Most workplaces still light every hour of the day exactly the same way: one brightness, one
colour, from 9 to 6. But human beings are not designed to work under a flat, unchanging sky.
Human-centric lighting (HCL) — sometimes called circadian or tunable lighting —
adjusts light through the day to match how our bodies naturally respond. The results show up in
alertness, comfort, and how tired people feel by evening.
The Science, Simply Explained
Our internal body clock reads light. Bright, cooler light (higher colour temperature)
signals daytime and supports alertness. Warmer, dimmer light signals evening and helps us wind
down. In an office with no daylight and one fixed light setting, that signal never changes —
which can leave people feeling flat in the afternoon and wired at night.
HCL recreates the natural arc: cooler and brighter through the morning, gently warmer
towards the end of the day.
A Typical Human-Centric Lighting Day
| Time | Colour Temperature | Effect |
|---|---|---|
| Early morning | ~4000K neutral | Gentle wake-up, easing in |
| Mid-morning to noon | 5000–6000K cool | Peak alertness and focus |
| Early afternoon | ~5000K cool | Counters the post-lunch dip |
| Late afternoon | ~4000K neutral | Sustained comfort |
| Evening | 3000–3500K warm | Winding down, less strain |
It Is Not Only About Colour
Colour temperature gets the attention, but three other factors matter just as much:
- Glare control: the most common complaint in offices. Fixtures with
proper diffusers and shielding stop light shining directly into eyes and screens. - Flicker-free drivers: invisible flicker causes headaches and eye strain
over a full working day. - CRI (colour rendering): aim for CRI 80+ in offices and 90+ where colour
accuracy matters, so skin tones, print and materials look natural.
Recommended Light Levels for Workspaces
| Area | Recommended Lux |
|---|---|
| Corridors, lobbies | 100–200 lux |
| General open office | 300–500 lux |
| Detailed / drawing work | 500–750 lux |
| Meeting rooms | 300–500 lux (dimmable) |
The Business Case
Salaries are by far the largest cost in any office — far bigger than the electricity bill.
So even a modest improvement in comfort, alertness, and reduced eye strain pays back faster
than the energy saving alone. Add the energy efficiency of modern LED (endorsed by India’s Bureau of Energy Efficiency)
and you improve two lines on the P&L at once.
How to Specify HCL Without Overspending
- Start with the fundamentals: glare-free, flicker-free, CRI 80+ fixtures at the right lux
- Add dimming and zoning — huge comfort gain, modest cost
- Use tunable-white fixtures in the areas where people sit longest
- Maximise daylight and let sensors dim electric light near windows
- Give meeting rooms and focus areas their own controls
Frequently Asked Questions
What is human-centric lighting?
Lighting designed around human needs — adjusting brightness and colour temperature through
the day to support alertness, comfort and wellbeing.
What colour temperature is best for an office?
4000K neutral white suits most offices. Human-centric systems shift between roughly 3000K
and 6000K across the day.
Is human-centric lighting expensive?
Tunable systems cost more than basic fixtures, but the biggest gains — glare control,
flicker-free light, good CRI and dimming — are affordable and deliver most of the benefit.
Does lighting really affect productivity?
Poor lighting demonstrably causes eye strain, headaches and fatigue. Comfortable,
well-designed light removes those barriers and helps people work comfortably for longer.
Reway supplies glare-free, high-CRI
commercial LED lighting — including CLARITY, SHINE, SWIFT and FOCUS — for offices and
workspaces. Get an office lighting plan →