It is the middle of the day and you have switched on all the lights. The kitchen is dark despite the north-facing window. The living room has one window in the west-facing gable end, and the light does not reach the dining table. Lack of daylight is one of the most common problems in Danish homes — and one of those that affects wellbeing and health most.
Here is what you can do, from the inexpensive to the comprehensive.
Why daylight matters so much
Daylight is not just lighting. It is biology:
- Circadian rhythm. Morning daylight synchronises the body’s internal clock and improves sleep quality at night.
- Mood. Lack of daylight is a documented cause of winter depression (SAD). 200,000 Danes suffer from SAD, according to The Danish Health Authority.
- Concentration. Studies show 15–20% better performance in daylit rooms — relevant for working from home and children’s homework.
- Energy. More daylight = less artificial lighting = lower electricity bills.
BR18 requires a minimum glazed area of 10% relative to floor area in residential rooms. But 10% is a minimum — many homes would benefit from double that.
What you can do — from cheap to major
Step 1: Light surfaces (2,000–10,000 DKK)
White or light walls and ceilings reflect 80–90% of light. Dark surfaces absorb it. In a dark room, white paint alone can double the perceived brightness. Light floors and furniture also contribute.
Step 2: Remove obstructions (0–5,000 DKK)
- Thin curtains instead of heavy, dark ones.
- Mirrors opposite the window reflect and distribute light.
- Move furniture away from windows — a sofa in front of a window blocks incoming light.
- Prune trees and shrubs in front of windows.
Step 3: New or larger windows (15,000–50,000 DKK per window)
New windows with slimmer frames provide 10–15% more glass in the same wall opening. Enlarging an existing window requires structural calculations and a building permit, but has a dramatic effect in dark rooms.
A facade window enlarged from 1.2 × 1.2 m to 1.5 × 1.5 m: 56% more glazed area. The effect is transformative.
Step 4: Skylights (8,000–25,000 DKK each)
A skylight provides up to twice as much daylight as a facade window of the same size — because the light falls directly downward. Ideal for:
- Kitchens with sloping ceilings
- Stairwells
- Bathrooms without windows (via a light tube)
- Rooms beneath the roof structure
Light tubes (solar tubes) channel daylight down through the ceiling via a reflective duct. Cost: 5,000–15,000 DKK. Provides light but not a view.
Step 5: New floor plan (30,000–150,000 DKK)
Removing walls between rooms allows daylight to travel:
- Opening between kitchen and living room: A north-facing kitchen gets light from the south-facing window in the living room.
- Glass doors instead of solid ones: Light passes through, but sound insulation is maintained.
- Internal glass wall: Defines rooms without blocking light. Particularly effective towards hallways and corridors.
Step 6: Extension focused on light (200,000–600,000 DKK)
An extension can be designed with maximum light intake — large glazed sections, skylights and correct orientation. A glazed roof over a dark courtyard (atrium solution) brings light into the centre of the house.
Which homes are most at risk?
Single-aspect flats. Windows in only one direction — typically north. No possibility of cross-lighting.
Houses from 1940–60. Small, deep windows with wide reveals and heavy lintels. The glazed area is insufficient.
Terraced houses. Narrow and deep floor plans where daylight only reaches the front and rear rooms.
Basement dwellings. Minimal daylight — often below legal requirements. Not permitted as primary accommodation without sufficient daylight.
Ground floor flats. Shadow from buildings, trees and fencing significantly reduces daylight compared to upper floors.
Daylight and energy
More glass means more heat loss — but with modern energy glazing (windows rated class A), south-facing windows can actually contribute more energy through solar gain than they lose. North-facing windows always lose more than they contribute — but the human benefit of daylight outweighs the additional heating cost.
Solar shading (external screens, awnings, or glass with solar film) prevents overheating in summer without reducing daylight in winter.
Daylight and mental health
The research is unequivocal: daylight significantly affects our mental health. Studies from The Danish Building Research Institute (BUILD) show:
- Residents in homes with good daylight access report 30% fewer depressive symptoms in winter
- Children in daylit rooms show better concentration and fewer behavioural problems
- Older people with good daylight access have fewer falls and better sleep patterns
In a Danish context with 7 hours of daylight at the height of December, the home’s ability to make use of available light is crucial. A well-positioned window facing south-east provides morning sun and helps the body start the day — it cannot be replaced by artificial light.
Daylight during renovation — checklist
Every renovation is an opportunity for more daylight. Ask yourself these questions:
- Can a window be made larger if it is being replaced anyway?
- Can a wall be removed to allow light to travel between rooms?
- Is there room for a skylight when the roof is already open?
- Can solid doors be replaced with glass doors?
- Are eaves or canopies too deep and blocking light?
Daylight optimisation costs almost nothing extra when built into a renovation already underway. But it requires someone to think about it — and that rarely happens if planning is left entirely to the builders.
How to move forward
Start with the inexpensive measures — light walls, thin curtains, move furniture away from windows. Consider new windows or skylights at the next renovation. And think daylight into every building project — it is the single factor that makes the greatest difference to how your home feels to live in.
Daylight is closely linked to air and ventilation — both affect how the home is experienced. And if you generally lack space, a revised floor plan can both bring in more light and create a better distribution of rooms.
Sources: BUILD/SBi — daylight, Danish Health Authority, BR18