Modern and energy efficient work environment

Today, we spend around 90% of our time indoors. Therefore, it is important to take care of the environment in which we stay most of the time. Inadequate lighting levels and poor air quality are often the main reasons, why the productivity and well-being of employees decline.

In the webinar “Modern and Energy Efficient Work Environment” organised by the Elektrum Energy Efficiency Centre on 24 November this year, it was possible to found out what indoor environment parameters affect employee productivity and how to improve them by providing adequate lighting and air quality, as well as how modern engineering systems help solve indoor climate problems.

WHAT AFFECTS THE WORK ENVIRONMENT?

Aneka Kļaviņa, a researcher at the Institute of Occupational Safety and Environmental Health of Riga Stradiņš University, explains that the way we feel in any room is determined by temperature, relative humidity, air flow rate and surface temperature.

For example, in winter the air at the outer walls and floor is much colder than in the rest of the room. At the ceiling and heat sources - warmer than in the middle of the room. In order not to disarrange the heat balance and to prevent the body from cooling or overheating unilaterally, it must be ensured that the difference in air temperature from the outer wall horizontally to any point in the room does not exceed 2 ^oC. Such a temperature difference in a room condition is usually not felt by a human.

Vertical fluctuations of the air temperature between the floor and one and a half metres above it are more hygienically important and more dangerous to health. Low temperatures on the floor contribute to a drop in the skin temperature of the feet and also the whole body, which can cause one to catch a cold. A drop in temperature of 4 ^oC makes the skin of the feet cool by 7 to 10 ^oC and causes discomfort. If the floors have good thermal insulation, then the vertical air temperature fluctuations do not exceed 3 ^oC.

Too high speed of air during ventilation will create a feeling of draught and discomfort, too low - overheating, because the evaporating moisture will not be removed from the body.

The effect of temperature on a person depends on the humidity in the room. If the relative humidity is too low - employees complain of eye irritation, dry skin, exposure to static electricity. Too high a relative humidity also interferes with the normal exchange of moisture with the environment.

Temperatures above 25 °C and below 15 °C are considered unfavourable because they disrupt the body's heat exchange. On the other hand, air temperature in the range of 18 to 22 °C is considered optimal, as is relative humidity in the range of 40 to 60% and air movement speed of 0.1 m/s. However, the fact that how comfortable a person feels depends on the work they do, should be taken into account. In each situation, the conditions must be adapted to the feeling of the employees, because the maximum and minimum parameters specified in the legislation do not always ensure a comfortable working environment.

 

THE LIGHTING SHOULD FOLLOW THE DAY RHYTHM

Another important factor that affects the working environment is lighting. Ingmārs Felcis, the head of the laboratory of Baltic Research Center SIA, reveals that lighting which is directed to a person and which mimics natural daylight, improves a person’s performance, comfort, health and well-being. It balances one’s visual, emotional and biological needs for lighting.

 

The first steps to achieve this - dimming the light and changing the colour of the light, which allows one to follow the rhythm of the day. The first part of the day is dominated by whiter light tones with a higher proportion of blue light and a higher intensity. At the end of the working day, allowing the body to rest, the light is less intense, with more yellow and much less blue tones. It is the yellow tones of light that are mostly used in modern lighting. In response to the blue part of the light spectrum, our body is awake. However, if there is too much blue light, anxiety and other unpleasant feelings arise.

Smartphone, computer and monitor manufacturers also offer the ability to adapt to the 24-hour cycle with screen light tones. After all, these devices are also light sources that affect us on a daily basis. In addition, there are special applications that allow you to manage this process.

The requirements for permissible flicker of the light source and thus uneven illumination of objects must also be observed. The colour rendering index is also very important.

It is also important to know, if the light sources used have any danger which, if viewed, could damage your eyesight. LED luminaires usually have a risk group of 0 or 1. If it is higher, the safety distance to the light source must be indicated.

 

NEW LABELLING

As of 1 September 2021, changes in the regulation of energy labelling of luminaires and light bulbs have entered into force in the European Union. The existing scale from A +++ to E is replaced by the scale from A to G without the plus signs added. For example, an A ++ class lamp with an efficiency of 120 lm/W according to the new energy labelling corresponds to class D. All types of filament lamps, incl. halogen lamps, are in class G. The label also has a QR code, which can be scanned to check the device's tests and other parameters.

What to look for when buying light bulbs and luminaires? Ingmārs Felcis emphasises that it is necessary to make sure that the full efficiency of the luminaire is indicated, and not only the efficiency of the LED used. For example, for a diode with an efficiency of 124 lm/W, the efficiency can be reduced to 75 lm/W, when using a diffuser, which is 40% light loss. The impact resistance, luminance and control of the light source must also be considered.

A FEW IMPORTANT DIGITS

Reinis Ernestsons, a representative of ADDO Energy SIA, states that the criteria for ergonomic lighting are measurable and in the office space they are:

• Optimal intensity. E average ≥ 500 lx (lux);
• Adequate evenness - the ratio of light intensity at different points in the room. E min/E average ≥ 0.6;
• True colour reproduction. Coefficient CRI or Ra ≥ 80;
• Eye comfort - the lighting does not dazzle. Coefficient UGR ≤ 19;
• No flicker. Coefficient flicker or ripple current < 5%;
• Suitable light colour temperature. 2700-6500 K (Kelvin).

In turn, the energy efficiency of the luminaire is characterised by the same luminaire efficiency - lm/W and lighting system power density in space - W/m²/100 lx, which is consumed in watts per square metre to reach 100 lux illumination. The last parameter is the most objective way to compare emerging lighting solutions. It will vary depending on the optics and light distribution of the luminaire, as well as its location in the room.

The flicker of the light source can be detected in an elementary way - by pointing at the camera of the smartphone. If lines run across the image - the light source is blinking too much. 

On the other hand, it is more difficult to measure whether a light source is dazzling, but this parameter can be calculated during the design of a lighting system using 3D modelling systems.

The conclusion is that what will be maximally ergonomic will not be maximally efficient and cheap. There is a need to find a medium or a priority direction. Approaching the desired medium, which would be both an ergonomic and efficient and inexpensive lighting system, allows the creation of an intelligent lighting system with many luminaires and sensor control for individual luminaire dimming. 

 

NOT TOO DRY, NOT TOO WET!

Uldis Strauts, project manager of Menerga Baltic SIA, provided an explanation about the provision of relative humidity and its impact on the microclimate of the room.

"Relative humidity, expressed as a percentage, is the mass fraction of water vapour in the air in relation to the maximum mass fraction of water vapour at that temperature. As the temperature increases, the relative humidity decreases, but the moisture content does not change. Also, as the temperature increases, the moisture content that saturated air can contain increases," explained Uldis Strauts.

When the relative humidity exceeds the comfort zone, the air must either be dried if it is too humid or humidified if it is too dry. Ensuring an optimal level of humidity is necessary in offices to take care of the comfort of employees, in specific public buildings, such as swimming pools, ice rinks, museums, where it is more necessary to preserve structures and materials. It is also important in production facilities, especially in pharmacy, woodworking and elsewhere.

The problem of dry air is more common in winter. Humidification of the air can be performed isometrically (humidification does not change the air temperature) by spraying water vapour into the air stream. In this case, use humidifiers with a tubular heater or electrodes that consume electricity. The air can also be humidified in an adiabatic process as the temperature drops. In this case, nozzle or surface humidifiers are used, as well as “air-washers”, which consume heat during operation. The air can also be humidified using a recuperator. In winter, such a system increases the overall efficiency by reusing the heat recovered in the recuperator to heat the cold, fresh air. It is possible to provide effective humidification, which is especially needed in offices. In summer, the recuperator allows indirect adiabatic cooling.

In summer, however, the biggest problem is too much humidity, when dehumidification is required. The process can be done by using cooling sections or evaporators, so the air may need to be heated after the process. Dehumidification is also possible with liquid or solid absorbents. During the process, the temperature rises and air cooling is required.

 

INTELLIGENT MANAGEMENT SYSTEMS HELP TO SAVE

There are different situations and needs in life. Gatis Arājums, Product Development Manager of Schneider Electric Latvija in the Baltic states, explained how to adapt the workplace to the changing needs of the workplace. He discovered the benefits of the KNX intelligent building management system. The system can be used to control and manage lighting, blinds, heating and cooling of the building, visualisation and control systems in a single system, which allows one to draw conclusions about the processes happening in the building and perform energy monitoring. 

The KNX system allows you to control outdoor and indoor lighting in automatic mode depending on the selected mode, allowing one not only to create a modern environment, but also to save electricity.

The blinds, on the other hand, are operated according to the user's habits and use, including in emergencies, for protection against rain and wind. However, these systems have not yet gained as much popularity in Latvia as elsewhere in the world.

In the field of heating and cooling control, the KNX system not only enables automatic climate control, but also predicts the optimal heating performance via information flow, for example in response to window openings.

It is important that the system allows data to be stored and analysed through the automatic monitoring of energy consumption and control of unnecessary consumers. The KNX system can be connected to the systems of other service providers via gateways.

 

Elektrum Energy Efficiency Centre with more than 23 years of experience and know-how creates public awareness of the efficient use of energy resources, educates on various solutions to increase energy efficiency, organises webinars and events, provides consultations. All materials of this webinar and lecturers' presentations are available to everyone free of charge in the seminar archive section of the Elektrum website, as well as it is possible to apply for a free consultation on energy efficiency.