Reid Cunningham shares some of the core considerations for successful energy benchmarking, adapted from the IWFM Guidance Note on Energy Benchmarking.
07 October 2019 | Reid Cunningham
Benchmarking is a great tool to compare the performance of services and facilities. For energy benchmarking variables such as a building's location, size and type as well as the activities and operating hours can affect the results of energy benchmarking.
In addition, there will be differences between energy targets derived from a designer's calculations, which are prepared for new or refurbished facilities, and actual energy performance
Bearing this in mind, define your objectives for benchmarking and allow for appropriate tolerance between facilities.
1 Collect and process data
Combine the collection and analysis of data with discussions with the site teams to understand variances between buildings and why they are managed the way they are. The simplest method of comparison is to use a ratio of energy and relevant output per building.
Industrial processes have historically referred to a specific energy ratio (SER) to measure energy (gas/heat, electricity or both) in kilowatt hours (kWh) against relevant output units, which may be an individual manufactured item or a batch of products.
Thus: SER = Energy (kWh) / Unit(s) (that is, number of items in a batch and so forth.)
For accommodation buildings, energy performance is usually measured by the normalised performance indicator (NPI) ratio, which tends to be a weather-adjusted per unit of floor area.
Calculated ratios can be used to compare data from different buildings or against published comparisons. Alternative 'units' can also be considered, either square feet or square metres, and can vary for gross internal floor area or net usable floor area and so on.
2 Identify and collect benchmarks
Data for comparison benchmarks tends to fall into two categories:
- Compare a single facility from year to year:
- Pros: FMs tend to have more control over this data, as they know the operational history of the facility during each time period. It is easier to see performance trends and track energy-efficiency improvements.
Cons: Analysis is restricted to a single building so increasing or decreasing consumption does not necessarily demonstrate good or bad performance.
- Compare multiple facilities
To overcome the restricted analysis of a single facility, compare performance with other facilities, either within a portfolio or externally. Additionally, this type of peer group analysis can be used to develop improved consistency across all of a group of properties.
3 Compare energy data
Start with the ratios from comparing facilities' SERs or NPIs and progress to further detailed analysis. You will need annual energy consumption and a measurement of 'units' to do this.
SER energy in kWhs can be converted into energy cost by substituting the billed cost for the consumption. Cost comparisons for energy will add a further level of variance to energy benchmarking because the cost of energy may vary between organisation, suppliers and building locations based on specific supply contracts and volumes.
Note: This might not be apparent in a £/sq m analysis.
Gain greater insight by comparing the profile or shape of energy use over a chosen day, week or month as this identifies consumption that does not align with normal occupation or organisational activities.
With advances in controls, meters and telemetry, FMs should be able to gather energy data in a digital half-hourly format from their energy suppliers. This data shows where usage is occurring outside of the expected pattern. Alternatively, FMs should procure an automatic meter-reading service to achieve this level of analysis.
Now you have the energy profile of your facility, you can determine how changes such as energy-saving and offsetting peak demand charges can be achieved.
Reid Cunningham is strategic development director at BAM FM and BAM Energy