Daylight, Sunlight and Amenity – Page 2

Adequate natural light as a Class MA prior approval matter

Adequate natural light carries a duty to refuse, not a discretion to weigh, and it is assessed on your drawings. Here is what to submit and how deep floorplates are made to work.

Overshadowing of a public park by a tall building

The sun on ground test gives one number for an amenity space. A park is many spaces. Here is how to zone it, baseline it and report it so the result survives committee.

Obscure glazing conditions and their daylight effect

Obscuring glass leaves the geometric daylight metrics untouched and alters everything calculated from transmittance. What changes, what does not, and the alternatives.

Amenity harm and the presumption in favour of development

A failed Vertical Sky Component test is an input, not a reason for refusal. How to turn daylight findings into weight an inspector can use in the planning balance.

Measuring existing windows for a daylight survey

External geometry can be measured from the street. Room depth and room use cannot, and that is where most daylight assessments are challenged at committee and on appeal.

Sunlight to balconies and private terraces

There is no published sunlight criterion for balconies. Assessors adapt the ground level two hour test, and the bigger issue is usually the daylight an inset balcony takes from the room behind.

Light wells and daylight to lower ground floor flats

A lower ground room sees only a slice of sky, so daylight has to be engineered rather than assumed. These are the geometric moves that work, and the ones councils refuse.

Setting a daylight baseline where a neighbour holds consent

Where the neighbouring site holds a permission nobody has built, the existing condition may flatter your scheme or punish it. This sets out when a consented baseline is realistic and how to present both without inviting a double counting objection.

Outlook and enclosure: the 45 and 25 degree tests

The 45 degree test is a local design guide proxy for outlook. The 25 degree line is a BRE daylight screening check. They are not the same thing.

Transient overshadowing plots and how officers use them

Transient shadow diagrams show extent at an instant, not duration. Here is how to produce them properly and keep them separate from the BRE sun on ground test.

Right to light against planning daylight: two tests

A right to light is an easement enforceable in the courts and measured by sky factor. Planning daylight is a material consideration assessed against BRE 209. Planning permission is no defence to an injunction.

Assessing daylight to a window serving two rooms

Where one window serves a combined kitchen, dining and living space, the assessment treats it as a single room and applies the most demanding illuminance target of the three uses.

Mirror massing and the notional compliant envelope

Where absolute daylight values are unachievable, a comparison against a notional envelope can explain the result. It is also the most abused technique in daylight evidence.

The no sky line test and how room depth drives it

Daylight distribution is a plan test, not a window test. Draw the line at 0.85 metres above floor level, compare the retained lit area against 0.8 of the former value, and room depth does the rest.

Daylight, Sunlight and Amenity6 min read

Daylight to a school, nursery or hospital next door

The daylight tests apply where the affected neighbour is a school, nursery or health facility, with different rooms in scope and the sun-on-ground test extended to play space. Here is how to scope and report it.

Mirror image and policy compliant schemes as a comparator

Where BRE 209 results fail for contextual reasons, a mirror image massing or a policy compliant alternative supplies the missing baseline. Here is how to build one that an inspector will accept.

Daylight, Sunlight and Amenity6 min read

Daylight obstruction from boundary walls and fences

Most boundary fences pass the 25 degree test without an assessment. Low windows, patio doors, basements and gardens are where walls and fences cause genuine loss.

Rooflights and daylight to a converted roof space

Rooflights deliver more daylight per square metre than vertical glazing because they see an unobstructed sky. How to size and position them, and where a dormer wins instead.

Briefing a daylight consultant: the inputs to supply

A defensible daylight assessment needs a correctly oriented model, survey levels to ordnance datum and an agreed list of affected properties. What to put in the brief.

Light wells and basement flats: achieving usable daylight

A light well needs a clear width at least equal to its depth before a basement room behaves like an ordinary one. Geometry, drainage, flood risk and the assessment method.

Daylight, Sunlight and Amenity6 min read

Daylight baseline choice when the site is already cleared

Open sky as a baseline makes almost any building look harmful. The demolished building makes it look benign. Report the primary baseline and label every alternative.

Daylight to inset balconies and the overhang problem

Balconies are the daylight input most often left out of the model. Why the slab above a window matters more than a building across the street, and what recovers the light.

Sunlight to gardens and the two hour criterion

The sun on ground test is a ground-level area calculation at the spring equinox, separate from window sunlight tests. What it covers, how trees are treated, and what to do when a courtyard cannot comply.

Climate based daylight modelling against the BRE method

BRE 209 neighbour tests and BS EN 17037 illuminance modelling answer different questions. Which method to use where, the inputs a model needs, and how the results diverge by orientation and plan depth.