Effective Ventilation in Office Buildings, or Improving the Physical and Mental State and Efficiency of Employees

A modern office does not only require a state-of-the-art building and stylish furnishings, but also the right indoor environment that suits employee expectations, who increasingly recognize its importance. Ensuring proper working conditions within office space (thermal, acoustic, and visual comfort, as well as proper air quality) is the basis for the employees’ well-being, but also higher productivity in everyday work. Technical systems should create suitable microclimate conditions in rooms, and at the same time meet the energy efficiency requirements.

A properly designed and effective ventilation system ensures the good quality of indoor environment, including the right rate of air exchange, purity, specific temperature, relative humidity and air velocity in rooms. It should also be in conformity with separate rules and guidelines of Polish standards regarding ventilation, and meet the fire safety and acoustic requirements alike. The air exchange in rooms has become a well recognized requirement for all kinds of buildings. For this reason, the air exchange system in any office building must be designed and made in order to provide adequate thermal and moisture conditions in individual rooms (according to their destination), and to ensure the proper conditions of hygiene for occupants.

Effective Ventilation of Office Settings in the Light of the Regulations

The basic Polish legal act regarding ventilation systems is the Regulation of the Minister of Infrastructure of 12 April 2002 on Technical Conditions for Buildings and their Location. More detailed requirements may be found in the following Polish standards: PN-83/B-03430/Az3:2000 and PN-73/B-03431.

The standards concerning air exchange in office buildings are much more restrictive than the ones regarding residential buildings. It stems from the fact that ventilation systems in office buildings should efficiently handle high amounts of CO2 emitted by employees and office equipment, and remove excess of heat, while at the same time provide clean air. Natural ventilation is not sufficient as it does not ensure required hygiene standards and air exchange. Hermetically sealed doors and windows are installed in office buildings, and the panoramic glazing completely restricts the possibility of external air infiltration, which leads to the stagnation of air and worsening microclimate conditions, and the general well-being.
Room occupants are the factor that causes the change of air quality. The CO2 content is the basic quantity describing the quality of air – it should not exceed 0.1% of air volume (to compare, the natural CO2 concentration in air is equal to 0.03%). The underlying goal of the air exchange is to maintain CO2 content at the appropriate level, which means removing the excess of this gas, and not “pumping” oxygen in, as many people may think. The amount of CO2 that a person generates during office work is equal to 19–26 l/h, and the necessary amount of fresh air is equal to 32–42 m3/h. The CO2 concentration varies over time and depends on the number of people present in a room. In order to dilute it an adequate amount of external air is needed. This has become the foundation for developing ventilation systems that adjust required ventilation air stream volume to the current concentration of CO2. They are called demand controlled ventilation systems or DCV.

Did you know…

An adult breathes 12–16 times per minute on average, inhaling 7.5 l of air. It can amount to 10.5 m3 per day, and oxygen only constitutes 20% of it. The remaining 80% consists of nitrogen and other components, including viruses, bacteria, allergens, smog (PM2.5, PM10, and benzopyrene), mites, fungi, and mould.

Air humidity is another significant parameter impacting the feeling of comfort in rooms. It requires removing the water steam from air and keeping the relative humidity at a level between 40% and 60%. When breathing, every person releases water to the environment in the form of steam. Its amount depends on the type of physical activity, and it lies within the range between 45 g/h during sleep and 170 g/h during intensive manual labour. If the lower limit of air relative humidity is exceeded (RH below 40%) for a long time, it may lead to breathing problems, because a very low value of this parameter will cause dryness and irritation of eyes and airways. However, it is also important not to exceed the upper limit (RH above 60%), as excessive humidity may lead to the development of fungi and mould, and cause construction damage.

Air exchange is the flow rate of external supplied air (measured in m3/h) that gets inside a building through the ventilation system. The need for air exchange arises from the user requirements and functions of rooms, heat balance, and humidity, as well as solid and gaseous pollutions. Depending on the physical activity, a human being needs about 30 m3 of fresh air per hour.

The air exchange rate is used for determining the optimal amount of fresh air. It is equal to 1, when the entire volume of air in a room is exchanged within an hour, whereas the value of 0.5 means that half of the air volume will be exchanged within that time. It is accepted that in order to ensure right air quality during the normal use of rooms, the air exchange rate should be between 0.3 and 0.8. The lower level of exchange rate can lead to the problems described above, while the higher level – to unnecessary energy loss.

The Requirements for Effective Ventilation Systems in the Office Buildings

In order to ensure adequate working conditions in an office setting, it is necessary to pay attention to the proposed building ventilation system. The major requirements for ventilation systems are as follows:
• Ability to provide sufficient amount of fresh and clean air,
• Removing exhaust air from rooms,
• Keeping an acceptable level of noise,
• Low energy consumption level,
• Adjustable to every interior and meeting aesthetic requirements,
• Removing excess humidity from rooms,
• Purifying air with filters placed in ventilation systems to reduce the risk of allergic sensitization,
• Continuous exchange of air to ensure adequate humidity in rooms (below 45%),
• Measuring and control of such parameters as CO2 concentration and temperature, as well as parameters connected with air quality (VOC) and humidity level,
• Tracing the presence of people in rooms, i.e. using demand controlled ventilation systems (DCV),
• Individual configuration of the occupation schedule for each room,
• Convenient management, e.g. by means of the BMS system functionality, and ability to change the system working parameters by the user from the web server.

Air Exchange – The Response to the Users’ Requirements (Effective Ventilation)

When it comes to the thermal comfort, every person has individual preferences, thus it is impossible to satisfy all people who are present in a given room. However, experts have managed to establish some general building design rules to provide comfort for most users. Effective ventilation plays a key role here, too.

In fact, properly designed, built and adjusted ventilation systems are completely unnoticeable to users. Air should be removed from rooms upon using all of its assimilative properties. The correct selection of the type of diffusers and the manner of air distribution guarantees appropriate supplied air movement in rooms, without creating so-called dead zones (i.e. zones without air exchange), extraction of heat gain or humidity, and dilution of air polluted with dust or gases to a point where the concentration of pollutions reaches an acceptable level. Therefore, it is very important to correctly select all ventilation elements that impact air distribution in rooms.

In response to the market expectations, SMAY offers an innovative solution for mechanical ventilation system, known as iFlow. The solution was created to optimise building ventilation systems by implementing variable air volume (VAV) regulators. Providing the right amount of air supplied by the ventilation system is indispensable for creating proper indoor environment. The amount of supplied air varies not only depending on the type of room, but also the number of users. Office buildings are characterized by varying number of users, depending on the time of day or season. Due to the number of factors that influence variable airflow rate it is impossible to determine required volume of supplied air in advance. It is possible to adjust the ventilation system efficiency to current needs by analysing different signals (current temperature in a given room, CO2 concentration, business hours, and information from motion detectors or window sensors). This is specifically why the iFlow system was designed. It provides building users with both a high level of comfort and operating cost savings. The airflow may depend on the CO2 concentration in rooms. It is directly proportional to the number of people in a given room.

In order to lower the level of pollution and provide required amount of air in offices, we propose the ELIXAIR filtration solution. This device neutralises bacteria and viruses, and provides users with clean and healthy air. The duct filters catch and neutralize up to 99.8% of all air pollution, including the smallest nanoparticles, even those as tiny as 0.03 μm. The ELIXAIR filters are used in intake and exhaust duct ventilation systems. They remove particle pollutions from indoor air very efficiently. What is more, they are equipped with activated carbon filters that remove a considerable number of harmful gases and odours that get into the building along with outside air. The filter operating principle is based on the most effective known way of air purification – the electrostatic method.

A healthy microclimate and well-being greatly depend on a properly designed building ventilation system. When it comes to environmental conditions, the sufficient inflow of fresh air is one of the basic needs of office workers. It improves the quality of air in rooms by diluting pollutions, including CO2 and biological pollutions released by people, as well as pollution secreted by building materials and room equipment. The broad range of products available in SMAY’s offer allows designers to select appropriate solutions and to design ventilation systems for all kinds of rooms.

Monika Garbacz

SMAY Sales and Technical Adviser

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