Evaluating Environmental Performance in Low-Carbon Energy Systems [E-BOOK]

Case 2 - Low-Energy House heating system

In this case study, the analysis targets a comparison between heating systems in a low-energy house. The definition of a low-energy house can be found in the Glossary.

Heating systems today are still largely fossil fuel-based, although electric heating systems are also gaining ground. Considerable debate surrounds the use of electric heaters versus efficient (~100%) gas heaters. While gas is the cleanest of fossil fuels with regards to emissions, and the heat gain is also very high, electric power has the potential to improve its emission profile by the incorporation of more and more renewable resources. Today, however, electric power is both inefficient (a single unit of usable energy produces 2 units of losses) and still largely dependent on fossil fuels.

In this case study, the Best Available Technology of both heating systems will be compared, namely gas condensing boilers and heat pumps. The efficiency of gas condensing boilers lies in their capacity to capture the latent heat of water vapour produced through the burning process that would otherwise (in older designs) escape through the vent. On the other hand, the heat pump utilises the thermal energy in air or groundwater to pump heat into the house, and while the pumping itself requires energy, the produced thermal energy (heat) is four times higher than the electricity consumed by the equipment.

In addition to comparing different heating technologies, the case study also endeavours to assess them using different future grid mixes. Current scenarios refer to the use of the latest GaBi power grid mix dataset for EU-25 countries. Therefore the analysis not only compares the best available technologies today, but also looks at how the relationship may change in circumstances where electric power provision will derive increasingly from renewable resources. While it may seem unfair to show potential improvement for only one of the technologies under scrutiny, it is indeed only realistic to expect an increase in renewable energy sources in the grid mix, while there is little to no room left for improvement in gas-based heating systems. The basis for comparison is the provision of heating for the life cycle of the same low-energy house.

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