A deep floorplate is why your flat has one window

There is a short answer about floorplate depth and a useful one, and they are not the same. What follows is the useful one.

Daylight has a working range

Useful daylight from a vertical window reaches only a limited depth into a room before artificial light is needed during the day. The rule of thumb used in many design guides ties usable depth to window head height, which is why high ceilings and tall windows push light further back. A deep room with a standard window has a bright zone near the glass and a permanently dim zone behind it.

No amount of white paint changes the physics; it changes the reflectance, which helps at the margin.

Deep buildings force single aspect

A block that is deep in plan and served by a central corridor gives most flats windows on one side only. Single-aspect flats cannot cross-ventilate, so they rely on mechanical ventilation or on opening windows onto whichever side they have. North-facing single-aspect flats in temperate climates get little direct sun; south or west-facing ones overheat.

Several housing design standards discourage or restrict single-aspect flats for these reasons, with the details varying by jurisdiction.

Depth is chosen for site efficiency

A deeper building puts more sellable floor area on a given plot and shares the cost of cores, corridors and external walls across more homes. Facade is expensive per square metre, so reducing external wall area per unit is a direct margin improvement.

This is a real economic pressure, not laziness, and it explains why deep plans recur across very different markets. The cost lands on residents as reduced daylight and ventilation, which is not priced in the transaction.

Corridor arrangement follows from depth

A double-loaded corridor with flats on both sides is the most efficient arrangement and the one that guarantees single aspect. Single-loaded access with a deck or gallery on one side allows dual aspect and costs more circulation area per home. Point blocks with a central core and flats wrapped around it give corner units dual aspect and leave the units between them compromised.

The access strategy chosen at concept stage effectively decides the daylight quality of every home in the building.

Dual aspect does several jobs at once

Openings on two orientations allow cross-ventilation, which is the main passive tool against summer overheating. They give a choice of outlook, so a resident can sleep on the quiet side of a noisy street. They also spread daylight more evenly, reducing the contrast between a glaring window wall and a dark interior.

It is one design decision that improves thermal, acoustic and visual comfort together, which is unusual.

The data here is patchy — most cities do not publish it consistently.

Retrofit cannot easily fix it

Depth is structural, so a deep plan stays deep for the life of the frame. Light wells and atria can be cut into large plans and are expensive and lose floor area permanently.

This is why the depth decision, made in a week of early massing work, outlives every other choice in the project. When assessing a plan, measure from the window to the back wall before looking at anything else.

The takeaway

Look at the plan depth before the finishes. It decides how the home will feel in fifty years.

Measure the walk, not the map.