BUILDING LOG BOOK | What and Why?

August 21, 2022 |

Under the Building Regulations [England], Approved Document L2A, a Building Log Book should be written and issued to the building owner/operator no later than five days after all building works have been completed. The document is to provide enough detailed information to allow the energy-efficient running and maintaining of the building services systems in line with the design intent, helping to control and minimize the energy consumption and use of fuel and power.

Below, we will run through a logbook, who should produce it, its format, and issuing it to facilities.

Quick, What is a Building Logbook?

It’s a simple live high-level handbook issued to the building operator providing them with an overview of the design and operation of the building services systems, allowing better maintenance, more efficient operation and logging/documenting of future data.

Who should produce and write the building logbook?

The overall responsibility of the logbook is the client/building owner to ensure it is completed.

To do this, they will usually pass the responsibility onto their design team, where the Building Services Designer will usually be tasked with specifying, writing, overseeing, and managing it.

The designer will need to manage the multiple inputs from differing parties required to ensure it is completed and the correct detail. Parties involved would be:

  • Other elements of the design team
  • Other team members [building services engineers, facilities manager, maintenance department]
  • Main/General Contractor
  • Sub Contractor
  • Specialist Vendors [Equipment, BMS, Controls]
  • Other specialist authors

Under What Circumstances should they be Issued?

Building Logbooks are a requirement and should be written upon the construction/completion of the following types of works:

  • Construction of any New Building [other than dwellings]
  • Fitout works if part of a new building
  • First fit-out of shell and core floor, if the shell is sold or let before the fit-out work is completed. We would however specify in the tenancy agreements that a log book should be provided for any fit-out works.
  • Existing building extensions, not dwellings, where the total useful floor area is 1. greater [>] than 100m2 and 2. greater [>] than 25% of the total useful floor area of the existing building.

Exempt non-dwellings, per Approved Document L2A, are noted as:

  • Places of worship
  • Temporary buildings
  • Industrial sites, workshops, and agricultural buildings with low energy demands.

When should the Document be Started, Updated and Issued?

The document should be specified from the outset of the project to ensure that all parties in the future tendering process fully understand and allow for the expectations.

We would integrate and manage the progress in line with the commissioning process activities and tasks planned and delivered throughout the project, making a note in each monthly update.

Where to Store it for Future Reference?

The document should be stored as a digital building logbook [.doc] & [PDF] and a controlled hardcopy format.

The hardcopy should be stored electronically with any operating and maintenance manuals; this would usually be within the project/building’s electronic document storage and retrieval system.

How Big should the Document be?

It depends upon the size and complexity of the project; the larger and more complex the construction, the larger the document.

Overall the document should provide enough detailed information that provides the building manager with confidence they can understand how the systems work and are to be operated.

As electronic document storage and retrieval systems are used in the industry [Aconex, Asite, Conject, Procore], our building logbooks should become more of a list of clickable links to the information stored in them.

What Format should be used?

To try and keep a standardized approach for the industry, in the past, we have generally formatted our documents in line with the CIBSE ‘TM-31 | Building Log Book Tool Kit’, covering:

  • Building/Facility overview,
  • Overview of areas and occupancy,
  • Responsibility matrix,
  • Contact list,
  • Other important information, key documents, schedules, data,
  • Overview of commissioning activities completed, outstanding observations, documentation obtained, and locations,
  • Overview of the building services design and intent,
  • Summary of main building services plant and equipment and system layouts,
  • Description for the sequence of operations/control logics covering each system,
  • Systems metering, monitoring, and intended strategy,
  • Building performance records for the building [Energy performance certificate] including the data used to calculate the Target CO2 Emission Rate [TER] and Building CO2 Emission Rate [BER],
  • Overview of maintenance activities and safety precautions in managing them,
  • Results of in-use investigations, where any systems under full operation are evaluated and fine-tuned.

Issuing of Building Log books & Training Requirements

Like with the operating and maintenance manual, before issuing to the facilities managers for handover, the document should be presented, showing its purpose and how to use/update it.

The presentation would usually be completed by the building services systems designer in a ‘page turn’ workshop.

The outcome of the workshop should be that:

  • the facilities managers understand the general operation allowing of the building and its systems,
  • any areas of the document that should be updated and information record keeping throughout the building’s life is explained,
  • the ongoing building energy performance monitoring and recording, detailed, and
  • the document is ‘live’ and should be updated upon any changes to the systems that impact the information contained,

Updating Responsibilities

Once the project and documentation have been handed over to the building owner/operator, managing and keeping the logbook up to date will be their responsibility unless the contract states otherwise.

CIBSE TM-31 notes that the facilities manager should review and update the document information at least once a year [annually].

Upon review, it may be determined that no significant changes have been made to the systems that would change the document’s information.

The review would inspect:

  • Any refurbishment/modifications/new works conducted that have changed the use of the building or space,
  • Updating of any new commissioning activities completed,
  • Review and update any maintenance activities and safety precautions,
  • Review the overview relating to the main building services plant, systems, and equipment,
  • Has the design intent within the document been changed or affected,
  • Has there been any modifications to the plant and equipment sequence of operations/controls
  • Any modifications to set points, design flow rates,
  • Update system metering, monitoring, and strategies,
  • Changes to equipment and system timers,
  • Changes to contacts or responsibilities,
  • Update the ongoing building energy performance and metering.

Building Log Book Template [PDF]

We have found a PDF template of the logbook below that can be used for reference if needed.


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