Jordan Noffke, Senior Energy and Carbon Analyst. Salix
How do you know whether an energy efficiency measure is actually delivering savings? As Salix delivers energy efficiency and low carbon heating projects across the UK’s housing and public sectors, measuring real-world performance is essential.
For our public sector programmes, this forms part of our Annual Carbon Reporting process, through which grant recipients submit energy usage data so that savings can be monitored and verified.
This process is important because it enables us to assess whether funded projects are achieving the intended carbon and energy savings in practice. By reviewing annual energy data against expected performance, we can evaluate the effectiveness of different measures, strengthen accountability for public funding, and build evidence on what works in reducing emissions across the public sector.
This year we’ve implemented some basic principles of Measurement and Verification (M&V) based on guidelines from the International Performance Measurement and Verification Protocol (IPMVP).
While our focus is on verifying carbon savings, good M&V is also vital for building managers and users. It enables them to see whether upgrades are reducing energy use, identify underperforming equipment, and understand project outcomes more clearly.
Our M&V journey is following a ‘good, better, best’ trajectory. The ‘good’ improvements to our processes we’ve made this year are easy to apply and require minimal additional work.
We’re keen to share our learning. The first key step for ‘good’ M&V is to consider your measurement boundary. What data are you able to collect? One option, what IPMVP calls ‘retrofit isolation’, involves either: 1) a comparison of known values when swapping equipment like-for-like, e.g. a new chiller at a lower rated kW input for the same use case, or 2) installing a submeter on new equipment to directly measure its energy draw. The latter case requires submetering to be installed before the measures are installed, to properly measure the baseline. The other type of M&V, and the one that we expect our public sector grant recipients to adhere to, is the ‘whole facility’ approach, which is more suited for projects where submetering is not installed, and baseline data is limited to entire site values, such as gas or electricity meter readings.
Measuring an accurate baseline before any measures are installed is essential to ensure that post-installation readings are compared against the most accurate use-case of the building. Granular baseline data is essential for being able to weather-adjust energy savings, as each year will have different heating demands based on the external temperature. You don’t want to be comparing the use of heat pumps in a very cold year to gas boilers in a warm one!
Ideally, a building should operate in the same way before and after energy efficiency measures are installed, with the only change being the measures themselves. In practice, however, it is not always possible to identify a baseline year that reflects this. For example, the Covid lockdowns significantly altered building energy use compared with a typical year.
Where the baseline period does not fully reflect changes to the site since installation, good M&V practice requires non-routine adjustments. These account for factors such as changes in heated floor area, occupancy patterns, set point temperatures, or equipment additions and outages.
The impact of these changes on energy use within the measurement boundary should be quantified. While engineering calculations would provide the most robust approach, the limited technical capacity of many public sector bodies meant we instead requested estimated impacts on energy use.
The application of M&V practices is relatively sparse in the building decarbonisation sphere.
A robust M&V approach requires not only establishing and weather-adjusting a baseline but also documenting the process in an M&V plan before measures are installed. These plans are essential for transparency and accountability between energy users, installers and measurers, particularly in energy performance contracts where payments depend on verified savings.
Plans developed by suppliers generally reflected strong technical expertise but sometimes prioritised reducing supplier risk over transparency of whole-building performance. For example, measuring a heat pump’s efficiency alone reveals little about overall decarbonisation if retained boiler gas use is not also tracked. By contrast, plans developed by grant recipients often took a more whole-building, outcome-focused approach, but key adjustments such as weather and occupancy were sometimes overlooked.
Good M&V is essential for a building sector that is racing to reduce both its energy intensity and its carbon footprint.
At Salix, applying robust M&V practices has strengthened the credibility of the carbon savings reported through our schemes, giving stakeholders and partners greater confidence that public funding is delivering measurable, repeatable results.
Of course, effective M&V also provides building managers and users with clear evidence of whether installed measures are performing as intended, where further intervention may be needed, and the confidence to report verified energy and carbon savings.
We’re proud to deliver results for the people and organisations we work with – improving homes in the housing sector and creating better public buildings for everyone.
Salix’s role is to support the UK government in driving the transition to a low carbon future and meet challenging net zero targets. We deliver and administer grant and loan funding on behalf of the Department for Energy Security and Net Zero, and the Scottish and Welsh governments. This is delivered across housing and the public sector. www.salixfinance.co.uk
This article appeared in the June 2026 issue of Energy Manager magazine. Subscribe here.
