Commissioning services.

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What are commissioning services?

Commissioning is a vital process that ensures mechanical and electrical installations operate as intended, achieving the performance and environmental conditions specified in the design. It confirms that all systems are safe, efficient, and fully functional before handover.

At Complii, we provide a complete range of commissioning services for new and existing buildings, helping clients meet the highest standards of quality, safety, and environmental performance. All work is undertaken in accordance with CIBSE, BSRIA, and Health & Safety Executive guidelines.

We are certified to BS EN ISO 9001, BS EN ISO 14001, and OHSAS 18001 standards, and are proud members of BSRIA, BESA, and the CSA (Commissioning Specialists Association). Our experienced engineers ensure every project is delivered with precision, professionalism, and compliance at its core.

Our memberships and accreditations

Why choose Complii?

How we can help.

Protect your people, property, and business. Here’s why we’re the right choice for commissioning services.

Ensures design intent is achieved

Commissioning verifies that systems perform as designed, ensuring environmental conditions such as temperature, air quality, and energy use meet specification.

Improves building performance and efficiency

Through careful testing and balancing, we identify inefficiencies, optimise system operation, and help reduce long-term running costs.

Reduces defects and operational issues

Thorough pre-commissioning checks and fault finding help prevent costly breakdowns, ensuring reliable performance from day one.

Ensures compliance and quality assurance

Our commissioning work follows recognised industry standards including CIBSE codes A & W and BSRIA BG29/2021, providing full traceability and documentation.

Supports sustainability targets

Effective commissioning helps buildings meet environmental and energy efficiency requirements, supporting BREEAM and LEED certification where applicable.

Provides complete project transparency

We supply comprehensive documentation and test packs, giving project teams and building operators clear insight into system functionality and performance.

Your questions answered.

Commissioning ensures that building systems operate correctly, safely, and efficiently. It verifies performance against design intent and reduces the risk of post-occupancy issues.
Commissioning should begin during the late stages of installation and continue through system testing, adjustment, and verification before project handover.
Yes. We offer commissioning management and supervision services to coordinate all activities, ensuring smooth integration between contractors and compliance with industry standards.
All work is completed in accordance with CIBSE codes A & W, BSRIA guidance, and HSE requirements, ensuring full quality and safety compliance.
Yes. Our commissioning services support BREEAM credits and sustainability objectives by demonstrating that systems meet performance and efficiency standards.

News & insights

News / November 1, 2025

Introducing Complii: A new chapter in building safety and compliance

For years, navigating the world of building safety and regulatory compliance has felt complicated and fragmented. You might work with one specialist for your fire systems, another for water quality, and yet another for electrical testing. It's a system that creates administrative waste, unnecessary risk, and makes it hard to get a complete, clear picture of your building's health.

Insights / September 23, 2025

The benefits of thermographic imaging

Thermographic imaging is a powerful tool for identifying potential electrical faults before they become serious problems. By using specialist thermal cameras, engineers can detect heat patterns that indicate issues such as overloading, loose connections, or failing components.

For businesses, this proactive approach helps reduce risks, avoid costly downtime, and demonstrate compliance with electrical safety regulations.

News / September 23, 2025

PH Water and Air Technologies joins Complii

We are pleased to announce that PH Water and Air Technologies has joined Complii. This addition strengthens our water and air compliance services and further supports our mission to provide trusted, integrated compliance solutions across the built environment.

See all news and insights

Compliance with confidence.

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