Indicators for monitoring progress towards sustainable development are needed in order to assist decision-makers and policy-makers at all levels and to increase focus on sustainable development. Beyond the commonly used economic indicators of well being, however, social, environmental and institutional indicators have to be taken into account as well to arrive at a broader, more complete picture of societal development. Indicators are signposts that can point the way to sustainable development. While there is still no precise definition of sustainable development, indicators can help to show whether we are moving in the right direction. Unifying economics and environment in decision-making may be the key to understanding how well we are navigating the course to sustainable development. To move to sustainable development, decision-makers need information. They need information about where they are at the moment. They need information on developing trends and pressure points. They need information about the impacts or effects of interventions or policies put into place. They need feedback on which adjustments to make to speed up or slow down the effects of their interventions. They need information about milestones achieved or about failures that frustrate progress.

Indicators are useful because they point to trends and relationships in a concise way. They provide meaning beyond the attributes directly associated with them. In this sense, they are different from primary data or statistics, providing a bridge between detailed data and interpreted information. Indicators have been used for many years and are common in planning an economics where indicators such as GDP, the unemployment rate, the literacy rate and the population growth rate are widely monitored. Indicators can be used for many purposes such as measuring progress towards pre-established targets and goals or simply getting a picture of where things stand at a particular point in time. They can help to guide national policies for sustainable development and facilitate national reporting on measures to implement sustainable development.

What about energy indices?

Energy and environment are intimately related. To put it simply, using energy produces a large fraction of the overall amount of pollution in our society. If we use less energy, with all other factors remaining equal, we will have less pollution. If we use the same amount of energy, but juggle oil against natural gas, renewable energy sources against coal, we will obtain different types and quantities of pollution that affect environmental indices in different ways.

NPI (Normalised Performance Indicator)

Many indices have been produced concerning energy consumption. One of them is the NPI (Normalised Performance Indicator), which is a government accredited scheme to assess and allow for the comparisons of energy performances of buildings. It is, put simply, the benchmark to which comparisons of performance are made.

The steps to produce the NPI are the following:

  1. Convert all energy units to kWh.
  2. Determine energy used for space heating.
  3. Modification of energy used for space heating to account for weather influences to produce a weather factor Cw.
  4. Modify energy used for space heating to account for exposure influences to produce an exposure factor CE.
  5. Determination of energy used for non-heating purposes.
  6. Determine hours of use factor, Ch.
  7. Determine floor area or volume, m2 or m3.
  8. Calculation of NPI.
  9. Comparison with government classification or previous recorded NPI figures.

So there is a credible index responsible for the performance of a building. Taking this into account we decided that the output of our index should be in such a type that it could be integrated to this existing index. And so we did.

Project's Indicators

The main task of our project was the development of a software tool that could help in the decision making of the Energy Management function taking into account the new concept of Embodied Energy. The tool is aiming to the evaluation of any possible Energy Management option as far as the energy efficiency and the environmental impact is concerned. Therefore the results of the tool had to be presented in a suitable and convenient way for the user. The form of indicators, seemed to be the most appropriate way to evaluate the results differentiating different Energy Management options.

The Energy Index is a modified NPI that takes into account, in its calculation, the Embodied Energy of a selected Energy management option.

The Environmental Index that emerge from the Energy Index converted into kg of CO2 emissions through an emissions calculation tool (EMISCAL).

Indicators Formulas

Energy Index = Modified NPI with Embodied Energy considered in its calculation

Environmental Index = Normalised CO2 emissions after the implemented Energy Management change (kg CO2/m2 yr)

Working Example

Building specification

Type of building: Primary school

Location: West Scotland

Floor area: 2000 m2

Occupancy: 1470 hours

Energy Characteristics

Energy consumption: 550000 kWh/year

NPI : 259 kWh/yr m2

A significant heat loss from the windows of the school was identified by an Energy Manager so the replacement of the glazing of the 300 windows of the school with advanced glazing was decided. This retrofit option was estimated to achieve a 10% savings of the energy consumption (55000 kWh/year). The building was expected to improve its rating from "Poor" to "Fair" after the Energy management implementation according to the Energy Efficiency Ratings that the Energy Efficiency Office has published.

All these data has been input to DESTEM, the software tool that our team has developed, and we got the following results:

NPI: 259 kWh/m2yr

NPI (after E.M implementation without Embodied Energy considered): 233 kWh/m2yr

Energy Index (taking into account the Embodied energy of the implemented change): 249 kWh/m2yr

Environmental Index : 60,5 kg CO2/m2yr

The Energy Efficiency Ratings for this type of the building is:




Less than 180 kWh/m2yr

180-240 kWh/m2yr

More than 240 kWh/m2yr

The Environmental rating, our team produced based on EMISCAL, for this type of the building is:




Less than 36,85 kg CO2/m2yr

36,85 -49,13 kg CO2/m2yr

More than 49,13 kg CO2/m2yr


Through this simple case study example it is clearly illustrated the significance of the Embodied Energy of the selected option to the Energy performance of the building as if this energy would not have taken into account the practice of this Energy management option would have been characterised successful as the target of "Fair" rating for the building was achieved. But by considering the Embodied Energy of the selected option the building remains at the same "Poor" rating so the Energy Management practice did not achieve its target.

Trying to evaluate the environmental performance of the building we found out that it is again rated in the "Poor" category.

Finaly the above example demonstrates clearly the function of the two indicators and verifies their usefulness in the decision making of the Energy Management function.