[B]Heating Boilers[/B]
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Many oil and gas boilers must be replaced after 30 years. Systems installed before 1985 are no longer approved for operation. "This particularly affects constant temperature boilers," says Christian Stolte from the German Energy Agency (dena). Low-temperature and condensing boilers with high efficiency, as well as systems in multi-family houses with more than 400 kilowatts rated output, are exempt from this obligation. However, anyone currently buying a house must replace boilers subject to replacement obligations within two years.
[B]Roof Insulation[/B]
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If the property is heated to more than 19 degrees Celsius for at least four months per year, the uppermost accessible ceiling above heated rooms must be insulated according to the Energy Saving Ordinance. Alternatively, the roof above can be sealed, explains expert Lührsen. A deadline of two years after purchase also applies here. After insulation, the so-called heat transfer coefficient must not exceed the value of 0.24 watts per square meter and degree Kelvin.
However, if the minimum thermal protection according to DIN 4108-2 is met, the insulation obligation does not apply. This corresponds to a thermal resistance (R-value) of 0.90. If the uppermost ceiling or the roof in its current state meets the standard, there is no obligation to insulate according to the Federal Ministry of Construction. The minimum thermal protection ensures that the building structure is not damaged by condensation and that the indoor climate does not become damp.
Buildings are also exempted if insulation does not prove economical within a reasonable period. How home buyers can prove uneconomical conditions is not regulated in the Energy Saving Ordinance, according to the ministry. The responsible state authority provides assistance in case of doubt. Exceptions are also possible for listed buildings, according to dena expert Stolte. Either if the construction work would involve disproportionate effort or if the substance and appearance of the property would be impaired.
[B]Pipes[/B]
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In unheated rooms, all accessible heat-carrying pipes, fittings, and valves must be insulated. The Energy Saving Ordinance sets minimum requirements for this. Lührsen recommends insulating the pipes also within the masonry. Otherwise, the pipes could corrode upon contact with mortar or concrete.
Whether a house meets the requirements of the Energy Saving Ordinance is usually checked by the local building authorities. For boilers and heat pipes, however, Stolte states that the district chimney sweep is responsible. Violations can result in fines. Not only for this reason can modernization be worthwhile: "Modernizations are generally sensible to save energy," emphasizes Lührsen. They also usually increase the value of the house "considerably."
Musketier is therefore right ;) Among other things, that is why I always recommend buying an existing property with the involvement of an expert!
Source: n-TV, as it is described in an easily understandable way.
Rhenish greetings