This energy efficient home is located on a lush green hill on the outskirts of Thessaloniki. Built in the early 1990s, this two-storied house is a remarkable example of an energy-efficient building with low energy consumption even with today’s standards. The use of passive solar building design for solar heating and natural air ventilation, creates a comfortable living environment with low heating costs.
The implementation of bioclimatic design principles and the use of renewable energy systems such as photovoltaic panels and solar water heaters, achieve energy self-sufficiency and reduce the ecological footprint of the building.
It is medium size, compact orthogonal shape elongated along the east-west axis, gabled roof and well-sealed envelope (air-tightness) are certain features that affect positively its energy behavior due to reduced thermal bridging.
The layout of the home is simple and very functional. On the ground floor an open-plan luminous living space combines the kitchen, dining room and living room into one shared space, with a sunspace attached on the south facade. On the upper floor, a master bedroom, two smaller bedrooms and a large bathroom are located in the perimeter of a central corridor. The two smaller bedrooms have autonomous entrances and an oversized sliding door between them so that users can share the space, converting it from two rooms into a single one.
On the south side of the building a passive solar design system was applied, the Trombe wall, which achieves natural indoor heating by taking advantage of direct sunlight.
The southern facing Trombe wall consists of a 50cm (17″) thick, high thermal mass, masonry wall painted black, a heat-absorbing color and faced with a single layer of glass. The glass is placed 15cm (6″) away from the masonry wall to create a small airspace. Heat from sunlight passing through the glass is absorbed by the black surface, stored in the wall, and conducted slowly inward through the masonry.
The glass prevents the escape of radiant heat from the warm surface of the storage wall. The heat radiated by the wall is therefore trapped within the air gap, further heating the wall surface. For a 50cm (17″) thick Trombe wall, heat will take about 8 to 10 hours to reach the interior of the building. This means that the room behind remains comfortable through the day and receives slow, even heating for many hours after the sun sets. Such designs are ideal for use in residential living spaces and bedrooms.
In addition to radiant heat, the Trombe wall heats the internal air within the house. Upper and lower air vents in the wall allow convection currents, as cooler air from the room enters the sun-space from the bottom vents, is heated and returns into the room from the top vents. These vents are operable to prevent reverse convention currents occurring at night, which would cool the house. The vents also allow the occupants to control the temperature.
The attached sun-space of the Trombe wall was built as a continuation of the open-plan living space. The Trombe wall and sun-space function in the same way. The difference is that the space between the glass and the thermal mass of the sun-space creates a habitable space. The sun-space works much like the vented Trombe wall. It heats space both through radiation and convection.
The sun-space is 30 square feet, south-faced. It is glazing is tilted at a 23.90 degree angle (longitude) between the northern horizon and the plane of the glazing. The sloped glazing in combination with sloped overhead glazing collects more heat in the winter, although losing more heat at night. In order to avoid overheating in the warmer months of the year, shades can be deployed to evenly balance solar heat delivery. For the summer, the windows at the top and bottom of the glass construction can be opened allowing passive venting of the hot air. The got air exits from the top windows pulling cool air from the bottom windows. The sun-space is sealed well enough to have an infiltration rate of 0.7 air changes per hour.
The system has a maximum indoor heat transmission of seven meters from the Trombe wall inwards. The interior layout has been adjusted to that limitation by not using walls parallel to the Trombe wall that would limit the indoor heat transmission.
The Trombe wall with the attached sun-space optimize heat gain, minimize heat loss during cold times and avoid excess heat gain in hot times.