The summer comfort in buildings was and is still highly underestimated. Over the last century, the efforts to improve the thermal comfort in buildings have been focused on the thermal comfort during winter. Since the beginning of the century, more and more attention has been paid to the summer comfort of the buildings. Different solutions and approaches for cooling of the buildings were developed, many of which are less effective or too expensive. At the same time, cooling costs in Central and South Europe reached the levels of heating costs during winter.
To ensure the summer comfort, the Passive House Institute has developed the PHPP, so summer comfort can be calculated with high precision. These calculations are an excellent tool for Passive House designers because they allow optimized, functional and cost-effective design to achieve summer comfort.
2. Approaches in the Certified Passive House in Sofia
Achieving summer comfort is now extremely important, and it must fully satisfy the occupants. At the same time, the achievement of summer comfort should not burden the project costs, as well as the subsequent maintenance costs.
2.1 Choice of construction
The massive construction assures high specific capacity of the building which results in savings of 2.3 kWh/(m2a) for cooling demand. Due to the large heating capacity of the building, the indoor daily temperature fluctuations are extremely slow and at night the temperature of the air aligns with the temperature of the external walls.
2.2 Careful design of permanent shading elements
Vertical shading elements are calculated for maximum winter and summer comfort. During summer they don’t allow the penetration of high midday summer sun and during winter assure all-day penetration of the sun which results in savings of 3.5 kWh/(m2a).
Compared to 90° reveals, the use of canted on 30° lateral and top reveals is equal to a 7cm thinner wall were used also.
2.3 Careful design of temporary sun protection
To ensure maximum external and internal comfort, tents with automatic control are used on all southern windows. There are other solutions as window shutters, exterior blinds and more but it is important to think always for their operation and the occupant comfort before taking the proper decision. The temporary sun protection results in savings for cooling demand of 8.4 kWh/(m2a).
2.4 Careful assessment of passive night ventilation
All openable windows are equipped with mosquito nets and are provided for double-opening opening. For the night ventilation are used two opposite window located on the 2nd and 3rd floor so used the chimney effect and this saves 3.8 kWh/(m2a).