Energy-efficient lighting technologies

Lecture content:

1. Regulatory framework
2. Natural lighting
3. Artificial lighting
4. Light sources
5. Energy-efficient measures
6. Lighting check
7. Active links (NPA, standards, resources)
8. Glossary
9. Questions for self-test

1. Regulatory framework

When we talk about lighting in buildings — both those that already exist and those that are just being designed — we always rely on standards. The current document that defines the requirements is the State Construction Standards “Buildings and Structures”. It clearly spells out the indicators for both public buildings and residential buildings.

In addition, we have several other important documents. These include:

• DSTU 9191 – defines the methodology for calculating the energy consumption of a building: heating, cooling, ventilation, lighting, hot water supply. That is, everything related to energy efficiency.
• DBN V.2.5-28:2018 “Natural and artificial lighting” – the main document for designing and assessing lighting.

According to DBN V.2.5-28:2018 “Natural and artificial lighting”, we distinguish three types of lighting:

• first, natural lighting;
• second, artificial;
• and, accordingly, combined lighting, when these two options work together.

2. Natural lighting

Natural lighting is, in essence, light from the sky, direct or reflected, which enters the room through windows, skylights, light guides. That is, any openings in the external structures of the building.

Important point: according to the standards, all rooms where people are constantly present must have natural lighting. This is clearly stated in DBN V.2.5-28-2018. An exception is allowed only where there is no constant presence of people – for example, warehouses or technical rooms. But even then, it is necessary to ensure appropriate ventilation and high-quality artificial lighting.

DBN distinguishes five types of natural lighting.

• The first is lateral, when light enters through windows in the outer walls.
• The second is upper, when light enters through skylights or openings in roofs or in places of elevation changes.
• The third is combined, that is, both lateral and upper together.
• The fourth is accumulated, when lamps accumulate energy during the day and give it away at night.
• And the fifth is transported, this is a more modern solution when light is brought into the room through a system of light pipes.

What affects the level of natural lighting?

There are external factors:

• geographical latitude of the area, climate (number of cloudy days and light climate) terrain;
• seasons of the year;
• hours of the day;
• presence of shading objects (buildings, trees, mountains).

There are also internal factors:

• name and purpose of the premises;
• orientation of windows to the cardinal points;
• floor;
• type of natural lighting, i.e. placement of light openings (one-sided, two-sided, upper, combined);
• number of windows, their design (single-frame, double-frame, paired);
• quality and purity of glass;
• presence of shading objects (flowers, curtains);
• height of the window sill, distance from the upper edge of the window to the ceiling;
• brightness (reflectivity) of the ceiling, walls, equipment and furniture.

And now about the losses: glass contamination (30–50%), curtains (≈40%). Therefore, even under the best conditions in the room, we will always have 75% less light than outside.

3. Artificial lighting

Now let’s move on to artificial lighting.

According to DBN V.2.5-28-2018, it is divided into several types according to its functional purpose.

The first is working lighting. This is the main light that provides standardized conditions for people to work and stay. It must meet the standards of brightness, uniformity, quality, and applies to both indoor and outdoor work areas.

The second is emergency lighting. It is turned on in the event that the main working one suddenly turns off. Emergency lighting allows you to safely complete work, stop equipment, or leave the premises in an organized manner.

The third is security lighting. It is installed along the border of the protected area. The task is simple: to ensure control and safety of the facility during the dark.

And the fourth is duty lighting. It is used in those rooms or facilities where there is currently no active work process, but a minimum level of lighting is required – for example, at night or during breaks between work shifts.

There is another important type – combined lighting. It is determinedь DBN V.2.5-28-2018. The essence is simple: when natural light is not enough, then it is supplemented with artificial light. That is, this is a combined option that helps maintain the normalized level of illumination at any time of the day or under any conditions.

Emergency lighting. It is divided into two subspecies: safety lighting and evacuation lighting.

Safety lighting is needed where the shutdown of working light can cause serious consequences. For example:

• explosion, fire or poisoning of people;
• serious disruptions in the technological process;
• stoppage of facilities that cannot remain without work – power plants, communication nodes, television and radio transmission centers, dispatching, pumping stations for water supply, heat supply, sewage;
• or, which is very important, violation of the regime in children’s institutions – regardless of the number of children.

That is, we understand: emergency lighting is not “secondary light”, but a critically important element of safety.

4. Light sources

Now let’s deal with light sources. The most common of them are:

• incandescent lamps,
• halogen lamps,
• gas discharge lamps (this includes metal halide, xenon, sodium, mercury fluorescent, conventional fluorescent and compact fluorescent),
• and modern LED lamps.

Let’s start with incandescent lamps. This is a thermal light source: when an electric current passes through a tungsten filament, it heats up and begins to glow. The pros are simple design, low price, wide choice of powers. The cons are very low energy efficiency.

A slightly better option is halogen lamps. They give twice as much light flux, a light output of about 30 lumens per watt. The color temperature can vary from 3000 to 6000K, which is pleasing to designers. But the service life is short – 2-4 thousand hours, and this is their weak point.

Next – gas discharge lamps. They work due to an electric discharge in an environment of inert gases or metal vapors. Thanks to this, they emit light. Their main advantage is economy. The light output is 40-100 lumens per watt, that is, several times more than that of an incandescent lamp. The service life is up to 10 thousand hours. This includes fluorescent lamps, which we know well: a glass tube with mercury vapor, inside a phosphor. They are durable and economical, but at low temperatures they work worse.

And, finally, LED lamps. This is the modern standard. They consume 80–90% less energy than incandescent lamps, at the same brightness. The luminous efficiency can reach 100–150 lumens per watt. They last an average of 30 thousand hours, and in some cases up to 100 thousand. They do not contain mercury, do not heat up, are compact, withstand impacts and work even at -50 °C. In addition, you can get any color of light. This makes them the most efficient and safest option for modern buildings.

5. Energy-efficient measures

Now a few practical measures that can increase the energy efficiency of lighting.

The first and easiest is cleanliness. It often happens that the lamps are dirty, the shades are dusty, the covers have not been washed for a long time. Just remove the dust, wash the shades – and we already get a noticeable increase in illumination.

Next is individual lighting of workplaces. This means that instead of lighting the entire room as brightly as possible, you can locally illuminate the area where a person works. This reduces electricity costs.

The next step is abandoning incandescent lamps in favor of LED lamps. LED lamps consume many times less energy, last much longer, and have better light output. If we are talking about efficiency, then you need to choose lamps with the highest possible luminous flux per unit of power – that is, lumens per watt.

Another criterion is service life. It is worth giving preference to lamps with a life cycle of 40–75 thousand hours. This reduces replacement and maintenance costs.

Automated solutions are also useful. For example, motion sensors in rooms that are rarely used – pantries, corridors. The light turns on only when there is a person there. For outdoor lighting, it is appropriate to install light sensors that respond to the level of natural light.

There is another interesting aspect – interior. Light colors of surfaces significantly increase the efficiency of lighting. For example, an aluminum reflector has a reflection coefficient of 0.98, white – 0.8, yellow – 0.6. But gray – only 0.2, and black, anthracite – 0.04. That is, the right choice of wall or ceiling color can increase the illumination of the room without additional costs.

And one more point – the use of electronic starters. They significantly increase the service life of lamps, especially fluorescent ones.

6. Checking the lighting

Instruments

When we talk about measuring illumination, special instruments are needed. The most common are luxmeters, as well as photometers, luminometers, pulse meters with built-in sensors. Voltmeters are also used, and it is very important that all these instruments have a certificate of metrological verification. For voltmeters, the accuracy class must be at least 1.5.

Preparation

Before taking measurements, you need to prepare the lighting installation. First, replace all burned-out lamps, clean the fixtures. Of course, sometimes measurements are carried out without such preparation, but then a note is necessarily made in the protocol. Secondly, control points are marked on the room plan, taking into account the location of the fixtures.

Next – placement of control points.

If we measure the minimum illumination from working lighting, then the points are placed in the center of the room, under the lamps, between the lamps and near the walls.

If we are talking about emergency lighting, the points should be at the workplaces.

If we are talking about evacuation lighting, then on the floor, directly on the evacuation routes.

When determining the average illumination, the plan of the room is divided into squares and points are placed in the center of each square. Their number depends on the size of the room and the height of the suspension of the lamps.

Measurements

Regarding the measurements themselves. They are always performed in the dark. First and at the end, you need to check the voltage on the panels of the lighting distribution networks. In this case, it is important that the shadow of people does not fall on the photosensor and that the device is not located near strong magnetic fields.

Result processing

The results are recorded in the protocol. And only after that the results are processed. The minimum illumination is defined as the lowest value of all control points. This is the objective indicator that is then used to evaluate the lighting system.

Active links

• DBN V.2.5-28:2018 “Natural and artificial lighting”: https://e-construction.gov.ua/laws_detail/3074958732556240833?doc_type=2
• DBN V.2.2-9:2018 “Public buildings and structures. Basic provisions”: https://e-construction.gov.ua/laws_detail/3199648113669179181?doc_type=2
• DBN V.2.2-10:2001 “Buildings and structures. Healthcare facilities” (natural light standards without permanent occupancy):
  https://e-construction.gov.ua/files/new_doc/3489455790882817955/2024-10-29/45d453b8-54d4-45f8-adda-a8f29ac5bcb0.pdf
• DSTU 9191 (energy efficiency of buildings: methodology for accounting for lighting in consumption calculations)
  https://online.budstandart.com/ua/catalog/doc-page.html?id_doc=98996
• Luxury levels for typical premises (guidelines)
  https://svetum.com.ua/ua/blog/sovety-pokupatelyam/chto-takoe-lyuksy-i-lyumeny/?srsltid=AfmBOooMNreB5wHcUIvwX83CSVEuzS0D6-_wAvkUSvE8gpUiwsfYUhZ-