The Slovenian pilots

There are roughly 524.000 residential buildings in Slovenia and a vast majority – 89% represent single-family houses (464.352 units). Most houses were built in 1970’s (18%), followed by 80’s (15%), 60’s (11%) and even 19th century (11%). Only 5% were built after year 2000. Characteristics of houses built during these periods in Slovenia are relatively large heated volumes, often with non-optimal use of living space (large heated hallways, stairs, etc.), with very little or no thermal insulation, therefore resulting in large operating costs, often accompanied with mold problems. This is also a source of pollution and carbonization of environment, which could be reduced substantially.

Energy renovations of residential buildings are popular in Slovenia, especially due to available subsidies from a national Eco fund. But often renovations are partial and unprofessional, only pursuing low investment cost. There are often noticeable discrepancies between the calculated and actual savings due to poor quality of installation works and frequent changes to cheaper solutions than designed, leading in results which aren’t as good as they could be. Complete quality energy renovation of old houses is an important topic also in neighboring countries, so there is a high replication potential throughout Europe.

Within this project we decided to find three representative residential houses as described above and do quality deep renovation using at least three energy saving and indoor environment quality (IEQ) improving measures. Besides energy and IEQ we would also focus on sustainability aspects such as environmental impact, imbedded carbon and raise awareness about circularity in construction renovation works.

We already found three interested investors with their houses at different locations in Slovenia. We did pre-monitoring measures (inspection with thermal camera, sound insulation measurements, installation of remote sensors for IEQ (CO2 level, temperature, relative humidity), technical inspection, technical advisory on insulation of building envelope, certain calculations and started the energy renovations of building envelope. For improving building envelope in all-round sustainability aspects we proposed quality installation of mineral wool insulation for facades, roof and floor (where possible), which provide all-in-one thermal, acoustic and fire insulation. Mineral wool is also made of high recycled content, can be fully recycled and Knauf Insulation offers wide range of mineral wool insulation product with bio-based binder or no binder at all.

At the moment of writing this article, energy renovation of pilot case B in Radovljica is complete. The house made in 1970s has had two extensions and is inhabited by 6 permanent family residents. Although the house has five different external wall build-ups, it had basically no thermal insulation and thus high costs of heating in winter and cooling in summer. There was also a wish from the investor to improve indoor air quality and indoor natural lighting.

Initial inspection with a thermal camera has shown the building leaks a lot of heat through existing walls, windows, cellar ceiling and also the roof. As improvement of building envelope, first quality, triple-glazing windows were installed and holes for local ventilation units were made. The second step was the installation of the ETICS facade with 16cm of rock mineral wool insulation. The pitched roof and loft areas were filled with a mechanically blown mineral wool insulation called Supafil Timber Frame, which doesn’t have any binder and is also non-flammable, with excellent thermal and acoustic properties. The ceiling of non-heated cellar was insulated with non-flammable rock mineral wool lamellas with coating, which eliminate the need of additional plastering. Additionally, two pieces of Velux pitched roof skylights were installed for more natural light in the hallway; all old light bulbs were replaced by LED’s. Nine local ventilation devices with high efficiency of heat regeneration were installed on external walls for indoor air quality improvement, a new heat pump was installed for renewable heating and cooling of the house. The existing solar water heating collectors and hot water reservoir were in good condition and are still perfectly functional.

Below: Case B house before, during and after renovation:

Below: The installation of blown mineral wool insulation Supafil and Velux skylights:

Below: The finished cellar ceiling (right, initial situation on the left) where only insulating rock mineral wool lamellas and integrated LED light were installed:

Post monitoring activities are not finished yet, so it is still too early to talk about the results. But from current data we see the renovation was successful and we expect around 75% lower energy needs, combined with higher indoor environment quality and tenant’s satisfaction. The later will be checked via comparison of anthropological interview we do with owner before and after the renovation.

Below: a thermographic image of front façade before (top) and after (bottom) the renovation

Circularity aspects: glass from old windows was separated and delivered to an official recycling facility. Some wooden roof cladding and window frames were cut and used for the heating of another holiday house. Old mineral wool was removed from the roof and delivered together with cutoffs of the new mineral wool to Knauf Insulation facility where it was entirely recycled.

Renovation works on Case A house are currently on hold due to third party reasons. The Case C demonstrational house is currently in the preparation of renovation works on loft and facades. Pre-monitoring activities and anthropological interview were completed. More information on those cases will follow in the future newsletters 🙂