Тhe family passive house is situated in Delta Hill, the south green slopes of Bulgaria's Vitosha mountain in a picturesque area.
The challenge was to fit successfully the large scale one-storey building in the green landscape without appearing foreign and superfluous there. The design follows separating the garage and the cold service premises from the residential part by their volumes and structure. This approach solved many technological and energy problems with the external surface thermal bridges. The volume of the garage is fitted at street level, dug into the rock and the house is partially over it, standing broad.
The building was built with a lightweight ecological load bearing structure. Only the foundations, the supporting frames and the roof of the garage are made of reinforced concrete. Everything else is designed with a lightweight steel and timber structures. This lightens the weight of the structure and reduces the budget as well. Laminated wood beams and columns pergola with built-in sun protection form the appearance and the elements of the architectural envelope.
The house is designed in accordance with the passive house standard with specific heating energy demand of 12 kWh/m2 annually. The ecological building reached excellent air-tightness level with a Blower door test result of 0.19 h-1 compared to the required 0.6 h-1 for a passive house. These results were achieved with excellent insulation, optimized compact size and careful balance of glazing, with PHPP calculations, sun protection, reduced or no thermal bridges, innovative electricity services and lighting, and last but not least - a ventilation system with heat recovery with the highest characteristics.
The house will generate more energy than will consume per year. This makes it not just passive but an energy-plus building. This will be achieved by the installed on the roof 12.25 kWp photovoltaic panels. They will charge the battery station of the backup system of the house, which allows the generated energy to be used in the everyday household and the surplus during the summer months to be delivered via the grid. There are also 12 units of solar collectors which will mainly heat the swimming pool in summer, while during wintertime will assist the heating system.
The estimated budget for the construction amounts to roughly 1000 €/m2. During the construction a high quality of the construction materials and systems and the costs were optimized and reduced through better management of processes. The additional investments to reach the passive house standard are calculated to 4.43% from the overall construction costs and further to reach positive energy balance with the plus-energy standard - 9.24% from the overall construction costs.
What is the outcome? - A beautiful and comfortable house which provides joy and comfort to the residents, fresh air inside, smooth, very cheap and easy operation. A reliable and truly comfortable home complying with the most advanced international environmental standards.
Designer: Studio APXE Ltd.
Design team: Georgi Nikolov (lead architect), Silvia Draganova, Boshko Takov
Project & construction management: Studio APXE Ltd.
Construction companies: K V Engineering; Schloss; NG Technology, AByU Engineering, Bultherm, Muharski, DSV, Citybuild studio, Filkab and many more;