Net gains for sustainability and fire safety - living walls

Lauren Lee

Lauren Lee
Senior Consultant, Assurity Consulting
10th July 2024

With biodiversity a growing component of our sustainable development - and not forgetting Biodiversity net gain (BNG) requirements - the introduction of green living walls in our buildings is also on the rise, and some properties have even incorporated these into cladding and external wall systems. These are seen to benefit city biodiversity, air purity, thermal environment, and noise abatement, as well as benefiting wellbeing and mental health.

We’ve all encountered situations whereby designs have been introduced by architects, with little thought to the practicalities and risks associated after install. With regards to living walls, this is hopefully about to change.

A new guide was published last month by the FPA, developed between key living wall providers and UK insurers via the RISCAuthority research scheme to address the potential risks from fire, escape of water, and weather events that living walls may present if incorrectly designed, installed and/or managed. The document is separated into two key parts; Part 1: Living Walls questionnaire, and Part 2: Background information and guidance.

The questionnaire in Part 1 provides an opportunity for the specifier, façade designer, or architect to describe the proposed living wall system to any authority having jurisdiction (AHJ) – a term used throughout the document, be that local building control, the insurer or fire authority etc.. The responses given to the questions will allow the AHJ to quickly determine if the system presents any potential challenges or not, and to communicate these back to the specifier, façade designer, or architect.

The questions aren’t ground breaking but reflect basic questions and considerations that would be captured in a fire risk assessment. For example: 

  • Is the planted material of limited combustibility?
  • Is there a dependency on an irrigation system and maintenance to keep ignition and fire spread potential to a minimum?
  • Has plastic been used in the installation (which tends to be a highly problematic material)?
  • Are neighbouring buildings put at risk should a fire occur?
  • What would the management plan look like in the event of a fire?

The plant material will always have the potential to burn. Therefore, the control measures recommended in the guidance document stem from wild-fire management and address plant selection, plant placement, and the use of fire breaks, irrigation, building design features, and management controls.

Given that there will always be a residual risk from the plant matter and its associated high dependency on irrigation, maintenance, design detailing, and accuracy of installation, adherence to the guidance can only achieve so much and it will be down to the authority having jurisdiction (AHJ) (local building control, the insurer or fire authority etc.) to consider if the measures taken are enough in relation to their own risk appetite thresholds.

I think this is a great step forward towards closing the gap between design and operation. We’ve already seen several guidance documents now published in relation to risks associated with EV vehicles, e-bikes, and e-scooters, so I expect (and hope) that there is more to come. Managing fire safety in a sustainable world should be cohesive and mutually beneficial, not a hindrance.