Calculation methods

Common questions

Q. What types of commercial sites are eligible under the Commercial Lighting Method?

A: As stated in Clause 9.4 the ESS Rule, a commercial premises is defined as a building classified under the Building Code of Australia, Classes: 3, 5, 6, 7, 8, 9 or 10b. This means that the Commercial Lighting Formula can be applied to lighting upgrades at most non-residential premises including industrial facilities, public facilities, office buildings, hotels, motels and shopping centres.  It also covers common areas of Class 2 buildings.

See       ESS Rule Clause 9.4

Q. What information do I need for the Commercial Lighting Tool?

A: For the original and new lighting equipment you will need to evidence the lamp type, ballast type, number of lamps replaced and the Nominal Lamp Powers. You will also need to document the types of control systems and if the area is air-conditioned or not. For installations that do not involve the replacement of lamps and control gear and are not CFL, Halogen, or Incandescent, the rated lifetime will need to be evidence to include in the calculation.

Documentation is essential to your Record Keeping Arrangements to evidence all the variable inputs. For example, photos of old lamp types and control gear, and floor plans should be kept on file for each site.

Q. Can I use the Commercial Lighting calculation method for new installations?

A: No. The Commercial Lighting calculation method is only applicable for upgrades of existing lighting equipment. For applications involving installations of new energy efficient lighting end user equipment, a different calculation method will need to be used.

See       ESS Rule Clause 7

Q. What is the Project Impact Assessment Method?

A: The Project Impact Assessment Method allows the Accredited Certificate Provider to calculate the energy savings from an engineering assessment. This is usually in the form of measured consumption data before and after the implementation of the activity, combined with industry recognised engineering calculations. This method is commonly used where energy savings are small compared to the overall site consumption, or data for a site’s past electricity consumption is unavailable.

This method can be used for residential, commercial or industrial sites and allows you to forward create certificates for 5 years with a discount, or to claim the energy savings on an annual basis.

This is a very flexible calculation method that can allow an Accredited Certificate Provider to create certificates for a wide range of activities.

See     Project Impact Assessment Method

Q. What is the Metered Baseline Method?

A: The Metered Baseline Method lets the user establish a consumption baseline from which the energy savings can be calculated after the implementations of energy savings activities.

By submitting of up to 5 years consumption data the Accredited Certificate Provider can establish the baseline. After the activity has been implemented the energy savings are calculated from the difference between the ‘before’ baseline and the ‘after’ consumption.

This method is used where energy savings result in a significant reduction in a site’s electricity consumption, and representative historical site electricity consumption data is available. This method can be use by commercial and industrial sites in three ways:

  • Baseline per unit of output, for an industrial facility such as a factory
  • Baseline unaffected by output, for commercial facilities such as a school or an office building
  • Normalised baseline, where a typical variation in electricity use during baseline period can be normalised base on known factors that cause the variations
  • National Australian Building Environment Rating System, for a commercial office buildings, hotels or shopping centers, that have a NABERS rating (commercial only).

See     Metered Baseline Method

Q. What is the Deemed Energy Savings Method?

The Deemed Energy Savings Method allows an Accredited Certificate Provider  to undertake an energy savings activity without any direct measurements or complex calculations. All the energy savings are predetermined via default values and equations listed in Clause 9 of the ESS Rule. There are four ways in which to use this method.

  1. Default Savings Factor provides default savings for the installation or sale or certain products, such as down lights, refrigerators, fridge and dishwashers.
  2. Commercial Lighting Energy Savings Formula determines the energy savings by calculating the difference between the consumption of the original and upgraded lighting equipment. This method uses default values and allows the forward creation of 10 years of energy savings.
  3. High Efficiency Motor Energy Savings Formula assigns default energy savings to certain upgrades of efficient motors and is based on the type of industry.
  4. Power Factor Correction Energy Savings Formula allows you to create certificates for improvements to a sites power factor using standard equations.

See     Deemed Energy Savings Method

Q. How are the Default Savings Factors calculated?

A: Default Savings factors are provided for those activities which:

  • lifetime Energy Savings can be estimated to a high degree of confidence.
  • for which the savings associated with each instance of the activity is relatively small (hence not amenable to the use of one of the other methods of the Rule).

The Rule Maker estimates lifetime Energy Savings using standard accepted methods and formulae with the results discounted to provide a conservative estimate of Energy Savings over the deemed lifetime.  These factors are then given approval by the Minister for Energy.

Q. Will Default Savings Factors be changed in the future?

A: Default Savings Factors (DSFs) will be amended in line with new information relating to historical and predicted energy savings, market factors or a change in mandated performance standards.

In most circumstances, the DSFs will only be changed after consultation with stakeholders. However, there are currently no plans to amend the ESS Rule to include any new types of products.

Q. How do I apply for Extended Operating Hours in the Commercial Lighting Tool?

A: Under the Commercial Lighting Energy Savings Formula, the default Annual Operation Hours for commercial premises is 3,000 hours. This is indicative of the operation of offices, retails stores and food outlets. However, there are a number of commercial premises that have considerably longer operating hours. For example car parks are generally lit 24 hours a day and some restaurants and bars operate up to 18 hours a day.

To use extended operating hours in the Commercial Lighting Calculation Tool you will need to submit evidence to the Scheme Administrator for approval. Once the hours have been approved you will receive a customised Calculation Tool based on these values.

Typical evidence would normally include a combination of:

  • Daily opening and closing times, published on the internet or other prominent location
  • Security logs
  • Employee timecards
  • Licensed operating hours
  • Logged data
  • Regulation requirements.

For sites that have multiple areas with different extended operating hours, a Completed Calculation Tool must be submitted along with the evidence to be modified by the Scheme Administrator.

Q. How is the Confidence Factor determined?

A: Confidence Factors are used for calculations in the Project Impact Assessment Method (PIAM) and the Metered Baseline Method (MBM) to make corrections for uncertainties, variations and errors in the calculation method. For example, if the engineering assessment was based on measurements made during winter for a HVAC system, this would not accurately reflect the consumption over the whole year.

For the PIAM the Confidence Factor is set as 1.0, 0.9 or 0.8 depending on the accuracy of the engineering assessment, where a 1.0 reflects a high level of accuracy and 0.8 (or a lower value) if the assessment in inadequate. Factors that determine the Confidence Factor include

  • Length and accuracy of measurements, if used, or quality or records kept
  • Complexity of calculations
  • Variances of loads and treatment
  • Operating environment and ambient conditions
  • End user equipment characteristics
  • Performance degradation over time.

For the MBM the Confidence Factor is calculated by a simple equation based on the measured data for the baseline and the consumption after the activity has been implemented. The formulas differs between the different types of MBM but is based on the variability of the data of the baseline and the electricity consumption. For the NABERS method it is constant at 0.95.