Single Family Passive House in Sveti Mitar, Lozen, Sofia

The project is for a single family ecological passive house in good correspondence with the natural environment, in which it was designed – at the foot of Lozen Mountain, in the village of Lozen, 15 km east from the city of Sofia.

The functional organization of the house is the following: the ground floor is settled generally with the daily activities and the first floor – with the night ones. The big garage and the spacious south terrace on the ground in front of the living room add extra comfort to the house.

To the west, the terrace ends with one of the most distinctive elements forming the character of the building and, at the same time, the most picturesque place for its inhabitants – the “hearth” of the house, represented as a family BBQ, standing high above the ground. It offers both privacy and magnificent view of the surrounding nature.

One of the main principles in designing a passive house is the compact shape. By separating the additional functions out of the basic volume and treating them with the same design manner, the house looks smaller and fits better in the surrounding mountain topography.
The highly sloped double-pitched roof, typical for mountain houses, moulds the character of the building.

Our approach to the energy efficiency of the house was to reach as close as possible to the net-zero energy goal. That’s why we used the detached south sloped roof, so as to install a photovoltaic system and solar panels for hot water supply.

As a result of all the measures (appropriate insulation, avoiding thermal bridges, best orientation of the house, etc.), the energy calculations of the house, measured in PHPP, are the following:

  • Specific space heat demand: 14.8 kWh/m2 annually;
  • Primary energy demand: 53 kWh/m2 annually;
  • Energy conservation by solar electricity: 29 kWh/m2 annually;
  • Result from Blower door test n50: 0.27 h-1 (the compulsory result for a passive house is not more than 0.6 h-1).

By means of contemporary interpretation of traditional building techniques and by using natural materials like wood and stone, the project successfully manages to reproduce the spirit and to express its belonging to the surrounding nature.

Building the family house in Lozen is a serial success for Studio APXE, not only as the author of the project, but also as the project manager during the whole construction process. The successful Blowerdoor test in Lozen with a result of that kind (0.27 h-1), is remarkable for lightweight structure houses and is the best prerequisite for even lower running costs, as well as being witness to high quality installation job.

To meet the passive house standard requirements, 9,08% additional investments were calculated on the stage of full completion of the construction. These costs were calculated in comparison to a construction that complies with the current energy efficiency standard, built with the use of quality materials and systems.

Look through the passive house in Lozen on the architectural platform Architizer.

Area: 333
Designer: Studio APXE
Design Team: Georgi Nikolov, Boshko Takov
Investor: Private family
Project management: Studio APXE
Construction company: Mirat group Ltd