How much does a building digital twin cost?

Two proposals for a building digital twin can carry the same label and describe entirely different things: a 3D viewer with a dashboard, or a verified, integrated operational model with analytics and an obligation to keep it current. Because the label is used so loosely, there is no dependable universal price, whether per square metre or per building. Cost follows the intended capability, the condition of the existing information, the number of systems to be integrated, and what it takes to run and maintain the twin afterwards.

The owner's task, then, is not to discover "the price". It is to define the scope tightly enough that quotations describe comparable work, and then to judge them on whole-life cost, not the first invoice.

What you are actually paying for

Suppliers should be asked to price each of these elements separately:

A low software subscription can sit alongside substantial implementation effort, and the reverse is also true. The last row is where quotations are usually vaguest, so ask exactly what happens, and who pays, when a chiller is replaced or a floor is refitted.

Look five years ahead, and state your assumptions

Initial cost alone can mislead. A comparison over at least five years is more revealing, provided it says whether the figures are discounted.

Over five years, undiscounted, A totals €60,000 + 5 × €12,000 = €120,000 and B totals €25,000 + 5 × €20,000 = €125,000, so A looks cheaper. Discounting the annual costs at an assumed 5% a year (paid at the end of each year) gives present values of about €111,950 for A and €111,590 for B, and B is now marginally cheaper. The ranking depends on the assumptions, and the difference is small either way. The questions that matter more are whether both proposals cover the same assets, data points, users and functions, and which of them includes keeping the twin current.

Make the proposals describe the same thing

Comparable quotations start from a comparable request. Ask for a focused first-use-case option, with clearly priced expansion options, and define in each the assets and systems in scope, the number of data points and integrations, the users and their tasks, the analytical functions and the acceptance tests. A viewer and a validated operational model are not equivalent proposals, however similar their headings.

The costs no supplier will quote

Some of the spending falls on the owner. Staff have to provide records, escort surveyors and answer questions while information is prepared. Each new connection to building systems needs an IT and OT security review. Existing contractors, such as the BMS or metering supplier, may charge to provide points lists, open an interface or attend testing. The information manager needs time to check deliverables and accept the twin, and operators need training and time to learn a new tool. Then there is the effort of acting on the twin's findings, which is where any benefit is actually produced.

These internal costs can decide whether even a modest first use case is affordable, so they should be estimated before suppliers are compared.

Questions that make quotations comparable

• What exactly is included in the first-year price, and what is charged from year two?
• How do prices change with the number of points, assets, users, buildings or integrations?
• What does a typical change cost, such as adding a floor, replacing a chiller or connecting a new meter?
• Does the price include integration with the existing BMS, or assume the BMS contractor's work is paid separately?
• Can the owner export the asset data, relationships and mappings in a documented format, and is there a charge?
• What happens to the model, the mappings and the history if the contract ends?

Test the value before scaling it

A business case should name the decision the twin is meant to improve and how that might affect energy use, maintenance cost, risk or staff time. Energy savings and cost savings need to be kept distinct, since the latter depend on tariffs and contracts, and hypothetical benefits should never be counted as committed savings. The pilot is best designed to test the weakest material assumption in the case. The budget should also cover maintaining the information afterwards: ISO 19650-3 specifies an information-management process for the operational phase of assets, not only for their delivery.