Lighting and Pressurization Calculations

The rules on the Preliminary project of lifts are defined by the “COMMUNIQUE ON THE PRINCIPLES AND PROCEDURES REGARDING THE DESIGN OF LIFTS (SGM: 2017/18)”. This Communiqué provides definitions regarding the preparation and content of Preliminary, Traffic and Implementation Projects for Lifts. The definitions relating to the preliminary projects for lifts are stated in Article 7. Subclause 2)b) of this article stipulates that lighting and, if necessary, pressurization calculations must be made.

“Lift preliminary project

ARTICLE 7 – 1)

2) The preliminary project is prepared jointly by authorized engineers from the related professional disciplines specified in the national zoning legislation. The preliminary project contains the following information:

a) Number of lifts according to the structure/building traffic calculation, drive type, control system, number of stops, travel distance, rated speed, rated load, carrier/car dimensions, location and dimensions of the machine/pulley room, machine motor power, load calculation to the building/structure, grounding and cable cross-section calculations, voltage drop calculation, separate column line and lighting luminaires from the main distribution table of the structure/building, lighting lumen calculations and well pressurization calculation if applicable,

b) The other calculations were already known and performed, but when research started on this new lighting and pressurization calculation requirements, I thought it would be convenient to present a general study to help. I hope it will be useful.

A) Lighting Calculation

Lighting calculation is necessary to account for the lighting to be used in a place. In our daily lives, the fact that lighting is provided in an area does not necessarily suffice to provide the expected illumination for the desired work to be carried out. To be able to carry out certain tasks, it is necessary to attain specified levels of illumination and to provide an intensity of illumination that would allow a visual action to be carried out with the required precision and for the required period of time. Lighting calculation can be summarized as the calculation for providing the required Luminous Flux to achieve the desired Luminous Intensity. First, these need to be defined.

Definition of Luminous Intensity (Lux): The total amount of luminous flux per unit area is called luminous intensity. (Lux is a measure of illuminance, the total amount of light that falls on a surface.) Its unit is Lux, represented by the letter E. These illuminance levels are specified for particular tasks depending on the sensitivity of the work. EN 81-20 Standard specifies the luminous intensities to be used in lifts as follows: 200 lux in machine area and pulley rooms where fine wiring tasks will be carried out, 100 lux inside the car, 50 lux at the bottom and top of the well. The challenge now is to find the luminous flux, which is the lumen of the light source, that will deliver these specified lux values.

Definition of Luminous Flux (Lumens): Luminous flux is a measure of luminous flux, the total amount of light emitted in all directions. (Lumens is a measure of luminous flux, the total amount of light emitted in all directions.) Its unit is Lumens, represented by the letter φ. However, the intensity of illumination created by a light source on a given surface depends on various factors. The luminous flux created by all sources is called “total luminous flux”. It is represented by the letter Φ. These include the illumination efficiency, which is based on the distance of the light source to the area to be illuminated and the reflection qualities of the space, the contamination factor of the facility and the surface of the area to be illuminated. For interior lighting spaces, the general lighting calculations are performed according to the utilization factor method. This method is also referred to as the “luminous flux or efficiency method (EN 12464). This method is preferred as a method that is easy to apply and calculate. Let’s write the formula and then try to define them one by one for lifts. 

Measurement of total luminous flux

d= maintenance factor
A = Area of the surface to be illuminated
E =  Average illuminance level
η = value of utilization factor

The “contamination factor of the facility” denoted by the letter d is obtained from the Contamination Factor Table. Values for various situations are provided in this table, however, we assume this number as d=1.25, except for some special cases, taking into account a case of continuous maintenance performed in the lift. For special lighting applications, the value may be assumed as d=1.35. However, since a general evaluation will be made in the preliminary project, d=1,25 can be adopted as a general value as shown in the colored rows in the table and it is suitable for lifts.

We have previously seen that the part indicated by the letter E is the “Luminous intensity”. The required luminous intensity (lux) defined in the standard for each type of area should be calculated. This value is 200 lux in calculations for machine areas and pulley rooms, 100 lux in car lighting calculations and 50 lux in other areas such as the top of the car, bottom and top of the well. The letter A indicates the “area to be illuminated”. The width and length are multiplied in meters to determine the area.

A= a*b m²

η indicates the “room lighting efficiency” (value of room utilization factor), which depends on two separate factors. One of these is the “room index”, denoted as k, and is a coefficient.

Room Index Calculation

k = room index
a = length of the room
b = width of the room
H = horizantal distance between armature and referance plane

The coefficient k can be easily calculated considering the dimensions of the borders of the area to be illuminated and the distance of the light source to the area to be illuminated in meters. This coefficient is used in the room lighting efficiency table, but to be able to use this table, the reflectance details of the area to be illuminated must first be determined. 

Using this table, a reflectance value of 80% for the ceiling of the car, 50% for the walls and 30% for the floor can be obtained. We can establish an approximation if we assume the reflectance values for the ceiling in the machine room to be 80%, and 30% for the walls and floor. For the well, the ceiling can be considered as 50% and the walls as 50-30%. A 10% reflectance value for the bottom of the well would be appropriate, as this area can be dusty and oily. It would be a more appropriate approach to assume the lower values in preliminary projects, while values closer to real values should be considered in implementation projects. Based on this evaluation, we can use the table of surface reflectance multipliers by room index. However, I would like to note that the efficiency tables for each luminaire are different, and a low-value efficiency table is used here for the preliminary project. Calculating based on the efficiency tables of the luminaires used in implementation projects will ensure more accurate results in practice.

If we examine the reflectance values based on the selections made above, we can see that the first column (80-50-30%) complies with the car coverage values, but since this is a preliminary project and no selection has been made for the car yet, there is no calculation for this in the preliminary project. This portion is a calculation belonging to implementation projects. 

Again, the values given for the (80-30-30%) column marked in blue right next to it can generally be regarded as valid for the machine room. For the well, plastered concrete (80-30-10%), normal concrete (50-50-10%) or brick (50-30-10%) values marked in pink can be considered suitable. After making these evaluations, we can use the room efficiency table to determine the residual η value depending on the k value. The areas related to lifts in the room efficiency table are marked with the colors specified above. Using worse values in preliminary projects provides convenience in implementation.

Using the reflectance values table, we have determined the values for the car, machine room and well. For the k value we have obtained, we can determine the room efficiency by looking at the respective columns for these values. Once this value is determined, it will be easy to find the value of φ. 

When performing lighting calculations, the requirements set by the standard must be complied with. 

“EN 81-20; 5.2.1.4 Lighting

5.2.1.4.1 The well shall be provided with permanently installed electric lighting, giving the following intensity of illumination, even when all doors are closed, at any position of the car throughout its travel in the well: 

a)  at least 50 lux, 1,0 m above the car roof within its vertical projection; 

b)  at least 50 lux, 1,0 m above the pit floor everywhere a person can stand, work and/or move between the working areas; 

c)  at least 20 lux outside of the locations defined in a) and b), excluding shadows created by car or components. 

To achieve this, sufficient number of lamps shall be fixed throughout the well and where necessary additional lamp(s) may be fixed on the car roof as a part of the well lighting system. 

Lighting elements shall be protected against mechanical damage.”

It should be noted that clauses a and b of this article state that the distance at which the intensity of illumination is to be measured should be 1 meter above the measured surface. The subject mentioned in clause c) is a matter to be taken into account during the manufacturing phase and should be ensured by the installer. It should also be noted that the luminaires to be used must be protected against mechanical damage, i.e. they must be “waterproof” luminaires. 

Machine room lighting requirements are specified in the article below. 

“5.2.1.4.2 Machinery spaces and pulley rooms shall be provided with permanently installed electric lighting with an intensity of at least 200 lux at floor level everywhere a person needs to work and 50 lux at floor level to move between working areas. The supply for this lighting shall be in conformity with 5.10.7.1. 

NOTE This lighting may be part of the lighting of the well. “

There are two definitions for the machine areas and pulley room. Machine areas include all areas including the machine room where the machines and control panels are placed, inside or outside the well, and the areas where 200 lux lighting must be installed are the working areas. In other words, the areas where machines and panels are located and the areas where recoveries are made are considered as working areas. 50 lux lighting in other areas, which are for moving between floors, is sufficient. There is no need to provide 200 lux lighting throughout the whole machine room. 

To provide a small example, let’s choose a luminaire that will provide 200 lux illumination on the base of a machine room.  Let’s say the height of the ceiling above the mound is 2.1 meters and the sides are 2.2 meters * 2.4 meters. Assuming that the Panel and Machine are located here, it should be ensured that 200 lux illumination is provided here, and it should also be checked that the lighting provides 50 lux illumination in the border transition areas.

In this case

 k = (a*b)/(H*(a+b))  

 k = (2.2*2.4)/(2.1(2.2+2.4)) =0.5465

Using the room lighting efficiency table for the machine room, η = 0.18 for k = 0.6. We have already determined that we will assume the d value as 1.25 from the table. We can simply insert the Lux and area values to solve the formula. 

Φ  = d*E*A/ η
Φ  = 1.25*200*(2.2*2.4)/0.18
Φ = 7333.3 Lumens.

Table of Power and Luminous Fluxes of Various Lamps

We need to select the lumen values for the armatures and determine the number of armatures to be used. Some simple armature values are given below. In practice, the Lumen value of the lamp used should be taken as basis. For a broader range, the Technical Information section of the EMO Agenda can be used. 

Make sure that the type of lighting used in the machine room does not cause stroboscopic effect (frequency-dependent eye burn). In case fluorescent lamps are used, feeding the armatures from different phases eliminates this effect. 

Let’s assume that we are using a 40 Watt fluorescent armature for machine room lighting. Based on the values obtained from the table, the luminous flux is 2100 lumens. The number of armatures should be determined accordingly. By dividing the total required luminous flux value by the luminous flux value of the armature used, we can determine the number of armatures. This is considered as a mathematical sum. 

All values calculated should be rounded up to the next whole number. In this case, 4 fluorescent armatures will be required.  The luminous flux should be recalculated for double checking the total lumens used.

E = φ*Z* η /(d*A) 
E = 2100*4*0.18/(1.25*(2.2*2.4))
E = 229 Lux > 200 lux. Standard requirements met

Compliance with the requirement of 50 lux for the general illumination of the machine room should be checked.  Let’s say the sides of the machine room are 4 meters by 5 meters, and assume the height of the base as 1 meter. In this case 

H = (2.10 +1.00) = 3.10 mt 
k = (4*5)/(3.10*(4+5)) 
k = 0.716 which corresponds to the following in the table 
η = 0.24.

E = φ*Z* η /(d*A) 

E = 2100*4*0.24/(1.25*(4*5))

E = 80.64 Lux > 50 lux . Standard requirements met  Machine room lighting is suitable.

The calculations made for the machine room should also be made for the bottom and top of the well. If a lift without a machine room is being built, the lighting above the well should be calculated as the machine area. In such implementations, well values applicable for the efficiency coefficient should be used. For bottom of the well lighting, it is necessary to measure the light intensity of the armature closest to the pit bottom when it is one meter above the ground. It should be noted that the section specified for the well in the well efficiency table should be used. The same is true for the top of the car. When the car passes the nearest armature, the light intensity that the armature directly above it will create at a distance of 1 meter above the car roof should be more than 50 lux. The top of the 1 meter above the car roof should be taken as the illumination area. If this creates a challenge in larger wells, fixed lighting equipment installed on top of the car can be used to supplement the fixed lighting installation in the well, as stated in the Standard. However, an unwritten but commonly practiced method is that it is acceptable for the light intensity of the well lighting to meet at least half of the required light intensity on top of the car.

In lifts without a machine room, since the top of the well is regarded as the machine area, a light intensity of 200 lux is required on the car at 2.10 meters below the ceiling of the top armature.  This may require additional armatures to be used in addition to the well’s fixed lighting. In practice, it should be ensured that the switch for the illumination of the machine area is located outside the well. 

Car lighting is a calculation that does not need to be performed in the preliminary project. This is done and measured by installers according to the selected car finish and the lighting armatures used. Since it is a measurement required for the registration controls of lifts, it is not required in the preliminary project.

A lighting calculation that meets the conditions specified above will meet the lighting calculation required in the Regulation. Despite my long explanation, it is a simple calculation that can be performed simply when you are familiar with the method. Although Lighting Calculation is a very extensive and detailed subject, this simplified method can be easily used for lifts. Below is a sample drawing for distances at the bottom of the well. 

B) Well Pressurization Calculation

Fire and fire escape and protection systems are extremely broad and complex procedures. Preparing the fire scenario of a building requires extensive knowledge and experience. We are only required by the Regulation to make a basic calculation for the pressurization to be created in the well of the lift, if necessary, and to assist in the general pressurization calculation of the building. The determination of the areas to be pressurized or depressurized outside the well, as well as the methods and calculations should be done by experts in this field. The purpose here is to provide a brief and basic overview. We use the Standard “EN 12101-6: 2005; Smoke and heat control systems Part 6: Specification for pressure differential systems – Kits” as the main source on this subject. This standard specifies the measures and methods to be followed in detail. Scope 1 states “ This document specifies pressure differential systems designed to hold back smoke at a leaky physical barrier  in a building, such as a door (either open or closed) or other similarly restricted openings. It covers methods for calculating the parameters of pressure differential smoke control systems as part of the design procedure.”  

Various classifications and methods are described.

The pictures above demonstrate the pressurization system made from the roof or from the ground and the pressurization distribution ducts with overpressure relief damper (60 Pa) placement. Overpressure relief system is defined in Article 5.4. Article 6.5 defines the conditions for pressurization of the stairwell and lift shaft. Article 6.8 defines the requirements and working procedures for stairwells, lobbies and lift shafts. Article 6.8.2.4 states “The stairwells, lobbies and lift shaft shall all be pressurized separately to ensure that the contamination of smoke to each area is kept to a minimum.” and a pressure of 50 Pa is foreseen for the lift shaft. This is shown in Figure 13. Electrical system requirements are defined in Article 11.6 Electrical requirements (main and secondary). Pressure distribution ducts can be made with the distribution system in the elevator well as shown in the figure, as well as through the pressurization shaft connected to the well at intervals at the sides of the well. The requirements for distribution ductwork for pressure differential systems installation are defined in Article 11.8 of the standard. The requirement that we have to meet here is to calculate the air flow that will create a pressure of 50 Pa in the well. Below is a method of calculation for this is described.

Lift Shafts

The Standard provides an explanation for lift shafts in Article 6.5. If smoke enters an unpressurized lobby or corridor, the lift shaft creates a potential path for smoke to spread from the fire floor to other floors. By pressurizing the lift shaft, the spread of smoke from the fire floor to other floors through the lift shaft can be limited. There should be a pressure difference of 50 Pa between the lift shaft and operating area.

 The standard proposes a method for calculations in the ” Annex A (informative) Design recommendations” section. The amount of air required to maintain the pressure difference criterion can be calculated. A method for this is proposed in Annex A, Article A.3.2 Calculation of air flow. As air flows through an opening, the flow restriction area and the pressure difference across the opening can be calculated using the following equation:

Q = 0.83 * AE * Δp^1/R 

Q = The air flow (m³/s)

AE = Area of the restriction (m²)

Δp = Pressure differential across the opening (Pa)

For value R, the Standard specifies “Annex A 3.2 Note : For wide cracks such as those around doors and large openings, the value R may be taken to be 2 but for narrow leakage paths formed by cracks around Windows a more appropriate value of R is 1.6.”.

We assume that the openings are more unrestricted in the lift and use R value as 2. Since we know that Δp value is 50, the only value that needs to be calculated is the total leakage areas AET. If we perform this calculation for a lift with a well area of 2.1*2.2 meters and a well height of 70 meters with 20 stops; 

There are four possible leakage routes into the lift.

1. Lift well ventilation shaft and rope holes; 

Consists of rope holes or smoke shaft opening in the lift well. With a shaft area of 0.30*0.30 meters, if 2*(0.15*0.15) meters of rope holes and other regulator and openings are taken into account, we can assume this area to be approximately 0.15 m².

2. Leakage from closed doors of the lift;

The standard establishes a general assumption for closed elevator doors. In Annex A, Table A3, this value is accepted as 0.06 m2. It should be calculated as the total of the number of closed doors. For door 19, this value is 1.14 m2. We will assume that door 20 is opened and we will calculate it in the next article.

3. Leakage from the opened door of the lift

During rescue or recovery, one of the doors of the lift will be open. However, there is a car in front of it. Assuming that there is a 3 cm gap between frame of the open landing door and the car door, the leakage area around the door frame needs to be calculated. Assuming a door with dimensions of 1.00*2.10 meters, we find an area of (2*(1.0+2.1)*0.03) = 0.186 m2. For a 0.90*2.00 meters door, this area will be 0.174m².  [(2*(0.9+2.0)*0.03) = 0.174 m²]

4. Lift shaft leakages

Air leakage data per m2 for walls are presented in Annex A, Table A.5.  The surface area of the lift shaft must be multiplied by this multiplier. Looking at the section related to lift shafts, we see three different categories. It is appropriate to refer to the first line for complete concrete wells and the second line for wells containing bricks. The third line can be applied for wells with high leakage. In this case, the leakage area in a 70-meter-long well and 2.1*2.2 meters perimeter with brick walls will be (S*k) = [2*(2.1+2.2)*70] * 0.00084 = 0.505 m². 

Since all of these leakage areas flow directly from the well, they should be considered as parallel and summed arithmetically. (Annex 1 A.1.2.)

If we calculate the total leakage areas

1. Lift well rope and ventilation shaft = 0.15m² 

2. Closed doors of the lift; (19 pcsx0.06) = 1,14 m² 

3. Lift open door; = 0.174 m² 

4. Well 70 meters height = 0.505 m² 

Total leakage area for the lift well AET =1.97 m²

Necessary air flow

Q = 0.83 * AET * Δp^1/R 

Q = 0.83*1.97*501/2 = 11.561 m³ air flow rate is required.

If the lift doors do not open into a pressurized lobby or fire hall, 50% more flow is assumed for doors opening directly into a corridor, 

QS = 1.5 x QDC      (Annex A, A.3.2)

Fan Selection:

Flow rate = 11.561*3600 = 41622,85 m³/h calculation will be sufficient to make the elevator pressurization calculation. 

As I said before, both lighting and pressurization topics are very extensive and complex. We tried to create a calculation method that is simple enough to be used for lifts. It is important to keep in mind that the work does not stop there and that it is necessary to examine the necessary standards for more detailed studies and to make calculations according to the actual values of the materials used. This is only a preview study for preliminary projects and it does not include adequate calculations for implementation projects. I hope it will be helpful. Best regards,