Most homeowners in tropical countries know there are two types of lightbulbs that they can buy when they need to replace blown bulbs (called globes or lamps in some countries). That’s the daylight bulbs and warm white bulbs. In temperate climates, most people go for the warm white option because they make the house feel warmer in the colder months, but in the tropics, we usually want to feel cooler.
So, what’s the difference between daylight and warm white bulbs? And is one better than the other in tropical house designs, especially ones which are usually more open to the outdoors than the houses in temperate climates? Can we use different bulbs in different rooms of the home? And how can we use lighting to create different moods in the home? Let’s start by addressing each of these questions.
Firstly, the differences between daylight and warm white bulbs. To understand this, we need to understand a few concepts first.
The terms “daylight” and “warm” refer to the colour temperature scale of the light that is emitted. This temperature is measured in Kelvin (K) and it ranges from 1000K to 10000K. For residential and commercial purposes, most lights fall within that part of the scale from 2000K to 6500K.
On this scale, the light produced in the 2000K to 3000K range, is classified as “warm”. This is due to its orange to yellowish appearance. This warm light gives off a cozy and welcoming feeling to the people in the room. It also entails a sense of warmth.
When we look at the higher end of this scale, the light produced in the 4500K to 6500K range, is classified as “daylight”. This temperature will give off a blueish white shade which is where it derives its name from. This daylight bulb sets up an ambiance of coldness and spreads energy throughout the room.
Now when it comes to tropical house design, where the environment is often warmer than many people are comfortable with, the ambiance of the lighting is very important. The use of a cooler tone of light is preferable in such situations, and it also helps bring out a contrast between the indoors and the outdoors.
Daylight bulbs also, as the name suggests, share the blue tone of a daytime sky. So, after sunset, as a cool breeze chimes in through the open porch doors, it makes us think it’s not as hot as it actually is.
This is in contrast with houses in temperate climates. The same daylight bulbs would have a different effect on the room. These houses need warmth, as the environment around them is cold for much of the time.
The colour temperature of the lights in your room should always correlate to the task you intend to do in that room. A daylight bulb will help you to feel cooler, so is a good choice for the living room, and some people like them in the bedroom too.
But if you have a study and like to catch up on some reading at night, then you should go for a warmer bulb for the reading lamp. It’ll put less strain on your eye. Also, children’s rooms should always have warm bulbs. It’ll help them sleep better and also make it easier for them to read while doing their homework.
However, to a large extent the choice of warm or daylight bulbs comes down to personal preferences and what you are comfortable with. Even though the use of a warmer light is preferred by many people for their living spaces, it is not ideal for all situations.
If you like being productive, and are working from home during the day, or are just setting up a corner of a room as an office for work, it is better to set up the area with daylight bulbs. It will help you to stay more alert. In some countries these are available in different colour temperatures and may be called white light (3000K-4000K) or cool-white light (4500K to 6500K).
Using white light in the living room is also a good idea if you collect art as it will help in accurately showcasing all your collection or picture wall. Daylight lighting is very functional and helps to create a more sober and open atmosphere, which is more suitable for houses with open architecture.
Even if you are one of those people who prefer warm lighting through most of the house, it’s advisable to have daylight lighting in the kitchen. This provides more accurate colour rendition. You would want to know if the sauce has turned red or if it is still orange. For kitchens, a lighting temperature of 3000K to 4000K provides the most accurate colours.
Even though daylight bulbs have many advantages in a tropical climate, you should be lenient towards the extensive use of daylight bulbs because they do suffer from several disadvantages.
Cool-white bulbs and LEDs, and especially those tending towards the blue end of the colour spectrum aren’t calibrated that well. There is a possibility of these lights might exceed the safety limits of something called blue-light hazard.
(The Blue-light Standard is defined in the eye specifications such as ANSI/IESNA RP-27.1-05: Recommended Practice for Photobiological Safety for Lamp and Lamp Systems).
Blue light pollution is an issue caused by cool-white lights. They emit more blue light than other conventional outdoor light sources. And due to the strong wavelength dependence of Rayleigh scattering means that cooler light sources produce more pollution than other sources. This is why the International Dark-Sky Association discourages the use of white light sources with correlated colour temperatures above 3000K.
The colour accuracy pertained by your eyes is heavily influenced when under cool-white light. The spectra differ significantly from when under the sun or incandescent light. And due to metamerism, red surfaces are rendered poorly under the cool-white light.
Thanks to new technology, it has never been easier to set up the lighting in your house to personal preferences. Every room in your house is different, has a different light spread, number of windows for natural sunlight, even the placement of the furniture affects the amount of light in the room.
There are different junctions and devices used for granular control of the lights, and a general classification of them include:
Colour temperature tunable lights
These give the user the free rein to shift the temperature from warm whites to white light and cool-white. This can help you maintain your body’s biological clock. You can use these to adjust the colour temperature in every corner of your house, changing them according to your needs or automate them to shift with the time of day.
Automatic dimming lights
These lights are useful in corridors and on stairs, or other areas where the temperature doesn’t matter but adequate lighting is required for practical use. The strength of the light will change with time, getting more brighter the darker it gets outside, maintaining a balance of consistent lighting.
Full colour tunable
These act the same as normal tunable lights, but along with the capability to change the temperature, you’ll also be able to change them along part of the RGB spectrum. These lights are referred to as RGBA, RGBW, spectrally tunable, or colour-changing, and are used to produce a variety of colours in the room.
This means that instead of just shifting the light’s warmness, changes to its RGB values will produce distinct colours with specific saturation according to the user. They can mimic most lighting environments and are also very soothing to the eyes.
RGB LEDs can be used in various scenarios too. You can mimic the lighting of a restaurant in the dining room, the warm glow of a sunset, or you can even get a little creative using different colours to emphasise different moods, like turning the LEDs red on date night.
The form of lighting you choose for your home has a big effect on your living states in the household. The advantage of living in a tropical region is that you have lots of legroom to experiment with different lighting and ambiances.
Header image: Inno Kurnia