As most of us spend the majority of our time indoors these days, the air we breathe inside our homes and workplaces is of major importance.If not designed, installed, used, and maintained correctly, HVAC systems can make us ill.
Ventilation is a vital type of technology intended to help create a healthy and comfortable indoor environment.It is the V in HVAC; Heating, Ventilation, and Air Conditioning.It is a major part of commercial building maintenance.
A major factor in creating a safe and suitable indoor environment is the indoor air quality (IAQ).The Australian and New Zealand Standard (AS/NZS) for use of ventilation and air conditioning in buildings (ventilation design for indoor air contaminant control) is AS/NZS1668.2 (mechanical) and AS/NZS1668.4 (natural).
This Standard (1668) for building ventilation is widely appreciated and referenced in the Building Code of Australia (BCA) and superseding National Construction Code (NCC).IAQ is so important that the Australian Building Codes Board (ABCB) has produced a 121 page guide about it, titled Indoor Air Quality Handbook 2018.
Ventilation can also contribute significantly to electricity demand and overall energy usage of a building.In fact, HVAC systems in a commercial building typically account for 30% of energy usage.As with all technologies, HVAC systems are evolving each year and efficiency is continually improving.
In this article, we will explore ventilation, what it is, why it is important, and when and where it is used.We will also go through car park ventilation as an example.
What is ventilation?
Ventilation refers to the intended movement of outside air into and around an indoor space.It also involves the displacement of air and its extraction from indoors to the outside.It can be part of a commercial HVAC system, or stand-alone set up.
Ventilation consists of 3 main parts:
- Ventilation rate – the amount and quality of the outdoor air,
- Airflow direction – the flow of air within a building, from “clean” to “dirty” areas, and,
- Air distribution – the delivery of outside air and removal of pollutants.
A building can be ventilated in 1 of 3 main ways:
- Mechanical ventilation – relies on mechanical fans,
- Natural ventilation – relies on natural forces, or,
- Hybrid/Mixed-mode ventilation – relies on natural forces, with fans used when ventilation rate/s become too low.
The ventilation method used in a building depends on many factors, such as climate, architectural design, building usage, and occupant behaviour.These factors can further impact the types of equipment used within each ventilation type.For example, internal/external pressures vary between hot and humid vs cold and dry climates, impacting ventilation design.
In warm, humid regions such as Brisbane and South East Queensland, infiltration needs to be minimised and positive pressure mechanical ventilation is often used.The use of positive pressure can also help with moisture management and humidity control for commercial buildings.
In cooler climates, exfiltration must be minimised and negative pressure mechanical ventilation can be used.Natural and mixed-mode ventilation is also more practical in cooler, drier climates.
For the most suitable install, service, or repair, it is recommended to use a Brisbane HVAC company or company local to your business.This way, the company is an expert at dealing with your particular climate, challenges, and requirements.
Why is ventilation important?
Ventilation is primarily intended to improve indoor air quality (IAQ).The aim is to provide healthy air and a comfortable climate for people occupying or visiting a building.
It is also a requirement of any employer to provide a safe and suitable workplace.Part of that responsibility involves taken reasonable action to prevent workers from harm, including illness.
Ventilation improves indoor air quality in 2 main ways:
- Dilute pollutants within the building, and,
- Remove pollutants from the building.
Inadequate air quality should be a concern for any business owner. Poor IAQ is a major contributor to sick building syndrome, resulting in occupants becoming ill or even suffering chronic disease.
The World Health Organization (WHO) reports that up to 30% of new and renovated buildings have inadequate IAQ. The indoor environment for older buildings is even worse!This can see workers not even involved in hazardous works end up with illness caused by their work environment, thanks to sick building syndrome.
Inadequate ventilation has also been linked to reduced productivity in the workplace and impaired learning in educational facilities.Fortunately, the opposite is true; A suitable, maintained HVAC system has many benefits, beyond what you may think at first thought.
There are a wide range of pollutants that ventilation can help to manage, including, but not limited to:
- Dust particles,
- Cleaning chemicals,
- Volatile organic compounds (VOC’s) including formaldehyde, ethylene, benzene, glycol, etc.,
- Contaminants from offgassing,
- Carbon monoxide (CO),
- Carbon dioxide (CO2),
- Nitrogen dioxide (NO2),
- Grease particles,
- Lead, and,
While all the pollutants are important to consider, each workplace has their own specific areas of concern.For example, in a kitchen, smoke and grease may be the major pollutants, with smoke exhaust factored into kitchen design.For an office environment, dust, mould and even cleaning chemicals can cause issues.
When and where is ventilation used?
Ventilation is used in a wide range of settings and applications.Just about every indoor space requires some form of ventilation.Common areas of usage include office spaces, warehouses, production floors, kitchens, toilets, bathrooms, and car parks.
Major reasons for ventilation usage include the management of:
- Fresh air,
- Organic compounds,
- Smoke, and,
- Car exhaust.
Some ventilation happens naturally (natural ventilation), while mechanical intervention is needed in many settings (mechanical ventilation).Alternatively, a hybrid ventilation method may be suitable.
When designing a ventilation system, factors to consider include but are not limited to:
- Type of building/structure,
- Usage of the space,
- Volume of the area,
- Number of airflow changes required per 24 hours,
- How exhaust air will be vented,
- Structural requirements and availabilities,
- Electrical requirements and availabilities, and,
- Budget available.
Choosing the right ventilation system takes careful consideration and technical design.It is recommended to consult an expert commercial HVAC contractor before undertaking any ventilation project.
Example: Car Park Ventilation
Car parks prevent a unique setting where heating and cooling may not be required, yet ventilation is critical.As a result, car park ventilation is often a stand-alone system, as opposed to being part of a larger heating, ventilation, and air conditioning (HVAC) system.
Car parks are a hot spot for pollutants due to emissions from vehicles using the space.A major emission of concern is Carbon Monoxide (CO).CO is produced as a result the incomplete combustion reaction with fuel that happens in certain in vehicles.
The 2 main reasons why car park carbon monoxide is such a concern is actually the same abbreviation as its name: CO; Colourless and Odourless.This means that humans cannot see or smell the dangerous gas.
Carbon monoxide is harmful to human health, primarily because of its affect on breathing.The gas is absorbed by the lungs, attaches itself to red blood cells, and thereby reduces the uptake of oxygen by the body.
Initial consequences of CO poisoning can include shortness of breath, dizziness, blurred vision, confusion, headache, and nausea.Prolonged or excessive exposure can lead to loss of consciousness and even death.
At least two different types of mechanical fans are used in standard car park ventilation.One type removes the exhaust gases produced by the vehicles, while the other provides fresh air into the parking space.
Common components of car park ventilation systems includes:
- Car park exhaust fans,
- Car park supply air fans,
- Carbon monoxide (CO) sensors,
- Cables and wiring,
- Lights, and,
- Note: Variable Speed Drives (VSD) and Time Clocks may also be included in the system.
Open air car parks are naturally ventilated with fresh air.This is the only level of a car park that doesn’t usually require mechanical ventilation, as per the National Construction Code (NCC).
According to the NCC, every car park level requires:
- A mechanical ventilation system that complies with AS/NZS 1668:2-2012.
- A natural ventilation system that complies with AS/NZS 1668:4-2012.
One of the main requirements in car park ventilation is carbon monoxide CO sensors.These are sometimes referred to as carbon dioxide CO2 sensors, as a consequence of CO2 being the more well-known gas.However, it is the carbon monoxide that is of greatest concern, hence why car parks typically only have CO sensors.
Carbon monoxide sensors must be suitably installed in a carpark.Once installed, they must be maintained routinely throughout the year.Furthermore, they should be calibrated annually or sooner if replaced, repaired, or otherwise required for a given setting.
Routine service of car park carbon dioxide CO sensor controls includes, but is not limited to,:
- Inspect devices and sensors,
- Test CO sensors,
- Mark and apply sensors with tag showing test date,
- Check controller operation,
- Check time clock operation (if applicable),
- Check variable speed drives (if applicable),
- Check control panel wiring,
- Provide record for onsite, and,
- Provide service report.
Maintenance of CO sensors is not only a requirement to ensure the health and safety of occupants, it can also contribute to significant energy savings.With regular servicing, issues can be detected early, and repairs or adjustments made accordingly.This not only helps to save the environment, but also the hip pocket with cost savings as a result.
Given the importance of ventilation in a commercial building, it is best to consult an HVAC professional that can provide a holistic solution and ongoing support, from start to finish.Given the implications of inadequate ventilation, it’s not something you can afford to mess around with at any level!
If you require any help with design, install, maintenance, calibration, repair, or replacement of a ventilation system, please don’t hesitate to contact us.We would welcome the opportunity to provide an obligation free quote.