from sustainable
energy production
renewable and environmentally friendly
The environmental benefit of a heat pump strongly depends on the amount of electricity required for heat production. In other words, how much environmental energy from water, soil or air is used. The ratio of the amount of heat emitted in the course of a year to the electrical energy used is called the seasonal performance factor. Taking all EWZ plants into account, the seasonal performance factor is 3.6. This means that in our company, we generate 3.6 kWh of heat and cooling with 1 kWh of electricity. And of course, we do use electricity from renewable sources for this.
One possible energy source for heat pumps is the waste heat from wastewater treatment plants and data centres. Geothermal energy, wood, groundwater and lake and river water can also be used as heat or cooling sources. All of these renewable energy sources are locally available. Import is not necessary. The following graph shows that heating oil and natural gas boilers account for the largest share of greenhouse gas (GHG) emissions per unit of heat produced. Heat pumps powered by renewable electricity, on the other hand, have the best values. The average greenhouse gas emissions of the ewz energy networks are 52 g CO₂-eq per kWh*. As a comparison, the average district heating supply in Switzerland amounts to 67 g CO₂-eq per kWh.
* According to the accounting rules of the Coordination Conference for Public Sector Construction and Property Services (KBOB)
The Environmental impact points (EIPs) shown below indicate the degree of environmental pollution caused by different types of heat generation. EIPs are based on the method of ecological scarcity, which was developed in Switzerland. Their calculation takes into account a wide range of environmental impacts. Heating oil and natural gas heating systems have the greatest environmental impact. This is a consequence of fossil fuel extraction and CO₂ emissions during operation. The lowest values are for heat pumps powered by renewable electricity. A comparison with Swiss district heating networks shows that they are significantly more environmentally friendly than fossil fuel heating systems.
Local and district heating networks can be operated with different energy sources and are therefore feasible almost everywhere. Locations with a strong demand for heat and/or cooling are particularly well suited for development. In the city of Zurich and in many other municipalities in Switzerland, the conditions are ideal.
The implementation of a high number of climate-friendly heating and cooling systems is one of the main challenges of the next two decades. The energy renovation of many older properties also needs to be prioritised.
CO₂-eq is a unit of measure used to standardise the greenhouse gas impact of different climate gases. Here’s an example: Methane (CH₄) is 25 times more damaging to the climate than CO₂. The greenhouse gas potential of 1 g of methane therefore corresponds to 25 g of CO₂‑eq.
Environmental impact points (EIPs) are a method of depicting the environmental impacts of products or processes. They are calculated according to the ecological scarcity method developed in Switzerland, which takes into account a wide range of environmental impacts and is summarised in an indicator (the environmental impact points).
