Building materials such as dense concrete have been specified for their innate ability to absorb, store and release heat. In winter, the heat will be absorbed by the concrete during the day, and released into the room when the temperature drops at night. In summer, the concrete will absorb any heat not stopped by sun shading and blinds. When this excess heat is released into the room it will be removed by ventilation.
For the theory to work, the building must be airtight. In conventional houses, heat escapes through a variety of barely discernible gaps, such as between window frames and walls. In this project, special attention will be paid to the way joints are sealed, in order to make the building airtight, so that ventilation is controlled.
"Without air conditioning, residents will need to let more cool air in by leaving windows open on security stays on warm summer nights," says Falbe-Hansen.
Each apartment has a large, south-facing terrace or sunspace,' letting the sun in and providing a thermal buffer during the winter, and creating a shaded porch to minimise heat gain in summer. With glazed sliding panels right along its external facade, and glazed doors and windows between the sunspace and the apartment, the area can be shut in winter to form a conservatory which traps heat. In summer, the panels on the external facade can be left open when necessary to reduce heat build-up, thus creating a shaded balcony. Solar blinds will be provided to help block the sunlight in summer, thereby preventing the thermal mass from absorbing and storing too much heat.
Although the apartment buildings are curved, no dwelling is angled more than 20 degrees away from due south in order to maximise the amount of sun each receives. Buildings are placed a suitable distance apart to reduce overshadowing, while the roof line angles upward by 25 degrees to allow the low winter sun to filter deep into the apartments.
In terms of heat-efficient building design, clearly what works well in summer will not necessarily work well in winter, and vice versa. The design of the Schio Central Park development is a matter of carefully balancing the needs of each season.