Invest smarter, decarbonise faster
When judged on upfront cost alone, low carbon systems can appear more expensive. But when assessed on whole-life performance, energy, maintenance, resilience and asset value, they often reduce the total cost of ownership. Here, Laurie McKelvie, Technical Delivery Lead at IES, challenges the myth that Net Zero building services are financially harmful.
The built environment sector has spent too long treating decarbonisation as a burden on balance sheets, when in reality the greater financial risk is failing to act.
Too often, low carbon design is still viewed through the narrow lens of upfront capital expenditure; installing a heat pump or investing in an early stage modelling exercise may look like an added cost when viewed in isolation, but both can have major financial benefits in the long-term. The installation cost should always be weighed against its long-term impact on energy use, maintenance, resilience, compliance and asset value over the next 20, 30 or 40 years.
Early engagement
This is particularly important for building services engineers, because many of the most important performance decisions are made at the design stage. Once the form, orientation, façade and space use assumptions are locked in, the room for improvement narrows quickly. Early engagement enables project teams to test different servicing strategies, interrogate likely operational performance and understand the financial implications of decisions before they become more expensive to reverse.
For buildings already in operation, the same principle applies through retrofit. Most of the buildings that will exist in the coming decades are already standing, so Net Zero cannot be delivered through new-build design alone. Existing assets need a clear, evidence-led route to better performance, whether that means improving controls, upgrading HVAC systems, electrifying heat, adding renewables or prioritising fabric improvements.
The risk is that retrofit is sometimes treated as a shopping list of low carbon measures, rather than a whole-building performance challenge. Installing new technology without understanding how the building actually behaves can lead to poor payback, comfort issues and missed savings. Before capital is committed, owners and operators need to know which interventions will have the greatest impact, in which order they should be delivered, and how they will affect cost, carbon and comfort in practice.
Gathering the data first
Performance modelling technology is central to this shift. Dynamic simulation and whole-life building performance modelling enable teams to test how a building is likely to behave in real-world conditions. That includes energy use, carbon emissions, internal comfort, peak loads and the likely impact of different technologies or control strategies. For existing buildings, calibrated models and operational digital twins can then compare expected performance with live data, helping facilities teams identify waste and prioritise the interventions most likely to pay back.
Take the University of Liverpool, for example. The IES Live performance modelling tool was used to evaluate the real-time impact of an HVAC refurbishment project, resulting in operational cost savings of £50,000 and a 20.9% reduction in energy consumption from February 2023 until May 2025.
Take United Wholesale Scotland (UWS) as another example. At its Queenslie headquarters in Glasgow, the IES Live performance modelling tool identified potential annual savings of £25,000 to £30,600 within the first 12 weeks, followed by a further £18,000 to £21,700 in the project’s second phase. This is equivalent to 117 to 140MWh of annual energy savings and an 8% to 10% reduction in site energy intensity.
The sector needs to move away from the assumption that low carbon building services are a financial burden. The better question is: which poorly evidenced decisions are already costing us? Net Zero does require upfront investment, but with the right data, used early enough and carried through into operation, it can also be one of the clearest routes to lower operating costs and better performing buildings.
