M40 CAMPUSTHE PROPOSAL, EXPLAINED
Follow every important figure

The evidence.
In the open.

Developer proposals and predictions are labelled as such. Source links let you inspect the material and reach your own conclusions.

Web sources checked 25 September 2026 · Page publication dates not stated unless noted in the originals.
01
Developer environmental report

Green Belt, heritage and landscape setting

SDC M40 Campus · CCER printed pp. 5 and 23: the site lies in the Metropolitan Green Belt (a draft council assessment calls the area “provisional grey belt”); nearby conservation areas at Hedgerley Green (c. 220m), Hedgerley Village (c. 950m), Beaconsfield Old Town (c. 1.2km) and Gerrards Cross Common (c. 1.4km); Chilterns National Landscape c. 1.75km.

02
Developer assessment assumptions

Backup generators and operating assumptions

SDC M40 Campus · CCER printed pp. 10 and 32–33: 216 units; diesel assumed for worst-case air-quality modelling; monthly and annual testing; all generators operating for 72 hours in a total-supply-failure scenario.

03
Developer assessment, not regulatory approval

Emergency emissions and mitigation qualifications

SDC M40 Campus · CCER printed p. 33: possible small human-health threshold exceedances in the 72-hour emergency case, considered acceptable by the developer. Printed pp. 40–41: SCR and ammonia-slip considerations; final controls under development.

04
Official guidance

Emergency backup diesel engines: best available techniques

Environment Agency · Scope-specific guidance on engine emissions and testing: minimise tests, less than 50 hours annually, one engine at a time, avoiding poor air quality. Not SDC-specific permit conditions.

05
Official technical guidance

Combustion emissions explained

Environment Agency · Emissions to air from fossil-fuel combustion, including nitrogen oxides, particulate matter, carbon dioxide and carbon monoxide; other pollutants depend on fuel and technology.

06
Preliminary developer design and modelling

Building and flue heights — Community Consultation Environmental Report

SDC M40 Campus · Page 10: buildings approximately 40m; backup stacks estimated up to 66m above ground. Page 12: energy-centre stacks modelled at 140–180m (reference level not specified in this passage). Page 33: final stack heights still to be determined.

07
Developer photomontage

Stage Two visualisations pack — Photomontages B

SDC M40 Campus · September 2026 pack. Pages 3–12: context and project plans; 13–15: campus and power options; 16: site section; 17–19: methodology and viewpoint map; 20–82: proposed views. Pages 28/29 and 44/45: completion and year-15 comparisons. Page 25: opening image.

08
User-supplied consultation material

Workshop booklet — Photomontages B

SDC M40 Campus · user-supplied photograph · View looking southwest from Footpath CSP/35/1. Power strategy scenario 1, technology solution 1B. Title transcribed from the supplied photograph; booklet edition and date not established.

09
Operator-published capacity

Spalding Energy Expansion capacity

InterGen · 300 MW open-cycle gas plant, operational since 2019; excludes the adjacent combined-cycle plant.

10
Operator-published capacity

King’s Lynn capacity

RWE · 382 MW combined-cycle gas plant, from the operator’s decarbonisation overview.

11
Operator-published capacities

UK power station capacities

RWE · Grimsby 40 MW; Cowes 140 MW (diesel); Great Yarmouth 411 MW; Didcot B 1,440 MW. Operator-published capacities. Dedicated Little Barford page gives up to 750 MW gross, used in the comparison.

12
Official guidance

Noise and vibration management

Environment Agency · Sound character and noise assessment

13
Official science explainer

Particulate Matter Basics

US Environmental Protection Agency · Particle sizes and human hair reference

14
Developer proposal

The data centre campus

SDC M40 Campus · Dimensions, generators and cooling

3 hyperscale buildings40m approximate maximum height65,000m² maximum combined footprint300MW approximate maximum IT load216 potential backup generators
15
Developer proposal

Our power strategy

SDC M40 Campus · Scenarios 1 and 2

200MW approximate gas capacity, Scenario 1
16
Developer forecast

Site access, transport and construction

SDC M40 Campus · Construction programme and access

9+ years in SDC’s programme statement
17
Developer forecast

Delivering local benefits

SDC M40 Campus · Employment and economic forecasts

400 forecast operational jobs198m forecast regional construction benefit3.8m forecast local spending during construction
18
Developer assessment summary

Environmental approach

SDC M40 Campus · Air quality, noise and ground conditions

19
Developer proposal

Landscaping and green spaces

SDC M40 Campus · Bunding, planting and nature trails

20
Official consultation

Stage Two Community Consultation

SDC M40 Campus · Deadline, response routes and events

21
Developer programme

The planning process

SDC M40 Campus · DCO route and indicative timetable

22
Developer proposal

Our illustrative masterplan

SDC M40 Campus · Illustrative layout; subject to change

23
Developer mapping

Wider site area and interactive map

SDC M40 Campus · Published location map and interactive map

24
Primary evidence library

Consultation documents

SDC M40 Campus · Community Consultation Environmental Report and supporting material

25
Government evidence

Air quality statistics

Defra · Nitrogen dioxide and particulate matter

26
Official process guidance

How to register to have your say

Planning Inspectorate · Relevant representations and interested parties

27
Developer photography

Project overview

SDC M40 Campus · Existing-site aerial photograph

Methodology & limitations

How we visualise
the proposal.

Source before interpretation

Project dimensions come from the developer’s published consultation pages. These establish what is proposed, not whether a prediction will come true. The environmental report and underlying assessment should be read alongside summaries.

Comparisons with stated assumptions

The height study uses a linear 0–200m scale in its default all-stacks view and 0–70m in the building and backup-flue detail views: an illustrative 8m house, an approximately 40m building and backup-generator flues estimated up to 66m above ground (CCER, p. 10). The 26m difference is 66 minus 40. Widths, forms and flue count are schematic. The energy-centre range of 140–180m (pp. 12 and 33) is included as a distinct column of reported numerical values. Its common zero is a comparison reference, not surveyed ground: the quoted passage does not specify the energy-centre height datum. These are preliminary modelling figures, not final approved heights. The football-pitch comparison uses a stated rectangular area. Neither graphic is a verified architectural view or site layout.

Power station comparison

The chart uses a linear scale starting at zero: 0–500 MW in the closer-size view, and 0–1,600 MW in the wider view. Selected UK generating plants use RWE and InterGen published capacities, checked on 25 September 2026. Cowes uses diesel fuel; Spalding Expansion is the 300 MW open-cycle plant, excluding the adjacent CCGT. Little Barford uses its dedicated operator page’s up-to-750 MW gross rating, while Didcot B is 1,440 MW net. The published figures therefore do not all use identical net/gross conventions. SDC’s approximate 200 MW proposal is shown separately. Its summary does not specify the net/gross basis. The comparison does not establish similar annual output, equipment, land area, emissions or noise.

Illustrative sound samples

The 15-second airflow, hum and pulsing examples are original synthesised audio with gentle fades. They demonstrate sound character only. They are not site recordings, modelled receptor noise, calibrated decibel levels or equal-loudness comparisons. Actual effects require site-specific assessment.

Maps and images

The developer’s published location map retains its boundaries and original legend. The masterplan is indicative. The opening image comes from page 25 of SDC’s published Stage Two visualisations pack: Photomontages B, looking southwest from Footpath CSP/35/1, power strategy scenario 1, technology solution 1B. This is the digital version of the view in the user-supplied workshop photograph. It depicts the proposal, not an existing built development. The PDF page was rendered at 3,000 pixels wide; the hero crops the page to exclude margins and the key, while a full-resolution page is linked. No AI-generated enhancement is used. The supplied booklet photograph remains linked in the sources. The printed 50 cm viewing instruction relates to the physical page; this screen display is not a calibrated visual assessment. The conceptual night graphic is not a photomontage or impact prediction.

Exploring the visualisation pack

The viewpoint explorer uses original views A–M (including D1 and D2), pages 20–82. Scenario labels follow the visible page headings. The planting comparison uses matched completion and year-15 illustrations from pages 28–29 and 44–45, holding Scenario 1, technology 1A constant. These are proposed outcomes, not before-and-after photographs. The campus diagram and alternative power layouts come from page 13. The three aligned land sections come from page 16. Map topics reproduce separate original plans with their keys; they are not registered overlay layers. Website crops remove page furniture without generating new landscape or buildings. The full source pages remain linked. Pack pages 17–18 explain viewing methodology and the limitations of extended panoramas.

What is not established here

The website reports SDC’s qualification about potential threshold exceedances in its modelled emergency-generator scenario; it does not independently predict an exceedance or establish regulatory acceptance. No prediction is made that screening will fail. The construction programme dates need clarification. Independent validation of the developer’s assessments has not been carried out for this website.

Evidence priority: statutory and official documents; the developer’s original project material; authoritative technical explainers; then clearly labelled interpretation. Source availability does not establish independent verification.