EV charging in enclosed car parks and the fire case

Two requirements now meet in the same car park and pull in opposite directions. Building regulations and local policy require electric vehicle charging provision in new parking. Fire authorities and building control want charging kept away from the places where a vehicle fire would be hardest to fight. On an enclosed or undercroft deck, the ev charging car park fire question is a layout problem that has to be solved at planning stage, because moving bays after the structural grid is set is expensive and sometimes impossible.

There is no single national standard that resolves it. Approved Document S sets the charging infrastructure requirement, Approved Document B deals with fire, and the published guidance on charging inside covered car parks has developed faster than either. That gap is where applications get stuck.

What policy requires on charging provision

Approved Document S, in force since June 2022, requires charge points and cable routes in new residential buildings with associated parking and in new non-residential buildings with parking, with provision also triggered by certain material changes of use and major renovations.

Local policy frequently goes further. In London, the London Plan sets out active and passive provision requirements for residential and non-residential parking, with a proportion of spaces fitted out from the start and the remainder cabled for later. Outside London, parking standards in local plans and parking supplementary planning documents set their own rates, and the figures differ enough between neighbouring authorities that assuming a national rate is a mistake.

The practical consequence is that a scheme usually has to show both the fitted bays and the passive capacity on a drawing, with the electrical capacity and substation position to support them. A Travel Plan is often where the provision and its management end up described, and the drawing has to agree with it.

Why fire dominates the consultation response

Fire and rescue services have become consistently engaged on enclosed parking with charging, and their concerns are about consequence rather than frequency. A lithium-ion battery fire behaves differently from a petrol fire: it can reignite after apparent extinguishment, it is hard to cool from outside the pack, and suppressing it uses large volumes of water over a long period.

That shapes four questions you will be asked. Can the fire service reach the vehicle. Can the heat be prevented from spreading to adjacent vehicles and to the structure. Where does the water go. And can the supply be isolated safely.

Be careful with evidence here. The published data on relative fire frequency between vehicle types is contested and still developing, and an application that leans on a statistic will be challenged on it. The stronger approach is to design for the consequence and say so plainly, without arguing about likelihood.

Locating charging bays within a structure

Layout does most of the work, and the moves available are straightforward once they are considered early.

• Put charging bays on open-sided decks or the uppermost level where the scheme has one, rather than in the most enclosed part of the structure.
• Keep them away from the only means of escape, from stair and lift cores, and from beneath or adjacent to residential accommodation.
• Position them near a fire service access point so a vehicle can be reached, and where possible where it could be removed.
• Separate charging bays from the main body of parking with a distance, a structural element or an unoccupied bay, rather than placing a continuous run of charging in a single aisle.
• Avoid putting charging directly beneath primary structural members where prolonged heat would have the greatest consequence.

None of those moves is costly at concept stage. All of them are costly once the frame is designed and the drainage is set out.

Ventilation, detection and suppression

Enclosed car parks need smoke control for the fire scenarios Approved Document B contemplates, and the design assumptions for that system are where a charging layout can quietly cause a problem. A fire that burns longer and hotter than the design scenario changes the extract duty and the structural fire protection required.

Three design elements normally come up in consultation.

1. Detection in the charging area, usually earlier and more sensitive than elsewhere in the car park, with a link to the building's alarm and to the charging supply so that charging stops on activation.
2. Smoke ventilation sized and tested against the assumed fire, with the assumption stated in the fire strategy rather than left implicit.
3. Water supply and containment, covering hydrant provision, the volume available, and where firewater goes once it leaves the deck, because a large volume of contaminated water discharging to a surface water drain is a pollution issue as well as a fire one.

A fire engineer should settle these, and a Fire Safety Strategy to BS 9991 or BS 9999 is the document that records the decisions. It is fire engineering work, and a drafted document is a starting point for the engineer rather than a replacement for them.

Basement and undercroft parking

Below ground parking is the hardest case. Access is restricted, ventilation is mechanical, the structure above is usually occupied, and firefighting water has nowhere natural to go.

Some schemes respond by keeping charging out of the basement entirely and locating all provision at surface level or on an open deck, then arguing the point with the authority's parking policy. That is a legitimate position, and it is easier to run at pre-application stage than after an officer has read a layout showing charging on the lowest level.

Where charging in a basement is unavoidable, expect requirements around enhanced detection, suppression, compartmentation of the charging area, mechanical extract designed for a longer duration fire, and a clear firefighting strategy agreed with the fire and rescue service. A basement also brings ground and water constraints of its own, and groundwater control for a basement below the water table covers the part of that problem which has nothing to do with vehicles.

Coordinating with the fire statement at Gateway One

For relevant buildings, a Fire Statement accompanies the planning application under Article 9A of the Development Management Procedure Order 2015, and the Health and Safety Executive is consulted on it. That document is where the charging strategy and the fire strategy have to agree.

The failure mode is predictable. The transport and sustainability chapters promise charging to the local standard, the fire statement describes a car park fire scenario that does not mention charging, and the inconsistency is spotted either by the consultee or, worse, at Gateway Two when the design is fixed and the planning permission constrains what can change.

Write the fire statement with the charging layout in front of you. Name the number and location of bays, state the fire scenario assumed, and describe the detection, isolation and containment arrangements. If the position is still being developed, say which parts are settled and which are not, rather than leaving a silence that reads as an omission.

Conditions that secure provision and safety together

Authorities commonly condition charging provision and fire safety separately, which creates a trap. A condition requiring charging provision in accordance with a drawing, and a separate condition requiring a fire strategy to be approved, can produce two approved documents that contradict each other.

Ask for condition wording that ties them. A single condition requiring details of the charging installation, including its location, the detection and isolation arrangements and the firefighting provision, to be submitted and approved before installation, keeps the two strands in one approval. Where the authority prefers separate conditions, at least ensure the fire strategy condition expressly requires the charging layout to be addressed.

Two further points are worth settling at the condition stage. Who maintains the charge points and the associated safety systems through the life of the building, which belongs in a management plan rather than in the planning drawings. And what happens when charging technology changes, because a condition locking the installation to a specific product will need varying within a few years.

You can see which reports a scheme with enclosed parking is likely to need and draft the planning stage documents from your own site details, then have the fire engineering reviewed by a competent professional.

For specialist technical reports, qualified professional input may be required. This is general guidance, not legal advice, and guidance on charging in covered car parks is still developing, so check the current position with your fire and rescue service, the building control body or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.