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Anamariya Kozarova, Student of Architecture, Nicholas Galabov Dipl. Arch

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Architectural design competition for Passive house in Bulgaria.
Anamariya Kozarova – student of architecture
Arch. Nicholas Galabov

The project is called “House+” because the design not only complies with the competition requirements for passive house, but also incorporates standards of environmental assessment methods such as LEED, BREEAM, DGNB and of Energy-plus house. The estimated project initial cost is affordable, and presents a smart investment from life-cycle assessment standpoint. It is constructible with materials produced locally and available at the market. The selected building materials are with recycled content and/or recyclable, and contributing for a healthy indoor air quality, reduced utility costs, minimized needs for maintenance, and major future renovations.
The house can be upgraded to Zero-Energy-Building if the optional photovoltaic panels and equipment are installed. The load-bearing SIP panels also provide superinsulation and diminish thermal bridges. The house design is efficient, and at one level for full accessibility of people with disabilities or elderly. “Noisy” and “quite” zones are separated and additional noise attenuation measures (Z-flashings etc.) are specified. The exterior is economic, but aims at creating pleasant and inspiring build environment, and sense of luxury, thus demonstrating that a Passive house is more attractive than ordinary buildings. The project is ready to be developed into technical and working drawings. The design specifies location for installation of art.

Building statistics:
Building footprint without garage - 135.41m2
Total Building footprint - 175.88m2
Carbon footprint - 0
Annual heating and cooling   ≤ 15 kWh/m2/year
Primary energy  ≤ 120 kWh/m2/year
Airtight building shell  ≤ 0.6 ACH @ 50 pascal pressure
Thermal bridge free construction  ≤ 0.01 W/mK

Idea and the concept of the design:
Site, placement, orientation and landscaping.

  • The true North is pointing at street direction.
  • The house is located at the Northern part of the plot, next to the street to free up space for outdoor activities, and for short utility and road connections.
  • The house footprint is along East-West direction allowing all livable spaces to have direct South exposure for maximal use of solar radiation and passive solar design principles. More than 95% of the glazing is facing South.
  • The (optional) garage is situated at the North-West corner. Evergreen trees will also be planted on the Northwest side to shelter the house from prevailing cold winter wind.
  • A one way car access with canopy cover is designed to shelter the entrance and for luxury feeling. Driveway and alleys are from porous materials, allowing water to percolate through them.
  • Indigenous plants requiring less maintenance and water are specified. In the backyard we provide for fruit trees and a vegetable garden.
  • Deciduous trees and shading overhang are placed on the South façade to reduce summer heat gains.
  • A retention pond from recycled plastics in the backyard will collect storm rainwater for irrigation.
  • On the roof, hidden from street view, could be installed enough photovoltaic panels to meet Zero-Energy-Building standards.

Building layout and design

  • Open, functional floor plan with short connections, sufficient storage and technical premises. Generous spaces for a modern, luxury life style.
  • Visibility from all livable spaces to courtyard amenities.
  • Garage, storage and utility rooms are placed on the north façade. “Sun pipes” are used to provide daylight in utility premises.
  • Interior clear heights related with room functions. Main entrance is emphasized with a small tower creating an imageable exterior with clear orientation of the entrance, daylight through a South facing window.
  • The building layout is designed with flexibility in mind and possibility of future improvements.
  • Locally available Structural Insulated Panels (SIP) for all load-bearing walls and the roof. Optionally the house can be designed with skeletal structural scheme from recyclable members (shown in gray on the floorplan).
  • Foundation: Concrete with fly-ash and recycled content, insulated by 15+ cm XPS on the outside and inside to reduce heat loss.
  • Triple-pane, super-insulated low-e glazing windows with thermal break frames. Roof and exterior wall thermo-insulation over 30 cm EPS. The overall heat transfer coefficient for the windows is maximum 0.85 W/m2K.
  • South side external shading dimensions based on solar solstice for the lot latitude.
  • Double skin facade specified at the living space exterior. Deciduous trees and shading overhang on the South façade to block sun rays during the summer and allow them in winter.
  • Exterior and in-house bike rack in the garage to stimulate healthy lifestyle.
  • A recycling storage center is designed into the garage to divert waste from landfill.

Construction materials

  • Superinsulation at building envelope and additional at least 10cm insulation of expanded polystyrene with graphite added on the building exterior.
  • External wall finishes: Stucco painted with insulating exterior paint, and recycled wooden cladding for curb appeal. Lumber from certified, finger-jointed or recycled wood.
  • Recyclable roof hydro-isolation covered with light reflective coating. The roof is designed to host photovoltaic and solar panel areas. Solar PV reflectors to be installed on the roof to augment ratio of the panels.
  • Thermal mass on floor and selected walls to minimize temperature variations in solar heated spaces.
  • Durable, easily maintained materials and equipment for minimal future replacement.

Indoor air quality

  • The house will be sealed for preventing air leakages and moisture entering the building. A heat recovery ventilation system to condition the air, and a low-velocity whole house fan (for night ventilation) is specified to be installed.
  • Only low- or zero- VOC (Volatile Organic Compounds) emitting materials such as adhesives, sealants, paints and coatings will be used in the house. Wood products that contain no urea-formaldehyde resins.
  • To make the building more environmentally friendly, only rapidly renewable wood materials are specified. Wheatgrass, bamboo finish wood, etc. OSB instead of plywood.
  • We have employed an entryway system to capture dirt and particulates from entering the house.
  • Principles of natural and cross-ventilation (controlled operable windows) are used, and optional heat recovery/whole house fan (and passive cooling) is installed at roof level.
  • Building management system and programmable controllers are intended to regulate air quality, humidity and natural ventilation, through automatic mechanisms, thermostats and sensors for ease of the occupant.
  • Weatherization. Minimal controlled infiltration through tight sealing of all penetrations, door and windows frames. Airtight membrane and two-part urethane sealants, for successful blow door test.

Water efficiency, electrical and HVAC installations

  • Rainwater collected from the roofs is used for toilet flushing.
  • No potable water will be used for irrigation, but rainwater collected from the site along with underground (well) water.
  • Indigenous vegetation with low consumption of water will be planted
  • Low water-use faucets and showerheads are specified.
  • Geothermal water-to-water heat pump system will provide the heating/cooling of the house for energy efficiency.
  • Radiant water floor heating/cooling system with artistically finished, chemically stained concrete floor finish.
  • The House+ balance of Energy conservation versus Renewable energy harvest is left to the investor.
  • Optional installation of a Trombe-Michelle wall combined with a solar chimney on the South façade of living space double skin façade, to use passive solar design principles of passive heating, cooling and ventilation. High efficiency fire place on the interior.
  • All equipment, machinery and appliances will be consuming low-energy, and will be labeled for superior green compliance.
  • House+ will have high efficiency LED and fluorescent lighting with sensors for movement control (in transitional spaces).
  • CFC refrigerants
  • Possibility to recharge an electrical vehicle while parked in the garage.