How do savings differ from investments

Environmental Pact Bavaria

Sometimes energy can be saved through inexpensive organizational measures, e.g. B. by switching off systems during non-operating times. However, investments are often necessary to increase energy efficiency and save energy. Such measures to increase energy efficiency should also be economical so that they have a chance of being implemented.

The profitability can be estimated with the help of an investment calculation. The costs avoided by the investment are set in relation to the investment costs. This results in key figures with the help of which the profitability of an investment can be assessed.

There are different methods for calculating the profitability of capital goods and systems. The VDI guideline 6025 "Business calculations for capital goods and systems" compiles the basics of the most common procedures.
Generally recognized calculation methods for the technical building equipment (TGA) heating, air conditioning etc. can be found z. B. in the VDI guideline 2067. This guideline enables an evaluation and comparison of different concepts for the technical equipment of a building.
The VDI guideline 2884 "Procurement, operation and maintenance of production equipment using Life Cycle Costing (LCC)" is a support for product planning in line with life cycle costs.

Take the useful life into account when investing

There are several ways to evaluate an investment. In practice, the payback period is often used as a criterion. However, it only indicates when the capital invested flowed back again. It makes no statement about profitability.
In many cases, investment projects fail because of the short payback times required. This may be justified in the case of short-lived projects. In the case of investments in the energy sector with a long useful life, considerable savings potential may remain unused. To avoid this, it is better to consider profitability and total useful life. A suitable measure of profitability is e.g. B. the return on investment (internal rate of return).

Economic feasibility study - static and dynamic calculation methods


Static process are usually associated with less calculation effort, since they assume uniform returns (here: reduction of energy costs) and only consider one period (e.g. the cost and profit comparison calculation). The amortization of an investment is most often calculated: The investment is set in relation to the annual savings, resulting in the amortization period in years.

Dynamic procedure are more complex and require knowledge (or a reliable estimate) of costs and savings over the entire service life. Costs and savings that differ over time are taken into account. However, they are worthwhile for investments with a long useful life, because they provide much more meaningful results.

A distinction is made between the following dynamic investment calculation types:
  • Net present value method
  • Internal rate of return method
  • Annuity method.

Additional information

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