Regulation 40 (Provision of Information), of the Building Regulations 2010, requires a project team to provide a building owner with sufficient information on the building’s services to ensure they can operate the building properly and efficiently as per the technical standard requirements of Approved Document L (Conservation of Fuel and Power) and Approved Document F (Ventilation), of the Building Regulations 2010.   A building logbook is designed to bridge the operational gap between the complex technical data contained in O&M Manuals and the day-to-day needs of the building operator.

The CIBSE TM31 Logbook is the industry’s standard, accepted way of presenting this energy-focused, high-level summary to satisfy the Part L requirement. 

The CIBSE TM31 Logbook is “live” and dynamic document used throughout the operational lifetime of the building, not just a handover file. Responsibility for its maintenance transfers to the Building Owner or Facilities Manager (FM) upon practical completion. This owner/FM is required to review and update the building logbook at least annually to ensure its continued accuracy and relevance.

Which buildings / projects does this apply to?

Enforced by Regulation 40 of the Building Regulations 2010, a building logbook is mandatory for virtually all new non-domestic construction projects in England and Wales.  Specifically, the requirement is mandatory for the following types of projects:

New Non-Domestic Buildings

A logbook must be produced for the construction of virtually all new buildings other than dwellings, including:

• New offices, retail units, and commercial premises.
• New industrial buildings, factories, and warehouses (unless specifically exempted due to low energy demand).
• New public buildings (e.g., schools, hospitals, libraries).

Existing Buildings Undergoing Major Work

The requirement also applies when significant building work is carried out on an existing non-domestic building, particularly if the work affects energy performance or services, including:

• Major refurbishments that involve altering or replacing the fixed building services (e.g., HVAC, lighting, hot water systems).
• Projects where a significant replacement of controlled services or fittings occurs (e.g., installing a new boiler or chiller). In this case, the existing logbook must be updated, or a new one created if none exists.
• The initial fit-out of a shell-and-core building that was sold or let before the fit-out was completed.

Buildings Exempted from Part L Requirements

The logbook requirement does not apply to buildings that are exempt from the energy efficiency requirements of Part L. These typically include:

• Dwellings (covered by separate Part L guidance).
• Temporary buildings, used for less than two years.
• Certain industrial sites, workshops, or agricultural buildings with low predicted energy demands.
• Stand-alone buildings with a total useful floor area of less than 50 m².

Essential Content and Logbook Structure

The CIBSE TM31 Logbook provides a standardised structure to ensure industry consistency and usability. The document is intentionally kept concise, typically running between 20 to 50 pages for a large building, though smaller premises may have a logbook of 5 to 10 pages. Key areas of content that must be summarised include:

• Building Overview: providing foundational information, including the official site address, a description of the building’s function, typical occupancy levels, and the overall architectural and engineering design philosophy. Crucially, it summarises any incorporated passive design measures (e.g., thermal mass, external shading, natural light strategies) and how they are intended to contribute to low energy consumption.
• Design and Performance Data: which establishes the initial energy benchmark for the building. It outlines the initial design parameters and includes the calculated Target CO2 Emission Rate (TER) and the resultant Building CO2 Emission Rate (BER) as assessed through the UK National Calculation Methodology (NCM). This section provides the core numbers against which the FM must compare actual energy use in the future, identifying the ‘performance gap’.
• Building Services Summary: providing a high-level overview of all major fixed plant and equipment installed, focusing on the systems that consume or conserve energy. It includes simplified key system diagrams (not full schematics) for major services (e.g., boilers, chillers, air handling units, and primary electrical distribution). The summary details the key control philosophies, interlocks, and lists the optimal operational setpoints and seasonal switchover procedures to ensure efficient running.
• Metering and Energy Strategy: detailing all energy and water meters, sub-meters, and billing meters physical locations and function. More importantly, this section details the established protocol for logging and monitoring usage data over time, setting up the framework for the FM to gather the data needed for the annual review and energy reporting.
• Maintenance Summary: a simplified, non-technical list of essential routine maintenance checks and schedules for the main plant (distinguishing weekly/monthly checks from annual services) with links to the detailed O&M Manual maintenance processes and procedures. This is designed to be easily accessible for planning and scheduling. It also includes general safety notes and precautions specifically related to accessing and isolating the building services systems.

Relationship to Other Documents

It is important to note that a CIBSE TM31 Logbook does not replace other mandatory documents but functions as a critical high-level reference to them. It is distinct from the comprehensive O&M Manuals, which contain the in-depth technical specifications, maintenance procedures, and manufacturer details as required under the Construction (Design and Management) Regulations 2015 (CDM 2015).  The CIBSE TM31 Logbook simply summarises the key operational information from the O&M Manuals. 

It is also separate from the Health and Safety File, as per Construction (Design and Management) Regulations 2015 (CDM 2015), which details residual hazards and safety information for the building.

Responsibilities, Handover, and Lifetime Use

A defining characteristic of the CIBSE TM31 Logbook is its dynamic nature; it is intended to be maintained and updated throughout the operational life of the building.  The CIBSE TM31 Logbook is increasingly delivered in a digital format (often a hyperlinked PDF or structured data file) to facilitate easy searching, reference, and most importantly, updating.

During the Design and Production phase, the Lead Designer or the Building Services Engineer is responsible for coordinating all necessary input, ensuring compliance with the CIBSE TM31 Logbook format, and managing the document’s compilation.

At the Submission and Handover stage, the Main Contractor or Design Team is responsible for issuing the completed Logbook to the building owner and the Facilities Manager at practical completion. A copy is typically submitted to Building Control as direct evidence of Part L compliance for Regulation 40 approval / sign off. 

Finally, throughout the building’s Operational Lifetime, the Building Owner or Facilities Manager takes over full ownership. They are required to review and update the document annually to log energy performance data, record any system changes or refurbishments, and ensure the Logbook retains its accuracy and relevance for efficient building management.

This crucial, ongoing process involves logging actual building performance data (like energy and water consumption) against the design targets (TER/BER), and recording any system modifications, plant replacements, control changes, or minor refurbishments. This regular update cycle is essential, as it provides an invaluable historical record of performance and changes, allowing management teams to effectively benchmark energy use, troubleshoot discrepancies, and ensure the building continues to be operated efficiently in line with its original regulatory compliance requirements.

Outsourcing Technical Documentation

For contractors and project managers, technical authoring of a CIBSE TM31 Logbook often presents a significant challenge due to time pressure, technical expertise and the need to focus on on-site duties. Outsourcing to specialist technical writing experts becomes invaluable in these situations to ensure that documentation is accurate, concise, delivered on time and cost effective.

Why Choose Dewick & Associates?

Dewick & Associates’ team are fully knowledgeable in the stringent requirements of the Building Regulations and associated construction documentation requirements. By choosing to outsource to us, contractors achieve three key advantages:

• Technical Knowledge: our in-house Chartered Engineers (CIBSE CEng / CPEng. Mech MIEAust) technically author all of our CIBSE TM31 Logbooks.  This professional expertise is crucial for accurately translating complex commissioning and calculation data (TER/BER figures, control sequences and installation details) into the concise, high-level, and non-technical language required.
• Time & Cost Efficiency: freeing up expensive on-site management time.
• Guaranteed Compliance: delivering the complete, verified document necessary for timely Practical Completion and successful handover.
• Complete handover package: proactive document management and early-stage compilation throughout the project lifecycle, preventing last-minute information scrambles and reducing the risk of delays to Practical Completion.

We are able to transform complex, fragmented site data into an accessible, auditable, and high-quality documentation for your project handover.

Coupled with providing fully comprehensive construction documentation, including Building Handover Manuals, O&M Manuals, Health & Safety Files and Regulation 38 Files, CIBSE TM31 Logbooks complete the mandatory documentation provision at handover for your projects. Outsource this to the experts so you can concentrate on the pressing onsite works to complete the project to the high standard required.

Author: Louise Gardner, D&A General Manager