LED Lighting Knowledge

UV Fluence (Dose) recommended for 90% or 99% disinfection from Viruses, Bacteria, Protozoa and Algae

 When designing, building or installing a UV light, two key questions must be answered first:

"How irradiance does it need to have?"

"What is the required exposure time?"

While there are many studies that show the effectiveness of UV light in disinfection or sterilization, a high variance of the results exists, which presents a challenge to find an answer to these questions. 

We will present our recommendations by analyzing the results of 413 reasearch papers, as found in the compilation "Fluence (UV Dose) Required for up to 99% disinfection from Viruses, Bacteria, Protozoa and Algae"  that can be downloaded at the links below:

PDF: Fluence (UV Dose) Required to Achieve Incremental Log Inactivation of Bacteria, Protozoa, Viruses and Algae

The research studies present the fluence required to achieve a log reduction from 1 to 5, for different types of UV sources.

The effectiveness of sterilization or disinfection with UV light depends on the exposuretimewavelength and irradiance.

  • Exposure or fluence (sometimes called dose) is measured in mJ/cm2 (where 1 mJ/cm2 = 10 J/m2)
  • Exposure time is measured in seconds (s), minutes (m) or hours (h)
  • Irradiance is the flux of radiant energy per unit area, in other words how much of the UV radiation power (measured in W = 1000 “miliwatts” mW = 1.000.000,00 “microwatts” μW ) reaches the surface. Irradiance is measured in mW/cmor W/m2 (1 mW/cm2 = 10 W/m2) and is dependent on the radiant power, distance and dispersion of the radiation emitted by the lamp source.

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Disinfection with UV Light can deliver 99% Kill Rate for Bacteria and Viruses (incl COVID-19)

UV light breaks the DNA of viruses and bacteria

Effective and cost efficient disinfection or sterilizing of surfaces, water and objects can have a significant, positive effect on the general health of our society. The impact of pandemics, present such of the COVID-19 (coronavirus), and future can be greatly reduced, as well as a major decrease of illnesses in general, including from drug resistant pathogens or hospital-acquired infections (HAI).

Disinfection or sterilization with ultraviolet (UV) light can be the way to achieve such goals. However, challenges of using UV light still exist and the ways to overcome them are presented in this article.

"UV light annihilates viruses and bacteria by destroying their ability to reproduce. "

Using ultraviolet (UV) light to disinfect or sterilize1 has actually been embraced by some hospitals since years, by using large, industrial-grade machines to kill microorganisms (including COVID-19) in hospital rooms or on furniture, objects, clothing or instruments. However, such machines are the perfect showcase of the challenges of using UV light. They are prohibitively expensive for private or business use, as a mobile platform with UV lamps can cost more than 60.000 USD2. Their deep UV radiation is also dangerous for people and must be used only in empty rooms.

UV robot for hospital use

With the current advances in UV LED lighting technology both problems can be overcome.

Smaller versions of UV disinfection lamps can be built at affordable cost, so they are accessible to consumers and companies looking to clean pretty much everything, from office spaces, elevators and living rooms, to phones, computers and even toilet seats.

Different UV wavelengths with precise control of intensity and radiation pattern can make disinfection safe to be used when people are present.

The most promising practical application of the above is the continuous disinfection with low intensity UVA LEDs .

"Continuous disinfection: UVA radiation functioning for 8 hours, daily. Safe for people*. Will kill up to 99% of viruses and bacteria**. "

*Irradiance limited to 10W/m2 at 2m from the floor.

**According to two independent studies quoted in this article.

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Recommended color rendering index CRI base on your project

The CRI, colour rendering index, is a one-number quantification that indicates the performance of an artificial light source in terms of colour rendering compared to a reference standard light source modelled on daylight. The highest number is 100, for daylight and incandescent/halogen lamps, while gas discharge lamps range from 17 to 96, with even a negative value for low sodium pressure (the yellow type used in street lamps).

Due to this variation in the ability to reproduce colour with the white light emitted by the many types of gas lamps on the market, CRI index was introduced in 1974 by the International Commission on Illumination (CIE). 

Today, with more than 40 years of use, the CRI index is firmly rooted in the lighting industry and among professionals. However, it has not been very well understood by the public. The reason was that such knowledge was not really useful as most lamps were built for specific applications that required a minimum CRI value, so one could not go wrong when choosing a lamp.

For example, for office or other linear lighting, the lamps of choice where Tri-Phospor linear fluorescent tubes on the market since the 1970s, all with a CRI value above 80. For domestic lighting, there was a mix between incandescent and halogen lamps, both with CRI100, for retail and other high intensity spot lighting, metal halide lamps with CRI min 85. Street lighting was reserved for high intensity and very efficient sodium vapour lamps, which had a poor CRI but this was considered not important.

From the year 2000 this changed with LED technology, the first light source that can be used for any application while having a broad performance and quality level, including the ability to reproduce colours accurately. It is therefore essential that you choose LEDs with the right CRI level for your application.

CRI comparison

The picture above shows how colors can look different based on the CRI of the light source that illuminates them. A vibrant red under sunlight or a high CRI light can look dull or even orange under a low CRI light.

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Tips on how to build the best lines of light or linear light fixtures with LED strips

Lines of light are a new trend in lighting design and are usually made with an LED strip inside an aluminum profile that has a translucent white cover. The attraction of using such a linear light fixture is that it can be personalized. You can choose as you desire the pattern, place of installation, length (up to many meters), geometric shape or a combination of these elements.  

Line of Light with LED strip inside a profileBecause of their way of construction lines of light are a type of direct lighting. Compared with coves that are indirect lighting, lines of light are more energy efficient but can have greatly increased glare. For this reason lines of light should be designed with care and almost always be dimmable. 

Let's see how we can achieve the best results with lines of light.

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Tips on how to have the best illuminated stretch ceiling with LED modules

The illuminated ceiling or stretch ceiling is very interesting trend in interior lighting. By using a translucent material many square meters in size with a backlighting system, a diffuse, even and relaxing illumination of interiors can be created. The main advantage of this type of lighting is the absence of glare, as the light sources are distributed over a large area and hidden behind the material.

The backlight source is usually low or medium brightness LEDs (5 to 50 lumens) mounted on strips or modules. Since the illuminated surface has a large area, such low power illumination is the best choice.

Illuminated stretch ceiling with LEDs, inside an office

Illuminated stretch ceilings can have personalized shapes and even feature translucent images. They can therefore influence the overall design of a room much more than other lighting fixtures. From a lighting design perspective, uniform light should be supplemented by spotlights or lamps that can draw attention to specific areas or objects.

The proper design and installation of a luminous ceiling has a number of unique challenges that we will address in this article.

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Cove lighting with LED strips: HOW TO

A Cove light is a line of light can obtained via a LED strip hidden from view inside a cove in the wall or ceiling that illuminates an adjacent surface. Light is reflected from this surface into the space that has to be illuminated. That is why lines of light are commonly known as cove or indirect lighting.

Cove lighting is beneficial trend to design lighting, with focus on human nature and how natural light behaves. It is today widely adopted, with lines of light as a principal way to illuminate interiors.

The allure is the similarity with natural light. With the proper light source used, we could imagine that the cove is actually a hidden window to the outside from where sunlight flows in.

Lets explore how we can have the best results with cove lighting

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What does IP wateproof rating means and what value are recommended IP levels for the bathroom

WHAT DOES IP PROTECTION MEAN?

The IP protection index is an essential feature of most electrical equipments and indicates the degree of protection of the device against external factors such as solid objects or liquids. This protection is expressed by the word "IP", followed by 2 numbers that indicate

  • The first digit describes the degree of protection against solid objects, dust, solid particles and bodies
  • The second digit describes the degree of protection against liquids

The IP rating is relevant when the environmental conditions are standard; in special cases and hazardous environments, special protection is required.


Although there are numerous combinations of IP ratings for LED strips, the most common are IP67, IP65, IP44, IP20. In general, all LED strips have IP20 protection,  IP44 can be found for LED strips within an aluminium profile with closed end caps and IP65 or more is normally used for waterproof LED strips.

The first digit – protection from foreign bodies

  • 0 – no protection from foreign bodies;
  • 1 – protected against solid objects greater than 50mm(e.g. accidental touch by hands);
  • 2 – protected against solid objects up to 12mm(e.g. fingers);
  • 3 – protected against solid objects greater than 2.5mm(e.g. tools and wires);
  • 4 – protected against solid objects greater than 1mm(e.g. small tools and wires);
  • 5 – protected against dust, limited ingress(e.g. no harmful deposit);
  • 6 – totally protected against dust.

The second digit – protection from liquids

  • 0 – no protection from liquids;
  • 1 – protection against vertically falling drops of water(e.g. condensation);
  • 2 – protection against direct sprays of water up to 15 degrees from vertical;
  • 3 – protection against direct sprays of water up to 60 degrees from vertical;
  • 4 – protection against water sprayed from all directions – limited ingress permitted;
  • 5 – protected against low pressure jets of water from all directions – limited ingress permitted;
  • 6 – protected against high pressure jets of water (use on ship deck) – limited ingress permitted;
  • 7 – protected against the effects of immersion between 15cm and 1m;
  • 8 – protected against long periods of immersion under pressure.

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Home lighting guide with LED strips and luminaires

Home lighting with LEDRISE Lumistrips in covelights

Good design of your home lighting will ensure that the right amount of light can be switched on conveniently and will light where and when it is needed. A proper home lighting should avoid over-lit areas and give control and flexibility to create lighting effects for different situations. Well-designed lighting will be inherently easier to use and more likely be energy-efficient.

The recommended approach to home lighting is to use three lighting levels or layers: general lighting, task lighting and accent lighting. By combining these three levels, the recommended lighting level for each room or activity can be obtained, as below: 

Recommended lighting levels for the Home  in Lux
Living rooms general 50-150
Casual reading 150
Study 150-750
Bedroom general 50-150
Kitchen general 150
Kitchen working areas 400
Bathrooms 150-300
Halls and landings 100-150
Stairs 100-150
Dining rooms 150-450


The three levels of lighting

General lighting should ensure a sufficient minimum level of light in the room. There are many LED light sources that can be used for this purpose: LED modules, strips, luminaries or spotlights. Decide on the desired illuminance level (lux). In living rooms and bedrooms give a certain degree of flexibility (through control settings/dimmers) so...

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LED Lifetime, Lumen Maintenance: Explained

LED is the only light source that looses a significant amount of its initial brightness overtime, before it fails completely. This particularity can lead to a confusion in what LED lifetime means. 

For all reputable lighting manufacturers and sellers, LED lifetime is equal with L70 lifetime which is the time it takes the LED to reach 70% of the initial brightness. At this point the LED is considered end-of-life and has to be replaced.

1.How to measure LED lifetime?

With LEDs such as the Nichia 757 series having more than 60.000 hours L70 lifetime it begs the question of who tests an LED for such a long time? One year has 8760 hours, so a 60.000 hours test will last more than 6 years!

To solve this problem the industry has created the IES LM80-80-2008 measuring standard and the IES TM21-2011 Projecting Long Term Lumen Maintenance of LED Light Sources.

2.IES LM80

IES LM80 or “Measuring Lumen Maintenance of LED Light Sources” is the industry standard method for testing LEDs to determine lumen depreciation over time. It is carried out over a 6000 to 10,000 hour period, with luminous flux measured at 1000 hour intervals of multiple LEDs of the same type, running at different currents and operating temperatures. 

The LM80 test is a Department of Energy (DOE) approved method for measuring lumen depreciation of solid state (LED) light sources, arrays, and modules. The Illumination Engineering Society (IES) and DOE Solid State Lighting Standards Development group worked together to create the LM80 test criteria.


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Human Centric Lighting: Explained

Human Centric Lighting is lighting specifically designed to produce a beneficial physiological and/or psychological effect upon humans. It consists of adapting the light colour and intensity during the course of the day via tunable white LED lighting solutions.

Human Centric Lighting (HCL) supports human health, well-being and performance by considering and then properly planning the implementation of a light system according to the desired visual, emotional and especially biological effects of light. The main focus of Human Centric Lighting is on people's needs for their living, leisure and working environment. The study is based on the characteristics and effects of natural light, a dynamic source with changing tone and brightness, as a day goes by and seasons change. 


To implement an adequate Human Centric Lighting a combination of white LED light sources is used, usually warm white (2700K) and cold white (6500K). This solution is also called Tunable White lighting. By adjusting the intensity of each, bright or dim white light with a hue between 2700K and 6500K can be obtained. It is a new way to use and implement artificial light, in accordance with changes in natural light and research about effects on people.

More light, more productivity

Increased lighting intensity will empower people to work in a more concentrated way, tire less quickly, make fewer errors, and detect errors more precisely. And what makes life more pleasant for the individual, is more lucrative overall for the company.

More concentration and creativity

Human Centric Lighting coordinates the interplay of light, atmosphere and space to match the well-being of people in their environment. It is particularly important for modern office environments because it focuses on people.

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