Get in touch

CDM 2015 – The principles of a principled Principal Designer

Energy transition projects commonly involve more than one designer and so require the appointment of a “Principal Designer” (PD). The PD role is crucial in fulfilling and discharging the legal obligations, responsibilities and commitments set out in The Construction (Design and Management) Regulations 2015 (CDM 2015). Often named as the “Principle Designer”, the misspelling perhaps better communicates what this role entails on a typical energy transition project.

Who is the Principal Designer?

Under CDM 2015, a PD is an organisation or individual appointed by the client to take control of the pre-construction phase of a construction project involving more than one designer.

It is the PD’s role to ensure:

  • The asset design evolves in such a way that the risks associated with its entire lifecycle are eliminated wherever reasonably practicable through design or, where not, are reduced As Low As Reasonably Practicable (ALARP) through the provision of effective mitigations.
  • The residual risk is clearly understood by the principal contractor, allowing the design to be implemented with adequate and appropriate mitigations to ensure construction risks are ALARP.
  • The handover to asset owners and those responsible for operations and maintenance is effective, enabling the residual risk to be managed ALARP throughout the operating life of the asset.

The PD must lead all design activities; hence the spelling “principal” is correct. However, the success of leaders is invariably governed by their principles, so perhaps the misspelling “principle” is inadvertently appropriate. As Thomas Jefferson once said, “In matters of style, swim with the current; in matters of principle, stand like a rock.”

But what principles should the PD uphold to deliver the role most effectively?

Principle 1: Know your place

The PD does not need to undertake detailed design – that is the responsibility of suitably qualified and experienced designers appointed by the client for different work packages within the project. The PD’s role is to oversee each design package and coordinate the interfaces to ensure that the overall design coalesces into a final position which ensures that the most significant risks are reduced ALARP.

Principle 2: Trust the process

The basic Safety Assurance Process (SAP) shown in Figure 1 provides a framework to guide each design package to meet the three fundamental requirements of effective risk management:

  • Do you know what can go wrong?
  • Do you have systems in place that will stop this from happening?
  • Can you ensure these systems are working effectively?
Risk Management Process - 5 Complete

Figure 1: Safety Assurance Process

It is the responsibility of each design package to ensure its design evolves in a way that meets these requirements. There are different ways to achieve this. It is important to enable individual designers to adopt the best approach to suit their specific activities for effective project delivery and performance.

The SAP framework is sufficiently high level to provide flexibility to accommodate different approaches and can be used by designers to steer their design towards the desired outcome.

Principle 3: Mind the gap

Energy transition projects are often complex, multi-disciplinary and multi-faceted. As such, one of the biggest risks to their successful delivery is the failure to effectively manage the interfaces between numerous design packages.

If constraints, limitations, hazards and risks which transcend design packages are not adequately shared, then each design package will not be optimised from a health and safety perspective. Careful management of these interfaces is a key priority in executing the PD role.

Principle 4: Consider the full lifecycle

A key characteristic of a typical energy transition project is that it assembles products, designed and built by others, into a specific configuration unique to that project. Examples of such products include a wind turbine, electrical plant and equipment or a hydrogen electrolyser. A large portion of the project’s risk is locked into the design of the product.

Similarly, a significant proportion of the project risk will be bound to the logistics arrangements, for example transportation and installation. It is therefore essential for the PD to look beyond the project risks into the product and logistics elements illustrated in Figure 2.

Services Flow diagram

Figure 2: Lifecycle Approach

The risks associated with the complete lifecycle of the “project”, including “product” and “logistics” elements, must be identified as early as possible in the design process. This provides the opportunity to design out these risks wherever reasonably practicable.

Principle 5: Respect the hierarchy

The principle of ALARP lies at the heart of the UK’s health and safety legislation – a fundamental principle originally enshrined within the Health and Safety at Work etc. Act 1974 and carried forward into CDM 2015.

Assessing whether a risk has been reduced ALARP is about weighing the risk against the sacrifice needed to further reduce it. A condition of “gross disproportion” skews decision making in favour of taking positive steps to reduce safety risk.

If it is shown that the cost, time or trouble to further reduce risk is grossly disproportionate to the risk reduction benefit achieved, then there is no obligation to implement these additional measures. If it is not grossly disproportionate, then there is a legal obligation to implement these further measures.

It is the responsibility of each design package to eliminate or reduce risk to ALARP levels. This is best done by selecting mitigations which follow the principle of “hierarchy of risk control”, or “ERICPD” (Eliminate, Reduce, Isolate, Control, PPE and Discipline) as it is often referred, as illustrated in Figure 3.

Hierarchy of Risk Controls

Figure 3: Hierarchy of Risk Control

Principle 6: Know your onions

It is essential that the PD has a sound, practical understanding of all project design elements. Without this it is difficult to effectively oversee and coordinate the design packages to ensure the objectives of the PD role are achieved.

Given the complexity of energy transition projects, this is impractical to achieve with one individual, given the numerous disciplines and elements involved. A team-based approach offers the opportunity to select individuals who are expert in the different design elements and hence, collectively, are suitably qualified and experienced to oversee the complete design scope.

Principle 7: Implement safety as an enabler

Unlike more mature industries, there are limited precedents and data to rely on to help justify safe operations in many energy transition projects. As a young industry, creative and innovative thinking is needed to develop robust arguments as to why technologies are safe. Otherwise, the safe delivery of projects needed to combat climate change may be jeopardised. Safety must be a key enabler of the energy transition and this proactive, can-do attitude is fundamental to successful projects.

Principle 8: Stick to your principles

A PD can only fulfil its commitments if afforded full visibility of the evolving design in the context of the wider project status. Furthermore, the PD needs the freedom to interact with all stakeholders to challenge whether risk has been reduced ALARP. This requires an open, trusting relationship with the client and for the PD to be an integral part of the project team.

Where there are barriers to this, the PD must work with the client to proactively resolve the situation. If the hurdles are too high, the PD should make the ultimate decision to walk away.

The PD is not there to rubber-stamp designs or perform cursory reviews from afar. The PD must be immersed in the detail, as and when appropriate, to steer the project towards a position that is safe by design. Failure to do this, for whatever reason, is in breach of CDM 2015 and putting people at risk.


The Principal Designer is principled. This article sets out eight key principles for the PD to uphold. Standing “like a rock” on these principles will help to enable projects in the energy transition to meet the goal of ensuring risks are reduced ALARP.


Debunking the myths of CDM 2015 for the Energy Transition
Debunking the myths of CDM 2015 for the Energy Transition
Beyond borders – comparing UK and Irish regulations for construction safety
Beyond borders – comparing UK and Irish regulations for construction safety
Towards a unified approach – Guidance for applying CDM2015 to offshore wind
Towards a unified approach – Guidance for applying CDM2015 to offshore wind

Contact Us

Want to discuss your requirements?
Get in touch

Jump to Top