Fresh Air Ventilation & Exhaust Fan Systems

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Maintaining indoor air quality ( fresh air ventilation) is a critical to the promotion of worker productivity and environmental safety. Good  fresh air ventilation
helps to dilute or remove unpleasant odours as well as smoke, dust, carbon dioxide, and airborne pathogens, rather than merely circulating air within a building. This reduces disease and “sick building syndrome” and therefore sick days, improving productivity. For this reason, building regulations often require businesses to provide enough fresh, clean air to the occupants of the building. 

In commercial establishments, the variety, variability and scale of human activities taking place will determine the demands made on the ventilation system. HVAC efficiency can reduce costs significantly while reducing the carbon footprint of the business, so it is important to select the right fans and equipment and ensure that they are properly installed. The correct extraction rates must be known to size and select the appropriate fans. In addition, energy consumption can increase significantly due to poor ducting or fan placement, which can shorten equipment life and increase maintenance costs. A carefully designed system will avoid creating annoying draughts which can impede work.

Different enterprises have different ventilation needs. While there are some rules of thumb that apply to a broad range of situations, it is often best to tailor a system to the needs of your particular business. Consider the following situations:

• Shops and malls have storage rooms where stale, damp air can accumulate. Commercial ventilation fans are needed to exchange this air.
• Commercial kitchens (in restaurants, for example) produce fumes, vapours, grease and odours during cooking. To ensure fire safety, facilitate cleaning and reduce maintenance, as well as for the comfort of workers, custom ventilation solutions are needed.
• Offices, hotels and other businesses need bathroom ventilation to remove odours and prevent problems caused by humid and stagnant air. Printing, painting and other activities also produce fumes that can be unpleasant and cause health problems if they are not removed.

Offices may need only two air changes per hour, while commercial laundries may need 15 or more. Larger spaces need more powerful ventilation fans to ensure that stale air is removed from all parts of the room.

Depending on the area, ventilation may be continuous or intermittent. Offices and large shops often continuously ventilate the building using a centralised system with ceiling fans, vents and ducts. Intermittent ventilation is used on and off as needed in specific areas such as bathrooms and kitchens, and often use occupancy sensors, connections to lighting or other means of automating their use times. Areas with carrying occupancy can also be equipped with local exhaust ventilation (LEV) using variable speed drive (VSD) (also known as variable frequency drives or VFD) fans, that can work harder at peak times and idle when few or no occupants are present. Inline ventilation, which might be either continuous or intermittent, means that the fans (typically centrifugal fans) are installed away from the ventilated area. This is a popular option for commercial buildings because it keeps noise levels in working areas low. 

• Aircon installation
• Air conditioning repair service
• Fresh air ventilation
• Cape Town. Durbanville

A key merit of a professional turnkey solution is that all factors are taken into account in designing the system. A “quick fix” will often lead to higher costs in the long run.

Ducting is one area in which this is true. The goals of low fan noise and the delivery of enough fresh air can only be achieved with ducting of the right size and configuration. Long ducts and too many bends will increase the requirements placed on fans, reducing the efficiency of the entire ventilation system. For this reason, many manufacturers of kitchen hoods state that their guarantees will be invalid should incorrect ducting be used. The following points should be observed in the ducting system:

• Minimize distances and bends to the extent possible.
• Ensure that ducts are accessible for maintenance.
• Secure ducts with a good sealant, especially if they cannot be made accessible.
• Choose the duct diameter to match the power of the fan and check the whole system.
• Where possible, choose round ducting to maximise airflow and reduce noise. It may be necessary to other shapes where there are space constraints or aesthetic requirements.
• Where possible, choose rigid ducts as they are more efficient. If flexible ducts must be used, straighten them and keep them taut as much as possible, and restrict their use to slow moving air streams as much as possible.
• Select accessories such as dampers carefully, as they reduce system efficiency.

The building envelope (that is, the space enclosed within the building) needs to be sealed as much as possible for mechanical ventilation to work effectively. Tight envelopes more effectively retain conditioned air, reducing the load put on the HVAC system. It is also important to insulate the building properly to minimise the power expended on temperature control. These measures will help extend the life of your equipment. Since ventilation introduces air from outside and exhausts air from the building, the building envelope is inevitably affected, and likewise, effective insulation and tight enveloped mean that natural ventilation is reduced.

fresh air ventilation

Cape Town, Durbanville, Bloubergstrand

CFW supplies a diverse array of ventilation equipment, including

• Exhaust fans (roof-mounted or sidewall)
• Circulation fans
• Ducting and vents
• Filters and dust extraction systems
• Cowls, louvers and other fan accessories
• Makeup air units
• Evaporative coolers, misting fans and dryers
• Kitchen hoods and canopies
• Smoke extraction ventilation
• Heat recovery ventilation (HRV) solutions for saving energy