The right illumination can bring not only comfort to hard-working people, but also efficient work for the team.

However, how to design the right lighting and give the office environment the right illumination to work seems to have always been a difficult problem for people.

So, is there an estimation method for quickly judging the wattage and corresponding number of lamps to be selected according to the office area?

## How does a lamp illuminate a room?

Let’s analyze the light on the most important working surface in the room, first of all, part of the light emitted by the lamp will directly reach the working surface, and the other part of the light will be reflected by the wall to the working surface, and at the same time, the reflection on the wall will also be reflected to the ceiling and then part of the light will be separated to the working surface in the same way.

And so on, so the light perceived by the visual working surface is actually composed of different reflections from multiple angles and the most direct irradiation. We also call the light that hits the working surface most directly as primary light, and the reflected light as secondary light.

According to this working principle, if we want to calculate the specific number of lamps and wattages in the space, then we must not avoid the evaluation of the lamps to be placed, and calculate how much light can reach the working surface you need, and this needs to be calculated by combining primary light and secondary light.

## How to calculate the number of lighting fixtures

We can quickly calculate how much illuminance can be achieved with how many lamps in a space can be achieved through a method, this method is called lumen calculation method or utilization coefficient method.

The definition of illuminance We all know that the luminous flux obtained above the unit square is called illuminance.

So according to the proportion, how much of the luminous flux emitted by our lamp falls on your working surface? Without further ado, Xiaozhi directly sent the results.

{Luminous flux × utilization coefficient× one maintenance coefficient ÷ space area}

This is the rapid estimation method of illuminance of the working surface in the room.

Lumen calculation method is also known as “utilization coefficient method”

average illumination = (luminous flux of light source) ×(utilization coefficient)× (maintenance coefficient) ÷ Area of irradiation

Knowing the answer so quickly, surprised, not surprised.

But how do you not understand it? Don’t worry, we’ll tell you what each parameter is.

How much of the light emitted by the lamp falls on the working surface is related to the utilization coefficient, and the size of the utilization coefficient has a great relationship with the environment of the space and the light distribution of the lamp. In the generally used space, the utilization coefficient of conventional traditional lamps is generally 0.3 to 0.5. This means that 30% to 50% of the light can fall on your working surface, and the remaining 50% to 70% of the light is inside the lamp, or blocked by the reflective lamp on the wall, so that it does not fall on your working surface and is simply wasted.

The current LED lamp does not consider the loss inside the lamp, and its luminous flux is the luminous flux of the entire lamp, so its utilization coefficient will appear to be higher than .

Therefore, the utilization coefficient of general LED lamps ranges from 0.5 to 0.8. The specific amount is affected by many factors, so it should be 0.5 or 0.8 needs to be judged by more experience.

Then there are also factors related to the utilization coefficient:

1, the light distribution of the lamp

2, the installation position of the lamp

3, the light efficiency of the lamp

4, the reflectivity of the space material

5, the space chamber shape index

Of course, the entire LED lamp generally considers the luminous flux of the entire lamp, so for LED lamps, there is no luminous efficiency of the lamp, remember this tip.

As for the maintenance coefficient that has not been mentioned, it is related to the cleanliness of the space, the clean space is higher, the dirty space must be lower, and the value is generally between 0.7 and 0.8.

Each lamp has a unique utilization coefficient table, which can find more accurate utilization coefficient values according to the maintenance coefficient of space, that is, the room shape index and the reflectivity of space materials. Different lamps have different utilization coefficient tables, so it is necessary to check the table accordingly according to the actual situation to find the required data.

Of course, this is a calculation method that requires high accuracy to use such a table lookup tool, and the general situation is based on the experience of the usual operation to make estimates.

Therefore, for this illuminance estimation method, the most critical choice is the utilization coefficient. The level of utilization factor is based on the light distribution of different lamps, but also according to your experience and the environment of the space.

Some students raised their hands, saying why is there no space height, height will also affect the illuminance in the space?

In fact, the parameters of space height directly affect the utilization coefficient, so you can set a reasonable utilization coefficient according to the specific situation according to experience. For example, the utilization coefficient is selected lower for space comparison, and the utilization coefficient is selected higher for space comparison.

So much for that, let’s give an example. For example, there is a 4X5m room with nine 3X36W traditional fluorescent lamp plates.

So how should illuminance be calculated?

Remember the formula? {Total luminous flux× utilization coefficient× maintenance factor re÷ area}

Flat object illuminance = The total luminous flux of the light source × Utilization factor × Maintenance factor ÷ area

= (2500×3×9)

One lamp has a illuminance of 2500L, a lamp plate has three tubes, and the multiplied reuse coefficient of nine lamp disks is reduced to 0.4. Then the maintenance coefficient is 0.8, divided by the area of the space, and the final result is about 1000ix. So if you use such a light plate, the illuminance in the room will eventually be about 1000x, which is a method of estimation.

Of course, the example we gave above is a positive process, knowing the type and number of lamps, so as to calculate the illuminance value in the room.

We can also perform reverse calculations, for example, your gonggong needs 300x illuminance, calculate the area value of the space to reverse the formula, and you can get the result. And if the total luminous flux is calculated, you can know what wattage of lamps you need, and how many you want. Because of different wattage lamps, its luminous flux is not the same, and the number of lamps will be different.