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Energy Recovery Ventilation

Indoor air can be 2 to 5 times more polluted than outdoor air; therefore, most HVAC system designers understand that increased outdoor air intake generally improves Indoor Air Quality (IAQ). However, there are concerns about the effects of this additional outdoor air supply on the initial cost and operating cost of the HVAC system, as well as its impact on humidity control (too wet or too dry) within the building.

As a result, building designers generally aim to reduce the outdoor air intake to the minimum required for buildings, which is typically equivalent to or even lower than 15 cubic feet per minute (cfm) of outdoor air per person, as prescribed by authorities. In many locations, achieving these targets can be easily accomplished by applying basic engineering principles and readily available HVAC equipment.

The initial cost, energy expenses, and humidity control do not have to contradict good Indoor Air Quality (IAQ). Energy recovery ventilation equipment can maintain the IAQ benefits of 15 cfm per person of outdoor air intake while reducing the adverse effects of outdoor air to as low as 5 cfm per person. This approach has been proven in many buildings across various regions to offer significant operational cost savings and IAQ advantages, while roughly equating the initial cost of advanced HVAC systems with traditional systems.

Outside Air Amount

Classrooms and other school areas should be ventilated to remove odors and other pollutants.

If outdoor air is supplied through a mechanical system, a minimum of 15 cubic feet per minute (cfm) of outdoor air per occupant should be provided. For example, a room with 30 people would require a minimum of 15 x 30 = 450 cfm of outdoor air.

In areas with highly variable occupancy such as gyms, auditoriums, and multipurpose spaces, Demand Controlled Ventilation (DCV) systems can be used to adjust the outdoor air ventilation based on the number of occupants. One technique to achieve this is to install carbon dioxide (CO2) sensors that measure concentrations and adjust the volume of outdoor air accordingly.

If an auditorium fills up for a school assembly, CO2 concentrations will increase, signaling the HVAC system to increase outdoor air volumes accordingly. When areas served by an air handling unit (AHU) have highly variable occupancy rates, this type of control can provide both energy savings and help control moisture (and mold) by reducing the amount of humid outdoor air when ventilation is not needed. CO2 and other sensors should be calibrated and maintained periodically.

Selection of HVAC Equipment

The climate conditions in most parts of the country require the addition of HVAC systems to provide acceptable thermal comfort for building occupants, necessitating the heating and cooling of outdoor air. Selecting equipment to heat, cool, and ventilate the building involves balancing several factors, including:

• Heating and cooling needs
• Energy efficiency
• Humidity control
• Natural ventilation potential
• Adherence to codes and standards
• Quantity and quality of outdoor air
• Indoor air quality
• Cost

Where possible, use central HVAC air handling units (AHUs) that serve multiple rooms instead of unit ventilators or individual heat pumps. Although there are many different types of air handling units, they can generally be categorized into two groups for their overall IAQ impacts in buildings: unit ventilators and individual heat pump units serving a single room via ductless operation; and central HVAC air handling units serving multiple rooms via ductwork.

Unit ventilators and heat pumps have the advantage of requiring reduced floor space and do not circulate air between rooms. However, ensuring proper maintenance of multiple units over time can be more challenging, and they present additional opportunities for humidity issues due to wall penetrations, drain pan, and drainage problems.Central HVAC air handling units (AHUs), on the other hand, offer several advantages over unit ventilators and heat pumps serving individual rooms. These include:

1. It is quieter and therefore more likely to be switched on or off by teachers and staff;
2. Less airflow due to multiple consumables and a turn away from passengers;
3. It is better at controlling humidity and intensive moisture drainage;
4. Maintenance is easier due to the reduced number of components and fewer access units;
5. More space around the units and accessible without interfering with classroom activities;
6. Space for higher efficiency air filters and more surface area;
7. Made of heavier duty components;
8. Unintentional reduction of the amount of external air supply is less likely.

The following features are important for all air handling units:
Double sloping drain pan and drain siphon depth
Double sloping drain pan – A double sloping pan prevents water from standing and stagnating in the pan.
Non-corrosive drain pan – Made of stainless steel or plastic. Prevents corrosion that would cause water leakage inside the AHU.
Easy access doors – All access doors are hinged and use quick release latches that require no tools to open. Easy access to filters, drain pans and cooling coils is mandatory.
Double wall cabinet – The inner wall protects the insulation from moisture and mechanical damage, increases sound damping and is easier to clean.
Tightly sealed cabinet – Small but continuous air leaks in and out of the AHU cabinet can affect IAQ and energy. The largest pressure differentials that trigger leaks occur in the AHU.
Double skin doors with seals – Double skin doors provide better thermal and acoustic insulation and remain flatter, providing a better seal against door frame seals.
Minimum 2-inch thick filter housings – Filter housings must be able to accommodate filters 2 inches or thicker for better protection of equipment and ductwork as well as the indoor environment.

Expanded surface area filter bank – Designed to allow for more filter area, such as through a deep V approach or bags, to reduce filter maintenance frequency and fan energy costs.

Air filter arrangements designed for minimum leakage (racks and housings) – In the filter bank, all points where air can easily pass through the air filters, such as filter racks and access doors, should have gaskets and sealing materials for minimal leakage. Use appropriate gaskets and manufacturer-provided filter rack spacers with seals.

Air filter monitor – A differential pressure gauge that indicates the static pressure drop across the filter bank. This feature can be easily installed optionally in the field.

Corrosion-resistant dampers and connections – All moving parts such as pivot pins, damper actuators, and connections are designed to withstand corrosion due to weather conditions and moisture throughout the system’s lifetime.

About Infections in the Workplace

Workplace infections are infections caused by harmful microorganisms such as bacteria, fungi, viruses, internal parasites, and other infectious proteins known as prions. These are referred to as ‘biological agents’ in health and safety regulations. You can be harmed by microorganisms through microbial contamination, exposure to toxins produced by microorganisms, or by showing allergic reactions to microorganisms or substances they produce.

Microorganisms are found almost everywhere in the natural environment. Most of them are harmless to humans and perform many important tasks. They are used to produce medicines and can degrade petroleum from oil spills. They produce approximately half of the oxygen we breathe. However, some microorganisms can cause infection, allergies, or toxic harm.

For example, you may come into contact with microorganisms intentionally while working in a microbiology laboratory. However, depending on your job, such as being a farmer or a healthcare worker, your likelihood of exposure may be higher, meaning exposure depends on the purpose of the job.

In 2002, more than 2000 newly acquired occupational infection cases were reported, which represented an increase compared to the previous year. The most commonly reported type of infection was diarrheal disease, and the majority of infection cases were reported among healthcare workers.

In many workplaces where there is intentional work with microorganisms (such as microbiology laboratories and research facilities) or relatively high occupational exposure likelihood (such as hospitals and care homes), the regulatory body is usually the HSE (Health and Safety Executive). However, in some cases where the exposure likelihood depends on the nature of the work (as mentioned above), the regulatory authority may be the local authority. Examples of such workplaces where safety regulation falls under the responsibility of local authorities include skin piercing and tattoo parlors (where there may be a risk of transmission of bloodborne viruses) and large office blocks (where cooling towers could be a potential source).

In our environments, we sometimes need devices to protect us from harmful microorganisms, bacteria, or viruses that may be present. Recently, especially due to the profound impact felt in our lives, we have a great need for professional devices to protect us from the COVID-19 virus, which has significantly affected us. Particularly in workplaces, offices, factories, or any environment where people gather or spend time together, the effectiveness of these devices can be crucially important.

We have developed a product that has been proven by tests to inhibit such harmful pathogens almost 100%. For detailed information, you can check the link. https://hepavent.com/

Assessment of the Risk of Inadequate Ventilation

As part of your legal duty to provide adequate fresh air, your workplace risk assessment should identify poorly ventilated work areas:

• Look for areas where there is no natural ventilation (windows, doors, or vents) or mechanical ventilation (fans or ducts bringing in outside air).
• identify areas that are stuffy or badly smelling
• consider using a CO2 monitor to identify inadequate ventilation
• Using floor plans can be helpful to list areas in your workplace or record how spaces are ventilated. Don’t forget to include areas like locker rooms and cafeterias used for breaks.

Understanding When To Take Action
Ventilation Rate;
The ventilation rate refers to the volume of air supplied to a room over a specific period of time. What is necessary for adequate general ventilation will depend on various factors such as the amount of floor area per person and the nature of the activities conducted.

HSE’s Approved Code of Practice and guidance states, “The rate of fresh air supply should not normally fall below 5 to 8 litres per second per person.” Some building guides recommend a value of 10 litres per second per person as appropriate for most commercial buildings.

In workplaces like windy workshops, it is evident that there is sufficient air. In other more enclosed environments, especially for natural ventilation, estimating the airflow in an area can be challenging. However, a useful way to determine if there is an issue is to use CO2 monitors when you suspect there might be a problem.

Complex Ventilation Systems
If your workplace has a complex ventilation system, for example, due to multiple floors, you can obtain more detailed guidance from the Chartered Institution of Building Services Engineers (CIBSE).

You may need a ventilation engineer to provide expert advice on the best system for your workplace.

Table or Ceiling Fans
In poorly ventilated areas, you should not rely solely on table or ceiling fans. They will not improve fresh air.

Local Exhaust Ventilation
You can use local exhaust ventilation (LEV) to control risks from workplace hazards such as dust or welding fumes. If an LEV system exhausts outside air, it will also improve general ventilation in the area.

Talk To our Workers!
Talking to your employees will help you assess the risk and take effective measures to improve ventilation.

Questions to ask them;
How do we bring clean air (ventilation) to our workplace?
Consider natural ventilation through fully or partially operable windows, doors, and vents.
If using mechanical ventilation, ensure it is correctly adjusted and maintained.
How can we improve ventilation?
Consider areas with stagnant or bad-smelling air – open windows, vents, and doors (excluding fire doors).
If we have recirculation systems, are we bringing in some fresh air?
What is the level and impact of temperatures in the workplace?
Discussing the results of your risk assessment and the identified measures will also help them understand how they can play a role in improving ventilation at the workplace.

Ventilation in Workplaces

How To İmprove Ventilation?

Practical ways to improve ventilation include:

• Increasing natural ventilation by opening doors, windows, and vents.
• Ensuring mechanical systems, including air conditioning systems, are designed with clean air intake and kept open to prevent air from becoming stagnant.
• You may need a combination of natural and mechanical ventilation.

How To İmprove Natural Ventilation?

You can improve natural ventilation by partially or fully opening windows, vents, and doors. However, do not open fire doors.

You should be able to open any window and keep ventilation grilles or vents that allow clean air to enter open. If any windows are closed, they should be reopened. If they cannot be opened, ventilation in that area will be less effective.

Ventilation Chambers
If ventilation is poor, you can temporarily improve it as a short-term measure while waiting for longer-term changes. Opening all doors and windows as fully as possible maximizes ventilation in a room.

If it is too cold for people in the room, you can do this when they leave for a break. Even 10 minutes per hour can help increase the amount of fresh air, depending on the size of the room.

How To İmprove Mechanical Ventilation?

Mechanical ventilation brings fresh air into a building from outside using ducts and fans. It has the advantage of continuously providing clean air when properly functioning. However, it can be more costly, requires energy to operate, and needs regular maintenance.

Instead of assuming that outdoor air is clean, it’s important to ensure that clean outdoor air is actually being provided. If you expect the incoming air to be heavily polluted with particles like traffic emissions or smoke, it should be filtered.

You should speak to the people who manage the day-to-day operations of the mechanical ventilation systems of your workplace to

• understand how they work
• they provide fresh air to an area and how much
• ensure that they are stored in accordance with the manufacturers’ instructions
• You may need a ventilation engineer to check whether your system provides adequate ventilation.

Use Of Recirculation Air
The recirculated air must be sufficiently filtered to remove particles and fresh air must be added to it before it is reintroduced into the workplace.

HSE’s Approved Code of Practice states, “In mechanical ventilation systems, including air conditioning systems, circulation air must be adequately filtered to remove contaminants. To prevent the air from becoming unhealthy, some fresh air must be added before recirculating purified air. Therefore, systems should be designed with clean air inlets that need to be kept open.””

If Your Ventilation İs Still Poor

If your ventilation is still inadequate, for example, if CO2 readings are above recommended levels or if the room remains stuffy, consider the following:

– Changing how the workspace is used, such as limiting the time people spend there or restricting the number of people using it simultaneously.
– Installing a mechanical ventilation system (upon the advice of a ventilation engineer), if there is currently no mechanical ventilation or if the existing system does not provide fresh or purified air.