Reports for a small-scale data centre

A small data centre is not a warehouse with servers in it, and the data centre planning documents that get one permitted reflect that. Two issues decide most applications: noise from chillers and standby generators at night, and whether the grid connection exists. Everything else is ordinary industrial or employment-land assessment. Get those two wrong and the scheme either gets refused on amenity grounds or gets permitted and then cannot be built for four years.

Data centres have no use class of their own. Authorities have treated them variously as falling within storage and distribution, general industrial or sui generis depending on the operation, and the December 2024 revision of the National Planning Policy Framework added explicit support for data centres and digital infrastructure alongside other modern economy uses, carried through into the current edition published on 17 August 2026. Check the policy code in the current edition and state the edition when you cite it.

Use class and the employment land argument

Start by fixing the use class, because it governs whether the site's allocation supports the proposal and whether any future change needs permission. Describe the operation honestly in the application: rack capacity, staffing level, vehicle movements, whether there is any trade counter or office element, whether it is a colocation facility or dedicated to one occupier.

On an allocated employment site, the policy argument is usually about job density. A data centre employs very few people per square metre compared with light industrial or office use, and authorities with employment land policies framed around job creation will raise that. The answer is not to inflate the headcount. It is to set out the operational employment, the construction employment, the supply chain and the role of the facility in supporting other businesses, and to engage with the local plan's own wording on employment land. An Employment Land Assessment or an Economic Impact Assessment carries that case where the allocation is contested.

Where the site is not allocated for employment, the argument is about the suitability of the location, which comes back to grid capacity and access rather than to policy generalities.

Noise from chillers and the nighttime baseline

This is the one that decides the application. A data centre runs continuously, so the relevant assessment period includes the quietest hour of the night, and the background sound level at 3am on a Tuesday is often 10 or more decibels below the daytime figure.

The assessment follows the British Standard method for rating industrial and commercial sound affecting mixed residential and industrial areas, with the rating level compared to the background at the nearest noise sensitive receptors. Three things need to be right:

• the baseline survey must cover the full nighttime period, over enough nights to be representative, with the measurement positions agreed with the environmental health officer in advance
• the plant schedule in the acoustic model must match the mechanical design, including the number of units running at design condition and at part load
• character corrections for tonality and intermittency must be applied where the plant produces them, and fan noise frequently does

A Noise Impact Assessment that reports only a daytime figure, or that models plant at part load without saying so, will be sent back. Where the receptors are close, the mitigation is acoustic louvres, attenuators, enclosures and screens, and all of those have a pressure drop and a space cost that the mechanical design has to absorb. Resolve it at design stage rather than at condition stage.

Generator testing regimes and the conditions that follow

Standby generators are the second noise source and they behave differently. They run rarely, they are loud, and they have to be tested.

A typical regime is a short no-load or load-bank test at intervals set by the operator's maintenance regime, plus occasional longer black-building tests. Authorities condition this tightly, and the conditions usually cover the days and hours during which testing may take place, the maximum duration of each test, the maximum number of tests in a period, and a requirement to keep a log available for inspection.

Offer a testing regime in the application rather than waiting to have one imposed. An operator who proposes weekday daytime testing within a stated window, with a logged record, will usually get a workable condition. An applicant who says nothing gets a condition drafted around the worst case.

Generators also bring an air quality dimension and a permitting dimension. Combustion plant above a threshold thermal input falls within the specified generator and medium combustion plant provisions of the Environmental Permitting (England and Wales) Regulations 2016, which is a separate consent from planning. Emissions from diesel standby plant need assessing where receptors are close or the site is in or near an air quality management area, and the same discipline that applies to an industrial extension inside an air quality management area applies here, with stack height and testing frequency as the main inputs to an Air Quality Assessment.

Grid capacity, the substation and programme risk

The electrical connection is the item most likely to stop the scheme, and it sits outside the planning system entirely. Get a connection offer, or at least a formal capacity enquiry response, before you commit to a site.

The planning consequences are physical. A connection at high voltage needs a substation compound, switchgear housing, possibly a new cable route through third party land requiring easements, and sometimes an off-site reinforcement scheme with its own consents. Show the compound on the application drawings, with its enclosure, access and noise emissions from transformers included in the acoustic assessment. A Utilities Assessment setting out the connection position, the reinforcement requirement and the indicative programme is worth submitting even where the authority has not asked for one, because it answers the deliverability question before an objector raises it.

Energy policy applies too. An Energy Statement has to deal with a building whose regulated energy use is small and whose unregulated process load is enormous, which does not fit the standard reporting template. Say so, report both, and address the power usage effectiveness of the design rather than pretending the process load is outside scope.

Water for cooling, and when it becomes the issue

Cooling design decides water demand. A closed-loop or air-cooled system uses very little. An evaporative or adiabatic system can use a great deal, concentrated in hot weather, which is exactly when the supply network is most stressed.

State the cooling method and the design water demand in the application. In a water-stressed catchment, or anywhere a water neutrality position applies, that figure determines whether the proposal is acceptable, and the water undertaker will comment. A Water Supply Assessment setting out demand, peak demand and the undertaker's confirmation of capacity is the document that settles it. Where water reuse forms part of the design, the approach to a rainwater and greywater reuse scheme applies directly.

Security, townscape and the box problem

Data centres want a blank, secure, single-storey box with a 2.4 metre fence, and planning officers want frontage, activity and a reduction in bulk. The negotiation is predictable.

What works: setting plant on the roof behind a parapet rather than at ground level on the boundary, breaking the elevation with material changes rather than applied panels, putting the small office and welfare element at the street frontage, and planting a structural landscape belt wide enough to mature rather than a 1 metre strip. Fencing is easier to resolve than most applicants expect if it is set behind planting and specified in a dark finish.

Lighting needs its own thought. A continuously staffed secure site wants perimeter lighting, and a lighting assessment addressing obtrusive light against the relevant environmental zone keeps that from becoming a late objection.

Illustrative example

A 2,800 m² facility on an allocated employment site has its nearest residential receptor 85 metres away. The nighttime background is low. The acoustic assessment models 14 dry coolers at design condition with a tonal correction, and the rating level exceeds the background until attenuators and a 4 metre acoustic screen are added. Two 1.5 MW standby generators sit in an enclosure with a testing regime offered at Tuesday and Thursday daytimes, 30 minutes each, logged. The grid connection requires a new substation compound and an off-site cable route, adding 18 months to the programme. This example is illustrative and is not based on a real application.

Enter your postcode on PlanScope to see which of the 66 report types the constraints at your site are likely to trigger for an industrial or data use. Start from the home page.

This is general guidance, not legal advice. Acoustic, air quality and electrical design for a facility of this kind requires suitably qualified professionals, and for specialist technical reports, qualified professional input may be required. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.