ARCHITECTURAL DESIGN COMPETITION

FOR PASSIVE HOUSE IN BULGARIA

Shreyas More, Intern Architect

(286 - user rating)

Building-Metric-Sheet-47.xls

 

The aim of the project is to produce a design for low cost/ low energy house which creates a dwelling that’s is sustainable, economical to build and to maintain, functioning on extremely low energy use and having minimal impact to the environment . Based on the vernacular shotgun typology, the affordable low energy single family house having insulated floor area of 165 sq.m. will help to revitalize the existing neighborhood of the Lozen village of Sofia.
Organized linearly along a circulation corridor, the long axis of the house runs east west. These organizations address strategies for natural ventilation, day lighting, shading and solar heat gain. The south façades roof slope is designed so as to provide passive solar heat gaining the winter. Triple glazed windows provide abundant daylight and natural ventilation while limiting solar heat gain.
The house reinterprets two blocks of traditional shotgun style plan. In the entry block is the open living plan optimizing natural flow of air and day lighting while the bedroom block is designed mirroring two bedroom and bathroom units on the either side of the family area. The open living plan optimizes natural flow and day lighting. The corridor opens southwards to a courtyard which forms a connection between the two building blocks of the design providing shaded outdoor living space. The flexibility of the channel shaped louvers designed to slide on a tract serves optimum shading at different hours of the day providing a flexibility in design according the changing needs of the family.
To achieve Passive House Standards, this house employs an airtight bridge free and super insulated envelop combined with passive shading in summer and solar gain in winter, concrete floor topping for thermal mass to temper solar heat gain and to re-radiate the heat into space as required, day lighting, natural ventilation and cooling and highly reflective self ventilating galvalume cladding. Additionally a balanced energy recover ventilation system and split-zoned high efficiency heating and cooling units with ultra high efficiency on demand water heater for domestic hot water and supplementary radiant floor heating reduce primary energy needs. The use of low cost, durable and long lasting materials and proven construction techniques assures an affordable maintenance cost for the house.

Strategies and solutions proposed in the design for passive house standards:
Shallow pitched roof on the south façade to provide passive solar protection for the building's interior, reducing inside cooling required in summers. Timber louvers provided on the roof filter the light entering the open living space and preventing over heating of the structure in summers.
Triple glazed windows on the south façade protect heat transfer in the interior and allow maximum efficiency of harnessing the light in daytime.
Heat reflective material finish on the roof helps to reflect excess of heat and dark color maintains a balance to heat transfer by conduction in summers.
Concrete floor topping provides thermal mass to absorb solar heat in the winter months. Pre installed air circulation pipes maintain a comfort temperature in the interior spaces through induction.
The concrete floor is also beneficial during the summer as it is naturally cool.
The sunken nature of the house benefits to maintain efficiency in climate control as 30% of the external wall surface is sunk in the earth free from direct effect of external climatic condition as earth forms a barrier avoiding direction conduction.
Double floor and double walls have air ventilation pipes running through which maintains a constant flow of fresh air inside the house minimizing heat loss inside the structure in winters and excessive heat gain in summers.
Water-permeable driveway surface minimizes environmental impact to the site

Passive Houses require superior design and components with respect to:
Insulation.
Design without thermal bridges.
Air tightness.
Ventilation with heat recovery.
Comfort windows.
Due to the sunken nature of the house the window cill falls close to the ground level resulting in the site landscaping to appear at eye level. This creates a closer contact to nature in an air tight environment inside the house.
The land excavated for construction of the first shotgun style block is used to fill up the elevated second block on the site. This gives rise to landscaped contours and the total embodied energy of the site remains balanced as its components stay within.
The double floor has air circulation pipes running through the footprint which warms up the floor by induction and maintains a uniform temperature
Wall materials and insulations
Exterior of the building are designed with 240mm thick local stone wall for easy and affordable construction and also adds an imposing load bearing look to the design. This thick wall acts as a primary insulator between the interior and exterior of the house.
To make the construction further economical, local agricultural dry waster is used as insulating material. Gunny sacks are filled with agricultural waste and piled over one another to form a 150mm thick insulating wall. It results into a faster way of construction and contributes in cost reduction.
Following is a 100mm thick partition plywood wall which gives a chic look to the interiors of the block one. The bedroom block has 120mm thick stone wall creating an earth space in the bedroom, toilets and the library overlooking the courtyard.