Total building digitalisation overcomes the need to source original architect drawings, which may be outdated due to internal changes, and does not rely on conventional manual site measuring systems, which can be time-consuming and inaccurate due to human error.

It uses a smart three-dimensional optical scanning system linked to laser-based lidar cameras placed at strategic points within and outside a building. This builds a detailed digital twin of the building by 'stitching together' successive scans, including individual spaces within floors and any existing HVAC services.

The high resolution file produced is imported into standard HVAC design and BIM applications to design a complete building services solution, ensuring all dimensions are accurate and equipment and pipe lengths sized accurately first time.

Jack Smelt, who heads BREng's Digital Buildings section, said: 'Using a 'digital twin' dramatically reduces the time it takes to design and plan air conditioning, heating and ventilating services for buildings, in both new and replacement projects.'

He added: 'It also eliminates guestimation from project design, as the building lay-out and all dimensions are rendered accurately, to the millimetre.'

In addition to their use in HVAC project design, the 3D renders can be used to create virtual 'walk-throughs' of buildings, with the ability to accurately measure dimensions.

Any building can be scanned, whether back-to-brick or fully fitted out. Buildings do not have to be empty – the process can be carried out on operating buildings, with an automatic face-blur function ensuring occupant privacy.

Smelt said: 'The conventional process for creating building plans often requires the contractor or consultant to visit a site and manually measure the building and individual spaces, including window and door dimensions, and accounting for existing services such as indoor units, radiators, ductwork, lights and electrical sockets.

'This is time-consuming and subject to error, leading to mistakes in project design that can result in time and cost penalties during installation. Using a digital building scan overcomes these issues and ensures a right-first-time result.'

BREng reports a 75% reduction in site visits required by project stakeholders, and a 70% reduction in survey costs and BIM file creation. In addition, three-quarters of project issues can be resolved without escalation.

With the need to improve building efficiency, BIM is increasingly being used across construction planning, particularly on HVAC services for large public and commercial buildings. As well as saving time and cost, digital scans can be used as records of pre-existing building condition before commencement of work on refurbishment projects, enabling any damage caused during work to be fairly apportioned.

To date, BREng has created digital twins of multi-storey offices, an NHS medical centre, internal HVAC plant rooms and building roof-tops.

'It is invaluable to be able to view and interact with the digital twin after a site visit, to check details of, say, window heights or pipework lay-out, to make sure our proposed new solution dovetails perfectly with the building fabric and any obstacles that need to be accommodated.'