Understanding and Measuring Light: The Role of Lux in Illumination Engineering

Abstract

For a specific surface, Lux is a measurement unit of the light quantity that reaches an area. Since light extends from its source in every direction, it may seem misleading for a light at a certain point in space. In lux equations, the light travels across the spherical surface and uses the value point as the point of view of the object. The images or soccer-candles of other lights that scientists and engineers use are equivalent to 10000 lux with 1 phot, and 1 foot-candle 10,7639 lux.

The light can also be determined as E by E= da / A for the 'phi' luminous flux and the field through which light passes A in m2. Light can also be measured by E.

In other words, because you know the area over which the luminous stream occurs, you can calculate lux from lumens. The light uses lux as units, and lumens as units are used for lumens. Don't get mixed up' flux' and' lux!' You then have the option of using luminous flux— a light source in the spectrum of a circular distance, which connects the light source to the point of interest in units of steradians (sr)— to evaluate intensity I and candela — omega —available by= ax —available in the candela.

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You can use 4 μsteradians as candela because the sphere is designated with 4μsteradians. If the illumination is spread in every sense and you want to measure a point on an imaginative surface area which extends from the light source. Take into account the angle over which a certain surface area is projected to determine how much of the surface of a sphere is stretched by that light source.

Introduction

The calculation of the basic U-value is quite simple. The U-value can be calculated by finding the reciprocal sum of the thermal resistances of each building element. Remember that the internal and external faces, as well as the substrate resistances, have to be applied to the resistors. These are values that are fixed. Through taking into account the design factor layer-by-layer, basic U-value calculations can be performed as follows. Nevertheless, it is important to note that this does not involve cold bridging, insulation air breakage, or thermal features such as morter joint properties. As the U-values calculation can take time and be complicated, especially when cold bridging needs to be taken into account. numerous U-value calculators have been released online.

However, many of these are available only on request, and free ones are too basic. Another alternative is to allow an insulation supplier, for example, whose commodity is listed, to quantify it. U = 1/Rt…. U = Thermal Transmittance (W/m²•K) ,Rt = Total Thermal Resistance of the element composed of layers (m²•K/W), obtained according to: Rt = Rsi + R1 + R2 + R3 + ... + Rn + Rse. Rsi = Interior Surface Thermal Resistance (according to the norm by climatic zone), Rse = Exterior Surface Thermal Resistance (according to the norm by climatic zone),R1, R2, R3, Rn = Thermal Resistance of each layer, which is obtained according to, R = D / λ. D = Material Thickness (m), λ = Thermal Conductivity of the Material (W/K•m) (according to each material).

The thermal transmission is inversely proportional to the thermal durability: the more resistant the materials that make up an envelope, the less heat they lose. U = 1/R … R = 1/U when our U-value is obtained, the value of maximum thermal transmission must be compared with the maximum thermal transmittance specified in winter and summer for the climate zone in our project. This number is determined by official local regulations which you must closely check to make sure that they work properly. W = Power (Watts) - K = Temperature difference (Kelvin).

Parameters should be taken from the air entering the local inlet and suction openings of the technological devices and other devices present in the working area according to GOST 12.1.005-76. The size of the room is 3 by 5 meters and its height is 3 meters, its volume is 45 cubic meters. Therefore, ventilation should provide an airflow rate of 90 cubic meters / hour. In summer, the air conditioner installation must be provided to avoid overheating in the room for the stable operation of the device. Due regard should be paid to the amount of dust in the air, as this directly affects the reliability and lifetime of the computer.

The power (more precisely, the cooling power) of the air conditioner is the main feature, it depends on the amount of space designed for it. For approximate calculations, a kilowatt is taken per 10 m 2 with a ceiling height of 2.8 to 3 m (according to SNiP 2.04.05-86 'HVAC').

To calculate the thermal flow of this room, a simplified technique was used:

Where: o - heat flow/ S - the area of the room/ H - the height of the room

q - coefficient 30-40 W / m3 (in this case, 35 W / m3)

For a room of 15 m 2 and a height of 3 m, the heat flow will be:

Q \ u003d 15 • 3 • 35 \ u003d 1575 watts

In addition, heat emission from office equipment and people must be taken into account, and it is believed (according to SNiP 2.04.05-86 'HVAC') that in a quiet state, a person emits 0.1 kilowatts of heat or a computer or copier 0.3 kW, by adding these values to your total heat gain, you can get the needed cooling power.

Q add \ u003d (Hâs oper) + (C •s comp) + (P •s print) (4.9)

Where: Q add - the sum of the additional heat gain. C - Computer temperature/ H - the thermostat operator/ D - Heat of the printer/ S comp - the number of workstations/ S print - the number of printers/ S opera - number of operators

The additional heat flow of the room will be:

Q add1 \ u003d (0.1 • 2) + (0.3 • 2) + (0.3 • 1) \ u003d 1.1 (kw)

The total amount of heat gain is equal to:

Total Q1 \ u003d 1575 + 1100 \ u003d 2675 (W)

According to these calculations, it is necessary to choose the appropriate power and number of air conditioners. For the room in which the calculation was performed, air conditioners of 3.0 kW capacity should be used. One unfavorable factor for the ITC production environment is the high level of noise caused by printers, air conditioners, and cooling system fans in the computer itself. To solve the problems of the necessity of noise reduction and its suitability, it is necessary to know the noise levels in the workplace of the operator.

The noise level generated by multiple incoherent sources working simultaneously is calculated based on the principle of collecting energy for radiation from individual sources:

L \ u003d 10 log (Li n), (4.10)

Where Li is the sound pressure level of the noise source i; n is the number of noise sources. The obtained calculation results are compared to the allowed value of the noise level in a particular workplace. If the results of the calculation are higher than the permissible value of the noise level, then special noise reduction measures are required. These include: room and ceiling lining for the room with sound absorbing materials, noise reduction at the source, proper equipment planning, and rational organization of the operator's workplace.

The audio pressure levels for the operator's noise sources are displayed in the workplace. Sound pressure levels from different sources,The operator's workplace is usually equipped with the following equipment: a system unit hard drive, a computer cooling system fan (s), a monitor, keyboard, printer, and scanner. Substituting the sound pressure level values for each type of equipment in formula, we get:

L \ u003d 10 log (104 + 104.5 + 101.7 + 101 + 104.5 + 104.2) \ u003d 49.5 dB

The resulting value does not exceed the permitted noise level at the operator's workplace, equivalent to 65 dB (GOST 12.1.003-83). Since it is unlikely that peripherals such as the scanner and printer will be used simultaneously, this number will be lower. Additionally, when the printer is turned on, the immediate presence of the player is optional. The printer is equipped with an automatic paper feeder. Voice accounts, Among the problems of improving the environment, noise control is one of the most relevant issues. In large cities, noise is one of the main physical factors that shape the environment.

The growth of industrial construction and housing, the rapid development of various types of transportation, the increased use of plumbing and engineering equipment, and household appliances in residential and public buildings, have resulted in higher levels of noise in residential areas of the city with noise levels in the workplace. The noise system for large cities is mainly formed by road and rail transport, which represents 60-70% of the total noise. A noticeable impact on the noise level is caused by increased density of air transport, the emergence of powerful new aircraft and helicopters, as well as rail, open metro and shallow underground metro. At the same time, in some major cities where measures are being taken to improve the noise environment, there is a decrease in noise levels.

Calculation ventilation Alveoli. Minute ventilation is the tidal volume times the respiratory rate, usually, 500 mL × 12 breaths/min = 6000 mL/min. Increasing respiratory rate or tidal volume will increase minute ventilation. Dead space refers to airway volumes not participating in gas exchange.

The general mechanical ventilation :

Ventilation rate (m^3/h) = air change rate (/h) x room volume (m^3)

Air change rate (/h) comes from CIBSE guide B2 table 3.1

Ventilation rate (m^3/h) = ventilation rate (m^3/h) / 3600

Practical Applications and Calculations

In practical terms, understanding lux and its calculation is paramount for creating optimal lighting environments. For instance, the basic U-value calculation in thermal engineering, which involves the reciprocal sum of thermal resistances, mirrors the importance of precise measurements in achieving desired outcomes. Whether optimizing the cooling power of air conditioners or calculating the thermal flow in a room, the principles of accurate measurement underpin effective design and operation.

Conclusion

The measurement of light, particularly through the unit of lux, is a cornerstone of illumination engineering and environmental design. By enabling precise quantification of light intensity, lux measurements inform the development of lighting solutions that enhance human spaces. The transition from lumens to lux, facilitated by a clear mathematical framework, underscores the importance of accurate, unit-specific measurements in achieving optimal illumination. As we continue to refine our understanding of light and its impacts, the role of lux as a critical metric in photometry will undoubtedly remain central to our endeavors in creating well-lit, functional, and aesthetically pleasing environments.