The Draft London Plan consultation ends on 15 October 2026 at 5:00 PM .
This is the first of two posts showing my working out whilst considering a response to the Draft Plan through the lenses of my two favourite soapboxes: natural light and green infrastructure around buildings.
This one is a summary of the Draft Plan’s implications for daylight.
City Hall is faced with the tricky task of setting spatial design metrics which increase the likelihood of realising the target of 558,000 new, energy-efficient, climate-resilient, healthy homes in London over the next decade. The Draft Plan’s joined-up thinking on daylight and passive design, especially overheating, is very welcome. However, as the Plan moves us towards greater urban density in the capital, how can we avoid daylight becoming a luxury quantity at a time when evidence for its crucial role in health is mounting?
Broadly, I wish the Plan’s step towards systems thinking was a bigger one. When a design features a single-aspect facade, deep room layouts, and a 2.4m ceiling, the rear halves of those homes become heavily reliant on artificial lighting, contradicting the Plan’s carbon efficiency objectives. It could also exacerbate the contrast between premium dual-aspect homes and affordable single-aspect layouts.
London is not homogeneous but as it stands, the Plan’s approach to daylight asks us to accept that people living in dense areas do not expect suburban daylight levels, but those living in the suburbs should expect the natural levels of zone 1. Living in the city does not have to mean dark rooms. The plan could do more to incentivise innovation, terraced or stepped forms, courtyards, lightwells, cunning floor plans and clever use of materials.
Tokyo uses Sky View Factor Zoning which is more flexible than static distance rules. Developers must prove through 3D modeling that a specific percentage of the open sky hemisphere remains visible from a series of public checkpoints on the ground. which measures the proportion of the visible sky from a specific ground point. It is one of the most critical variables governing the Urban Heat Island (UHI) effect: a low sky view cools cities during the day but aggressively traps heat at night If you’re running a city, it’s metric you might want to keep an eye on and have control over to mitigate the effect of heatwaves. It might guide placement and selection of trees for urban cooling, for example.
Model Environments will be contributing to the consultation, commenting on the policies below.Contributions can be made here https://consult.london.gov.uk/londonplan
Here are 5 key policy crunch points, their implications and our recommendations
| Implications | Recommendations | |
| #1 Single-Aspect Dwellings and Floor to Ceiling Heights: schemes are expected to maximize dual-aspect dwellings. However, single-aspect units (even north-facing ones) are permitted if the designer can robustly prove adequate daylight, privacy, ventilation, and protection from overheating (Policy HN8). The same policy reduces the minimum dwelling floor to ceiling height by 10cm to 2.4m | Adequate daylight can be expected in a single-aspect room at a distance of roughly double the floor to ceiling height from the window. Combining this with the proposed new minimum proposed floor to ceiling height, 2.4m, results in a maximum floorplan depth of around 4.8 metres for receipt of good daylight for an unobstructed window with the window head as high as possible in the wall. For obstructed windows, as is common on lower floors in London, or those with a fixed overhang or balcony above them, the limiting room depth will be lower. | Where single-aspect rooms are unavoidable, the Plan should provide them with protections:- increase the minimum floor to ceiling height to help with daylight and overheating, and to reduce the chances of occupants facing increased bills for electric lighting and cooling to compensate for poor design. – specify that the first choice for such rooms should be the east facade (south and west are most affected by solar gain, north facades experience a lack of sunlight)- make moveable external shading unavoidable (as unavoidable as single aspect dwellings;)- require design consideration of the external area immediately outside single-aspect rooms on lower floors to demonstrate potential from re-radiated heat has been minimised and potential for microclimate cooling e.g. from vegetation has been maximised . |
| #2 Kitchen Clash: The plan appears to say that all residential habitable rooms should receive natural light and have openable windows, with the exemption of the kitchen and/or dining room where they form part of an open-plan room that receives natural light. Worth considering the contrast here between the intent of the BRE Guidelines – the kitchen has the highest requirement for daylight to avoid accidents.The BRE Guidelines say that if a room has more than one use, the higher requirement should be the benchmark. The Draft Plan contradicts this. | There is a possibility that this erodes the BRE 2% kitchen target in multi-use spaces. In some parts of a city like London, many buildings are overshadowed by their neighbours, which reduces daylight levels, especially those spaces furthest from the window. Without protections, we could see kitchens and dining areas pushed into the darkest areas. This would carry with it an increase in electric lighting use and, potentially reduce daylight exposure of occupants below those experienced under current guidelines. . | If I have understood this policy correctly, it is hard to see how it will lead to good (daylight) design. Especially, in a dwelling with the minimum floor to ceiling height. If it does find its way into the adopted Plan, protections should be put in place to prevent rooms being designed which capitalise on all the new rule relaxations at once i.e. the Plan should not allow this to be used in conjunction with the minimum floor to ceiling height and/or single aspect permissability |
| #3 Daylight needs balanced with solar gain (at last!) To build a “Heat Ready London,” the plan introduces a strict passive design hierarchy. Designers must optimize window sizes and shading devices to ensure that maximizing natural daylight inside rooms does not accidentally cause excessive solar heat gain, which triggers dangerous summer overheating | It is good to see some joined-up thinking on the issues of daylight, energy and overheating, at last. Balancing window sizes for useful heat gain, overheating and year-round health requires attention to glazing type, orientation and shading. This policy might result in use of glazing which reduces daylight’s beneficial wavelengths on every orientation. Moveable external shading allows glazing sizes to be ample and not necessarily the cause of excessive heat gain or heat loss. | Concerns about overheating are valid. Can they be balanced with concerns over long term health impacts from poor interior daylight to ensure the homes, as the Draft Plan states “meet the needs of residents now and in the future”? The plan could specify a hierarchy of glazing types. A radical approach would be to require non-low-E or low g glazing in at least one room per dwelling. Dynamic thermal overheating modelling is required here, and joyously, the plan welcomes incorporating GI. There is currently no standardised way to do this. |
| #4 The BRE guidelines can be broken. The plan introduces an Optimisation Framework that sets height ranges and minimum densities in certain areas, like transport hubs. These prescriptions provide an opening for the daylight recommendations in the BRE Guide to be broken. If we are to see an end to those protections, it is worth taking a look at why they were put in place. | British courts in the early 1900s attempted to define how much light a human needed to live and work. The 25-degree rule for opposite obstructions was considered a safe neighbourly baseline where people would not suffer a nuisance. It derives from the UK’s latitude and climate, and roughly equates to the window catching about a quarter of the total diffuse light available from a completely unobstructed sky hemisphere. The rule was originally a public health intervention to ensure that natural light could penetrate down to street-level to keep occupants healthy, combating diseases like rickets, caused by vitamin D deficiency, and tuberculosis which thrives in dark, damp environments. We now know that natural light impacts on many other areas of health and wellbeing. | Use Sky View Factor Zoning instead. Promote terraced buildings and courtyards. Offer other protections to those living in development areas where the BRE rules will be watered down, to ensure existing residents’ access to natural light. E.g. roof gardens |
| #5 The Promise of Pocket ParksPocket parks are intentionally introduced into as a tool to to hit Urban Greening Factor (UGF) scores and mitigate the urban heat island effect via natural evapotranspiration and shade from tree canopies If they are surrounded by tall structures, will planting in these green spaces receive sufficient natural light under the BRE guidance ( 50% of the area receives two hours of direct sunlight on the Spring Equinox – 21 March) or will they be in shadow most of the year? | The building massing may need to be stepped back or opened to the south to avoid the pocket park missing the BRE target. Alternatively, the pocket park could serve as a source of shade and coolth during summer months, much as courtyards are used in mediterranean climates. In which case, meeting the BRE target may be undesirable, and shade-friendly design strategies should be employed. | Create clear guidance on planting and sunlight targets specifically for pocket parks, being explicit about their functions. If a space is to provide local food and good growing conditions in the summer, it should have different targets from a space intended to provide summer shade. London’s climate is becoming mediterranean in the summer but the winter’s short days, long shadows and overcast skies remain. Designs for pocket parks need to be pleasant in the October to April period as well as perform their summer function. . |