Green by design: why sustainability and national security are not in conflict

The two agendas are in tension, and when forced to choose, security wins. I do not accept this argument. And the evidence from projects across the defence estate suggests it is based on a false premise.

Sustainability and national security are not in conflict. Properly understood, they are complementary. A defence estate that is energy-efficient, resilient and designed for long-term performance is a stronger strategic asset than one that is expensive to run, carbon-intensive and dependent on energy sources that carry their own security risks.

The question is not whether to pursue sustainability in defence buildings. It is how to do it well.

The carbon reality of the defence estate

The MoD is one of the largest energy consumers in the UK public sector. The defence estate encompasses thousands of buildings across hundreds of sites, many of them technically complex and energy-intensive. Operational facilities, data centres, training and simulation environments, workshops and maintenance facilities along with the various types of residential accommodation all carry significant energy loads beyond what a standard commercial or residential building would consume.

Reducing the carbon footprint of this estate is not a simple task. But it is a necessary one. The Government’s net zero commitments apply to the public estate including defence, and the Strategic Defence Review (SDR) reinforces the expectation that sustainability is central to how the defence estate is managed and developed.

For new buildings this means designing to high performance standards from the outset. For the existing estate it means developing credible retrofit strategies that improve fabric performance, reduce energy demand and extend asset life.

Embodied and operational carbon

A meaningful approach to carbon in defence buildings must address both embodied and operational carbon.

Operational carbon, the energy consumed in running a building over its lifetime, has historically been the primary focus of sustainability efforts. Improving insulation, upgrading building services and installing renewable energy generation all reduce operational carbon and deliver measurable cost savings over the life of the asset.

But embodied carbon, the carbon associated with the manufacture, transport and construction of building materials, is increasingly recognised as equally significant, particularly as operational carbon reduces through improved standards and decarbonisation of the grid. For a major defence construction programme, the embodied carbon implications of material selection, structural system and construction methodology can be very substantial.

Modern methods of construction, including modular and offsite fabrication approaches, can support both embodied and operational carbon reduction. Factory-controlled production reduces material waste, improves quality control of the building envelope and, in the defence context, reduces disruption on live operational sites. Our experience at RAF Kinloss Barracks and Stafford Beacon Barracks, where we delivered modular SLA buildings designed to Passivhaus principles, demonstrates that this approach can deliver genuinely outstanding sustainability performance within the constraints and requirements of defence procurement.

Passivhaus and high-performance standards

Passivhaus is the most rigorous energy performance standard available for building design. It demands exceptional levels of fabric performance, airtightness and controlled ventilation, and delivers buildings with very low operational energy demand and genuinely comfortable internal environments.

It is sometimes assumed that Passivhaus standards are difficult to achieve within the constraints of defence procurement, where prescriptive technical requirements and complex security specifications may seem to conflict with the design freedom that high performance standards require. Our experience at Kinloss and Stafford demonstrates that this assumption is wrong.

Designing to Passivhaus principles within a JSP 315-compliant, DIO-approved defence accommodation project is challenging but entirely achievable. It requires design teams with genuine expertise in high-performance building design and a thorough understanding of the MoD and DIO requirements they are working within. When those two things come together the results are buildings that exceed Near Zero Carbon standards, achieve DREAM Excellent ratings and provide genuinely high-quality living environments for the personnel who use them.

As the SDR drives a substantial increase in accommodation investment across the defence estate, the opportunity to embed these standards across a much larger portfolio of projects is significant.

Retrofit and the existing estate

The sustainability challenge in defence is not primarily about new buildings. It is about the vast existing estate, much of which was built to standards that bear no relationship to current expectations of energy performance.

Retrofitting the existing defence estate at the scale required is a major undertaking. It requires a systematic approach to estate assessment, a clear understanding of the condition and performance of existing buildings and a prioritised investment strategy that directs resource to where it will deliver the greatest improvement in performance and value.

Whole-life cost thinking is essential in this context. The upfront cost of a comprehensive retrofit, improving fabric performance, upgrading building services and integrating energy monitoring, will in most cases be more than recovered through reduced operational expenditure over the life of the asset. Making that case credibly to defence clients requires the ability to model costs and benefits over realistic whole-life timeframes and to present the evidence clearly.

Social value in defence construction

Sustainability in the defence estate extends beyond the environmental performance of individual buildings. The social value generated through defence construction programmes, in terms of skills development, employment, supply chain investment and community benefit, is an increasingly important dimension of how these programmes are evaluated.

The Defence Growth Deals explicitly link defence industrial investment with regional economic development and community benefit. Construction programmes associated with defence estate investment represent an opportunity to deliver social value at significant scale: apprenticeships, local employment, supply chain development and investment in the built environments of defence communities.

Designing for social value requires thinking beyond the site boundary. How does a construction programme invest in local skills and employment? How does the design of defence facilities contribute to the wider quality of the communities they sit within? How can new community infrastructure, housing, green space and public realm, be planned in coordination with defence investment to create places that work for everyone?

These questions sit at the heart of what good masterplanning and community-focused design should be asking. They are also central to the social value agenda that is increasingly embedded in public sector procurement.

Why this matters now

The scale of defence investment committed in the SDR and the DIS 2025 creates a genuine opportunity to shift the sustainability profile of the UK defence estate. New buildings designed to high performance standards, retrofit programmes that systematically improve the existing estate, and construction programmes that generate social value in defence communities all contribute to a defence estate that is not only more operationally effective but more sustainable, more resilient and more economically beneficial.

This is not a soft agenda. It is a strategic one. An estate that costs less to run, generates less carbon and supports stronger communities is a strategic asset. The argument that sustainability and national security are in tension underestimates both.