How to draw a site analysis diagram
Order and principles for site analysis diagrams in a design report, the manual process, and the part sitedia automates.
Overview
A design report usually opens with site analysis. Analysis diagrams take the facts gathered in the survey through to design decisions.
| Stage | What it is | Example |
|---|---|---|
| Survey | Gathering facts | Surrounding buildings, conservation areas, station positions |
| Analysis | Drawing design decisions from those facts | The terraces around the site are four storeys, so the street frontage steps down; people walk from the station along one street, so the entrance faces it |
The common mistake is to mix the two stages. A diagram turns one fact into an image that reads in a few seconds, and the decision is drawn on top with an arrow. One fact per plate.
Basic themes
| Theme | Content | What it answers |
|---|---|---|
| Use (existing) | Residential, commercial, office, education | How the surroundings are used |
| Planning | London Plan designations, conservation areas, listed buildings, protected views | What constrains development |
| Height | High-rise and low-rise distribution | Skyline and sunlight |
| Age | Construction period | Historic fabric and where change has happened |
| Open space | Parks, squares, water | Outdoor space the site can connect to |
| Access | Road hierarchy, stations, bus stops | How people and vehicles arrive |
Add or remove themes for the brief. If one of these six is missing, the client or the planning officer will ask for it. The plates for each theme are listed in The 24 plates.
Radius
Decide the radius before the themes. The radius is the area the site relates to.
| Radius | What it covers | Note |
|---|---|---|
| 150–300 m | Immediate context (neighbouring heights, street width, direct shadow reach) | The only scale at which individual plots read clearly |
| 500 m | About 6 minutes' walk; the usual unit for a station area | The most used value; several blocks and the grain of the fabric appear |
| 800 m | 10 minutes' walk; neighbourhood analysis | Read by groups and routes, not building by building |
| 1,000–1,500 m | The site's position in the city (main roads, large parks, links between stations) | Plots and use colours no longer separate |
Choose the radius so that the reasons for the design decision fall inside it. If the station is 700 m away and the plate stops at 500 m, the plate does not support the station argument.
Frame shape
Circle
| Reason | Explanation |
|---|---|
| Matches planning terms | «Within 800 m of the station» and «10 minutes' walk» describe a catchment, and a circle shows one |
| Site at the centre | With one site marker at the centre, the eye returns to the same point on every plate |
| Plates in series | 6 or 12 circles of the same radius in a grid keep one scale across plates |
Same scale. If one plate covers 600 m and the next 850 m, they cannot be compared. Use one radius for all plates.
When a rectangle is better
| Case | Problem with a circle | Rectangle |
|---|---|---|
| Long site | Along a river or railway the circle cuts the ends, or leaves the centre empty if enlarged | Matches the proportion of the site |
| Report format | On a 16:9 slide or a two-column page the circle leaves wide margins | Fills the format |
| Boundary plates | A conservation area or Opportunity Area cut by a circle hides where the designation ends | Includes the whole area |
Use one shape for the whole report. Where the shape changes, state the scale again. Under «Shape», choose Circle, Square or Rectangle.
Colour and legend
| Principle | Content |
|---|---|
| One theme colour range | One range for the theme of the plate, everything else grey |
| Legend matches the drawing | If a category is hidden or a colour changed, change the legend too |
| Unknown stays unknown | Buildings with no use or age are light grey («Unknown», «no data»). An invented colour makes the whole plate a guess |
| One accent colour | If the site marker is red, use red for nothing else |
| North up | Do not rotate the plate; shadows, sun and wind cannot be checked on a rotated plate |
Five common mistakes
| Mistake | Effect | What to do |
|---|---|---|
| Two themes on one plate | The reader has to check the legend for every colour | Split the plates |
| Legend differs from the drawing | The plate loses credibility, and so do the others | Correct the legend with the drawing |
| Colouring what is not known | The plate becomes an assumption | Leave it grey |
| No scale or north | Common when plates are pasted onto slides one by one | State scale and north (on a circular frame the radius replaces the scale) |
| Facts without a decision | Ten plates ending in «this is the existing situation» are a survey, not an analysis | Write one conclusion sentence per plate |
Stating the limits of the data
| Method | Content |
|---|---|
| Mark the unknown | Leave unknown buildings grey and keep «Unknown» in the legend. Areas with many unknowns are the ones to check on site |
| State the date | One line with the data date in the caption (for example «Heights: Environment Agency LiDAR 2016–2022») |
| State estimates | Storeys estimated from height (LiDAR height ÷ 3.25 m), building age from EPC bands, crowns estimated from tree records |
Process
By hand
- Capture the map or aerial photo at one scale
- Place them under Illustrator and trace the building outlines
- Check uses on site and colour each building
- Add designations, roads and green space as layers
- Clip with a circular mask and add legend, scale and north
By hand, one plate takes 1–2 hours and 12 plates about a week. If the site changes, the work starts again.
Automated
The materials are open data. In the UK edition, footprints come from Overture Maps (© OpenStreetMap contributors), heights from Environment Agency LiDAR, building age from Energy Performance Certificates and Colouring Britain, planning designations from the GLA and Historic England, title polygons from HM Land Registry and stations from NaPTAN. sitedia assembles them from a postcode, an address or a place in Greater London and draws up to 24 plates with the principles above (circular frame, fixed scale, grey unknowns, legend in step with the drawing). PNG downloads are free; the editable SVG needs a Pro pass (Passes).
Open data can miss recent buildings or hold old uses, so the last step is a review by someone who knows the site. The output is editable vector for that reason; see Finishing the SVG.
Order in the report
- Location: location plan and aerial view
- Planning: London Plan designations, conservation areas and listed buildings, Land Registry plots
- Context: buildings, use, age, height
- Connections and access: green space, roads, rail and bus
- Physical conditions: terrain and slope, sun, wind
- Synthesis: one plate that summarises the decisions drawn from the others (the only plate with many arrows and notes)