4.4 Visualising Savings Achieved by Getting into a Higher Class
In order to visualise possible savings that can be achieved by changing the performance of the building by one class in the corresponding category the Display™ poster shows three elements of comparison.
The first step for depicting possible savings is to calculate the amount of necessary savings in order to achieve the next best class. Afterwards these savings are compared to the annual primary energy consumption per year of an average single family house, the CO2 emission of a car going once around the earth and the water consumption of a shower .
Please note that this is calculated following the ranking scheme:
If the building is classed in a certain category in one of the following rank [C, D, E, F], the improvement of the ratio corresponds to one whole class, e. g. not only the next five points that would lift the building into a higher class in a certain category.
If the building is already ranked in a certain category the rank B or G, the calculation of the savings that are achieved by lifting the building from class B to class A or from class G to class F is based on the current distance up to the threshold value.
If the building has already achieved class A in a certain category the text “Class A already achieved.” is shown on the poster.
Example C: Falk Comprehensive School
An improvement by one whole class in the category of annual primary energy consumption equals a reduction of the primary energy ratio by 65 kWh per m2 and per year. _ Depending on the floor area of the building this implies different amounts of primary energy savings, e.g. a building with a surface of 5.000 m2 that improves by one class would save a primary energy consumption of 325.000 kWh per year. This amount is now compared to the annual primary energy consumption of an average family house. _ Consequently, this building could reduce its annual primary energy consumption by an amount equal to the average annual consumption of 8 family houses.
Concerning the CO2 emissions an improvement by one whole class equals the reduction of the CO2 emissions by 13 kg of CO2 equivalents per m2 per year. Therefore, a building of 5.000 m2 that moves up one class contributes to a saving of CO2 emissions by 65.000 kg of CO2 equivalents. Compared to the CO2 emissions of a medium petrol car going once around the earth this corresponds to a tour 8 times around the earth.
Regarding the water consumption, an improvement by one class implies a reduction of the water ratio by 125 l per m2 per year. However, since the example building has already achieved class B with its water ratio of 180 l per m2 and year, the improvement by one class implies the reduction of the ratio up to the threshold value of 125 l per m2 and year. For the example building this reduction of 80 l per m2 and year means a saving of 400.000 l per year. Compared to an average shower the savings come to 13 333 showers . If the building had to improve by one whole class and not just by the distance to the threshold value it would save 500.000 l which comes to 16 667 showers.
Please note, that the calculated values of comparison are rounded to whole numbers. If the result is less than one it is rounded up to one. An extract of the corresponding section on the Display™ poster in shown in figure 11.
- Figure 11: Extract of the Display™ poster visualising savings achievable by improving the performance of a building