Clients often require validation of any investment they have made to improve energy efficiency. Geoff Newman highlights the key issues for building services engineers to be aware of
When building services engineers deliver energy-saving projects for clients they are often required to validate the savings that have been achieved following implementation. Very often this requires careful planning before the project begins to ensure meaningful comparisons can be made.

Evaluating the success of any such project obviously depends on being able to measure the energy that has been saved. To that end, sub-level metering will help to establish 'before and after' energy consumption - though the majority of buildings are not equipped with this level of sub-metering, especially for gas. This is a problem we have encountered on many occasions, having installed over 6,000 intelligent boiler load optimisers to existing boilers.

However, these challenges can be overcome through methodologies and processes that suit the circumstances of each project so that savings and ultimately the realisation of the investment can be demonstrated.

In the case of heating systems, energy consumption will clearly be influenced by weather variations. To ensure accurate calculations of savings it is vital to adjust energy consumption measurements using degree day data supplied by the meteorological office.

The changes in energy consumption over longer periods of time (pre, during and post project) can be established by CUSUM (cumulative sum) analysis.

It's also important to ensure that energy reduction initiatives are carried out one at a time. Two simultaneous projects with the same energy source, for instance, will make it virtually impossible to determine the savings achieved by each.

Additionally, ensure any variables are understood and agreed. Be aware of potential changes in the building that could impact the results, such as occupancy and occupant behaviour, alterations to building fabric or plant and changes to equipment configuration e.g. BMS. Also ensure that the boiler plant is operating as designed.

For example, are the boiler thermostats set correctly and is the BMS strategy aligned to the way the building is being used now - rather than when it was first commissioned?

Additionally, ensure that the technology supplier's methodology is robust, spend the time to understand this and to ensure the calculations actually relate to the energy being consumed or reduced.

With measurement and verification becoming integral to any energy efficiency project it is important to work with a Certified Measurement and Verification Professional (CMVP), who has been certified under the International Performance Measurement and Verification Protocol (IPMVP). This ensures that person or company is working within an internationally recognised and transparent framework.

Our experience of managing such projects and validating the savings comes from the retrofitting of boiler optimisation controls, often working closely with facilities and maintenance service providers. However, the same principles can be applied to any energy saving initiative. The important points are to capture and be aware of all the variables that might influence the results and how these can be managed.

// The author is sales & marketing director of Sabien Technology //