A passive building? What is that?
Not everyone may be familiar with this term. These buildings have low energy requirements for heating purposes.
Passive buildings consume no more than 15 kWh/m2,which corresponds to 1.5 m3 gas per 1 m2 of the surface.
The level of primary energy consumption in this kind of building cannot exceed 120 kWh/m2 year for all energy needs, which include heating, hot water and electricity consumption that are needed for living. At the same time, in currently erected residential buildings, the energy consumption (heating only) is up to 120 kWh / (m2 year). The demand for energy in passive buildings is eight times smaller than the in traditional ones.
The essence of the energy-efficient buildings is to minimize energy loss.
Here, each stage is of importance, whether we choose a right plot, a suitable project, and this until the very last details such as installing a window sill. Low energy house is, first of all, a perfectly insulated house that prevents heat from escaping.
Passive houses – what makes them different
The entire external layer of the passive building is air impermeable. However, the heat transfer coefficient (U) of the walls must be lower than 0.15 W/(m²K). This type of building requires appropriate windows, since untight window frames may lead to up to 30% of home’s energy loss. That is why the windows’ heat transfer coefficient should not exceed Uw= 0.80 W/(m²K). Passive houses often come equipped with a ground heat exchanger and a recuperator. These devices allow to regain the heat from air conditioning and hence reduce home energy loss by 75 – 90%. Solar collectors are becoming increasingly popular, and the energy they collect may be used to heat the tap water or provide 25 – 35 % of the energy for space heating purposes.
What might come as a surprise, passive buildings use a large amount of glazing (windows, glazed façades, etc.).
Glazed areas are installed mostly at the southern side of the building and are practically absent from the northern, as the passive solar gain is usually rather low in there. Today, the energy-efficient windows can greatly reduce the heat losses and enable the maximum daylighting of interior spaces. In addition, they provide free solar energy to heat the rooms.