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Low-temperature systems for existing buildings

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In times of massively rising energy prices and stricter legal requirements for existing buildings and their heating systems, it is important to maintain an overview of the possible measures for the energy-efficient refurbishment of existing buildings.

The renovation of a building is generally understood to structural changes that reduce energy consumption. This includes insulation measures for the façade and roof as well as the renewal of the heating system, windows and exterior doors. How much energy and money you can save through refurbishment depends on a number of factors. The most important of these include: the structural condition of the building, the planned refurbishment measures for the insulation and building technology, and the professional planning and execution of the measures.

The use of heat pumps in renovation projects is a much-discussed topic. At first glance, the heat pump appears to be a very efficient technology for generating heat. If such an appliance achieves an “annual coefficient of performance” of 3, then you can generate three kilowatt hours of heat with one kilowatt hour of electricity. In the practice of building services engineering, however, there are a number of premises that should be known and then evaluated both technically and economically.

In new buildings, as hardly any expert will deny, there are generally good to very good conditions for operating a heat pump efficiently. In the area of refurbishment, the situation is somewhat more complex. Heat pumps are particularly efficient, i.e. they require very little electrical drive power for the compressor if they are to provide heat at a low temperature level. Good building insulation reduces heat loss from the house. The better the insulation values, the lower the specific heating load of the building in W/m2. To cover the heating load, you should also work with heating surfaces that manage with the lowest possible heating water temperatures. Hot water underfloor heating systems in particular harmonize well with heat pumps.

The lowest possible heating load in conjunction with a low-temperature system as a heating surface is therefore good for the heat pump. But what to do if the house has an old heating system with radiators and is currently operated with heating water temperatures of 70°C or more?

In any case, obvious weak points in the building, such as old windows or doors and uninsulated roofs, should first be optimized in the course of a renovation. Full-surface insulation of the façade is not always necessary. Depending on the type of building, scope of refurbishment and budget, there are a number of options for upgrading an existing building to efficient heat pump operation. Low heating temperatures can be achieved with the largest possible (heating) surfaces. In the following articles, we present techniques that are suitable for preparing an old building for the operation of heat pumps.

Photo @ Adobe Fotostock

Photo @ Adobe Fotostock

Photo @ Adobe Fotostock