In the Nordsachsen district, a historic building, originally constructed as a dairy in 1895, has been repurposed in several construction phases into a modern multi-family house with a total of five residential units. The two-storey property in Zwochau has undergone comprehensive renovation since 2017. The aim of these measures was a significant reduction in energy consumption and the adaptation of living comfort to contemporary requirements.
The renovation work included a far-reaching modernisation of the building envelope. This encompassed insulating the roof and facade, replacing all windows and external doors, and integrating efficient heating technology. The latter is based on a heat pump combined with underfloor heating and is supplemented by a photovoltaic system for self-generation of electricity. A central aspect of the upgrade was also the subsequent insulation of the cellar ceiling to minimise heat loss and increase thermal comfort in the ground floor flats.
Energy Efficiency Upgrade of the Basement
The initial situation in the basement corresponded to a typical old building cellar from the 19th century with a solid ceiling and exposed pipework, with no thermal insulation previously present. This led to significant heat losses from the heated rooms above. The strategic goals of the cellar ceiling insulation included reducing the building's heating load, decreasing energy consumption for heating the ground-floor flats, and preventing the cellar ceiling from cooling down. This was intended to noticeably improve comfort in the areas above, particularly by reducing cold floors. These measures were also designed with an efficient cost structure in mind, which enabled implementation with a high degree of self-performed work.
For the insulation of the cellar ceiling, the non-combustible ceiling insulation board Ursa Tectonic UPh/Vv with a thickness of 120 millimetres was used. In a first step, relevant areas totalling approximately 25 square metres were insulated. The decisive factors for this material choice were the favourable thermal properties of the mineral wool insulation board with a thermal conductivity of ?D=0.035 W/m*K, its classification in Euroclass A1 for fire protection, and its sound-absorbing effects. Processing was characterised by easy adaptability to existing installations and low inherent weight, which simplified installation. Installation was carried out using adhesive mortar after preparing the substrate surface, with precise cut-outs made for pipework. The room height in the cellar remained sufficient despite the insulation layer. The execution of the work took approximately half a working day.
In addition to the measures on the cellar ceiling, the uppermost floor ceiling of the building had already been insulated in an earlier renovation phase over an area of around 150 square metres with Ursa Geo SF 32 tension felt. The coordinated combination of roof, facade, and cellar ceiling insulation creates a consistently improved thermal envelope that significantly reduces heat loss and thus lowers heating energy demand. This establishes the basis for energy-efficient operation of the heat pump and enhances living comfort throughout the building. The positive experiences of the property manager with the processing of the insulation boards underline the practical suitability of the chosen materials and methods.
