ARCHITECTURAL DESIGN COMPETITION

FOR PASSIVE HOUSE IN BULGARIA

Sonia Raetchi Dipl. Arch, Radu Andone Dipl. Arch.

(352 - user rating)

Building-Metric-Sheet-57.xls

The goal
A small, comfortable and affordable single family home which can be easily recognized as a passive house, made for the climate, with the use of local materials .

The design concept
The building volume is simple, compact, with roughly the same type of envelope enwrapping the whole house in an airtight cocoon made with local, natural materials. The volume resides atop a large wood deck which wraps around the house, making the connection between the natural and the anthropic. The ground floor is covered in stone, which heats during the winter months thru the southern glazing, providing good thermal mass .
The roof is single pitched, with the slope oriented to the north, thus minimizing the northern façade area, which has very little solar gain .
The sloped southern façade opens large glazed areas to the outer deck and privacy of the courtyard as well as to the surrounding hilled and forested landscape around Lozen Village .
We have chosen to add an wind fang on the eastern side for better marking the entrance to the house and for providing a thermal buffer between indoor and outdoor spaces. The access is made from the street situated on the northern side of the plot, thus giving space and intimacy for the house on the southern side. This provides an easy and quick access to the house, and allows a small distance between the car and the inside of the house .
The layout of the house is simple, with the day area downstairs and night area upstairs. The installation zones are compact and concentrated on the northern side of the house, because of their lower need of natural light. The kitchen is confined from the dining area, to keep smells and vapors from distributing trough the house. The floors layout provides the living areas ( living + dining downstairs and the bedrooms upstairs ) with efficient natural light all through the day, differentiating the solar gain, to be larger in the winter months than in the summer months .

The house is designed to be permanently inhabited by a family of 3 .
The ground floor contains: wind fang, dining/study area, living, kitchen, technical space, toilet, storage spaces .
The first floor contains: bathroom, master bedroom with dressing area and another bedroom with dressing area. The overall bathroom number is 1.5 for 3 persons .

The key design features:
Compact volume
Good ratio between envelope / interior volume – 0.85 ( envelope area = 315 mp, volume = 369 mc ) .
South oriented
The house benefits of an angled southern elevation, providing a bigger input of solar radiation in the winter months .
Because of the thickness of the outer southern wall, and the slate angle ( 70° ) a very small floor area is directly litten - 0.9 m wide in the summer compared to 5.60 m wide in the winter ( the full living area ) .
Flexibility for maximum solar gain
The angle of the solar panels on the southern elevation can be changed in the summer months ( from 70° to 20° ) to provide a maximum input of solar radiation. The change in angle aids in a second purpose - the solar panels serving as a shading device for the upper floor bedrooms .
Low solar intake on the north, east and west elevations
The glazed area on these elevations is less than 30 % of the total glazed area for the house .
Minimized winter shading
To avoid winter shading on the southern elevation (from sources as garden walls, vegetation, balconies, roof overhangs, outbuildings) the house is positioned near to the road, on the northern end of the plot.
Air tightness
Additional to the airtight windows and walls, the exterior wind fang provides a better control of the air inflow, when entering the house .
High performance triple-glazed windows, super-insulation, an airtight building shell, limitation of thermal bridging and balanced energy recovery ventilation make possible great reductions in energy use and carbon emission .

Thermal mass with the help of local materials
The ground floor is entirely paved with dark stone, acting as thermal mass during winter and decreasing the need for additional heating .
Intelligent ventilation combined with controlled air circulation
The heated air from the open space living + dining downstairs flows up the staircase, where it is collected in the central ventilation / heat recovery unit, situated in the space above the staircase, and adjacent to the bedrooms. Summer ventilation through tilted windows can be carried out when required ( especially at night ) .
Water management
The storm water can be collected from the roof and used for the first floor bathroom’s WC, the grey used bathwater from the first floor bathroom collected can be used for the ground floor WC .
No loggias, no balconies - no thermal bridges
The outdoor living area consists in a deck which wraps itself around the house. The exterior porch ( deck ) has an additional role, it traps storm water which can be used for gardening, meanwhile keeping it away from the house foundations. Balconies or loggias are not really necessary on the first floor because the bedroom’s large southern windows make a great connection between the exterior and interior .
The installation zones are compact and concentrated
The kitchen, bathrooms, and the technical room are all grouped on the northern side of the house. The kitchen is separated from the living and dining area, confining the hot air for the extractors connected to the ventilation system ( the extractors should be fitted with grease filters ). The superimposing sanitary facilities create the possibility of using shorter pipes .
Last but not least …. materials
We tried to embrace a sustainable use of resources and construction materials. Our main focus was trying to use recyclable and durable locally available materials such as timber or stone.
The substructure is made of concrete, with the ground floor slab insulated with XPS polystyrene. The entire structure is made of wood, with super thick cellulose thermal insulation on the exterior walls ( also great for sound insulation ) made from recycled newspapers. The interior partitions are also insulated with cellulose. Stone is used as a thermal mass, the ground floor is entirely paved with dark stone, decreasing the need for additional heating .