MEP design and installation: from site survey to commissioning

In short

MEP stands for mechanical, electrical and plumbing: the engineering systems that make a building usable. Fire protection is usually designed alongside them. A project runs from a site survey through concept and technical design to installation, testing and handover. The step most often underrated is commissioning, the documented check that the systems work as the owner needs. It pays for itself: in a study of about 1,500 North American buildings by Lawrence Berkeley National Laboratory, commissioning of existing buildings paid back in a median of 1.7 years. For fire safety, the key is the integrated test, which checks that fire alarm, ventilation, lifts and doors respond to each other correctly, not just one by one.

What MEP covers

• Mechanical, electrical, plumbing. US Air Force facility standards spell MEP out that way and name fire protection systems next to it, to be "coordinated into the overall design."
• Building services. The UK equivalent term covers, in the list of CIBSE (the UK engineering body for building services): lighting, heating and ventilation, lifts and escalators, acoustics, plumbing, power supply, energy management, and security and safety systems.
• One group in specifications. The US and Canadian specification format MasterFormat puts these trades together as the "Facility Services Subgroup": fire suppression, plumbing, HVAC, integrated automation, electrical, communications, and electronic safety and security.

How a project runs

The RIBA Plan of Work 2020, the UK framework for building projects, has eight stages:

0. Strategic Definition
1. Preparation and Briefing
2. Concept Design
3. Spatial Coordination
4. Technical Design
5. Manufacturing and Construction
6. Handover
7. Use

Three points matter for engineering systems:

• Surveys come first. Site surveys belong to Stage 1 and must be ready before concept design starts.
• Coordinate before drawing details. Stage 3 checks that the architectural and engineering designs fit together in space before the detailed construction information is produced in Stage 4.
• Commissioning is part of construction. Stage 5 ends with manufacturing, construction and commissioning completed. RIBA's fire safety tasks name commissioning of fire detection, alarm and ventilation systems.

In Russia, design documentation for a building has a section on engineering systems and a separate section on fire safety. It is followed by working documentation (working drawings and equipment specifications) that implements the design. The national standard GOST R 21.101-2020 marks the two as "P" and "R".

In Azerbaijan, under the Urban Planning and Construction Code:

• the project includes engineering surveys and a section on engineering utility systems;
• the author of the project supervises construction to check that it follows the approved design;
• to get permission to operate the building, the owner submits, where the norms require it, documents confirming that the building, its parts or its engineering systems were checked for readiness;
• the warranty for the building is at least two years from the day operation is permitted.

Commissioning is more than switching on

The word means different things in different standards, so it is worth agreeing on it in the contract:

• ASHRAE (USA) defines commissioning as a quality-focused process that verifies and documents that the systems are "planned, designed, installed, tested, operated, and maintained" to meet the owner's project requirements.
• RIBA (UK) uses a narrower sense: calibrating and adjusting the systems until they work as specified.
• NFPA 3, the US standard for commissioning fire protection and life safety systems, calls it a systematic process that provides documented confirmation that the systems work according to the design criteria.

The Whole Building Design Guide, a US reference maintained by the National Institute of Building Sciences, stresses that commissioning should start at the pre-design stage. It is not complete until off-season testing is done and the systems manual has been handed to the owner.

Test each system, then all of them together

NFPA 3 separates two kinds of test:

• An acceptance test checks one system against its approved design and the codes.
• An integrated test confirms that "operation, interaction, and coordination of multiple individual systems perform their intended function."

The companion standard NFPA 4 sets the minimum requirements for integrated testing of fire protection and life safety systems. The test checks the sequence of operations and the accuracy of the record documents. Its annex lists systems typically included:

• fire alarm;
• smoke control;
• emergency power;
• lifts;
• doors and shutters closed or opened by the fire alarm;
• ventilation and building management systems controlled by the fire alarm.

Where US jurisdictions adopt the 2021 International Building Code, high-rise buildings need an NFPA 4 integrated test before the certificate of occupancy. After that it is repeated at least every 10 years, unless the test plan sets another interval.

In the UK, the CIBSE Commissioning Code M (2022) sets out the sequence:

1. Factory acceptance tests.
2. Sample checks of the installation.
3. Pre-functional tests.
4. Functional performance tests.
5. Integrated systems tests.
6. Tests of continuous operational performance.
7. Training of users and operators.
8. Handover of the commissioning documents.

It is followed by fine-tuning and seasonal testing once the building is in use.

What commissioning finds, and what it pays back

Lawrence Berkeley National Laboratory (LBNL) analyzed commissioning in 643 US buildings in 2009:

In the projects with detailed records, commissioning found 6,652 deficiencies in existing buildings and 3,528 in new ones. In new construction, the mechanical systems had the most problems.

LBNL's 2020 update grew the sample to about 1,500 buildings. It reported:

• median costs down to $0.26 per ft² for existing buildings and $0.82 for new construction;
• a median payback of 1.7 years for existing buildings;
• energy savings rarely measured in new construction, so the 2009 figure is still the best available.

It also found benefits beyond energy in at least 75% of new construction projects, among them construction and occupancy on schedule, correctly sized equipment, thermal comfort and trained staff. The authors add that fixing design deficiencies before construction "can of course be expected to be more cost-effective" than fixing construction defects later.

Handover

• Documents. RIBA's building manual is a summary of all key information about a building, including the fire safety information. The US standard ASHRAE 202 now calls for a preliminary commissioning report at substantial completion and a final one at the end of the warranty period.
• Required by law. In England, the builder must notify building control that the fixed building services covered by the ventilation and energy efficiency requirements have been commissioned, and must hand fire safety information to the person responsible for the building.
• Aftercare. BSRIA's Soft Landings framework hands the building over gradually. It then evaluates it in use no sooner than 12 months after handover, repeating every 12 months up to month 36.

Why one team

The US Design-Build Institute of America calls a single contract for both design and construction "the fundamental difference between design-build and other project delivery systems." We found no study that measures the benefit of one team for building services. The case rests on the points above: commissioning should start at pre-design, design deficiencies are cheaper to fix before construction, and integrated tests check the joints between systems, which is exactly where separate contractors meet.

Common mistakes

• Starting commissioning at the end. WBDG advises starting it at pre-design.
• Testing systems only one by one. The fire alarm may work, and the smoke fans may work, but only an integrated test shows whether the alarm starts the fans, releases the doors and controls the lifts.
• Handing over without documents. WBDG says commissioning is not complete until the systems manual has been handed to the owner.
• Leaving "commissioning" undefined in the contract. ASHRAE, RIBA and NFPA mean different things by it.