Lighting environmental zones E0 to E4 and what they allow

Lighting environmental zones under GN01 run from E0, which is a protected dark site, to E4, a city centre with high night-time activity. The zone sets the numerical limits on obtrusive light that a scheme has to meet, and it does so twice over: once before the curfew hour and again, far more tightly, after it. Picking the wrong zone is the single most consequential error in a lighting report, because every figure downstream of it changes.

Most planning disputes about lighting are therefore disputes about which zone applies, not about the design.

How the zones are defined and assigned

The Institution of Lighting Professionals guidance on obtrusive light defines the zones by the character of the surroundings rather than by administrative boundary.

• E0 covers protected dark locations, including dark sky reserves and sites specifically designated for the quality of the night sky.
• E1 covers intrinsically dark areas, which in England generally means National Parks, National Landscapes and unlit open countryside.
• E2 covers low district brightness, meaning rural areas, villages and relatively dark edges of settlements.
• E3 covers medium district brightness, which fits small town centres and most suburbs.
• E4 covers high district brightness, meaning town and city centres with substantial night-time activity.

Assignment is a judgement about the receiving environment, taken at the position of the receptor rather than at the centre of the site. A development on the edge of a market town can sit in E3 looking inwards and E2 looking outwards across fields, and the limits that matter are the ones applying to the darker side.

Pre-curfew and post-curfew limits

The curfew is the hour after which stricter limits apply, commonly taken as 2300 unless the authority sets a different time. Post-curfew limits are not a modest tightening. In the darker zones they fall to zero, which means that for practical purposes the lighting must be off, dimmed to extinction, or shielded so that nothing reaches the receptor.

These follow the published guidance tables, which carry footnotes, including a relaxation in E1 where public road lighting is already present. Check the current edition before relying on the figures, because the tables have been revised more than once.

The design consequence is a control strategy rather than a different luminaire. Part-night operation, dimming profiles, presence detection in car parks and the ability to demonstrate the post-curfew state are what deliver compliance. A scheme that meets the pre-curfew figures and has no curfew strategy has answered half the question.

Sky glow, light intrusion and luminaire intensity

The guidance controls four separate quantities, and a scheme can comply with one while breaching another.

Upward light ratio controls sky glow, measured as the proportion of a luminaire's flux emitted above the horizontal when mounted in its installed position. A flat glass luminaire aimed downwards has an upward ratio near zero. The same unit tilted five degrees to cover a corner of a yard does not.

Light intrusion is the vertical illuminance at a window of a relevant property, which is what a resident experiences as light in a bedroom. It is measured in the plane of the glazing, so a luminaire that produces a low horizontal illuminance on the ground can still breach the window figure.

Luminaire intensity controls glare as seen from the receptor, and it is the quantity most often omitted from a report. It depends on the viewing direction, so it needs calculating from the receptor positions rather than from the luminaire schedule.

Building luminance limits apply to floodlit facades and signage, and they interact with advertisement consent where an illuminated sign is involved, which we cover in illuminated signs, luminance limits and advertisement consent.

Assigning a zone where the council has not

Few authorities map environmental zones. Most leave the applicant to propose one, then disagree with it after a consultee response.

Propose it properly and the disagreement usually does not happen. Set out, in a short section of the report, the character of the surroundings, the existing lighting within a stated radius, whether the surrounding roads are lit, the presence of any dark designation, and the nearest relevant receptors with their distances. Then state the zone and say what you considered and rejected.

Where the authority or a parish body argues for a darker zone, the useful response is evidence rather than argument. A measured baseline, taken on a clear night at the receptor positions with a calibrated meter, settles the question of how dark the area actually is. And it protects the applicant, since many sites described as dark are already receiving light from a neighbouring road or yard.

One honest uncertainty. The zone boundaries are descriptive, and two competent lighting engineers can reasonably reach different answers on a transitional site. Say which way the judgement went and why, rather than presenting it as a calculation.

Dark landscapes and intrinsically dark areas

In National Parks, National Landscapes and sites with a dark sky designation, the starting point is that new lighting is unacceptable unless it is necessary, and then only in the minimum quantity.

Expect these questions. Is the lighting needed at all, or is it being provided because the design assumes it. Can the task be met by low-level, low-output fittings rather than by column-mounted luminaires. Is the correlated colour temperature low enough to reduce the blue content, which matters for sky glow and for nocturnal wildlife. Can the scheme be dark for most of the night and lit only on demand.

Bats bring a separate overlay. Guidance jointly produced by the lighting and bat conservation bodies sets out buffer distances and lux limits for commuting routes, roost access points and foraging habitat, and an ecologist's input is needed where any of those are present. A lighting scheme that satisfies GN01 and ignores a hedgerow commuting route will still attract an objection.

Designing to the limits rather than to a lux level

The commonest design error is to start from a task illuminance taken from an indoor or workplace standard and then try to shoehorn the result into the zone limits. It rarely works, because the obtrusive light limits constrain where the light goes rather than how much lands on the task.

A better sequence:

1. Define the task and its required illuminance from the appropriate standard, and question whether the standard applies. A private car park is not a road.
2. Fix the receptor positions and the zone.
3. Choose optics that put light on the task without spill, which usually means asymmetric distributions and lower mounting heights than the default.
4. Model the result and check all four obtrusive light quantities, pre-curfew and post-curfew.
5. Only then adjust the task illuminance, downwards, if the limits cannot be met.

Car parks are the hardest case, because surveillance expectations, uniformity requirements and spill limits pull against each other, and we work through that in car park lighting, uniformity, spill and surveillance.

What the lighting report should contain

A Lighting Assessment that discharges a condition first time contains the zone with its justification, a receptor plan with distances, the luminaire schedule with photometric data files referenced, mounting heights and aiming angles, isolux contours on a site plan, vertical illuminance at each receptor window pre-curfew and post-curfew, upward light ratio and luminaire intensity figures against the limits, the correlated colour temperature, the control strategy including the curfew regime, and a maintenance factor with its basis.

Add the commissioning arrangement. A scheme designed to the limits and commissioned with the tilt angles set by eye will not comply, and the authority has no way of knowing. Offering a post-installation verification, with measurements at the receptor positions, is the thing that most improves an officer's confidence.

Artificial light can also amount to a statutory nuisance under the Environmental Protection Act 1990, separately from planning, so a compliant scheme that still disturbs a neighbour is not the end of the matter.

Enter your postcode on PlanScope to see which environmental reports your scheme is likely to need.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.