Nature-Inspired Protective Engineering: Blast EcoShield Brings Living Barriers to RHS Chelsea
A Cranfield University-sponsored spinout has taken a counter-terrorism product to the Great Pavilion at the Royal Horticultural Society’s flagship show. Conceived and founded by Dr Rachael Hazael and validated across more than fifty blast experiments, Blast EcoShield is a modular living barrier engineered to attenuate the peak overpressure of an explosive event, turning hedges and engineered vegetation into measurable protective infrastructure. After Chelsea, the entire garden relocates to the Defence College for Military Capability Integration at the UK Defence Academy. The tagline reads simply: saving lives one leaf at a time.
Among the flowering displays in the Great Pavilion at the 2026 Royal Horticultural Society Chelsea Flower Show sits an exhibit that does not, at first glance, belong in a horticultural showcase. Sponsored by Cranfield University and delivered through the GreenSTEM area, Blast EcoShield introduces visitors to the emerging field of nature-inspired protective engineering, the study of how vegetation and plant structures can mitigate the pressure waves generated by an explosive event. The display combines tested plant species, footage from controlled blast experiments and interactive demonstrations of how living material interacts with a simulated blast wave. The stand itself is built from reclaimed materials, including timber salvaged from aerodynamic wind tunnels, and is fully accessible with ramps and QR-coded audio commentary for visitors who learn better by listening than reading.
It is, deliberately, an unusual venue for a counter-terrorism product. Conceived, developed and founded by Dr Rachael Hazael, Reader in Applied Materials at Cranfield University, the underlying research is a four-year programme of explosive testing that has produced more than fifty controlled blast experiments against engineered living barriers. The display introduces audiences to the proposition that ordinary hedges and living walls, when arranged and engineered correctly, can absorb and deflect pressure to a measurable degree, reducing the peak overpressure of a blast wave substantially, and in doing so changing the nature of the injuries that an event would otherwise inflict.
The tagline the company prints on its stand, Nature Inspired Protective Engineering; saving lives one leaf at a time, designed by Blast EcoShield, is the marketing line. Behind it is a serious piece of work originating from Cranfield Defence and Security, a leadership bench drawn from the senior ranks of the UK’s bomb disposal and explosive engineering professions, and a company that is, at the time of writing, only weeks old as a registered legal entity.
From the Great Pavilion to the UK Defence Academy
The Chelsea garden is not a one-off marketing exercise. After the show closes, the entire installation will be relocated to the Defence College for Military Capability Integration at the UK Defence Academy, for which Cranfield University is the academic provider to the UK Ministry of Defence. There the garden will continue to function as a teaching aid, giving Defence Academy students a tangible illustration that protecting people from explosive blasts can be done in a way that is sustainable, biodiverse and visually acceptable, rather than through the standard reflex of bollards, concrete and steel mesh. That post-show destination is the single most useful signal in the entire Chelsea announcement. It places the product firmly inside the Ministry of Defence’s own training estate, and it positions Blast EcoShield’s thinking inside the audience that ultimately writes specifications for force-protection schemes overseas and for sensitive UK estate at home.
The context that makes this product commercially interesting is also a recent one. After Manchester Arena, London Bridge, and the 2017–2019 wave of European vehicle-ramming attacks, the UK adopted the Terrorism (Protection of Premises) Act 2025, known as Martyn’s Law, which imposes Protect Duty obligations on a wide category of public venues. Local authorities, event organisers and critical national infrastructure (CNI) operators are now legally required to consider and, where reasonable, deploy protective measures. But the default solutions, bollards, concrete blocks, high-impact steel fencing, signal threat, degrade the public realm, and routinely fail planning tests grounded in biodiversity net gain and urban greening requirements. That is the market opening Blast EcoShield is targeting, and it is consistent with policy alignment the company itself cites: Environmental, Social and Governance (ESG) policy, outputs of the UN Climate Summit COP27, and Martyn’s Law.
Choosing Chelsea rather than a defence trade show is a calculated route to market. The EcoShield only makes commercial sense if it is specified by landscape architects and public realm designers at the concept design stage, not retrofitted by security engineers afterwards. Putting the product in front of landscape architecture, horticulture, estate management and local authority audiences, the people who actually commission public realm schemes, is the way to get it written into a Royal Institute of British Architects (RIBA) Stage 0 brief. Blast EcoShield Ltd is a recently incorporated UK company (Companies House number 17070942, registered office in Bath) and the Chelsea appearance is its first major public outing.
The Technology: What Is an EcoShield?
The core proposition is an engineered living barrier. Each EcoShield combines four layered elements: locally available plant species selected for foliage density, resilience and biosecurity compatibility; engineered soil systems that provide additional mass and energy-dissipation capacity beneath the vegetation; a structural containment and load-bearing frame that gives the system predictable and repeatable mechanical behaviour; and a design geometry informed by analytical modelling and controlled experimental testing. The system is modular, allowing the same underlying engineering to scale from a temporary event perimeter to a semi-permanent government estate installation.
That design is the output of a four-year research programme during which Dr Hazael has conducted more than fifty controlled blast experiments to characterise how plants dissipate energy. The work identified plant types with the right balance of flexibility and strength, focusing on native species that look acceptable year-round, support UK biosecurity requirements, and can be colour-matched for major events such as state visits or sporting fixtures. The selection logic is not horticultural decoration; it is materials science applied to species that happen to also be plants.
The physical mechanism is, from a protective engineering perspective, entirely conventional. Blast waves interacting with dense, layered material are attenuated through four recognised processes: mass loading, energy dissipation through plastic deformation and shearing, impedance mismatch at material boundaries, and progressive material failure. The system is also engineered to capture fragmentation, arresting primary and secondary fragments generated by the event, which is a distinct protective function from overpressure attenuation and a common cause of casualties in urban terrorist incidents. Using plant matter, soil and landscaping as the attenuating media is unconventional; the underlying mechanics are not.
Blast EcoShield’s own materials are explicit that the product is intended to reduce the effects of blast waves from both terrorist attacks and accidental explosions. That dual use-case matters: it widens the addressable market from Protect Duty-driven counter-terrorism into industrial sites and any facility where an accidental detonation risk warrants perimeter attenuation. Application areas the company names include arenas, large-scale public events, high-profile venues such as conference centres, and critical national infrastructure.
The company describes its product range in three tiers. Standardised EcoShields are modular, experimentally validated systems intended for events, market entrances, temporary installations and public realm security enhancement. Bespoke EcoShields are site-specific, threat-aligned systems engineered for complex urban environments, government and defence estates, CNI, and high-value individual protection. A third research and innovation strand is investigating material optimisation, scalable infrastructure integration, and ESG-aligned protective engineering.
Performance claims are deliberately circumscribed. Public materials state that four years of controlled testing have “consistently demonstrated a significant reduction in peak blast overpressure in defined threat-based scenarios” and that, at the reduced pressure levels achieved, the dominant injury mechanism shifts from life-threatening blast lung and thoracic trauma toward lower-severity outcomes such as auditory injury. Quantitative test data is withheld behind non-disclosure agreement, standard commercial and security practice at this stage of the technology readiness curve, but a constraint on independent verification. Intellectual property is declared patent-pending.
Scientific Precedent in the Open Literature
The EcoShield concept does not exist in a vacuum. A 2020 peer-reviewed study published in the International Journal of Protective Structures and widely indexed on ScienceDirect, entitled Innovative Protection of Urban Areas: Experimental Research on the Blast Mitigating Potential of Hedges, conducted free-field explosion testing against a range of plant species. The authors reported that dense vegetation can reduce peak incident overpressure “by more than 40% compared to an unimpeded propagation,” with thuja hedges and yew trees recording between 39% and 45% peak-pressure attenuation. A parallel study on trees as natural barriers reported similar figures: yew and thuja performing best, bamboo performing worst at around 14.7% attenuation.
These are open, peer-reviewed findings against bare vegetation. Blast EcoShield’s proprietary system, which adds an engineered structural containment layer to the vegetated mass, is plausibly capable of comparable or greater attenuation, though the company has not released independent validation data. The open literature does, however, provide a credible ceiling-and-floor bracket for what a vegetated system can reasonably claim in a free-field test. For customers and regulators that bracket is important: it means the technology can be independently referenced in the academic literature even where the company’s own data remains NDA-gated.
Engineering Methodology and Assurance
Blast EcoShield describes a structured engineering workflow that mirrors established protective engineering practice: threat characterisation informed by global incident analysis and current attack methodologies; definition of protection objectives and site-specific constraints; analytical modelling to inform geometry and configuration; experimental testing to characterise performance, repeatability and limitations; and assurance through configuration control, documentation and defined operating envelopes.
This framework sits comfortably alongside the UK National Protective Security Authority (NPSA, successor to CPNI) Integrated Security Guide and the Public Realm Design Guide, Hostile Vehicle Mitigation (3rd edition), both of which emphasise that protective measures must be assurance-backed, performance-tested and proportionate to the assessed threat. The open question for Blast EcoShield is whether its living systems can achieve the type of certification now expected for hostile vehicle mitigation (HVM) products, typically PAS 68, IWA 14-1 or ISO 22343 impact-performance ratings, and for blast-rated infrastructure, equivalent assurance to glazing and curtain-walling tested against recognised fragment-hazard standards. Certification is the gating commercial constraint. Without it, deployment is confined to pilot studies and bespoke private installations; with it, the addressable market opens substantially.
The Leadership Bench
The technological credibility of Blast EcoShield rests primarily on the people. In this respect the company is unusually well-credentialled.
Dr Rachael Hazael CEng, Founder and Chief Technology Officer
Hazael is an internationally recognised researcher in blast phenomena and material response, with more than 60 peer-reviewed publications. She holds a PhD in Chemistry from University College London and is a Chartered Engineer and Member of the Institute of Materials, Minerals and Mining (IOM3). She heads the Advanced Materials for Protective Engineering Group (AMPEG) at Cranfield Defence and Security and is described on the company’s own materials as a survivability specialist. Her research investigates material response to extreme conditions, with a focus on novel materials, chemistries and biological systems, including the effects of improvised explosive device (IED) blast on personal protective equipment, carbon-zero soft armour vests, and sustainable alternatives to ballistic gelatine. She has worked alongside specialist agencies across government on safety in public and critical infrastructure domains. Named in the 2025 Top 50 Women in Engineering awards; shortlisted for the 2022 Women in Defence Awards (Research and Innovation) and a finalist in the Women in Engineering Awards (Safety and Security).
Dr Gareth Collett CBE CEng Hon. FIExpE, Chief Executive Officer
Collett is a former senior British Army officer and Diplomat whose 35-year career spanned Northern Ireland, the Balkans, Iraq, Afghanistan, and several less-publicised theatres. He rose to become Head of the United Kingdom’s bomb disposal profession, leading some of the world’s most experienced explosive ordnance disposal teams. He was appointed CBE in 2013 for life-saving contributions to blast mitigation in Afghanistan and the provision of specialist threat mitigation to the 2012 London Olympics. He holds a Doctorate in Defence and Security, and his specific areas of expertise are blast and fragmentation mitigation, the optimisation of venue security to counter explosive violence, and the assurance of protective products to the customer.
After retiring from the Army in 2018, Collett served for four years as the United Nations’ Chief Technical Advisor on weapons abatement, working across fragile environments to reduce the risks posed by explosive remnants of war and improvised explosive devices and to optimise force protection. He now serves as a Director in Higher Education with a focus on rebuilding national capacity in the energetics industry, supporting the safe innovation, production and management of explosive materials. He provides specialist advice to organisations including Action on Armed Violence and the Office of the High Commissioner for Human Rights, and contributes to war-crimes investigations involving explosive violence.
Edward Clinton MBE CEng FIExpE, Chief Operations Officer
Clinton previously headed the British Army’s Explosive Engineers, representing a cadre of approximately 450 specialist engineers, with more than 20 years of global Explosive Ordnance Disposal (EOD) operational experience. Awarded the Queen’s Commendation for Bravery in 2016 and the Harold Swinnerton Award in 2024. He holds the Cranfield MSc in Explosive Ordnance Engineering, is a Chartered Engineer and Fellow and Board Member of the Institute of Explosive Engineers. He was appointed MBE in 2025 for services to bomb disposal.
The advisory board adds commercial and institutional depth. Susan Robson MBE, CEO of the Women’s Engineering Society, brings 25 years across consulting, engineering and energy, with prior senior roles at PwC and National Grid; she holds an Executive Diploma in Strategy and Innovation from Oxford Saïd Business School and was awarded the MBE in 2024 for services to inclusion in engineering. Lieutenant General Sir George Norton KCVO CBE DL, appointed Commandant of the Royal College of Defence Studies in July 2020 after a 38-year Army career, was the UK’s longest-serving Military Representative to NATO and its final Military Representative to the European Union; he provides strategic access to NATO institutions and senior UK government defence circles, and is also Deputy Chair of the National Army Museum and Lieutenant of the Tower of London. Peter Shelley, founder of Onepoint4 Ltd, brings seventeen years of commercial leadership preceded by posts as Director of the UK Explosives Notified Body at the Health and Safety Laboratory and Head of the Explosion and Ballistic Protection section at the Home Office Scientific Development Branch; he is trained in munitions clearance to IMAS Level 2 and in Force Protection Engineering at Cranfield. Shelley’s Notified Body experience is directly relevant to the certification pathway the company must eventually navigate.
Taken together: a Cranfield-based materials scientist with 60+ publications, the former head of the UK’s bomb disposal profession, the former head of Army Explosive Engineers, a former NATO military representative and a former Home Office explosives protection chief. For an early-stage spinout targeting a regulated, assurance-intensive market, this is a leadership configuration that is essentially unmatched.
Market Positioning and Commercial Logic
Three markets sit inside the company’s addressable profile. The first is Protect Duty-driven public realm security: local authorities, events, festivals, transport hubs and crowded places that are required to deploy proportionate physical measures under the 2025 Act. Here the EcoShield proposition directly addresses the planning-aesthetic barrier that limits where conventional HVM can be deployed. The second is CNI and government estate, airports, energy infrastructure, diplomatic missions, defence estate perimeters, where bespoke threat-aligned systems carry higher margin and longer deployment cycles. The third is high-value individual residential protection, a niche where aesthetics are paramount and customers are prepared to pay premium pricing for visually inoffensive security.
The company itself names three customer types explicitly in its public positioning: developers, cities and infrastructure experts. That phrasing is instructive. “Developers” points at the commercial property and estate sector, where biodiversity net gain and Protect Duty obligations now converge on new-build planning. “Cities” points at local authorities and combined authority-level estate managers. “Infrastructure experts” points at the CNI operator community. All three are customer categories that historically would not have been in a defence products company’s immediate sales list, which is why Blast EcoShield is classified as a Civil Engineering company on LinkedIn, not a defence one, a classification that makes commercial sense when the buyer is a local authority estate team rather than a defence procurement officer.
The ESG framing is strategically important, not incidental. UK planning policy now embeds biodiversity net gain requirements (under the Environment Act 2021) and urban greening targets in most local plans. Conventional HVM barriers cannot contribute to either metric; a living EcoShield can. That single feature reframes the product from a pure security cost into a dual-purpose capital item that satisfies both protective and environmental planning obligations simultaneously, and a single capital item satisfying two planning gates is an unusually attractive proposition for developers, architects and public sector estate managers.
External trade coverage is now beginning to emerge. Manufacturing & Engineering Magazine published a 22 April 2026 feature, Saving Lives One Leaf at a Time, that confirmed the four-year programme, the fifty-plus blast experiments, the Chelsea exhibit and the post-show relocation of the garden to the UK Defence Academy. Mainstream defence trade-media coverage remains thin, which is consistent with an early-stage spinout operating under non-disclosure, pursuing patent grant, and focused on NPSA and CNI pilot engagement rather than open-market promotion. The company’s own LinkedIn page carries a deliberate cadence of posts, an introduction to the proposition, a trailer for “upcoming opportunities to interact with our EcoShields and team” naming Rachael Hazael, Gareth Collett and Ed Clinton, and the RHS Chelsea / GreenSTEM announcement. The company is registered on LinkedIn as a Civil Engineering firm of 2–10 employees, founded in 2026, a classification that fits the actual buyer (local authority and developer estate teams) better than a defence label would.
The Decision-Maker Landscape: Who Approves a Living Barrier
Counter-terrorism protective engineering in the UK is not an ordinary commercial sale. Between a product like the EcoShield and an installation on a government estate or a major event perimeter sits a layered, role-based approval architecture. Blast EcoShield’s commercial scale-up depends less on marketing to end-customers and more on positioning the product inside this ecosystem, because the people who sign off on deployment are not the people who pay for it. For any practitioner evaluating the product, the following decision-makers are the population that actually matters.
NPSA Advisers, the national technical authority
The National Protective Security Authority (NPSA), successor to the Centre for the Protection of National Infrastructure (CPNI), is the UK’s national technical authority for protective security. It is hosted within MI5 and provides technical advice to government departments, CNI operators, and designated customer organisations. Each customer organisation has a named NPSA adviser, whose engagement is mandatory at concept design stage for new build and major refurbishment projects. NPSA publishes the ruling guidance, Protection from Blast (updated 30 August 2024), the Integrated Security Guide, the Public Realm Design Guide, Hostile Vehicle Mitigation (3rd edition), and A Guide to Specifying Blast Resistance Requirements for Building Facades (October 2025). Any protective measure specified for a CNI or government site is assessed against these documents. Without NPSA technical acceptance, no living barrier reaches a government estate.
Counter Terrorism Security Advisers (CTSAs)
CTSAs are police officers embedded in territorial and specialist forces, coordinated nationally by the National Counter Terrorism Security Office (NaCTSO) and reachable through the ProtectUK platform (protectuk.police.uk). For businesses, events and non-CNI organisations, the CTSA is the gatekeeper. CTSAs conduct site surveys, advise on Protect Duty compliance, and sit on Safety Advisory Groups for major events. They are the people a venue operator or event organiser will ask first when deciding whether an EcoShield constitutes a reasonable and proportionate protective measure. Winning CTSA confidence is, in practical terms, a prerequisite to winning the commercial sale.
Register of Security Engineers and Specialists (RSES)
The RSES is a register maintained jointly by the Institution of Structural Engineers (IStructE) and the Institution of Engineering and Technology (IET) for chartered engineers with demonstrable protective security expertise. RSES-registered engineers perform the actual blast load analysis, structural response calculations, P–I diagram interpretation and component-level assurance for any serious protective design. Independent RSES validation of an EcoShield installation is the mechanism by which NPSA, a CTSA or a duty-holder can take comfort that claimed performance maps onto real site conditions. Engagement with RSES-registered engineers is a near-mandatory step for Blast EcoShield’s commercial route.
RIBA Plan of Work Stage 0/1 with the Security Overlay
The Royal Institute of British Architects (RIBA) Plan of Work is the standard framework for UK construction projects, structured across Stages 0 through 7. NPSA publishes a Security Overlay to the Plan of Work that requires protective security to be embedded from Stage 0 (Strategic Definition) or Stage 1 (Preparation and Brief). Security cannot be retrofitted successfully at Stage 4 or later; by then, site layout, perimeter geometry and stand-off distances are already fixed. For Blast EcoShield to be specified on a new government building, the landscape architect and security consultant must be in the room when the design brief is written, which is the strategic logic behind the RHS Chelsea appearance. Architects and estate managers at Stage 0/1 are the people who embed or exclude the product.
Build it Secure
NPSA’s Build it Secure programme is the institutional vehicle for promoting early-stage protective security integration into new developments. It provides guidance, case studies and adviser engagement for project sponsors. Products that align explicitly with Build it Secure principles, stand-off maximisation, layered defence, operational resilience, sustainability, have a more defensible specification story than those positioned purely on performance claims.
Safety Advisory Groups for major events
For large public and social events, festivals, concerts, processions, sporting fixtures, the local authority Safety Advisory Group (SAG) is the multi-agency forum that signs off on safety and security arrangements. SAGs are typically chaired by the local authority and include police (usually represented by the CTSA), fire service, ambulance, highways, the event organiser and the venue operator. Under Protect Duty, SAGs increasingly expect to see evidence of proportionate physical protective measures. An EcoShield deployed along a festival perimeter or a market entrance would be scrutinised by the SAG, advised by the CTSA, and have to satisfy the event organiser’s legal duty-holder obligation simultaneously.
Protect Duty duty-holders
Under the Terrorism (Protection of Premises) Act 2025, duty-holders at qualifying premises must conduct a “reasonable” assessment and deploy proportionate measures. These are the commercial end-customers: venue managers, event operators, local authority estate teams, shopping centre directors, transport hub security leads. They are the people who sign purchase orders. But they are risk-averse; they will deploy a product like the EcoShield only if it has been endorsed by their CTSA, specified by an RSES engineer, or referenced positively by NPSA. The duty-holder is the buyer; the adviser ecosystem is the gatekeeper.
The structural implication for Blast EcoShield is that the commercial pathway runs through the ecosystem rather than around it. A successful scale-up sequence looks like: pilot deployment on a non-sensitive site (e.g. a local authority public realm scheme) producing an independently witnessed performance record; RSES-engineer validation of a reference design; NPSA familiarisation and inclusion in Protect Duty-adjacent guidance; adoption by CTSAs as an acceptable proportionate measure for Protect Duty duty-holders; and specification at RIBA Stage 0/1 by landscape architects and security consultants working on new build estate projects. Each stage is slow, negotiated, and dependent on trust built in the previous one. The RHS Chelsea appearance is consistent with the first move in that sequence: making the product visible to the landscape and public realm community before the security community is asked to approve it.
Risks, Limitations and the Verification Gap
The substantive analytical risks fall into four categories.
Climate and species dependence. Unlike concrete, vegetation is seasonal and biological. Drought, disease, die-back or winter defoliation could affect performance in ways that a bollard simply does not present. The engineered structural layer is presumably the critical load-bearing element; the vegetation provides the blast and aesthetic function. But any customer assurance case will need to demonstrate how performance is maintained across the full environmental envelope, including deciduous cycles and adverse climatic events.
Verification and NDA gating. Performance data held under NDA is standard practice but limits independent cross-check. For CNI and government deployments the data will eventually need to be provided to a competent authority (NPSA, DE&S OME/OSE, or an accredited test house). Until that process is complete, performance claims remain unverifiable by third parties, a constraint Blast EcoShield will need to resolve through a formalised testing and certification programme.
The injury-mechanism shift. Public messaging states that the EcoShield shifts the dominant injury mechanism from life-threatening blast to lower-severity auditory injury. This is progress, it is not equivalent to full protection. Customer-facing communications must avoid any framing that could overstate capability, particularly for duty-holders who will need to demonstrate a defensible protective assessment to regulators and insurers.
Certification pathway. The route to formal HVM or blast-rated certification for a living system is not a well-trodden one. PAS 68 / IWA 14-1 / ISO 22343 are designed around rigid engineered products. Shelley’s Notified Body background is directly relevant, but the company will need to either achieve formal certification under existing standards or help shape a new assurance pathway, the latter being slow and politically negotiated.
Analytical Assessment
Blast EcoShield is a credible, well-credentialled entrant into a genuine capability gap. The science has independent open-source validation; the leadership bench is almost without peer for an early-stage UK defence technology spinout; the market timing is strong given Protect Duty and biodiversity net gain regulatory pressures; and the ESG framing positions the product as a dual-purpose capital item rather than a single-purpose security cost.
The primary constraint is the transition from academic research output to commercially scalable, assurance-certified infrastructure. That transition is exactly the problem that kills most university spinouts in the protective engineering space. The company appears to understand this, and its personnel choices, particularly the inclusion of Shelley with his explicit Notified Body background, suggest the leadership team has sized the certification challenge correctly.
The Chelsea appearance, taken together with the post-show relocation of the entire garden to the Defence College for Military Capability Integration at the UK Defence Academy, is the most useful single signal currently in the public domain. It places the product simultaneously in front of the landscape and public realm community (which writes Stage 0 briefs) and inside the Ministry of Defence’s (MoD) own training estate (which writes force-protection specifications). That dual placement is a deliberate piece of route-to-market design, and it is consistent with a leadership team that understands the assurance and adoption pathway it has to walk. For the Weapons, Ordnance, Munitions and Explosives (WOME) community more broadly, the Defence Academy destination is the part that matters: it puts a sustainability-framed protective product in the same physical space as the audience that drafts and signs off force-protection requirements.
ISC Defence Intelligence assesses Blast EcoShield as a company to track. The next inflection points worth monitoring are: first publicly announced pilot deployment, particularly with an NPSA-aligned customer; publication or limited release of independently validated performance data; patent grant status; formal engagement with PAS 68 / IWA 14-1 / ISO 22343 test houses; and any teaching, research or assurance work generated through the post-Chelsea installation at the UK Defence Academy. Each of those milestones materially changes the credibility profile of the product and, if achieved, would move the company from interesting research spinout to credible commercial entrant in a market segment that is expanding rapidly under Protect Duty.
Technical Annex: Blast Load Calculation for Civil Structures
This annex summarises the authoritative open-source framework used for blast loading assessment of civilian structures in UK practice, and its relationship to the NATO Allied Ammunition Storage and Transport Publication (AASTP-1). It is intended as a reference for practitioners evaluating the performance envelope in which products such as Blast EcoShield must ultimately be demonstrated.
Hopkinson–Cranz Scaling
Blast loading in UK civil practice is calculated using the Hopkinson–Cranz cube-root scaling law:
Z = R ÷ W1/3where Z is the scaled distance (m/kg1/3), R is the stand-off distance (m) between charge centre and target, and W is the explosive mass expressed as TNT equivalent (kg). The cube-root relationship means that stand-off distance is the single most effective mitigation parameter: every additional metre significantly reduces incident pressure and impulse. Doubling stand-off reduces scaled distance by a factor of two; halving the charge mass reduces scaled distance only by a factor of ~1.26, stand-off beats charge reduction for any proportionate increase.
Kingery–Bulmash Empirical Relations
From scaled distance, empirical methods, principally the Kingery–Bulmash (1984) equations and associated charts, give peak side-on overpressure Pso, reflected pressure Pr, positive phase duration t0, and impulse I. These parameters feed into pressure–impulse (P–I) diagrams against which component and structural damage are assessed. Glazing is a particular focus because flying glass is the dominant injury mechanism in most urban blast events.
UK Software Tools and Design Practice
In UK engineering practice the Kingery–Bulmash framework is embedded in two families of tools. Viper::Blast (developed by Arup with CPNI/NPSA input) is widely used for UK government and CNI projects and has been validated against UK-specific test data. ConWep-based tools, originating from US Army Corps of Engineers methodology, are used in international practice and academic research. Both implement the same underlying empirical relationships but differ in their default assumptions about charge geometry, reflective surfaces, and component libraries.
Blast loads are applied to exposed surfaces (front, side, roof, rear) as time-history pressure distributions, accounting for reflection, clearing and confinement effects. Damage is assessed against defined levels of protection, typically described as superficial, moderate, heavy or catastrophic, using P–I curves for the component of interest: glazing, cladding, walls, columns, slabs.
Primary UK Reference Documents
The authoritative references for civilian blast design in UK practice are:
Cormie, Mays and Smith, Blast Effects on Buildings (2nd Edition, 2009, ICE Publishing / Thomas Telford). The core UK reference for civilian blast engineering. Covers threat assessment, wave propagation and scaling, load determination on structures, structural response in steel, concrete and glazing, and mitigation strategies. Widely used across UK structural engineering practice and referenced in NPSA-adjacent work.
BS EN 1991-1-7:2006 (Eurocode 1 Part 1-7: Accidental Actions) with UK National Annex. The formal design standard covering accidental explosions. Its coverage of external blast loads is limited, internal gas explosions and vehicle impact receive more attention, so UK engineers supplement Eurocode 1-7 with the empirical methods described above.
Karlos and Solomos, Calculation of Blast Loads for Application to Structural Components (JRC/European Commission, 2013). A practical, self-contained EU guide that explicitly addresses the gap in Eurocode 1-7, reproducing Kingery–Bulmash charts and worked examples for external terrorist-type blast scenarios. Widely referenced in UK and European civil engineering practice.
NPSA (formerly CPNI) guidance is the ruling framework for UK government and CNI protective security and comprises several directly relevant publications. Protection from Blast (updated 30 August 2024) is the NPSA reference for blast threat assessment, stand-off definition and layered mitigation. A Guide to Specifying Blast Resistance Requirements for Building Facades (October 2025) is the authoritative UK guide for facade specifiers and is particularly relevant to the glazing and curtain-walling element of any integrated protective design. The Integrated Security Guide and the Public Realm Design Guide, Hostile Vehicle Mitigation (3rd edition) set out how to enforce stand-off through vehicle security barriers tested to PAS 68, IWA 14-1 or ISO 22343. NPSA also publishes specific notes on blast-resistant glazing, curtain walling, litter bins and internal glazing, and on fragment-hazard rating of windows.
SCI P244, Protection of Buildings against Explosions (Steel Construction Institute, 1999). Longstanding UK-relevant reference for explosion-resistant design of steel-framed structures; still cited in contemporary practice as a companion to the Cormie/Mays/Smith text.
NaCTSO, Protecting Crowded Places: Design and Technical Issues. The ruling guidance for crowded-place security produced by the National Counter Terrorism Security Office. Provides the framework within which Safety Advisory Groups and Counter Terrorism Security Advisers (CTSAs) assess whether proposed measures (including vegetated barriers) constitute proportionate Protect Duty compliance.
NPSA Protective Security Methodology: DBT and Layered Mitigation
For UK government buildings and CNI sites, the calculation framework described above is applied inside a wider NPSA methodology built on two central concepts. The first is the Design Basis Threat (DBT), a site-specific, intelligence-led definition of the weapon type, charge mass, delivery method (vehicle-borne IED, person-borne IED, projected device) and realistic stand-off that the design must defend against. DBT data itself is restricted and not published in open literature; NPSA and the CTSA network provide it to cleared customer organisations on a need-to-know basis.
The second concept is layered mitigation, captured in the Deter/Detect/Delay/Mitigate model. In hierarchy of effect: (1) maximise stand-off distance between the threat and the asset, the single most effective control; (2) keep the threat outside the building through screening, access control, and HVM barriers; (3) target-harden the asset itself through blast-resistant facades, structural robustness against progressive collapse, and internal measures. NPSA’s expectation is that any protective measure is assessed for its contribution to each layer, not just its notional overpressure reduction. A vegetated barrier that contributes to stand-off enhancement and to Layer 1 perimeter management is evaluated as a complement to, not a replacement for, certified HVM at the vehicle-delivered threat line.
The AASTP-1 Relationship
For NATO ammunition storage and transport scenarios, AASTP-1, Manual of NATO Safety Principles for the Storage of Military Ammunition and Explosives sets out quantity-distance (QD) relationships that would be used in place of the civilian framework described above. AASTP-1 is the ruling document for ammunition storage sites, training area risk assessments, and logistic handling of Net Explosive Quantity (NEQ) at military installations. It is not the applicable document for civilian office, retail or public realm buildings. Practitioners should not conflate the two: AASTP-1 QD tables are designed around ammunition magazines and potential explosion sites (PES), not around Protect Duty-driven threats in the public realm.
In the UK there is no single official “blast radius” table or formula for civil buildings (offices, crowded places, retail, general commercial structures) equivalent to the HSE quantity-distance tables used for explosives storage licensing. The empirical Kingery–Bulmash framework above, implemented through Viper::Blast or ConWep-family tools and interpreted against Cormie/Mays/Smith, is the de facto standard.
Implications for Living Protective Barriers
A product like the EcoShield must, ultimately, be characterised within this same framework: scaled-distance tests producing measured Pso reductions, P–I curves showing the shift in component damage state, and eventually, if intended for HVM duty, certification against PAS 68, IWA 14-1 or ISO 22343 impact standards. The 2020 hedge blast attenuation research sits credibly within this framework and provides a baseline against which engineered vegetated systems can be benchmarked. The commercial question is whether Blast EcoShield can move from the academic reference frame to the certified-product reference frame. That transition is the thing the company’s advisory structure, particularly Peter Shelley’s Notified Body experience, is best configured to enable.
References and Sources
- Blast EcoShield Ltd, company website (Home, About Us, Technology, Products). https://blastecoshield.co.uk/ and /about-us COMPANY
- Blast EcoShield Ltd, LinkedIn company page (RHS Chelsea 2026 / GreenSTEM announcement post, January 2026). LinkedIn announcement post COMPANY
- Pollinger, L., Saving Lives One Leaf at a Time: Blast EcoShield, a modular plant barrier at Chelsea Flower Show. Manufacturing & Engineering Magazine, 22 April 2026. memuknews.com TRADE MEDIA
- Companies House, Blast EcoShield Ltd (Company Number 17070942), registered England and Wales. https://find-and-update.company-information.service.gov.uk/company/17070942 UK OFFICIAL
- Cranfield University, Dr Rachael Hazael profile. cranfield.ac.uk/people/dr-rachael-hazael-17985503 ACADEMIC
- Cranfield University, institutional homepage. https://www.cranfield.ac.uk/ ACADEMIC
- UK Ministry of Defence, Defence College for Military Capability Integration, UK Defence Academy. Cranfield University is the academic provider. Defence Academy of the United Kingdom UK OFFICIAL
- Royal Horticultural Society, RHS Chelsea Flower Show 2026, Great Pavilion (GreenSTEM area). rhs.org.uk INDUSTRY EVENT
- ScienceDirect, Innovative Protection of Urban Areas: Experimental Research on the Blast Mitigating Potential of Hedges (2020). Peer-reviewed free-field blast testing of vegetation species. https://www.sciencedirect.com/science/article/abs/pii/S2352012420300321 PEER-REVIEWED
- Cormie, Mays and Smith, Blast Effects on Buildings (2nd edition, 2009), ICE Publishing / Thomas Telford. Core UK reference for civilian blast engineering. https://www.icevirtuallibrary.com/isbn/9780727735218 REFERENCE TEXT
- BS EN 1991-1-7:2006, Eurocode 1, Part 1-7: Accidental Actions, with UK National Annex. BSI Group STANDARD
- Karlos and Solomos, Calculation of Blast Loads for Application to Structural Components, JRC Technical Reports, European Commission (2013). https://publications.jrc.ec.europa.eu/repository/handle/JRC87200 EU OFFICIAL
- UK National Protective Security Authority (NPSA), Integrated Security Guide and Public Realm Design Guide, Hostile Vehicle Mitigation (3rd edition). https://www.npsa.gov.uk UK OFFICIAL
- NPSA, Protection from Blast guidance, updated 30 August 2024. https://www.npsa.gov.uk/protection-blast UK OFFICIAL
- NPSA, A Guide to Specifying Blast Resistance Requirements for Building Facades, October 2025. https://www.npsa.gov.uk UK OFFICIAL
- NPSA, Security Overlay to the RIBA Plan of Work and Build it Secure programme materials. https://www.npsa.gov.uk UK OFFICIAL
- NaCTSO, Protecting Crowded Places: Design and Technical Issues. ProtectUK / National Counter Terrorism Security Office. https://www.protectuk.police.uk UK OFFICIAL
- Register of Security Engineers and Specialists (RSES), maintained by the Institution of Structural Engineers (IStructE) and the Institution of Engineering and Technology (IET). RSES via IStructE PROFESSIONAL BODY
- SCI P244, Protection of Buildings against Explosions, Steel Construction Institute (1999). https://www.steel-sci.com REFERENCE TEXT
- RIBA, Plan of Work 2020. Royal Institute of British Architects. https://www.architecture.com PROFESSIONAL FRAMEWORK
- Terrorism (Protection of Premises) Act 2025, “Martyn’s Law”: Protect Duty obligations for UK public venues. https://www.legislation.gov.uk UK LEGISLATION
- NATO, AASTP-1: Manual of NATO Safety Principles for the Storage of Military Ammunition and Explosives. NATO Standardization Office. NATO STANDARD
- Kingery, C. N., and Bulmash, G. (1984). Airblast parameters from TNT spherical air burst and hemispherical surface burst. ARBRL-TR-02555, US Army Ballistic Research Laboratory. TECHNICAL REPORT
- Environment Act 2021, biodiversity net gain provisions. UK Government. https://www.legislation.gov.uk/ukpga/2021/30 UK LEGISLATION
- PAS 68:2013, IWA 14-1:2013, ISO 22343-1:2023, vehicle security barrier impact performance standards. ISO 22343-1 STANDARD
- FloralDaily, Taking a peek at the Great Pavilion at RHS Chelsea Flower Show (industry coverage of the Great Pavilion exhibitor lineup). floraldaily.com TRADE MEDIA
ISC Commentary
The choice of RHS Chelsea as a launch venue is the analytical point worth dwelling on. Counter-terrorism products do not usually appear in the Great Pavilion, and the GreenSTEM exhibit is a deliberate piece of route-to-market design. The Chelsea audience is the population that writes Stage 0 design briefs, landscape architects, public realm designers, local authority estate teams, the architectural community generally. Putting a living blast barrier in front of that audience, sponsored by Cranfield University and branded as “nature-inspired protective engineering,” is how a product gets specified into a new development at concept stage rather than retrofitted by a security engineer at Stage 4 when the geometry is already fixed.
What makes the announcement defence-relevant rather than merely horticultural is the post-show destination. Relocating the entire Chelsea garden to the Defence College for Military Capability Integration at the UK Defence Academy, with Cranfield as the academic provider, places the product directly inside the Ministry of Defence’s own training environment, in front of the audience that ultimately writes force-protection specifications. It is a quietly significant signal, and it is the kind of thing a leadership team containing a former head of the UK bomb disposal profession and a former head of Army Explosive Engineers would know how to arrange.
The constraints remain real. Performance data is NDA-gated; certification pathways for living systems are not yet well-defined under PAS 68, IWA 14-1 or ISO 22343; and the seasonal and climatic variability of vegetation is a genuine assurance challenge that concrete does not present. ISC Defence Intelligence assesses Blast EcoShield as a company to track closely. The key inflection points are first publicly announced pilot deployment, public release of independently validated performance data, engagement with a recognised test house, and any teaching or assurance work generated through the Defence Academy installation. Each materially changes the credibility profile; together they would move the company from credible research spinout into credible commercial entrant in a market that is expanding rapidly under regulatory pressure.