ventilation Systems

Ventilation systems here are the dedicated supply and exhaust systems that serve particular spaces and hazards, separate from the general air conditioning: car park ventilation, toilet and bathroom exhaust, commercial kitchen exhaust, laboratory fume cupboards and fume extraction, garbage room and plant room exhaust, local exhaust ventilation for workshops, and whole-dwelling mechanical ventilation in apartments. Smoke exhaust and stair pressurisation for fire are covered on the fire services pages.

Many of these are life-safety or occupational health systems with statutory testing regimes: car park ventilation and kitchen exhaust are commonly essential safety measures; fume cupboards and LEV have periodic test requirements; kitchen exhaust cleaning frequencies are prescribed by standards and insurers.

What shortens life:

• Grease build-up in kitchen exhaust.
• Corrosive vapours in laboratory and wet area exhausts.
• Lack of maintenance on systems that run out of sight.
• Changes of use: a car park converted to storage, a kitchen with heavier cooking, a lab with new chemicals.
• Disconnected ductwork in risers and ceilings.

Car park ventilation failures

Carbon monoxide sensors drift or fail, so fans either do not start when they should (CO builds up) or run continuously (wasting energy and masking the fault). Jet fans corrode in damp basements and are disabled when noisy. Supply air paths are blocked by storage or doors kept shut.

Kitchen exhaust grease

Grease condenses in hoods, filters, ductwork and fans. Without regular cleaning to the full length of the duct, it accumulates to the point where a flare-up at the cooker ignites the duct. Kitchen duct fires spread through buildings, which is why cleaning frequencies are set by cooking volume and type.

Fume cupboard failures

Face velocity falls as fans wear, ducts leak or the building's pressure regime changes; sashes stick; alarms are silenced; cupboards are used for chemicals they were not designed for. Exhaust discharged too low or near intakes re-enters the building.

Toilet and bathroom exhaust failures

Fans fail, ducts disconnect in ceilings and risers, and moisture is discharged into roof spaces and voids instead of outside, causing mould and decay.

Make-up air imbalance

Large exhaust without matching make-up air puts the building under negative pressure: doors slam or resist opening, flues backdraught (pulling combustion gases into the building), and dust and contaminants are drawn in through the envelope.

Exhaust re-entry

Exhausts discharging near air intakes, operable windows or terraces re-enter the building. Kitchen odour, car park fumes and laboratory vapours are the usual complaints.

Dwelling ventilation failures

MVHR filters are never changed, fans are switched off by residents because of noise, and boost controls do not work; condensation and mould follow in airtight apartments.

On site

• Car park: CO sensor locations and calibration labels; jet fans running or dead; storage blocking airflow.
• Kitchen: grease on hoods, filters and accessible duct sections; fan casing grease; cleaning labels.
• Labs: fume cupboard test labels, face velocity alarms, sash condition.
• Bathrooms: fans running; condensation and mould; discharge points on façades and roofs.
• Exhaust discharges relative to intakes and windows.
• Doors slamming or hard to open (pressure imbalance).

In the records

• Essential safety measure records for car park and kitchen exhaust.
• Kitchen exhaust cleaning certificates and frequencies.
• Fume cupboard and LEV test reports.
• CO sensor calibration records.
• Complaints of odour or fumes.

Findings are graded by what they demand: safety (can hurt someone now), failure (failed and damaging the building), condition (distress present and progressing), lifecycle (renewal due on age and exposure), deadline (a regulator or ordinance sets the date), check (investigate before sizing works) and nil (cosmetic or stable).

A mechanical services engineer, with specialists for kitchen exhaust, fume cupboards and LEV.

• Records review: essential safety measures, cleaning certificates, test reports, calibration records.
• Car park: CO sensor tests with calibration gas, fan operation, airflow paths.
• Kitchen exhaust: inspection of hood, filters, the full length of ductwork through access panels, fan; grease depth measured.
• Fume cupboards: face velocity and containment testing to the relevant standard; alarm function.
• LEV: thorough examination and test of capture and airflow.
• Toilet exhaust: sample airflow checks; riser and duct inspection.
• Pressure regime: building pressure relative to outside; make-up air.
• Discharge review: distances to intakes and windows.

The report should give the status of every safety-related system, test results, cleaning adequacy, and recommended works.

• Smoke test of exhaust discharges to see where plumes travel.

• Car park: replace and calibrate CO sensors; repair or replace jet fans; clear airflow paths.
• Kitchen exhaust: clean the full system; add access panels; set cleaning frequency to cooking volume; replace fans; fire suppression in hoods.
• Fume cupboards: repair fans and ductwork; rebalance; replace cupboards; raise discharge stacks.
• Toilet exhaust: reconnect ducts; replace fans; extend discharges outside.
• Make-up air: add or rebalance.
• Discharge relocation away from intakes.
• MVHR: maintenance programmes; quieter fans; resident guidance.

Interactions: kitchen exhaust changes often require fire-rated duct enclosures and access panels through finished spaces; fume cupboard and lab exhaust changes need the whole lab pressure regime rebalanced; car park changes interact with smoke exhaust and fire systems.

Kitchen exhaust cleaning, fume cupboard and LEV testing, and CO sensor calibration are recurring contracts at prescribed frequencies. CO sensor replacement and fan replacement are itemised. Kitchen exhaust duct replacement, access panel installation and fire-rated enclosures are lump sums. Fume cupboard replacement is per cupboard, with ductwork and controls. Discharge relocation and make-up air systems are lump sums.

Testing, cleaning and safety rectification are code compliance and recur; replacement is lifecycle; repairs are repairs and maintenance.

• Australia. AS 1668.2 sets ventilation including car parks with CO control; AS 1668.1 covers kitchen exhaust fire aspects; AS/NZS 2243.8 governs fume cupboards; car park and kitchen exhaust systems are commonly essential safety measures maintained under AS 1851 and state regulations.
• United Kingdom. Approved Document F; BESA TR/19 Grease sets kitchen extract cleaning frequencies; COSHH requires LEV thorough examination at least every 14 months; fume cupboards follow BS EN 14175.
• United States. NFPA 96 sets kitchen exhaust inspection frequencies (monthly for solid fuel cooking, quarterly for high volume, semi-annually for moderate, annually for low volume); the International Mechanical Code covers car park ventilation; ANSI/ASSP Z9.5 covers laboratory ventilation.

Planning conditions often govern kitchen exhaust discharge and odour control in all three countries.

• Essential safety measure records and annual statements for car park and kitchen exhaust.
• Kitchen exhaust cleaning certificates showing the extent cleaned, with frequency.
• Fume cupboard face velocity and containment test reports.
• LEV thorough examination reports.
• CO sensor calibration records and car park ventilation test records.
• Complaint records for odour, fumes or doors.
• Mechanical drawings showing exhaust discharge locations and air intakes.