Offsite Construction Dictionary

Offsite Construction - Offsite Terminologies

SIPTech Construction is committed to keeping the world of offsite technology and manufacture informed and connected. The below glossary has been devised to assist users understand the most common technical and industry specific terms. This glossary is continuously updated in accordance with industry changes and upon user request.


A heated building should be designed to limit uncontrolled air filtration through the building fabric, to reduce heat loss. Achieved by providing a continuous barrier that resists air movement through the insulation envelope and limits external air paths. Low air filtration measured by airtightness testing will contribute to energy performance but should not be so low as to affect the health of the occupants or the building fabric.

Building Information Modelling (BIM)

BIM is the utilisation of computer model data for effective creation, design and maintenance of building assets. This results in a collaborative way of working that is visualised via 3-dimensional computer models.

Computer Aided Design (CAD)

A CAD tool acts as a vessel for the end user to produce a bespoke conceptual design based on the standard components that reflects the end users’ requirements.

Computer Aided Manufacture (CAM)

Control of manufacture machinery via computer software is considered as computer aided manufacture, if integrated with the computer aided design it is classified as CAD/CAM.

Computer Numerical Control (CNC)

A production machine controlled electronically via computer technology to reduce production time and increase efficiency and quality. The CNC machine uses digital information to control movement of tools and parts for processes such as cutting etc.

Design For Manufacture And Assembly (DFMA)

Concept of designing out systems and products that are tailored for ease of manufacture, assembly and transport. Therefore, important to understand the available supply chain components, logistical arrangements, capabilities of the manufacturing process and any on-site restrictions.

Embodied Carbon

Represents the carbon emissions emitted as a result of primary energy use at each stage in a building’s lifetime.

Embodied Energy

All energy consumed in each lifecycle stage of an activity or product including energy used in winning raw materials, the processing and manufacture of products, maintenance, repair and end of life disposal.

Industrialised Building Systems (IBS)

Industrialised Building Systems (IBS) is a term coined to represent the prefabrication and construction industrialisation concept. The term was created in order to shift away from prefabrication with extra emphasis placed upon improved quality, safety and productivity.


Successful development or implementation of new ideas, products, processes or practices to increase organisational efficiency/performance.

Life Cycle Analysis (LCA)

Evaluation and compilation of all input/output flows and potential environmental impacts of a system throughout its lifecycle. 

Life Cycle Cost

The economic performance of a built system, taking into account initial, operating and maintenance costs.

Modern Methods of Construction (MMC)

Modern Methods of Construction serve to offer improved processes and products. MMC aim to improve quality, customer satisfaction, business efficiency, sustainability, environmental performance and the predictability of delivery schedules. MMC takes a broader generic stance as opposed to a particular focus on product. MMC induce people to seek improvement in better processes, in the delivery and performance of construction.

Modular Construction

Modularisation of construction is a way of reducing complexity but still offering bespoke and customised solutions. The Modular Building Institute (MBI) defines modular construction as an ‘offsite process, performed in a factory setting, yielding three-dimensional modules that are transported and assembled at the building’s final location’.

Offsite Manufacture (OSM)

Manufacture of systems or components in a factory environment to be transported and assembled on site.

Operational Energy

The amount of energy consumed during the normal functioning of the building systems such as water and space heating, lighting and appliances.


Process of maximising the impact of beneficial variables whilst minimising the effect of detrimental variables to create on balance the perfect end solution. An optimal sustainable solution therefore should achieve the correct balance between environmental, social and economic considerations in order to meet the present requirements without compromising the resources of future generations.

From a technical design perspective, an optimised solution should look to maximise acoustic, thermal and energy performance criteria without infringing upon cost (build and whole life cycle) giving due consideration to the manufacture and assembly process.


Two or more organisations collaborating to improved performance through agreeing mutual objectives, devising a way for resolving any disputes and committing to continuous improvement, measuring progress and sharing the results.

Prefabricated (Pre-Fab Construction)

Prefabrication can cover offsite prefabrication of components and subassemblies, prefabrication of parts and materials, as well as covering modules or volumetric units.


Extensive use of components, processes or methods in which there is repetition, regularity and a background of successful practice.

Sustainable Construction

To achieve sustainable construction, the basic ‘triple bottom line’ (social, environmental and economic) principles of sustainable development need to be incorporated. If achieved, the construction process would be environmentally responsible, socially aware and be both economic and profitable.

Sustainable Development

Ensures a better quality of life for everyone both now and in the future. Therefore must be capable of meeting the requirements of the present, without compromising the ability of future generations to meet their own needs. Sustainable development includes three broad components: social, environmental and economic, often known in industry as the ‘triple bottom line’.

Thermal Bridge

Caused by a break in the insulation of the building fabric resulting in heat loss, due to enhanced thermal conductivity between the internal and external.


Thermal Bridge can be found in 3 different situations:

1.    Repetition of regular pattern i.e. studs in a timber frame
2.    Inclusion of non-reptitive elements i.e. lintels etc
3.    Junction of two different planes in the building i.e. corners

U-Value (Thermal Transmission)

The flow rate of heat through and across a thickness of layered materials by given a difference of temperature at both sides. Materials with high resistance to heat transfer are generally good materials for a low thermal transmission. 

SIPTech Construction hope that you have found the offsite terminology glossary informative and of use, if you have any suggestions or requests for offsite keyword definitions, you are more than welcome to contact us to submit your request.